Westinghouse Pressurized Water Reactors: Fueling The Future With Uranium

Westinghouse is a world leader in delivering pressurized water reactor (PWR) nuclear fuel. PWRs are a type of light-water nuclear reactor that uses water as a neutron moderator and a coolant fluid for the reactor core. Westinghouse's PWRs are fueled by uranium dioxide (UO2) powder, which is fired in a high-temperature sintering furnace to create hard, ceramic pellets. These pellets are then clad in a corrosion-resistant zirconium metal alloy called Zircaloy. Westinghouse's PWRs are known for their innovative designs, advanced fuel features, and ability to support a changing market. The company has fuel fabrication facilities in the United States, Sweden, and the UK, delivering reliable fuel that meets the evolving needs of the nuclear industry.

Westinghouse is the world leader in PWR nuclear fuel

Westinghouse's PWR nuclear fuel is known for its innovative designs and technology, ensuring its dominance in the market. The company's robust fuel designs incorporate a range of proven and advanced fuel features, including fuel rods that have consistently demonstrated unrivalled performance. These components empower operating plants to customize their designs to optimize fuel cycles based on their specific requirements.

The Westinghouse High Energy Fuel Program is a testament to the company's leadership in PWR nuclear fuel. This program offers a comprehensive suite of products, technologies, and solutions that meet the evolving needs of the industry. It prioritizes safety, cost-effectiveness, and reliability, with features such as high-performance cladding that inhibits the zirconium-steam reaction and increases the maximum temperature.

Westinghouse's PWR fuel technology also includes the development of advanced fuel rod materials, such as silicon-carbide cladding, which boasts an extremely high melting point and minimal reaction with water and steam. The company's EnCore® Fuel program leverages these advancements to enhance safety and economics further.

Westinghouse's PWR nuclear fuel is not just about innovation; it's also about customization and flexibility. The company offers a wide array of PWR core components, enabling plants to customize their designs and optimize fuel cycles. With decades of experience, Westinghouse delivers excellent performance and enhances operational flexibility for its customers.

PWRs use light water as a coolant and moderator

Westinghouse's pressurized water reactors (PWRs) use light water as a coolant and moderator. PWRs are a type of light-water nuclear reactor, and constitute the majority of the world's nuclear power plants.

In a PWR, light water is used as a neutron moderator and as a coolant fluid for the reactor core. The water is heated by the energy released by the fission of atoms contained in the fuel. The use of high pressure (around 155 bar) ensures that the water stays in a liquid state. The heated water then flows to a steam generator, where it transfers its thermal energy to the water of a secondary cycle, which is kept at a lower pressure to allow it to vaporize. The resulting steam drives steam turbines linked to an electric generator.

The use of light water as a moderator and coolant is an important safety feature of PWRs. If the reactivity increases beyond normal, 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 PWRs very stable.

Westinghouse PWRs can be fueled with MOX-fuel and/or the Russian Remix Fuel, allowing for a (partially) closed nuclear fuel cycle. Westinghouse is a world leader in delivering PWR nuclear fuel, with innovative designs and technology to support a changing market. Their PWR fuel bundles are about 4 meters in length, and they offer a range of core components for different markets.

The use of water as a coolant and moderator has several advantages. Water is nontoxic, transparent, chemically unreactive, and liquid at room temperature, making visual inspection and maintenance easier. It is also easy and cheap to obtain, in contrast to heavy water or nuclear graphite.

PWRs are the most deployed type of reactor globally

Pressurized water reactors (PWRs) are the most deployed type of reactor globally, with about 300 operable reactors for power generation and several hundred more used for marine propulsion. PWRs make up almost 70% of the global reactor fleet. The design is distinguished by having a primary cooling circuit that flows through the core of the reactor and a secondary circuit in which steam is generated to drive the turbine.

PWRs were originally designed to serve as nuclear marine propulsion for nuclear submarines. The first purely commercial nuclear power plant at Shippingport Atomic Power Station was also designed as a PWR. PWRs are currently operated in the United States, France, Russia, China, South Korea, and several other countries.

The majority of PWRs are Generation II reactors, but newer Generation III designs such as the AP1000, Hualong One, EPR, and APR-1400 have entered service since 2018. PWRs are favoured by nations seeking to develop a nuclear navy due to their compact size, which makes them suitable for nuclear submarines and other nuclear ships.

Westinghouse is a world leader in delivering PWR nuclear fuel. Their robust fuel designs incorporate a variety of proven and advanced fuel features, enabling operating plants to customize designs to optimize fuel cycles based on specific requirements. Westinghouse's PWR fuel assemblies are fabricated worldwide to meet global demand and bolster the security of supply for customers.

