CN104662614A - Component cooling water system for nuclear power plant - Google Patents

Abstract

A component cooling water system for a nuclear power plant. In one embodiment, a system includes an inner containment vessel housing a nuclear reactor and an outer containment structure. An annular reservoir is formed between the containment vessel and the containment seal structure to provide a heat sink for dissipating thermal energy. A shell-less heat exchanger with a bare tube bundle immersed in the water of an annular reservoir is provided. Plant cooling water from the nuclear power plant flows through the tube bundle and is cooled by transferring heat to the annular water reservoir. In one non-limiting embodiment, the tube bundle can be U-shaped.

Description

Component cooling water systems for nuclear power plants

Cross References to Related Patent Applications

This application claims the benefit of U.S. Provisional Patent Application No. 61/691,533, filed August 21, 2012, PCT International Patent Application No. PCT/US13/42070, filed May 21, 2013 A continuation-in-part of the application, this PCT International Patent Application claims the benefit of US Provisional Patent Application No. 61/649,593, filed May 21, 2012; incorporated herein by reference in its entirety.

technical field

The present invention relates to nuclear reactors, and more particularly to reactor containment systems with passive heat release control.

Background technique

The containment vessel of a nuclear reactor is defined as an enclosure that provides environmental isolation for a nuclear steam supply system (NSSS) that uses nuclear fission to generate high-pressure steam in a nuclear power plant. Assuming a facility is subjected to the most severe nuclear accident, commercial nuclear reactors are required to be enclosed in a pressure-maintenance structure capable of withstanding the temperatures and pressures resulting from the nuclear accident. The most severe energy release accidents that can be assumed for a reactor and its containment are of two types.

First, events following a loss of coolant accident (LOCA) involve a rapid and massive release of thermal energy from the nuclear power plant's nuclear steam supply system (NSSS) due to the sudden release of reactor coolant within the containment space. The sudden depressurization of the reactor coolant will violently momentarily cause a rapid rise in pressure and temperature within the containment space. The space inside the containment becomes a mixture of air and steam. LOCA can be credibly assumed by assuming a sudden failure of the piping carrying the reactor coolant.

Another type II thermal event with potential risk to the containment as a whole is the situation where all thermal exhaust paths from the nuclear steam supply system (NSSS) of a nuclear power plant fail, forcing a "scram" of the reactor. A total power outage is one such event. The decay heat generated in the reactor must be removed to prevent the pressure from rising out of control.

More recently, containment structures have also been required by regulators to withstand the impact of a crashed aircraft. The containment structure is usually built as a huge reinforced concrete dome to resist the internal pressure from the LOCA. While its thick concrete walls can withstand aircraft strikes, it is also a good thermal insulator and requires a pumped cooling system (using heat exchangers and pumps) to dissipate unwanted heat to the outside environment (to minimize pressure rise or eliminate decay heat). However, this cooling system relies on a powerful power source, such as an off-site or local diesel generator, to power the pump. The site-wide blackout at the Fukushima nuclear power plant after the tsunami was a sobering reminder of the folly of relying on pumps.

It is extremely difficult and expensive to disassemble the containment structure of the current monolithic reinforced concrete construction, such as the steam generator in the NSSS enclosed in the containment structure requires huge capital. To replace important equipment, a hatch must be made in the thick concrete dome at great expense and reactor downtime. Unfortunately, too many steam generators of many nuclear reactors built over the past 25 years had to be replaced by penetrating the dome, at a cost of billions of dollars to the nuclear power industry.

In nuclear power plants, component cooling water (CCW) systems are closed-loop purified water used to cool various equipment in nuclear power plants. One of its important auxiliary roles is the removal of decay heat from the reactor water after a reactor shutdown, usually performed inside a tubular heat exchanger called a "decay heat cooler" or "waste heat removal heat exchanger". Heat transferred to the component cooling water by decay heat coolers or other heat exchangers used to cool electromechanical equipment is present throughout the tube walls that isolate or isolate the component cooling water from radioactive contamination that may be associated with the reactor water. As such, the equipment cooling system essentially serves to provide a means of removing waste heat from all equipment in a nuclear power plant that requires cooling, as well as to hinder the release of radiation into the environment.

However, the heat collected from the nuclear power plant equipment by the component cooling water raises its temperature. The heated component cooling water rejects heat to the environment usually in a once-through system through shell and tube heat exchangers using natural bodies of water such as lakes, rivers or oceans. The component cooling water system draws cold raw water from the natural water body, is pumped through the component cooling water heat exchanger, and returns hot water to the natural water body. However, such component cooling water systems (CCW) suffer from several operational problems such as the intrusion of debris carried by the raw cooling water, biofouling of the heat exchange tubes by the raw water and the pipes carrying the raw water to the heat exchanger of corrosion. Operating nuclear power plants often report that deposits and other fouling accumulate in component cooling water heat exchanger headers, requiring frequent maintenance and reducing thermal performance.

The above deficiencies using state-of-the-art technologies require improved nuclear reactor containment systems and component cooling water systems.

Summary of the invention

According to one aspect, the present invention provides a component cooling water system that overcomes deficiencies of existing systems.

In one embodiment, a component cooling water system for a nuclear power plant includes a containment vessel defining an enclosure configured to accommodate a nuclear reactor, a containment enclosure structure surrounding the containment vessel, an annular water reservoir formed between the containment vessel and the containment enclosure structure , the annular reservoir configured to provide a radiator for heat dissipation, and a shellless heat exchanger with exposed heat-conducting tube bundles immersed in the water of the annular reservoir. Component cooling water from the nuclear power plant flows through the tube bundle and is cooled by transferring heat to the annular reservoir. The tube bundle consists of multiple heat pipes. In one embodiment, the tube bundle is U-shaped.

In another embodiment, a component cooling water system for a nuclear power plant includes a containment vessel defining an enclosure configured to house a nuclear reactor, a containment containment structure surrounding the containment vessel, and an annular water reservoir formed between the containment vessel and the containment containment structure pool, the annular reservoir is configured to provide a radiator for dissipating heat, a shellless heat exchanger with an exposed heat-conducting tube bundle composed of a plurality of heat-conducting tubes immersed in the water of the annular reservoir and arranged in the annular reservoir Discharge sprinkler below the exposed tube bundle. The sprinklers are configured and arranged to discharge water recirculated from the annular reservoir through the tube bundle to cool the tubes. Component cooling water from the nuclear power plant flows through the tubes of the tube bundle and is cooled by transferring heat to the annular reservoir.

According to another embodiment, a component cooling water system of a nuclear power plant includes a containment vessel defining an enclosure configured to accommodate a nuclear reactor, a containment enclosure structure surrounding the containment vessel, and an annular water reservoir formed between the containment vessel and the containment enclosure structure. , the annular reservoir configured to provide a radiator for heat dissipation, a shellless heat exchanger with an exposed heat transfer tube bundle consisting of a plurality of heat transfer tubes immersed in the water of the annular reservoir, and from containment to containment A plurality of generally radial fins projecting outwardly from the closure structure and located within the annular reservoir. In this embodiment, the heat exchanger is located in a circumferentially extending bay formed in an annular reservoir between a pair of spaced adjacent fins. Component cooling water from the nuclear power plant flows through the tubes of the tube bundle and is cooled by transferring heat to the annular reservoir.

According to another aspect, the present invention provides a nuclear reactor containment system that overcomes deficiencies of existing containment system arrangements. The containment system generally includes an inner containment made of steel or other ductile materials and an outer containment closure structure (CES), thereby forming a double-walled containment system. In one embodiment, a water filled annulus is provided between the containment vessel and the containment enclosure structure providing an annular cooling reservoir. The containment vessel may include a plurality of longitudinal heat conducting fins extending radially outwardly from the containment vessel in a "fin" shape (substantially). In this way, the containment vessel not only serves as the primary structural containment vessel of the reactor, but is also configured and operable for a heat exchanger with the annular reservoir acting as a heat sink. Accordingly, as a further description, the containment conveniently provides a passive (non-pumped) heat removal system when required, during a heat release accident such as LOCA or a reactor scram requiring heat removal and cooling of the reactor.

The invention also provides a component cooling water system which overcomes the defects of the arrangement of the existing cooling water system. As a further description, the component cooling water system includes a heat exchanger that may be arranged and contained within a water-filled annulus (ie, an annular reservoir). The water in the ring cavity thus acts as an active heat transfer medium, removing heat from the cooling system by evaporation rather than by a natural body of water.

