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75-691: The CNP-300 is a pressurized water nuclear reactor developed by the China National Nuclear Corporation (CNNC). It is China's first domestic commercial nuclear reactor design, with development beginning in the 1970s based on a nuclear submarine reactor design. The reactor has a thermal capacity of 999 MW and a gross electrical capacity of 325 MW, with a net output of about 300 MWe and a single-loop design and . The first CNP-300 unit started operations in Qinshan Nuclear Power Plant in 1991. The CNP-300

150-442: A (partially) closed nuclear fuel cycle . Water is a nontoxic, transparent, chemically unreactive (by comparison with e.g. NaK ) coolant that is liquid at room temperature which makes visual inspection and maintenance easier. It is also easy and cheap to obtain unlike heavy water or even nuclear graphite . Compared to reactors operating on natural uranium , PWRs can achieve a relatively high burnup . A typical PWR will exchange

225-410: A 60-year design life, and would use a combination of passive and active safety systems with a double containment. It has a 177 assembly core design with an 18-month refuelling cycle. The power plant's utilisation rate is as high as 90%. CNNC has said its active and passive safety systems, double-layer containment and other technologies meet the highest international safety standards. According to CNNC,

300-551: A 60-year design life, and would use a combination of passive and active safety systems with a double containment. CNNC's 177 fuel assembly design was retained. Initially the merged design was to be called the ACC-1000, but ultimately it was named Hualong One . In August 2014 the Chinese nuclear regulator review panel classified the design as a Generation III reactor design, with independently owned intellectual property rights. As

375-453: A 60-year design life. No examples of this reactor type had been built. CNNC's largest CNP development was a three-loop 1000 MW version of the design designated CNP-1000. Work on the project began in the 1990s with the help of vendors Westinghouse and Framatome (now AREVA). The first CNP-1000 units were due to be built at Fangjiashan (the same site as Qinshan). However, the design was subsequently changed to CGN 's CPR-1000. Later, 4 units of

450-479: A CANDU reactor or any other heavy water reactor when ordinary light water is supplied to the reactor as an emergency coolant. Depending on burnup , boric acid or another neutron poison will have to be added to emergency coolant to avoid a criticality accident . PWRs are designed to be maintained in an undermoderated state, meaning that there is room for increased water volume or density to further increase moderation, because if moderation were near saturation, then

525-465: A PWR cannot exceed a temperature of 647 K (374 °C; 705 °F) or a pressure of 22.064 MPa (3200 psi or 218 atm), because those are the critical point of water. Supercritical water reactors are (as of 2022) only a proposed concept in which the coolant would never leave the supercritical state. However, as this requires even higher pressures than a PWR and can cause issues of corrosion, so far no such reactor has been built. Pressure in

600-405: A PWR design. Nuclear fuel in the reactor pressure vessel is engaged in a controlled fission chain reaction , which produces heat, heating the water in the primary coolant loop by thermal conduction through the fuel cladding. The hot primary coolant is pumped into a heat exchanger called the steam generator , where it flows through several thousand small tubes. Heat is transferred through

675-475: A PWR is not suitable for most industrial applications as those require temperatures in excess of 400 °C (752 °F). Radiolysis and certain accident scenarios which involve interactions between hot steam and zircalloy cladding can produce hydrogen from the cooling water leading to hydrogen explosions as a potential accident scenario. During the Fukushima nuclear accident a hydrogen explosion damaging

750-459: A PWR. It can, however, be used in a CANDU with only minimal reprocessing in a process called "DUPIC" - Direct Use of spent PWR fuel in CANDU. Thermal efficiency , while better than for boiling water reactors , cannot achieve the values of reactors with higher operating temperatures such as those cooled with high temperature gases, liquid metals or molten salts. Similarly process heat drawn from

825-656: A given temperature set by the position of the control rods. In contrast, the Soviet RBMK reactor design used at Chernobyl, which uses graphite instead of water as the moderator and uses boiling water as the coolant, has a large positive thermal coefficient of reactivity. This means reactivity and heat generation increases when coolant and fuel temperatures increase, which makes the RBMK design less stable than pressurized water reactors at high operating temperature. In addition to its property of slowing down neutrons when serving as

