3.1.1 Pressurized Water Reactors

Pressurized water reactors (PWRs) were originally designed to serve as nuclear submarine power plants and were commercialized to large-sized ones currently in operation. The nuclear propulsion allowed submarines to remain submerged without refueling for far longer than oil-fueled vessels. The Argonne National Laboratory (ANL) of the USA found out in the early research that a small reactor with enriched uranium and pressurized water was available to submarines. The development of a nuclear submarine was triggered by the Westinghouse Corpora­tion (WH) as the contractor of the United States navy in 1949. A land-based prototype nuclear propulsion reactor reached criticality at the National Reactor

Y. Oka (ed.), Nuclear Reactor Design, An Advanced Course in Nuclear Engineering 2, DOI 10.1007/978-4-431-54898-0_3, © Authors 2014

Testing Station (NRTS) in the Idaho desert in 1953. The world’s first nuclear — powered submarine, the USS Nautilus, was launched in 1955 and accomplished the first undersea voyage to the North Pole in summer, 1958.

The first prototype PWR for electric power generation was Shippingport Atomic Power Station built by the Atomic Energy Commission (AEC) and the WH, located near Pittsburgh, USA and operated from December 1957. The electric power was 60 MWe and supplied to the Pittsburgh city.

The first commercial PWR based on the technology, Yankee Rowe (185 MWe), began commercial operation in 1961. Connecticut Yankee (575 MWe) was ordered in 1963 and San Onofre (600 MWe) followed. In Japan, Mihama Unit 1 of the Kansai Electric Power Company started operation as the first Japanese PWR in 1970. The WH also developed a 20 MW-Saxton test reactor and applied to improvement in PWR.

The history of PWR technology is summarized in Fig. 3.1 and Table 3.1. For a higher power PWR, a scheme was devised in which the number of primary coolant loops increases as the power class was upgraded without increasing the capacity of the primary coolant pumps or steam generators: two loops for 600 MWe class, three loops for 800-900 MWe class, and four loops for 1,100 MWe class. Yankee Rowe reactor had a cruciform type control rod design which was inserted between fuel assemblies. Since Connecticut Yankee reactor, however, the current cluster type design for control rods has been employed in PWRs worldwide. Stainless steel was

PCCV prestressed concrete containment vessel, RCCV reinforced concrete containment vessel

used as fuel cladding material in the beginning and then zirconium alloy was developed and it is still used today. Fuel rods was made thinner in diameter and subsequently a larger number of fuel rods can be loaded into fuel assemblies. Improvements for achieving high burnup are still in progress by further by decreas­ing the fuel rod load.

The PWRs developed by the WH were introduced and improved in France and Germany (former West Germany). In the USA, the Babcock & Wilcox Corporation (B&W) and the Combustion Engineering Corporation (CE) also developed and built PWR design power plants. The CE-PWR design is similar to the WH-PWR one, but it has two steam generators even in a large class reactor. PWRs in Korea were based on the CE-PWR design. The PWR design developed in Russia, referred to as the VVER, features a hexagonal lattice fuel assembly, a hollow fuel, and a horizontal steam generator, and so on. China proceeds in parallel to independent PWR development based on the WH-PWR design and PWR construction by foreign companies from France and Russia.