In one embodiment according to the present invention, a nuclear reactor containment system includes a containment vessel configured to accommodate a nuclear reactor, a containment enclosure structure (CES) surrounding the containment vessel, and a containment vessel formed between the containment vessel and the containment enclosure structure (CES). , an annular reservoir that discharges heat from the containment space. If a heat release event occurs inside the containment, the heat generated by the containment is transferred to the annular water reservoir used to cool the containment. In one embodiment, the annular water reservoir contains water for cooling the containment. A portion of the containment vessel may include substantially radial thermally conductive fins disposed within the annular reservoir and extending between the containment vessel and the containment enclosure structure (CES) to improve heat dissipation from the water-filled annular reservoir . When a heat release event occurs inside the containment, part of the water in the annulus is evaporated and released into the air in the form of water vapor through the annular reservoir of the containment closure structure (CES).

Embodiments of the system also include an auxiliary air cooling system comprising a plurality of air ducts with vertical inlets arranged circumferentially around the containment vessel in an annular reservoir. The air conduit is in fluid communication with the annular reservoir and outside ambient air outside the containment enclosure structure (CES). When a heat release event occurs inside the containment and the annular reservoir is substantially depleted of water due to evaporation, the air cooling system comes into play by providing an air circulation path from the reservoir space to the external environment. In this way, the air circulation system can be regarded as an auxiliary system that can continue to cool the containment repeatedly.

According to another embodiment, a nuclear reactor containment system includes a containment vessel configured to house a nuclear reactor, a containment enclosure structure (CES) surrounding the containment vessel, a cooling containment vessel formed between the containment vessel and the containment enclosure structure (CES). A water-filled annulus and a plurality of generally radial fins projecting outwardly from the containment vessel and located in the annulus. In the event of a heat release event inside the containment, the heat generated by the containment is transferred to the water-filled reservoir in the annulus through direct contact with the containment outer surface and the generally radial cooling fins of the containment. In one embodiment, when a heat release event occurs inside the containment vessel and the water in the annulus is substantially depleted due to evaporation, the air cooling system comes into play to draw external ambient air into the annulus through air ducts to cool the containment vessel. Heat generated by the shell (decreases exponentially with time). The presence of water in the annular region completely surrounding the containment will maintain a consistent temperature distribution of the containment, preventing deformation of the containment during a heat release event or accident.

In another embodiment, a nuclear reactor containment system includes a containment vessel comprising a cylindrical shell configured to house a nuclear reactor, a containment enclosure structure (CES) surrounding the containment, formed between the containment shell and the containment enclosure structure (CES) Aqueous annular reservoir cooling the containment in between, a plurality of outer generally radial fins protruding outwardly from the containment into the annulus and containing a plurality of annular reservoirs surrounding the containment Air cooling system with circumferentially arranged air ducts with vertical inlets. The air conduit is in fluid communication with the annular reservoir and outside ambient air outside the containment enclosure structure (CES). In the event of a heat release event inside the containment, the heat generated by the containment is transferred into the annular reservoir through the (substantially) radial containment wall and its internal and external fins which serve to cool the containment.

Advantages and characteristics of the nuclear reactor containment system according to the present invention include the following aspects:

The containment structure and systems are configured such that the aforementioned heat release events are passively controllable (for example, without reliance on active equipment such as pumps, valves, heat exchangers, and motors);

Containment structures and systems that operate autonomously and continuously indefinitely;

without losing its primary functions (i.e., pressure and radionuclide (if any) retention and heat removal), with internal and external ribs (fins) configured to withstand impact from projectiles such as crashed aircraft ) reinforced containment structure; and

The containment is equipped with facilities that allow the removal (or installation) of vital equipment suitable for use through the containment structure.

Brief description of the drawings

Features of illustrative embodiments of the invention will be described with reference to the following drawings, in which like elements are labeled with like numerals, wherein:

1 is a side view of a finned primary reactor containment vessel forming part of a nuclear reactor containment system in accordance with the present invention, with the lower portions of some of the fins partially removed to reveal vertical support columns and circumferential ribs;

Fig. 2 is a transverse sectional view along the line II-II;

Fig. 3 is a detailed view of III in Fig. 2;

4 is a longitudinal sectional view of the nuclear reactor containment system showing the containment vessel in FIG. 1 and an external containment enclosure structure (CES) having a water-filled annular reservoir formed between the containment vessel and the containment vessel enclosure structure;

Figure 5 is a longitudinal sectional view through the containment vessel and the containment enclosure structure (CES);

Figure 6 is a side view of the nuclear reactor containment system visible at ground level when installed with the external containment enclosure structure (CES);

Fig. 7 is its plan view;

Fig. 8 is a longitudinal sectional view along the line VIII-VIII in Fig. 7, showing two parts of the nuclear reactor containment system above and below ground level;

Figure 9 is a side view of the main reactor containment vessel showing a cross-sectional cutout to reveal the contained equipment and other details of the containment vessel;

Fig. 10 is its plan view;

Fig. 11 is a longitudinal sectional view along line XI-XI among Fig. 10;

Fig. 12 is a longitudinal sectional view along line XII-XII in Fig. 10;

Fig. 13 is a longitudinal sectional view along line XIII-XIII in Fig. 9;

Fig. 14 is a longitudinal sectional view along line XIV-XIV in Fig. 9;

Fig. 15 is a longitudinal sectional view along line XV-XV among Fig. 9;

Figure 16 is a partial longitudinal sectional view of the nuclear reactor containment system, showing the auxiliary cooling system;

Figure 17 is an isometric view of the containment vessel with the lower portion of the (substantially) radial fins of the containment partially removed to reveal the vertical support struts and circumferential ribs;

Figure 18 is a longitudinal sectional view of a portion of the cooling system of Figure 16, showing the upper and lower annular headers and conduits attached to the containment shell;

Figure 19 is a schematic depiction of the general cross-section of the nuclear reactor containment system and the operation of the water-filled annular reservoir for heat dissipation and cooling of the containment during a heat release event;

20 is a schematic side cross-sectional view of a portion of a component cooling water system according to another aspect of the present invention;

Figure 21 is an enlarged detail view from Figure 20;

Fig. 22 is a top view from the first front view of the component cooling water system in Fig. 20;

Figure 23 is a second top view from the first front view of the component cooling water system of Figure 20, also schematically showing the annular reservoir recirculation and water replenishment system;

Figure 24 is a side cross-sectional view of the heat exchanger in Figure 20; and

Figure 25 is an overall top sectional view of the nuclear reactor containment and component cooling water system.

All drawings are schematic and not necessarily to scale.

Detailed description of the embodiment

The features and advantages of the invention are illustrated and described herein with reference to illustrative embodiments. The description of the illustrative embodiments is intended to be read in conjunction with the accompanying drawings as a part of the entire written description. In the description of the embodiments disclosed herein, any direction or orientation referred to is only for the convenience of description and is not intended to limit the scope of the present invention in any way. Related terms such as "below", "above", "horizontal", "vertical", "above", "below", "upward", "downward", "top", "Bottom" and derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the nominal direction in the discussion as being described therein or shown in the drawings. . These relative terms are for descriptive convenience only and do not strictly require that the facility be constructed or operated in the specific orientation indicated by the term. Terms such as "attached", "attached", "connected", "coupled", "interconnected" and the like refer to a structurally secure relationship or attachment to each other, directly or indirectly through intermediate structures Relationship, also refers to an active or rigid attachment or relationship, unless specifically described otherwise. Accordingly, the invention should not be particularly limited to the illustrative embodiments illustrating some possible non-limiting combinations of features which may exist alone or in other combinations of features.

Referring to Figures 1-15, there is shown a nuclear reactor containment system 100 in accordance with the present invention. System 100 generally includes an inner containment structure, such as containment vessel 200, and an outer containment enclosure structure (CES) 300, collectively defining containment-enclosure structure assemblies 200-300. Containment vessel 200 and containment enclosure structure (CES) 300 are elongated and oriented vertically and define a vertical axis VA.