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900-444: A heavy pressure vessel and hence increases construction costs. The higher pressure can increase the consequences of a loss-of-coolant accident . The reactor pressure vessel is manufactured from ductile steel but, as the plant is operated, neutron flux from the reactor causes this steel to become less ductile. Eventually the ductility of the steel will reach limits determined by the applicable boiler and pressure vessel standards, and

975-426: A moderator). The pressure in the primary coolant loop is typically 15–16 megapascals (150–160  bar ), which is notably higher than in other nuclear reactors , and nearly twice that of a boiling water reactor (BWR). As an effect of this, only localized boiling occurs and steam will recondense promptly in the bulk fluid. By contrast, in a boiling water reactor the primary coolant is designed to boil. Light water

1050-423: A moderator, water also has a property of absorbing neutrons, albeit to a lesser degree. When the coolant water temperature increases, the boiling increases, which creates voids. Thus there is less water to absorb thermal neutrons that have already been slowed by the graphite moderator, causing an increase in reactivity. This property is called the void coefficient of reactivity, and in an RBMK reactor like Chernobyl,

1125-542: A quarter to a third of its fuel load every 18-24 months and have maintenance and inspection, that requires the reactor to be shut down, scheduled for this window. While more uranium ore is consumed per unit of electricity produced than in a natural uranium fueled reactor, the amount of spent fuel is less with the balance being depleted uranium whose radiological danger is lower than that of natural uranium. The coolant water must be highly pressurized to remain liquid at high temperatures. This requires high strength piping and

1200-469: A reduction in density of the moderator/coolant could reduce neutron absorption significantly while reducing moderation only slightly, making the void coefficient positive. Also, light water is actually a somewhat stronger moderator of neutrons than heavy water, though heavy water's neutron absorption is much lower. Because of these two facts, light water reactors have a relatively small moderator volume and therefore have compact cores. One next generation design,

1275-703: A result of the success of the Hualong One project, no ACP-1000 reactors have been built to date. CNNC had originally planned to use the ACP-1000 in Fuqing reactor 5 and 6 but switched over to the Hualong One. Since 2011, CNNC has been progressively merging its ACP-1000 nuclear power station design with the CGN ACPR-1000 design, while allowing some differences, under direction of the Chinese nuclear regulator. Both are three-loop designs originally based on

1350-474: A result of the success of the merger, ACP-1000 and ACPR-1000 designs are no longer being offered. Pressurized water reactor A pressurized water reactor ( PWR ) is a type of light-water nuclear reactor . PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan and Canada). In a PWR, the primary coolant ( water ) is pumped under high pressure to

1425-420: A shaft used for propulsion . Direct mechanical action by expansion of the steam can be used for a steam-powered aircraft catapult or similar applications. District heating by the steam is used in some countries and direct heating is applied to internal plant applications. Two things are characteristic for the pressurized water reactor (PWR) when compared with other reactor types: coolant loop separation from

1500-505: Is a Chinese Generation III pressurized water nuclear reactor jointly developed by the China General Nuclear Power Group (CGN) and the China National Nuclear Corporation (CNNC). The CGN version, and its derived export version, is called HPR1000 . It is commonly mistakenly referred to in media as the "ACPR1000" and "ACP1000", which are in fact earlier reactors design programs by CGN and CNNC. Unit 5 of

1575-800: Is based both on China's first commercial domestic nuclear reactor design, the CNP-300 and the M310 reactor design used in Daya Bay Nuclear Power Plant . The reactor has a capacity of 650 MW, a 2-loop design and 121 fuel assemblies. Other features include single containment, 40-year design life and a 12-month fuel cycle. The first CNP-600 unit began operation at Qinshan Nuclear Power Plant in 2002, with other 3 units coming online between 2004 and 2011. There have been built two further CNP-600 reactors at Changjiang Nuclear Power Plant , which went into regular operation in 2015 and 2016. From