PWRs can be fuelled with MOX-fuel

Westinghouse is the world leader in delivering Pressurized Water Reactor (PWR) nuclear fuel. PWRs can be fuelled with MOX-fuel (mixed oxide fuel) and/or the Russian Remix Fuel, which has a lower Pu-239 content and a higher U-235 content than "regular" U/Pu MOX-fuel. MOX-fuel is manufactured from plutonium recovered from used reactor fuel, mixed with depleted uranium.

MOX-fuel provides almost 5% of the new nuclear fuel used today and fuels about 10% of France's fleet. It was first used in a thermal reactor in 1963 but did not come into commercial use until the 1980s. So far, more than 2000 tonnes of MOX-fuel has been fabricated and loaded into power reactors. In 2006, about 180 tonnes of MOX-fuel was loaded into over 30 reactors (mostly PWR) in Europe. By mid-2016, over 7500 MOX-fuel assemblies had been used in over 40 reactors.

MOX-fuel is widely used in Europe and Japan. Currently, about 40 reactors in Europe (Belgium, Switzerland, Germany, and France) are licensed to use MOX-fuel, and over 30 are doing so. In Japan, about ten reactors are licensed to use it and several do so. These reactors generally use MOX-fuel as about one-third of their core, but some will accept up to 50% MOX-fuel assemblies.

The use of up to about 50% of MOX-fuel does not change the operating characteristics of a reactor, though the plant must be designed or adapted slightly to take it. More control rods are needed. For more than 50% MOX-fuel loading, significant changes are necessary, and a reactor needs to be designed accordingly, as several new designs are. Burn-up of MOX-fuel is about the same as that for uranium oxide fuel.

An advantage of MOX-fuel is that the fissile concentration of the fuel and hence burn-up can be increased easily by adding a bit more plutonium, whereas enriching uranium to higher levels of U-235 is relatively expensive. As reactor operators seek to burn fuel harder and longer, increasing burn-up from around 30 GW days per tonne a few years ago to over 50 GWd/t now, MOX-fuel use becomes more attractive.

Reprocessing to separate plutonium for recycle as MOX-fuel is more economic when uranium prices are high. MOX-fuel use also becomes more attractive as the need to reduce the volume of spent fuel increases. Seven UO2 fuel assemblies give rise to one MOX-fuel assembly plus some vitrified high-level waste, resulting in only about 35% of the volume, mass, and cost of disposal.

MOX-fuel is also used in fast neutron reactors in several countries, particularly France and Russia. It was first developed for this purpose, with experimental work being done in the USA, Russia, UK, France, Germany, Belgium, and Japan. Today, Russia leads the way in fast reactor development and has long-term plans to build a new generation of fast reactors fuelled by MOX-fuel.

MOX-fuel can be used to burn weapons-grade plutonium (from military sources) to produce electricity. In the USA, MOX-fuel was used in several demonstration projects and performed acceptably and similarly to uranium oxide fuel.

Westinghouse's EnCore® Fuel program is centered on the use of high-performance features that are being developed and deployed on a strategic timeline so utilities can gain safety and cost benefits quickly. The program has begun with an improved chromium-coated cladding that inhibits the zirconium-steam reaction and increases the maximum temperature by an additional 300°C.

Westinghouse PWRs have been approved by the US Nuclear Regulatory Commission

Westinghouse's PWRs have been approved by the US Nuclear Regulatory Commission (NRC) on several occasions. In December 2005, the NRC approved the final design certification for the AP1000, a pressurized water reactor with two cooling loops. This was the first Generation III+ reactor to receive final design approval from the NRC.

In 2011, the NRC approved the construction of the first US plant to use the AP1000 design, and in February 2012, it approved the construction of two new reactors. In 2020, the NRC approved a small modular reactor with a modified PWR design developed by NuScale Power, the first US company to receive such approval.

The NRC has also approved several of Westinghouse's fuel programs for use in PWRs in the US. In July 2023, the NRC approved the reinsertion of lead test rods (LTRs) with ADOPT® fuel pellets for a third cycle of operation to achieve high burnup. This approval paved the way for achieving 75 GWd/MTU in a commercial reactor with Westinghouse's EnCore ATF technologies.

In December 2022, Westinghouse received approval from the NRC to use its AXIOM Fuel Rod Cladding in US PWRs. The AXIOM Fuel Rod Cladding offers several technical advantages, including dimensional stability, lower hydrogen pickup, and greater flexibility for coolant chemistry changes.

In November 2022, Westinghouse's ADOPT Fuel, a near-term fuel product within its EnCore Fuel program, was approved by the NRC for use in US PWRs. ADOPT Fuel's enlarged grain size and increased density result in key benefits such as increased fissile material density, higher burnups, and enhanced corrosion resistance.

Westinghouse's PWRs and fuel programs have undergone rigorous evaluation and received the necessary approvals from the NRC, ensuring their safety and compliance with US regulatory standards.

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