In one embodiment, the containment-enclosure structure assemblies 200-300 are configured to be buried in a foundation, at least partially below ground level (see also FIGS. 6-8). The containment-enclosure structural assemblies 200 - 300 may be supported by a concrete foundation consisting of a floor 302 and vertically extending side walls 303 rising from the floor forming a top slab 304 . As shown, sidewall 303 may circumferentially enclose containment vessel 200, wherein a lower portion of the containment vessel may be disposed within the sidewall. In some embodiments, after the containment vessel 200 is placed on the floor 302 (which may first be poured and seated), the side walls 303 may be poured such that the lower portion of the containment vessel 200 is fully embedded in the foundation. In some illustrated embodiments, foundation wall 303 may terminate below ground level to provide additional protection to containment-enclosure structure assembly 200-300 from projectile impact (eg, crashed aircraft, etc.). In top view, foundation 301 may have any suitable arrangement, including but not limited to polygonal (eg, rectangular, hexagonal, circular, etc.).

In one embodiment, the weight of containment vessel 200 may be supported primarily by base plate 302 on which the containment vessel rests, and containment enclosure structure (CES) 300 may be supported by base plate 304 formed on top of side wall 303 of foundation 301 . Other suitable vessel and containment closure structural support arrangements may also be used.

With continued reference to FIGS. 1-15 , the containment vessel structure 200 may be an elongated vessel 202 comprising a hollow cylindrical shell 204 having a circular cross-section with an outer diameter D1 , a top head 206 and a bottom head 208 . In one embodiment, the containment vessel 200 (ie, shell and head) may be fabricated from easily weldable metal sheets and rods of suitable strength and toughness (eg, mild steel). In one embodiment, mild steel housing 204 may have a thickness of at least 1 inch. Other suitable metallic materials may be used, including various alloys.

The top head 206 may be connected to the shell 204 by a flange joint 210 consisting of a first annular flange 212 at the lower or bottom end of the top head and a second mating annular flange 214 at the upper or top end of the shell. The flange joint 210 may be a bolted connection, further optionally welded sealed between adjacent flanges 212 and 214 after assembly by a circumferentially extending annular sealing weld.

The top head 206 of the containment vessel 200 may be an ASME (American Society of Mechanical Engineers) dome-shaped head with flanges and butterfly shapes for added structural strength (i.e., internal pressure retention and external impact resistance); however, other possible The configuration that includes the flat top head. The bottom head 208 may similarly be a domed butterfly head or alternatively flat in other possible embodiments. In a containment vessel configuration, the bottom head 208 may be welded directly to the lower portion or end of the outer shell 204 by a full flange of the head matching the diameter of the outer shell. In one embodiment, as a further description, the bottom of the containment vessel 200 may include a rib-shaped bracket 208a or similar structure connected to the bottom head 208 to facilitate stability and provide horizontal support for the containment vessel 200 on the bottom plate 302 of the foundation 301 .

In some embodiments, the top 216 of the containment shell 204 may be a diametrically enlarged portion of the shell forming an enclosure that supports and houses a slewing crane (not shown) for handling equipment, fuel, etc. within the containment. This will provide crane access to the inner perimeter of the containment and will allow equipment to be placed very close to the edge of the containment 200, making the containment compact. Thus, in one configuration, the portion above ground level of the containment vessel 200 may resemble a mushroom-shaped structure.

In one possible embodiment, the outer diameter D2 of the enlarged top 216 of the containment vessel 200 is greater than the outer diameter D1 of the remainder of the containment shell 204 adjacent the lower portion 218 . In one non-limiting example, the diameter D2 of the top 216 is approximately 10 feet greater than the diameter D1 of the lower portion 218 of the housing 204 . The top 216 of the enclosure 204 may have a suitably selected height H2 to accommodate a slewing crane requiring a working clearance, and H2 may be less than 50% of the overall height H1 of the containment vessel 200 . In one non-limiting example, approximately 10 feet (H2) of the top of the containment vessel 200 may be formed by an enlarged diameter top 216 as compared to the overall height H1 of the containment vessel 200 feet. The top 216 of the containment vessel 200 may terminate at an upper portion of a flanged 214 flanged to the containment top head 206 .

In one embodiment, the diameter D2 of the diametrically enlarged top portion 216 of the containment vessel 200 is smaller than the inner diameter D3 of the containment enclosure structure (CES) 300 to allow passage through a (substantially) radial gap or secondary annulus 330 (e.g. , see Figure 4). This provides a spatial cushion or buffer zone between the containment enclosure structure (CES) 300 and the containment roof 216 in the event of a projectile impact on the containment enclosure structure. Also, as a further illustration, annulus 330 is clearly further between main annulus 313 (between containment enclosure structure (CES) 300 and containment vessel 200 ) and between containment enclosure structure (CES) dome 316 and containment vessel 200 A flow path is created between the head spaces 318 between the top heads 206 for steam and/or air to flow out of the containment enclosure structure (CES). Accordingly, the secondary annulus 330 is in fluid communication with the primary annulus 313 and the head space 318 which in turn is in fluid communication with the outlet 317 through the dome 316 . In one embodiment, the secondary annular cavity 330 has a smaller (substantially) radial width than the primary annular cavity 313 .

Referring to Figures 1-4, a containment enclosure structure (CES) 300 may in some embodiments be a double-walled structure having two concentric shells 310 (inner) and 311 ( External) formed side walls 320 fitted with plain or reinforced concrete in the annular space between the two concentric shells. The concentric shells 310, 311 may be made of any suitable strength material, such as, but not limited to, ductile, easily weldable sheet metal (eg mild steel). Other suitable metallic materials may be used, including various alloys. In one non-limiting example, the double-walled containment enclosure structure (CES) 300 may have a concrete 312 thickness of 6 feet or greater, ensuring sufficient resistance to impact by high energy projectiles, such as from an airliner.

A containment enclosure structure (CES) 300 bounds the containment shell 204 and is (generally) radially spaced from the containment shell 204 , thereby creating a main annulus 313 . The annulus 313 may in one embodiment be water-filled (ie, an annular reservoir) to create a heat sink for receiving and dissipating heat from the containment vessel 200 in the event of a heat release event inside the containment vessel. In one embodiment, the water-filled annular reservoir preferably extends 360° circumferentially around the perimeter of the upper portion of the containment shell 204 above the concrete foundation 301 . Figure 4 shows a cross-section of the water-filled annulus 313 without the outer (generally) radial fins 221 for clarity. In one embodiment, the annulus 313 is filled with water from the base plate 304 at the bottom end 314 approximately to the top 315 of the concentric shells 310, 311 of the containment enclosure structure (CES) 300 to provide a connection between the containment shell 204 and the containment enclosure structure. An annular cooling water reservoir is formed between the inner shells 310 of the (CES) 300 . In some embodiments, the annular reservoir may be coated or lined with a suitable corrosion-resistant material, such as aluminum, stainless steel, or a suitable preservative for corrosion protection. In one representative and non-limiting example, annular cavity 313 may be approximately 10 feet wide and approximately 10 feet high.

In one embodiment, containment enclosure structure (CES) 300 includes a steel dome 316 that is suitably thick and reinforced to withstand crashed aircraft and other incoming projectiles. Domes 316 are removably secured to housings 310, 311 by robust flange joints. In one embodiment, the full shell enclosure structure (CES) 300 is entirely surrounded by the containment enclosure structure (CES) 300 at all exposed above ground level portions, which is preferably high enough to protect the containment vessel from aircraft hazards or similar projectiles body, maintaining the structural integrity of the water body in the annulus 313 surrounding the containment. In one embodiment, the containment enclosure structure (CES) 300 extends vertically below ground level to a remote solid portion up to the top of the base plate 304 as shown.

The containment enclosure structure (CES) 300 may further include at least one rainproof outlet 317 in fluid communication with the head space 318 below the dome 316 and the water-filled annulus 313 to allow water vapor to flow, escape, and drain into the air. In one embodiment, outlet 317 may be located in the center of dome 316 . In some embodiments, the outlet 317 may be formed by a short length of tubing covered with a rain shield of any suitable construction to allow steam to escape from the containment enclosure structure (CES) 300 with minimal ingress of water.

In some possible embodiments, the headspace 318 between the dome 316 and the top head 206 of the containment vessel 200 may be filled with energy-absorbing materials or structures to etc.) the impact load on the containment enclosure structure (CES) dome 316 is minimal. In one example, tightly compressed corrugated or wrinkled deformable aluminum plates can be arranged in part or the whole of the head space to form a wrinkle buffer zone, which is good for absorbing and dissipating the impact force on the dome 316 .