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1650-402: Is generated per unit of uranium ore even though a higher burnup can be achieved. Nuclear reprocessing can "stretch" the fuel supply of both natural uranium and enriched uranium reactors but is virtually only practiced for light water reactors operating with lightly enriched fuel as spent fuel from e.g. CANDU reactors is very low in fissile material. Because water acts as a neutron moderator, it

1725-432: Is more dense (more collisions will occur). The use of water as a moderator is an important safety feature of PWRs, as an increase in temperature may cause the water to expand, giving greater 'gaps' between the water molecules and reducing the probability of thermalization — thereby reducing the extent to which neutrons are slowed and hence reducing the reactivity in the reactor. Therefore, if reactivity increases beyond normal,

1800-401: Is not possible to build a fast-neutron reactor with a PWR design. A reduced moderation water reactor may however achieve a breeding ratio greater than unity, though this reactor design has disadvantages of its own. Spent fuel from a PWR usually has a higher content of fissile material than natural uranium. Without nuclear reprocessing , this fissile material cannot be used as fuel in

1875-527: Is on an 18–24 month cycle. Approximately one third of the core is replaced each refueling, though some more modern refueling schemes may reduce refuel time to a few days and allow refueling to occur on a shorter periodicity. In PWRs reactor power can be viewed as following steam (turbine) demand due to the reactivity feedback of the temperature change caused by increased or decreased steam flow. (See: Negative temperature coefficient .) Boron and cadmium control rods are used to maintain primary system temperature at

1950-465: Is used as the primary coolant in a PWR. Water enters through the bottom of the reactor's core at about 548  K (275 °C; 527 °F) and is heated as it flows upwards through the reactor core to a temperature of about 588 K (315 °C; 599 °F). The water remains liquid despite the high temperature due to the high pressure in the primary coolant loop, usually around 155 bar (15.5  MPa 153  atm , 2,250  psi ). The water in

2025-492: The CGN ACPR-1000 design, while allowing some differences, under direction of the Chinese nuclear regulator. Both are three-loop designs originally based on the same French M310 design used in Daya Bay with 157 fuel assemblies, but went through different development processes (CNNC's ACP-1000 has a more domestic design with 177 fuel assemblies while CGN's ACPR-1000 is a closer copy with 157 fuel assemblies). In early 2014, it

2100-595: The Fuqing Nuclear Power Plant was the first Hualong One to enter commercial service on 30 January 2021. Hualong One is jointly developed by the China National Nuclear Corporation (CNNC) and China General Nuclear Power Group (CGN), based on the three-loop ACP1000 of CNNC and ACPR1000 of CGN, which in turn are based on the French M310 . Since 2012, CNNC has been progressively merging its ACP-1000 nuclear power station design with

2175-562: The Oak Ridge National Laboratory for use as a nuclear submarine power plant with a fully operational submarine power plant located at the Idaho National Laboratory . Follow-on work was conducted by Westinghouse Bettis Atomic Power Laboratory . The first purely commercial nuclear power plant at Shippingport Atomic Power Station was originally designed as a pressurized water reactor (although

2250-758: The United Kingdom Office for Nuclear Regulation (ONR) started their Generic Design Assessment process for the Hualong One, expected to be completed in 2021, in advance of possible deployment at the Bradwell nuclear power station site. On 16 November 2017, the ONR and the Environment Agency announced they are progressing to the next phase of their Generic Design Assessment of the UK HPR1000 reactor. Step 2 formally commenced on this day and

2325-452: The supercritical water reactor , is even less moderated. A less moderated neutron energy spectrum does worsen the capture/fission ratio for U and especially Pu, meaning that more fissile nuclei fail to fission on neutron absorption and instead capture the neutron to become a heavier nonfissile isotope, wasting one or more neutrons and increasing accumulation of heavy transuranic actinides, some of which have long half-lives. After enrichment,

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2400-531: The uranium dioxide ( UO 2 ) powder is fired in a high-temperature, sintering furnace to create hard, ceramic pellets of enriched uranium dioxide. The cylindrical pellets are then clad in a corrosion-resistant zirconium metal alloy Zircaloy which are backfilled with helium to aid heat conduction and detect leakages. Zircaloy is chosen because of its mechanical properties and its low absorption cross section. The finished fuel rods are grouped in fuel assemblies, called fuel bundles, that are then used to build