Referring primarily to Figures 1-5 and 8-17, the buried portion of containment 200 with concrete foundation 301 below base plate 301 may have a plain shell with no external features. However, the portion of the containment shell 204 above the base plate 304 may include a plurality of longitudinal (substantially) outer radial ribs or fins 220 axially (substantially) parallel to the vertical direction of the containment-closure assembly 200-300. Axis VA. The outer longitudinal fins 220 are spaced circumferentially around the perimeter of the containment shell 204 and extend (generally) radially outward from the containment.

Ribs 220 serve several beneficial functions, including but not limited to (1) stiffening containment shell 204, (2) preventing excessive "sloshing" of water trapped in annulus 313 in the event of a seismic event, and (3) In the event of a fluid/vapour release event within the containment, apparently acting as thermally conductive "fins" are used to dissipate heat absorbed by conduction through the enclosure 204 into the environment of the annulus 313 .

Correspondingly, as a further description, in an embodiment that optimizes the heat conduction effect, the outer longitudinal fins 220 extend substantially vertically to the entire height of the water-filled annulus 313, covering the effective heat conduction surface of the containment vessel 200 (i.e., not buried in the concrete foundation) to transfer heat from the containment vessel 200 to the reservoir. In one embodiment, the outer longitudinal fins 220 have an upper horizontal end 220a terminating at or proximate to the underside or bottom of the larger diameter top 216 of the containment vessel 200 and a lower horizontal end 220b. 220b terminates at or proximate to the base plate 304 of the concrete foundation 301 . In one embodiment, the height H3 of the outer longitudinal fins 220 is equal to or greater than half the overall height of the containment shell.

In one embodiment, the upper horizontal ends 220a of the longitudinal fins 220 are free ends that are not permanently attached (eg, welded) to the containment vessel 200 or other mechanism. At least part of the lower horizontal end 220b of the longitudinal fin 220 adjoins and leans on the rib 222 welded on the outer surface of the containment shell 204 in the horizontal circumferential direction, so as to support the weight of the longitudinal fin 220 and make the force acting on the longitudinal fin 220 The stress on the rib-shell welds is minimal. The circumferential rib 222 is annular and may extend a full 360° around the circumference of the containment shell 204 . In one embodiment, the circumferential ribs 222 are positioned to rest against the base plate 304 of the concrete foundation 301, transferring the load of the longitudinal fins 220 to the foundation. The longitudinal fins 220 may have a transverse length or width, projecting outward beyond the peripheral edge of the circumferential rib 222 . Accordingly, in this embodiment, only the inner portion of the lower horizontal end 220b of each rib 220 contacts the circumferential rib 222 . In other possible embodiments, the circumferential ribs 222 may extend (substantially) radially outward far enough that substantially the entire lower horizontal end 220b of each longitudinal rib 220 rests on the circumferential ribs 222 . In some embodiments, the lower horizontal end 220b may be welded to the circumferential rib 222 to further strengthen or stiffen the longitudinal rib 220 .

The outer longitudinal fins 220 may be made of steel (such as mild steel), or other suitable metal materials, including alloys, and one side of each fin 220 extending longitudinally is welded to the exterior of the containment shell 204 . The opposite longitudinally extending side of each rib 220 is located closest to, but preferably not permanently attached to, the interior of the inner shell 310 of the containment enclosure structure (CES) 300 to maximize the heat transfer surface of the ribs as cooling fins . In one embodiment, the outer longitudinal fins 220 extend (substantially) radially outward beyond the larger diameter top 216 of the containment vessel 200, as shown. In one representative, but non-limiting example, steel ribs 220 may have a thickness of approximately 1 inch. Other suitable thicknesses of ribs may be used as appropriate. Accordingly, in some embodiments, the rib 220 has a radial width greater than 10 times the rib thickness.

In one embodiment, the longitudinal fins 220 are oriented at an oblique angle A1 to the containment shell 204 as best shown in FIGS. 2-3 and 5 . This direction forms a corrugated area extending 360° around the circumference of the containment vessel 200 to improve the function against projectile impact together with the outer containment enclosure structure (CES) 300 . Correspondingly, an impact that deforms the interior of the containment enclosure structure (CES) 300 shell 210, 211 will bend the longitudinal fins 220, and in the process will better distribute the impact force without direct transmission to the inner containment shell 204 and make it break, and at the same time there may be a 90° orientation between the rib and the containment shell 204. In other possible embodiments, depending on the structure of the containment enclosure structure (CES) 300 and other factors, the vertical arrangement of the ribs 220 relative to the containment shell 204 is appropriate.

In one embodiment, referring to FIGS. 6-8 , the portion of the containment shell 204 that has been protected from projectile impact by the outer (substantially) radial fins 220 may extend below ground level to Protection is provided slightly below ground level against impact of projectiles on the containment enclosure structure (CES) 300 . Accordingly, the base plate 304 is formed on top of the vertically extending side walls 303 of the foundation 301, and the fins 220 terminating at their lower ends may be located several feet below ground level to increase the impact resistance of the nuclear reactor containment system.

In one embodiment, the containment vessel 220 optionally includes a circumferentially spaced inner (substantially) radial plurality of fins 221 connected to the inner surface of the outer shell 204 (shown in phantom in FIGS. 2 and 3 ). . The inner fins 221 extend (generally) radially inwardly from the containment shell 204 and longitudinally in a vertical direction at a suitable height. In one embodiment, the inner (substantially) radial fins 221 may have a height substantially coextensive with the water-filled annulus 313 and extend from the base plate 304 to approximately the top of the housing 204 . In one non-limiting embodiment, the inner fins 221 may be oriented substantially perpendicular (ie, 90°) to the containment shell 204 . Other suitable angles and oblique orientations may also be used. The internal fins serve to increase the effective heat transfer surface area and structurally reinforce the containment shell against external impacts (such as projectiles) or increased internal pressure within the containment vessel 200 in the event of a containment pressurization event (such as LOCA or reactor scram) . In one non-limiting example, inner fins 221 may be made of steel.

1-15, a plurality of vertical structural support columns 331 may be attached to the outer surface of the containment shell 204 to help support the top 216 of the larger diameter containment vessel 200, the support columns 331 having an outer perimeter, such as a cantilever Projects (substantially) radially outwardly beyond the housing 204 . The support columns 331 are spaced circumferentially around the perimeter of the containment shell 204 . In one embodiment, support columns 331 may be fabricated from hollow steel structural members, such as without limitation members of C-shaped cross-section (ie, structural channels), welded to the outer surface of containment shell 204 . The two parallel legs of the channel may be welded to the containment shell 204 using continuous or intermittent welding (eg seam welding) along the height of each support column 331 .

The support column 331 extends vertically downward and is welded at its top end to the bottom/underside of the larger diameter top 216 of the containment housing the slewing crane. The bottom ends of the support columns 331 rest or are welded on the circumferential ribs 222 which engage the base plate 304 of the concrete foundation 301 adjacent to the buried part of the containment vessel. Support columns 331 help transfer a portion of the dead load or weight from the crane and top 216 of containment vessel 300 down to the foundation. In one embodiment, the hollow space inside the support column may be filled with concrete (with or without reinforcement) to make it strong and further support dead loads or weight. In other possible embodiments, other structural steel shapes may be used, including filled or unfilled box girders, I-beams, steel tubes, angles, and the like. The longitudinal fins 220 may further extend outward beyond the support posts 331 in a (substantially) radial direction, providing a structural rather than thermally conductive role like the ribs 220 . In certain embodiments, the (substantially) radial width of the rib 220 is at least twice the (substantially) radial width of the support column.

11-15 show various cross-sections (longitudinal and transverse) of the containment vessel 200 containing the equipment. In one embodiment, containment vessel 200 may be part of a Small Modular Reactor (SMR) system, such as the SMR-60 by Holtech International. The equipment may generally include a nuclear reactor pressure vessel 500 with a reactor core and circulating primary coolant located in a wet well 504, and a steam generator 502 fluidly connected to the reactor and circulating secondary coolant, constituting the core of the Rankine power generation cycle. part. Other appurtenances and equipment can be provided to create a complete steam generation system.

Referring now primarily to FIGS. 2-3 , 16 and 18 , the containment vessel 200 may further include an auxiliary heat dissipation system 340 comprising a plurality of internal longitudinal conduits 341 spaced circumferentially around the circumference of the containment vessel shell 204 . Conduit 341 extends vertically parallel to vertical axis VA and is connected to the inner surface of housing 204 in one embodiment. Conduit 341 may be made of metal, such as steel, and welded to the inner surface of housing 204 . In one possible non-limiting construction, conduit 341 may consist of a vertically oriented C-shaped (cross-sectional) structural channel such that the entire height of the channel's parallel legs are welded to housing 204 to define a sealed vertical flow pipes. Conduits of other suitable shapes or configurations may be provided so long that fluid conveyed in the conduits contacts at least a portion of the inner containment shell 204 to conduct heat to the water-filled annulus 313 .