2475-482: The ACPR1000) but the design is considered to be standardised. CNNC version emphasizes more passive safety due to influence from Westinghouse AP1000, with increased containment volume and two active safety trains, while CGN version has three active safety trains due to influence from Areva EPR. Some 90% of its components will be made domestically. The Hualong One power output will be 1170 MWe gross, 1090 MWe net, with

2550-537: The CNP-1000 were later built at Fuqing NPP . Further work on the CNP-1000 was stopped in favour of the ACP-1000. In 2013, CNNC announced that it had independently developed the ACP-1000, with Chinese authorities claiming full intellectual property rights over the design. The reactor has a gross output of 1100MW, a 3-loop design and 177 fuel assemblies (12 ft active length), and is designed to operate on an 18-month refuelling cycle for economic competitiveness. As

2625-514: The CNP-600, CNNC developed a Generation III successor named the ACP-600. Similar to the CNP-600, the reactor will contain 121 fuel assemblies, but will be designed to operate on a longer 18-24 month fuel cycle. Other features include double containment, active and passive safety systems, improved response capability in the case of a station blackout event, digital instrumentation and control, and

2700-436: The Chinese nuclear regulator review panel classified the design as a Generation III reactor design, with independently owned intellectual property rights. As a result of the success of the merger, ACP-1000 and ACPR-1000 designs are no longer being offered. After the merger, both companies retain their own supply chain and their versions of the Hualong One will differ slightly (units built by CGN will retain some features from

2775-580: The European Utility Requirements (EUR) organisation formally certified the Hualong One (HPR1000) as compliant after a four-step process which began in August 2017. The requirements covered a broad range of conditions for nuclear power plants to operate efficiently and safely. In February 2022, UK regulators announced that the Hualong One (HPR1000) had passed the four-step Generic Design Assessment (GDA) which started in August 2017 and

2850-606: The Hualong One has a construction cost of CNY17,000 per kW. A the end of August 2014, Chinese regulators were satisfied that Hualong One was a Generation III design and that intellectual property rights were fully held in China. Chinese media reports that all core components are manufactured in China and that 17 universities and research institutions, 58 state-owned enterprises and over 140 private firms across China worked on Hualong One's development to ensure all core components were able to be produced domestically. In November 2021,

2925-569: The United States are considered Generation II reactors . Russia's VVER reactors are similar to US PWRs, but the VVER-1200 is not considered Generation II (see below). France operates many PWRs to generate the bulk of its electricity. Several hundred PWRs are used for marine propulsion in aircraft carriers , nuclear submarines and ice breakers . In the US, they were originally designed at

3000-460: The containment building was a major concern, though the reactors at the plant were BWRs , which owing to the steam at the top of the pressure vessel by design carry a greater risk of this happening. Some reactors contain catalytic recombiners which let the hydrogen react with ambient oxygen in a non-explosive fashion. Hualong One The Hualong One ( Chinese : 华龙一号 ; pinyin : Huálóng yī hào ; lit. 'China Dragon №1')

3075-426: The core of the reactor. A typical PWR has fuel assemblies of 200 to 300 rods each, and a large reactor would have about 150–250 such assemblies with 80–100 tons of uranium in all. Generally, the fuel bundles consist of fuel rods bundled 14 × 14 to 17 × 17. A PWR produces on the order of 900 to 1,600 MW e . PWR fuel bundles are about 4 meters in length. Refuelings for most commercial PWRs

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3150-544: The desired point. In order to decrease power, the operator throttles shut turbine inlet valves. This would result in less steam being drawn from the steam generators. This results in the primary loop increasing in temperature. The higher temperature causes the density of the primary reactor coolant water to decrease, allowing higher neutron speeds, thus less fission and decreased power output. This decrease of power will eventually result in primary system temperature returning to its previous steady-state value. The operator can control