Any suitable number and arrangement of conduits 341 depends on the heat transfer surface area required to cool the fluid flowing through the conduits. The conduits 341 may be evenly or unevenly spaced inside the containment vessel shell 204, and in some embodiments, groups of conduit clusters may be circumferentially distributed around the containment vessel. Conduit 341 may have any suitable cross-sectional size depending on the flow rate and thermal conductivity factors of the fluid conveyed by the conduit.

Both open upper and lower ends 341a, 341b of conduit 341 are fluidly connected to a common upper input ring header 343 and lower output ring header 344 . Annular ring headers 343, 344 are vertically spaced and placed inside the containment vessel 200 at an appropriate height to maximize heat transfer between the fluid flowing vertically in the conduit 341 and the containment shell 204 in the active heat transfer zone, The active heat transfer zone is defined by sections of containment with outer longitudinal fins in the main annular cavity 313 . In order to utilize the main water-filled annulus 313 for heat conduction, the upper and lower annular headers 343, 344 may respectively be provided inside the containment shell 204, adjacent to and close to the top and bottom of the annulus.

In one embodiment, the ring headers 343, 344 may each be formed from multiple half-sections of steel pipe as shown, welded directly to the inner surface of the containment shell 204 in the manner shown. In other embodiments, the ring headers 343 , 344 may be formed in any suitable manner by means of a full length of arcuately curved tubing supported by and connected to the interior of the housing 204 .

In one embodiment, the cooling system 340 is fluidly connected to a source of steam that may be generated from a body of water inside the containment vessel 200 for removing the decay heat of radioactive materials. The surface of the containment surrounded by the duct 341 serves as a heat transfer surface to transfer the latent heat of the steam in the duct to the outer shell 204 of the containment 200 for cooling by the outer longitudinal fins 220 and the water-filled annulus 313 . During operation, steam enters the input ring header 343 and is distributed to the open input end of the conduit 341 passing through the ring header. The vapor enters conduit 341 where it flows down the interior height of containment shell 204 and undergoes a vapor-liquid phase change. In one embodiment, the condensed steam flows down the conduit by gravity and is collected by the lower ring header 344, preferably also returning by gravity to the steam source. It should be noted that no pumps are involved or required in the above process.

According to another aspect of the invention, if, for some reason, during a thermal reactor related event (e.g., LOCA or reactor scram), the stock of water in the main annulus 313 is depleted, the auxiliary or backup passive air A cooling system 400 is provided for establishing air cooling by natural convection of the containment vessel 200 . Referring to FIG. 8 , the air cooling system 400 may be composed of a plurality of vertical input air ducts 401 circumferentially spaced around the containment vessel 200 in the main annular cavity 313 . Each air duct 401 includes an inlet 402 through the side wall 320 of the containment enclosure structure (CES) 300 and opens to the outside air to extract cooling air from the environment. The inlet 402 is preferably disposed near the upper end of the side wall 320 of the containment enclosure structure. Air conduit 401 extends vertically downward inside annular cavity 313 and terminates a short distance (eg, about 1 foot) above underlying substrate 304 to allow air to escape from the bottom end of the conduit.

Using the air duct 401, in combination with the annular cavity 313, a natural convection cooling airflow path is established. If the stock of cooling water in the main annulus 313 is depleted due to evaporation during a thermal event, air cooling is automatically activated by natural convection as the air in the annulus continues to be heated by the containment vessel 200 . The hot air in the primary annular cavity 313 rises, passes through the secondary annular cavity 330 , enters the head space 318 , and flows out of the dome 316 of the containment enclosure structure (CES) 300 through the outlet 317 (see the flow direction arrow in FIG. 8 ). The rising hot air reduces the air pressure relative to the bottom of the main annulus 313 sufficiently to draw external ambient air down through the air duct 401 , thereby creating a natural air circulation pattern to continue cooling the hot containment vessel 200 . Advantageously, the passive air cooling system and circulation can continue to cool containment vessel 200 indefinitely.

It should be noted that the primary annulus 313 acts as a primary heat sink for heat generated inside the containment vessel 200 . The water in the annular reservoir is also used to maintain the temperature of all the crane vertical support columns 331 (described earlier) at substantially the same temperature, thus ensuring that the crane rails installed in the greater part of the containment vessel 200 (not shown) level.

The operation of the reactor containment system 100 as a heat exchanger will now be briefly described with reference to FIG. 19 . The figure is a simplified diagrammatic representation of the reactor containment system 100, not all equipment and structures are depicted here in describing the active heat transfer and dissipation processes performed by the system for the sake of clarity.

In a loss of coolant (LOCA) accident situation, an energetic fluid or liquid coolant (typically water) is splashed into the containment environment formed by containment vessel 200 . The liquid instantly turns into vapor, and the water vapor mixes with the air inside the containment vessel and transfers to the sidewall of containment vessel 200 or the inner surface of outer shell 204 (since the outer containment shell facing the water in annulus 313 is cooler). The water vapor then condenses on the vertical shell walls by releasing its latent heat to the containment structural metal which in turn rejects heat to the water in the annulus 313 through the longitudinal fins 220 and the exposed portion of the annulus inner shell 204 . The water in the annulus 313 heats up and eventually evaporates into water vapor, which rises within the annulus and passes through the sub-annulus 330, the head space 318 and finally exits the containment enclosure structure (CES) 300 to the atmosphere through the outlet 317.

When the water reservoir in the annulus 313 is located outside the containment environment, in some embodiments, external means (if present) may be used to conveniently replenish the stock of water to compensate for water evaporation losses. However, if no make-up water is provided or available, the height of the water column in the annulus 313 will begin to decrease. When the water level in the annulus 313 drops, the containment vessel 200 also begins to heat the air above the water level in the annulus, thereby dissipating some of the heat to the air, which rises and carries water vapor from the containment enclosure structure (CES) 300 through the outlet 317 flow out. When the water level drops suddenly, causing the open bottom end of the air duct 401 (see, for example, Figure 8) to be exposed above the waterline, fresh external ambient air will then be sucked in from the air duct 401 to establish natural convection as described above The air circulation mode continues to cool the containment vessel 200 .

In one embodiment, facilities such as water lines are provided through the containment enclosure structure (CES) 300 for replenishing the water in the annulus 313, although adequate heat dissipation need not be ensured. The total amount of stocked water in the annular reservoir is more or less determined such that the decay heat generated within the containment vessel 200 is sufficiently reduced that once the stocked water is depleted, the containment can dissipate all of its heat through independent air cooling. The containment vessel 200 preferably has sufficient heat removal capacity to limit the pressure and temperature of the water vapor mixture within the containment (within its design limits) by rapidly removing heat.

In the event of a total station blackout, where the reactor core is forced to "scramble", the passive core cooling system will exhaust core decay in the form of steam directed to the upper input ring header 343 of the cooling system 340 already described Heat (see Figures 16 and 18 for example). The vapor then flowing down through the network of internal longitudinal ducts 341 contacts the inner surface of the containment shell 204 enclosed within the heat dissipation ducts and condenses by rejecting its latent heat to the containment structural metal which in turn passes through the inner surface of the containment shell 204 which is formed by the longitudinal fins. The heat conduction aid provided by 220 dissipates heat to the water in the annular cavity 313 . The water in the annular reservoir (main annular chamber 313) is finally heated and evaporated. The containment vessel 200 rejects heat into the annulus by sensible heating, followed by a mixture of evaporation and air cooling, and then finally further air cooling by natural convection only as described. As mentioned above, the reactor containment system 100 is designed and configured such that once the effective inventory of water in the annulus 313 is completely depleted, independent air cooling is sufficient to remove the decay heat.

In both of the preceding cases, heat removal can continue indefinitely until alternative means are available to bring the plant back into operation. Not only does the system operate indefinitely, but this operation is completely passive, without the use of any pumps or operator intervention.

Component cooling water system

According to another aspect of the present invention shown in FIGS. 20-25, an improved component cooling water (CCW) system 600 is provided. In contrast to previous once-through cooling systems that utilize raw water from a natural body of water for cooling, the component cooling water system 600 generally includes a heat exchanger 610 and one or more cooling water piping loops 636 that recirculate through a substantially closed loop. The fluidly connected component cooling water pump 601 . Most of the cooling water pipe ring 636 can be provided in the nuclear power plant outside the nuclear reactor containment vessel 200 and the containment closure structure 300 surrounding the containment vessel (see FIG. 25 for example). The cooling water piping ring 636 collects heated and cooled cooling water from nuclear power plant ancillary equipment (represented by the CCW block in FIG. 25 ) fluidly connected to the piping ring and component cooling water system 600, and distributes the heated and cooled cooling water to the nuclear power plant Grouped equipment. Pump 601 provides power for driving water flow through pipe ring 636 and heat exchanger 610 . Pump 601 may be any suitable type of pump (eg, centrifugal pump, etc.) with suitable water suction and pressure heads for the application conditions and desired flow rates. Any number or arrangement of pumps 601 may be provided through the pipe ring 636 for circulating cooling water.

In one embodiment according to the invention, the component cooling water system 600 conveniently utilizes the water-filled annulus 313 (herein alternatively referred to as the annular The water in the reservoir 313) acts as a useful heat transfer medium or heat sink, conducting heat to and from the annular reservoir and component cooling water system 600. Accordingly, in this embodiment, the heat exchanger 610 may be fully positioned and submerged/submerged in the annular reservoir for direct heat transfer to the reservoir. In general, as further described, the cooling water piping ring 636 recirculates component cooling water within a closed flow loop between the annular reservoir 313 and the cooling equipment of the nuclear power plant.

Referring initially to FIG. 24 , in one non-limiting configuration, the heat exchanger 610 of the component cooling water system 600 is a shellless heat exchanger comprising a vertically elongated and oriented U-shaped tube bundle 611 with its opening facing upward, the U-shaped tube bundle 611 is composed of a plurality of U-shaped heat pipes 620 , both ends of which are connected to the tube plate 612 adjacent to the channel 613 . The channel 613 defines an interior space which can be divided into an input chamber 614 and an output chamber 615 by a vertical partition 616 . The bottom of the input/output chambers 614 , 615 is formed by the upper side of the tube sheet 612 . The top of the input/output chambers 614 , 615 is closed by a top cover 618 detachably connected to the upper end of the channel 613 .

The heat exchanger 610 includes an inlet nozzle 630 fluidly connected to the input chamber 614 through the sidewall of the channel 613 and an outlet nozzle 631 fluidly connected to the output chamber 615 through the sidewall of the channel. In one embodiment, the inlet and outlet nozzles 630, 631 may be positioned opposite each other on the channel 613, however, other suitable arrangements are possible. Inlet and outlet nozzles 630 , 631 fluidly connect heat exchanger 610 to input cooling water conduit 632 and output cooling water conduit 633 of component cooling water system 600 . The input and output cooling water conduits 632, 633 are in turn fluidly connected to a closed cooling water conduit ring 636 of the component cooling water system 600 (see also Fig. 25). In one embodiment, the inlet and outlet nozzles 630,631 may be provided with flanges for connection to mating flanges provided at the ports of the inlet and outlet cooling water pipes 632,633. The flange joint 617 between the nozzle and the pipe may be bolted in one embodiment, or welded in other embodiments. However, it should be understood that the input and output cooling water pipes 632, 633 could be welded directly to the inlet and outlet nozzles 630, 631 without flanges. Any suitable type of fluid connection type may be used.

In some embodiments, input and output cooling water conduits 632, 633 may be arranged to extend through suitably configured penetrations 635 formed through the outer containment enclosure structure 300 (see eg FIG. 22). Penetrations 635 may be provided at any suitable height to allow cooling water piping to be connected to inlet and outlet nozzles 630 , 631 of heat exchanger 610 . The piping can be any suitable metallic or non-metallic piping.

In one embodiment, a bolted flange joint 617 may be used to removably secure the top cover 618 to the channel 613 . However, other suitable methods may be used to connect the cap 618 to the channel 613 . Cap 618 provides a leak-proof seal for channel 613 and may include suitable gaskets and/or seals to form a watertight connection, as will be well known to those skilled in the art. Preferably, the bulkhead 616 is configured and arranged to engage and form a seal with the underside of the tube sheet 612 and top cover 618 . This is intended to prevent or minimize leakage of cooling water between the input chamber 614 and the output chamber 615 on opposite sides of the partition 616 . In one possible arrangement, the bulkhead 616 may have a linear bottom end or edge, and when the top cover is installed over the channel 613, the bulkhead 616 may be securely welded to the tube sheet via suitable gaskets and/or seals The upper side of the top cover 612 and the linear tip or edge removably engages the underside of the top cover 618. A removable top cover 618 provides access to the channel interior tube sheet 612 for insertion of leaking tubes, performing non-destructive testing and inspection of the tube sheet and tubes, or for other purposes.

Referring primarily to FIGS. 20-25 , especially FIG. 24 , in a typical embodiment, the heat exchanger 610 can be a shellless heat exchanger, wherein the U-shaped tube 620 is not enclosed and exposed, and is directly immersed or submerged in the In the water-filled annular cavity 313 of the nuclear reactor containment system 100 between the inner containment vessel 200 and the outer containment vessel sealing structure 300 . Each tube 620 may include two straight portions 621 and a U-shaped bent portion 622 disposed at the end of the tube plate 612 and on the opposite side of the tube plate 612 . Each tube 620 has a first end 623 connected to the straight portion 621 of the input chamber 614 through the tube sheet 612 and a second end 624 connected to the straight portion of the output chamber 615 through the tube sheet. In one embodiment, the ends of the tubes 620 adjacent the tube ends may extend entirely through vertical through holes formed in the tube sheet 612 from the underside to the top side of the tube sheet. The tubes may be secured to the tube sheet 612 by any suitable means, including but not limited to welding, explosive expansion of the tube ends relative to the tube sheet, or other methods known in the art.

The U-tube 620 may be bare or optionally include fins (eg, axial or helical), depending on the heat flow requirements of the intended application and other technical factors. Tube 620 may be made of any suitable ferrous or non-ferrous metal or metal alloy, as non-limiting examples, aluminum or steel pipe to which aluminized or solid stainless steel tube sheet 612 is attached, respectively. Preferably, the tube 620 is selected to be corrosion resistant. Tube 620 may have any suitable outer diameter and wall thickness.

Referring to FIGS. 20-25 , a heat exchanger 610 is shown installed in a water-filled annulus 313 (annular reservoir) surrounding the inner containment vessel 200 . The water in the annular reservoir can be kept in a non-quiescent state by the recirculation pump 663 of the reservoir recirculation system 662 (see FIG. 23 ), which draws water from the annular chamber 313 and returns the water to the annular chamber 313, Agitate the water to prevent algae growth. These pumps are also used to continuously filter the water in the reservoir to maintain its cleanliness. The movement of the water in the annular reservoir 313 also facilitates evaporation, assisting any cooling effect attributable to it, such as loss of coolant accident (LOCA) heat removal or during normal reactor operation by submerging the reservoir. The heat exchanger 610 in removes heat from the cooling water of the component cooling water system.

In one embodiment, the heat exchanger 610 is suspended in the water-filled annulus 313 (with suitable shock resistance) and positioned so that the bottom end of the tube bundle 611 (defined by the U-shaped tube 622) is vertically above the annular reservoir. The distance V1 is spaced apart, as shown in FIGS. 20 and 21 . In one non-limiting arrangement, the heat exchanger 610 includes one or more radially extending anchors or supports 640, preferably rigidly connected to the channel 613, when connected to a structural member in the annular reservoir (bottom described above) to limit the movement of the channel. This arrangement restricts the passage 613, but advantageously allows the tube bundle 611 length relative to the passage 613 during operation of the component cooling water system 600 as the tubes 620 are heated or cooled according to temperature changes of the component cooling water flowing in the tubes 620. Freely expand and shorten without constraints. In a typical embodiment, the supports 640 may be formed from horizontally oriented structural steel plates welded to the sides of the horizontal plates and channel 613 and reinforced by vertical stiffener plates. Many other variations and configurations of heat exchanger support 640 are possible and could be used.