3225-399: The fast fission neutrons to be slowed (a process called moderation or thermalizing) in order to interact with the nuclear fuel and sustain the chain reaction. In PWRs the coolant water is used as a moderator by letting the neutrons undergo multiple collisions with light hydrogen atoms in the water, losing speed in the process. This "moderating" of neutrons will happen more often when the water

3300-524: The first power plant connected to the grid was at Obninsk , USSR), on insistence from Admiral Hyman G. Rickover that a viable commercial plant would include none of the "crazy thermodynamic cycles that everyone else wants to build". The United States Army Nuclear Power Program operated pressurized water reactors from 1954 to 1974. Three Mile Island Nuclear Generating Station initially operated two pressurized water reactor plants, TMI-1 and TMI-2. The partial meltdown of TMI-2 in 1979 essentially ended

3375-559: The flawed RBMK control rods design. These design flaws, in addition to operator errors that pushed the reactor to its limits, are generally seen as the causes of the Chernobyl disaster . The Canadian CANDU heavy water reactor design have a slight positive void coefficient, these reactors mitigate this issues with a number of built-in advanced passive safety systems not found in the Soviet RBMK design. No criticality could occur in

3450-515: The growth in new construction of nuclear power plants in the United States for two decades. Watts Bar unit 2 (a Westinghouse 4-loop PWR) came online in 2016, becoming the first new nuclear reactor in the United States since 1996. The pressurized water reactor has several new Generation III reactor evolutionary designs: the AP1000 , VVER-1200, ACPR1000+, APR1400, Hualong One , IPWR-900 and EPR . The first AP1000 and EPR reactors were connected to

3525-460: The heaters or emptying the pressurizer. Pressure transients in the primary coolant system manifest as temperature transients in the pressurizer and are controlled through the use of automatic heaters and water spray, which raise and lower pressurizer temperature, respectively. The coolant is pumped around the primary circuit by powerful pumps. These pumps have a rate of ~100,000 gallons of coolant per minute. After picking up heat as it passes through

3600-518: The most deployed type of reactor globally, allowing for a wide range of suppliers of new plants and parts for existing plants. Due to long experience with their operation they are the closest thing to mature technology that exists in nuclear energy. PWRs - depending on type - can be fueled with MOX-fuel and/or the Russian Remix Fuel (which has a lower Pu and a higher U content than "regular" U/Pu MOX-fuel) allowing for

3675-430: The neutron activity correspondingly. An entire control system involving high pressure pumps (usually called the charging and letdown system) is required to remove water from the high pressure primary loop and re-inject the water back in with differing concentrations of boric acid. The reactor control rods, inserted through the reactor vessel head directly into the fuel bundles, are moved for the following reasons: to start up

3750-480: The nucleus of a boron-10 atom which subsequently splits into a lithium-7 and tritium atom. Pressurized water reactors annually emit several hundred curies of tritium to the environment as part of normal operation. Natural uranium is only 0.7% uranium-235, the isotope necessary for thermal reactors. This makes it necessary to enrich the uranium fuel, which significantly increases the costs of fuel production. Compared to reactors operating on natural uranium, less energy

3825-615: The power grid in China in 2018. In 2020, NuScale Power became the first U.S. company to receive regulatory approval from the Nuclear Regulatory Commission for a small modular reactor with a modified PWR design. Also in 2020, the Energy Impact Center introduced the OPEN100 project, which published open-source blueprints for the construction of a 100 MW electric nuclear power plant with

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3900-432: The pressure drop across the turbine, and hence the energy extracted from the steam, is maximized. Before being fed into the steam generator, the condensed steam (referred to as feedwater) is sometimes preheated in order to minimize thermal shock. The steam generated has other uses besides power generation. In nuclear ships and submarines, the steam is fed through a steam turbine connected to a set of speed reduction gears to

3975-518: The pressure vessel must be repaired or replaced. This might not be practical or economic, and so determines the life of the plant. Additional high pressure components such as reactor coolant pumps, pressurizer, and steam generators are also needed. This also increases the capital cost and complexity of a PWR power plant. The high temperature water coolant with boric acid dissolved in it is corrosive to carbon steel (but not stainless steel ); this can cause radioactive corrosion products to circulate in