The support 640 can be mounted to the containment-enclosure structure assemblies 200 - 300 in the water-filled annulus 313 in various ways. In one example, supports 640 may be bolted or welded to corresponding structural supports 641 located inside water-filled annulus 313 and connected to containment-closure structural assemblies 200-300. In various embodiments, the support 641 may be pedestal, as shown in some non-limiting examples, rising from the bottom 642 of the annular reservoir, from the steel inner shell of the outer containment seal structure 300 The inner surface of 310 is cantilevered (see 641 in Figure 21), or a combination thereof. Many other variations of support 641 may optionally be provided. Support 641 may be made of any suitable material or combination of materials, including steel, concrete, or others. Preferably, the heat exchanger supports and mounts are designed and arranged to provide seismically stable mounting of the heat exchanger 610 in the water-filled annulus 313 .

Referring to Figures 20-25, the heat exchanger 610 can be positioned and suspended in place in one of the "bays" 650 formed in the water-filled annulus 313 in a pair of adjacent compartments. between the open fins 220 . In one arrangement, the heat exchanger 610 may be located near the bottom 642 of the annular reservoir so that heat transfer can be continued whenever possible, such as when the water level in the annular chamber 313 decreases due to evaporation, if no provision is made for the reservoir to Emergency shut down event caused by water replenishment.

In one embodiment, it is preferred that the bay 650 in which the heat exchanger 610 is located is at a location where a recirculation pump 663 of at least one annular reservoir recirculation piping system 662 flows water through a placed discharge sprinkler 664 to agitate the body of water around the exposed tube bundle 611. In contrast, this arrangement is intended to improve flow through and between the tubes to enhance thermal conductivity, unlike other bays 650 where flow conditions are likely to be relatively more stagnant. Recirculation pump 663 draws water from annular reservoir 313 through outlet pipe 661 fluidly connected to the reservoir at one suitable location and discharges through inlet pipe 660 fluidly connected to sprinkler 664 immersed/submerged in the reservoir water. In some embodiments, the input and output conduits 660 and 661 may extend through suitable penetrations 635 formed by the side walls of the outer containment seal structure 300; The recirculated water is directed into the shower 664 by the location of the side walls, such as from the top of the annular reservoir 313 (eg, a pipe extending vertically downward from its top within the annular reservoir). Output pipe 661 may draw from annular reservoir 313 at any suitable location, such as, without limitation, in the same bay 650 containing sprinkler 664 or a different bay.

The recirculation pump 663 may be any suitable type of pump (eg, centrifugal, etc.) with suitable water suction and pressure heads for the application conditions and desired flow rates. The conduits may be any suitable metallic or non-metallic conduits. In various embodiments, more than one reservoir recirculation piping 662 and/or shower 664 may be provided.

Referring to Figures 21 and 23, in some embodiments, the shower 664 may be formed from a generally horizontally oriented header having a plurality of upwardly facing output holes 665 spaced by any suitable spacing. In a preferred embodiment, the shower 664 is located vertically below the heat exchanger tube bundle 661 and discharges recirculating water up the tube bundle. The showers 664 may be spaced at any suitable distance below the tube bundle 661 . The sprinkler creates a localized upward flow of reservoir water over its area and helps to draw additional water from the reservoir to create a recirculating upward flow pattern. Alternative sprinkler arrangements are possible in light of the teachings discussed herein.

In some embodiments, the bay 650 in which the heat exchanger 610 is mounted is preferably further at a location where "cold" makeup water is injected into the annular reservoir 313 to compensate for water loss from evaporation from the reservoir. Local makeup water entering bay 650 near heat exchanger 610 enhances thermal conductivity and cooling of hot component cooling water. As shown in FIG. 23 , make-up water system 670 may include a make-up water pump 671 that draws outward from any suitable make-up water source to annular reservoir 313 and discharges make-up water into the annular reservoir through input tube 672 . The inlet pipe 672 may be located at any suitable location in the bay 650 that does not interfere with the flow pattern produced by the shower 664, but is close enough to the heat exchanger 610 to obtain approximately Thermal performance benefits of colder water. The inlet pipe 672 may extend through the penetration 635 formed through the side wall of the outer containment seal structure 300; however, in other possible arrangements, the inlet pipe may be from a location other than through the side wall, such as from an annular reservoir. The top of pool 313 (such as a pipe extending vertically downward from the top of the annular reservoir) introduces make-up water. Pump 671 may be any suitable type of pump (eg, centrifugal, etc.) with suitable suction and displacement heads for the application conditions and desired flow rates. Conduit 672 may be any suitable metallic or non-metallic conduit.

It should be understood that the term "cold" with respect to make-up water is comparative and generally refers to the fact that the make-up water is obtained from an external source other than the annular reservoir, and preferably has a temperature generally lower than that of the water in the annular reservoir 313. temperature. The water in the annular reservoir may typically have a higher than ambient temperature due to the operation of the nuclear reactor within the reactor containment converting some of the water into water vapor that escapes from the reactor containment to the atmosphere, as described herein. temperature. Under certain operating conditions of the nuclear power plant, the make-up water may have a temperature equal to or even higher than the temperature of the water being replaced in the annular reservoir. Accordingly, the term "cold" is used here for descriptive purposes, to better describe the makeup water system, and not as a term of limitation.

In the normal operating mode of the reactor and component cooling water system 600, hot water received by the component cooling water pump 601 from various nuclear power plant equipment fluidly connected to the component cooling water system is pumped to the heat exchanger through the cooling water input pipe 632 610 (see Figures 22, 24 and 25). Hot cooling water flows into the input chamber 614 of the heat exchanger 610 through the inlet nozzle 630 . The hot cooling water then flows down through tube sheet 612 and tubes 620 of tube bundle 611 , reverses direction via tube bend 622 , and up through the tubes into output chamber 615 in channel 613 . The hot cooling water flowing in the tube 620 is cooled by conducting heat from the tube wall to the water in the water-filled annulus 313 (annular reservoir). The now chilled cooling water then flows from output chamber 615 through output pipe 635 connected to heat exchanger 610 and returns to component cooling water system 600 for distribution to cool the various nuclear power plant equipment. Heat stored in the annular reservoir by the heat exchanger 610 diffuses into the reservoir water and heats it, and is eventually dissipated to the environment by evaporation from the reactor containment system 100 to the environment, as already described herein. In one embodiment, heated water vapor from the annular reservoir 313 may flow to the environment through an outlet 317 on the dome 316 of the containment seal structure 300 .

The directional arrows shown in the figures indicate the flow paths of the fluids discussed herein with reference to the figures. Those skilled in the art will appreciate that the fluid piping systems described herein may include various auxiliary equipment and accessories such as valves, filters, pressure regulators, flow and pressure indicators, piping supports, etc. necessary to pass through a fully functional system wait.

Heat exchanger 610 has been described as an exemplary but non-limiting shellless heat exchanger having a U-shaped tube bundle configuration, since there is only a single split channel 613, and heat transfer tubes along its vertical sides and bottom to the annular reservoir 313 for maximum exposure to optimize flow through the tube bundle, the shellless heat exchanger has advantages such as: compact structure, low manufacturing cost (materials and processing). However, it should be understood that other tube configurations may be used that expose the tubes to the water of the annular reservoir 313 (such as a shellless heat exchanger). Other possible configurations may include straight tube bundles connected at each tube end between spaced and oppositely arranged input and output channels. It will be further appreciated that other than vertical orientations of the tube bundle may be employed, such as horizontal or at an angle between vertical and horizontal. Accordingly, the present invention is not limited by the configuration and orientation of the heat exchanger.

Advantages of the new invention include: Elimination of water supply to equipment cooling heat exchangers in current nuclear power plants and long water diversion lines which are notoriously susceptible to component corrosion and aging, heat exchanger tube bundles are not plagued by today's technology with feed water for long periods of time Contamination of heat transfer surfaces by contact. It should be understood that, in some embodiments, multiple heat exchangers 610 may be arranged in parallel to increase the cooling capacity of the component cooling water system 600 as required. If multiple units are used, maintenance work on any of the units can be performed while the reactor is running.

The foregoing description and drawings represent some example systems, and it should be understood that various additions, modifications and substitutions can be made without departing from the spirit, scope and equivalent scope of the appended claims. In particular, it is obvious to those skilled in the art that the present invention can be implemented in other forms, structures, arrangements, proportions, dimensions and other components, materials and devices without departing from its spirit or essential characteristics. Additionally, many of the methods/procedures described herein can be varied. Those skilled in the art will further understand that, without departing from the principle of the invention, the present invention can be used in the modification of many structures, arrangements, proportions, dimensions, materials and components, or, in the practice of the present invention, particularly suitable Use in specific circumstances and operating requirements. Accordingly, the presently disclosed embodiments should be considered in each case as illustrative and not restrictive, the scope of the invention being defined by the appended claims and their equivalents rather than by the foregoing description or practice. Example limited. Moreover, the appended claims should be interpreted broadly to include other changes and embodiments of the invention which may be made by those skilled in the art without departing from the scope and equivalents of the invention.