4050-419: The pressurized steam is fed through a steam turbine which drives an electrical generator connected to the electric grid for transmission. After passing through the turbine the secondary coolant (water-steam mixture) is cooled down and condensed in a condenser . The condenser converts the steam to a liquid so that it can be pumped back into the steam generator, and maintains a vacuum at the turbine outlet so that

4125-414: The pressurizer temperature and the highest temperature in the reactor core) of 30 °C (54 °F). As 345 °C is the boiling point of water at 155 bar, the liquid water is at the edge of a phase change. Thermal transients in the reactor coolant system result in large swings in pressurizer liquid/steam volume, and total pressurizer volume is designed around absorbing these transients without uncovering

4200-441: The primary circuit is maintained by a pressurizer, a separate vessel that is connected to the primary circuit and partially filled with water which is heated to the saturation temperature (boiling point) for the desired pressure by submerged electrical heaters. To achieve a pressure of 155 bars (15.5 MPa), the pressurizer temperature is maintained at 345 °C (653 °F), which gives a subcooling margin (the difference between

4275-423: The primary coolant loop. This not only limits the lifetime of the reactor, but the systems that filter out the corrosion products and adjust the boric acid concentration add significantly to the overall cost of the reactor and to radiation exposure. In one instance, this has resulted in severe corrosion to control rod drive mechanisms when the boric acid solution leaked through the seal between the mechanism itself and

4350-406: The primary system. Due to the requirement to load a pressurized water reactor's primary coolant loop with boron, undesirable radioactive secondary tritium production in the water is over 25 times greater than in boiling water reactors of similar power, owing to the latter's absence of the neutron moderating element in its coolant loop. The tritium is created by the absorption of a fast neutron in

4425-432: The reactor coolant and control the reactor power by adjusting the reactor coolant flow rate. PWR reactors are very stable due to their tendency to produce less power as temperatures increase; this makes the reactor easier to operate from a stability standpoint. PWR turbine cycle loop is separate from the primary loop, so the water in the secondary loop is not contaminated by radioactive materials. PWRs can passively scram

4500-422: The reactor core where it is heated by the energy released by the fission of atoms. The heated, high pressure water then flows to a steam generator , where it transfers its thermal energy to lower pressure water of a secondary system where steam is generated. The steam then drives turbines, which spin an electric generator. In contrast to a boiling water reactor (BWR), pressure in the primary coolant loop prevents

4575-455: The reactor core, the primary coolant transfers heat in a steam generator to water in a lower pressure secondary circuit, evaporating the secondary coolant to saturated steam — in most designs 6.2 MPa (60 atm, 900  psia ), 275 °C (530 °F) — for use in the steam turbine. The cooled primary coolant is then returned to the reactor vessel to be heated again. Pressurized water reactors, like all thermal reactor designs, require

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4650-403: The reactor in case offsite power is lost to immediately stop the primary nuclear reaction. The control rods are held by electromagnets and fall by gravity when current is lost; full insertion safely shuts down the primary nuclear reaction. PWR technology is favoured by nations seeking to develop a nuclear navy; the compact reactors fit well in nuclear submarines and other nuclear ships. PWRs are

4725-428: The reactor, to shut down the primary nuclear reactions in the reactor, to accommodate short term transients, such as changes to load on the turbine, The control rods can also be used to compensate for nuclear poison inventory and to compensate for nuclear fuel depletion. However, these effects are more usually accommodated by altering the primary coolant boric acid concentration. In contrast, BWRs have no boron in

4800-431: The reduced moderation of neutrons will cause the chain reaction to slow down, producing less heat. This property, known as the negative temperature coefficient of reactivity, makes PWR reactors very stable. This process is referred to as 'Self-Regulating', i.e. the hotter the coolant becomes, the less reactive the plant becomes, shutting itself down slightly to compensate and vice versa. Thus the plant controls itself around

4875-402: The same French M310 design used in Daya Bay with 157 fuel assemblies, but went through different development processes (CNNC's ACP-1000 has a more domestic design with 177 fuel assemblies while CGN's ACPR-1000 is a closer copy with 157 fuel assemblies). In early 2014, it was announced that the merged design was moving from preliminary design to detailed design. Power output will be 1150 MWe, with