Claims (40)

1. A cooling water system for nuclear power plant components, wherein the system comprises: A containment vessel defining an enclosed space configured to contain a nuclear reactor; a containment closure structure surrounding said containment vessel; an annular reservoir formed between the containment vessel and the containment enclosure structure, the annular reservoir configured to provide a heat sink for dissipating thermal energy; and a shellless heat exchanger having exposed heat-conducting tube bundles submerged in the water of said annular reservoir; Wherein equipment cooling water from the nuclear power plant flows through the tube bundle and is cooled by transferring heat to the annular reservoir. 2. The system of claim 1, wherein the tube bundle is comprised of a plurality of heat conducting tubes. 3. The system of claim 1 or 2, wherein the tube bundle is U-shaped. 4. The system of any one of claims 1-3, wherein the bottom end of the tube bundle is vertically spaced from the bottom of the annular reservoir. 5. The system of any one of claims 1-4, wherein the tube bundle is vertically oriented. 6. The system of claim 5, wherein the tube bundle is connected to a tube sheet supported by channels defining input and output chambers that are both fluidly connected to the tube bundle. 7. The system of claim 6, wherein: said channel is structurally supported and confined within said annular reservoir, and The tube bundles are suspended from the channels and expand and contract in length without restraint under thermal expansion. 8. The system of claim 1, wherein the equipment cooling water flows through a cooling water piping ring in the nuclear power plant, the cooling water piping ring being fluidly connected to the heat exchanger to cool the equipment Water is delivered to and from the heat exchanger for the equipment cooling water. 9. The system of claim 8, wherein the cooling water conduit loop recirculates heated and cooling equipment cooling water between the annular reservoir and equipment in the nuclear power plant. 10. The system of claim 9, further comprising at least one pump fluidly connected to the cooling water piping ring for driving equipment cooling water through the cooling water piping ring. 11. The system of claim 8, wherein the ring of cooling water piping is fluidly connected to channels formed on the heat exchanger and defining input and output chambers. 12. The system of claim 11, wherein the tubes of the tube bundle each have one end fluidly connected to the input chamber and a second end fluidly connected to the output chamber. 13. The system of claim 12, further comprising a partition disposed in the channel, the partition dividing the channel into the input chamber and the output chamber. 14. The system of claim 1, further comprising: a discharge shower disposed below the exposed pipe bundle in the annular reservoir, the shower configured and arranged to discharge water through the The tube bundle is used for cooling. 15. The system of claim 14, wherein the shower forms part of a pumped recirculation system fluidly connected to the annular reservoir, the recirculation system being configured and operable from The annular cistern draws water and returns water to the annular cistern through the shower. 16. The system of claim 1, further comprising a plurality of generally radial fins projecting outwardly from said containment vessel and located within said annular reservoir, said heat exchange The reservoir is located in a bay formed between adjacent fins spaced apart in the annular reservoir. 17. The system of claim 16, wherein the fins are oriented obliquely relative to the containment vessel. 18. The system of claim 1, wherein said heat exchanger is disposed at a location within said annular reservoir, proximate to an inlet from a reservoir makeup water supply system, said reservoir makeup water supply system Water is drained into said annular reservoir, thereby compensating for water lost due to evaporation. 19. The system of claims 14 and 16, wherein the inlets from the reservoir make-up water supply and sprinklers are located in the same bay. 20. A nuclear power plant component cooling water system, wherein the system comprises: A containment vessel defining an enclosed space configured to contain a nuclear reactor; a containment closure structure surrounding said containment vessel; an annular reservoir formed between the containment vessel and the containment enclosure structure, the annular reservoir configured to provide a radiator for dissipating heat; a shellless heat exchanger having a bare thermally conductive tube bundle consisting of a plurality of tubes submerged in the water of said annular reservoir; and a discharge shower disposed below said exposed tube bundle in said annular cistern, said shower being configured and arranged to discharge recirculated water from the annular cistern through said tube bundle for cooling of the tubes; Equipment cooling water from the nuclear power plant flows through the tubes of the tube bundle and is cooled by transferring heat to the annular reservoir. 21. The system of claim 20, wherein the shower forms part of a pumped recirculation system fluidly connected to the annular reservoir, the recirculation system being configured and operable from The annular cistern draws water and returns water to the annular cistern through the shower. 22. The system of claim 20, further comprising a plurality of generally radial fins projecting outwardly from said containment to said containment closure structure and located in said annular reservoir In the tank, the heat exchanger and shower are located in bays formed between adjacent fins spaced apart in the annular reservoir. 23. The system of claim 20, wherein the tube bundle is U-shaped. 24. The system of claim 20, wherein the bottom end of the tube bundle is vertically spaced from the bottom of the annular reservoir. 25. The system of claim 20, wherein the tube bundles are vertically oriented. 26. The system of claim 20, wherein the tube bundle is connected to a tube sheet supported by channels defining input and output chambers that are both fluidly connected to the tube bundle. 27. The system of claim 26, wherein: said channel is structurally supported and confined within said annular reservoir, and The tube bundles are suspended from the channels and expand and contract in length without restraint under thermal expansion. 28. The system of claim 26, wherein the tubes of the tube bundle each have one end fluidly connected to the input chamber and a second end fluidly connected to the output chamber. 29. The system of claim 20, wherein the equipment cooling water flows through a cooling water piping ring provided with a pump in the nuclear power plant, the cooling water piping ring being fluidly connected to the heat exchanger for The equipment cooling water is delivered to and from the heat exchanger. 30. A nuclear power plant component cooling water system, wherein the system comprises: A containment vessel defining an enclosed space configured to house a nuclear reactor; a containment closure structure surrounding said containment vessel; an annular reservoir formed between the containment vessel and the containment enclosure structure, the annular reservoir configured to provide a radiator for dissipating heat; a shellless heat exchanger having a bare thermally conductive tube bundle consisting of a plurality of tubes submerged in the water of said annular reservoir; and a plurality of generally radial fins projecting outwardly from the containment to the containment closure structure and located in the annular reservoir, the heat exchanger is located in a circumferentially extending bay, the said bay is formed in said annular reservoir between a pair of spaced apart adjacent fins; Wherein equipment cooling water from the nuclear power plant flows through the tubes of the tube bundle and is cooled by transferring heat to the annular reservoir. 31. The system of claim 30, further comprising: a cistern recirculation piping system provided with a pump, with a discharge shower disposed in said bay below said exposed pipe bundle in said annular cistern, Wherein the reservoir recirculation piping system is configured and operable to draw water from the annular reservoir and pump the drawn water through the discharge shower into the tube bundle cooling conduit. 32. The system of claim 30, further comprising a piping system that discharges reservoir make-up water into the bay housing the heat exchanger to compensate for water loss due to evaporation. 33. The system of claim 30, wherein the tubes of the tube bundle each have one end fluidly connected to an input chamber formed in the heat exchanger and one end fluidly connected to an inlet chamber formed in the heat exchanger. The second end of the output chamber. 34. The system of claim 33, wherein the input chamber and the output chamber are disposed adjacent to each other in a channel supporting the tube sheet, the input chamber and the output chamber being disposed in the channel The separators in are fluidly isolated from each other. 35. The system of claim 34, wherein each pipe has a first pipe end connected to a portion of the tube sheet fluidly connected to the input chamber; and a second pipe end connected to the The portion of the tube sheet to which the output chamber is fluidly connected. 36. The system of claim 35, wherein the first and second tube ends are fluidly connected together by a U-shaped tube bend. 37. The system of claim 35, wherein the tube bundle is U-shaped. 38. The system of claim 30, wherein the tube bundles are vertically oriented. 39. The system of claim 38, wherein the tube bundles depend downwardly from a tube sheet attached to channels defining inlet nozzles of the heat exchanger and outlet nozzles of the heat exchanger. 40. The system of claim 30, wherein the equipment cooling water flows through a cooling water piping ring provided with a pump in the nuclear power plant, the cooling water piping ring being fluidly connected to the heat exchanger for The equipment cooling water is delivered to and from the heat exchanger.