4950-426: The steady state operating temperature by addition of boric acid and/or movement of control rods. Reactivity adjustment to maintain 100% power as the fuel is burned up in most commercial PWRs is normally achieved by varying the concentration of boric acid dissolved in the primary reactor coolant. Boron readily absorbs neutrons and increasing or decreasing its concentration in the reactor coolant will therefore affect

5025-427: The steam system and pressure inside the primary coolant loop. In a PWR, there are two separate coolant loops (primary and secondary), which are both filled with demineralized/deionized water. A boiling water reactor, by contrast, has only one coolant loop, while more exotic designs such as breeder reactors use substances other than water for coolant and moderator (e.g. sodium in its liquid state as coolant or graphite as

5100-409: The void coefficient is positive, and fairly large, making it very hard to regulate when the reaction begins to run away. The RBMK reactors also have a flawed control rods design in which during rapid scrams, the graphite reaction enhancement tips of the rods would displace water at the bottom of the reactor and locally increase reactivity there. This is called the "positive scram effect" that is unique to

5175-414: The walls of these tubes to the lower pressure secondary coolant located on the shell side of the exchanger where the secondary coolant evaporates to pressurized steam. This transfer of heat is accomplished without mixing the two fluids to prevent the secondary coolant from becoming radioactive. Some common steam generator arrangements are u-tubes or single pass heat exchangers. In a nuclear power station,

5250-489: The water from boiling within the reactor. All light-water reactors use ordinary water as both coolant and neutron moderator . Most use anywhere from two to four vertically mounted steam generators; VVER reactors use horizontal steam generators. PWRs were originally designed to serve as nuclear marine propulsion for nuclear submarines and were used in the original design of the second commercial power plant at Shippingport Atomic Power Station . PWRs currently operating in

5325-409: Was announced that the merged design was moving from preliminary design to detailed design. Power output will be 1150 MWe, with a 60-year design life, and would use a combination of passive and active safety systems with a double containment. CNNC's 177 fuel assembly design was retained. Initially the merged design was to be called the ACC-1000, but ultimately it was named Hualong One. In August 2014

5400-467: Was connected to the grid on 10 January 2023. China's State Council approved the construction of six Hualong One units for Ningde (5 & 6), Shidaowan (1 & 2), and Zhangzhou (3 & 4). There are five Hualong One reactors planned for Pakistan , four reactors are planned at Karachi Nuclear Power Complex and one reactor at Chashma Nuclear Power Plant , out of which two are under construction at Karachi. Construction of another Hualong One reactor

5475-541: Was planned to start in 2020 in Argentina , but was stalled during negotiation. The project was reactivated in 2021 and expected to start construction in mid 2022, with completion date by 2028. In December 2015, CGN and CNNC agreed to create Hualong International Nuclear Power Technology Co as a joint venture to promote the Hualong One in overseas markets, which was officially launched in March 2016. On 19 January 2017,

5550-484: Was the first Chinese nuclear reactor to be exported, with the installation of the first unit at Chashma Nuclear Power Plant in Pakistan . The unit began operation in 2000. Another unit was completed in 2011 and two more units began operation in 2016 and 2017 at the same plant. The CNP-600 is a generation II reactor pressurized water nuclear reactor developed by the China National Nuclear Corporation (CNNC). It

5625-667: Was thus suitable for construction in the UK, possibly in the Bradwell B nuclear power station project. The Office for Nuclear Regulation issued a Design Acceptance Confirmation (DAC) and the UK Environment Agency issued a Statement of Design Acceptability (SoDA). The first units to be constructed will be Fuqing 5 and 6 (Fujian Province), followed by Fangchenggang 3 and 4 (Guangxi), Zhangzhou 1 and 2 (Fujian), Taipingling 1 and 2 (Guangdong), and San'Ao 1 and 2 (Zhejiang). Fuqing 5 began commercial operation on 30 January 2021. CGN's first Hualong One reactor (HPR1000)

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