# A Global Review of PWR Nuclear Power Plants
## 2 International Development of the PWR Design
### French PWR Evolution  
France, one of the great world powers that developed nuclear energy as a source of electricity generation, opted in the initial phase of its nuclear program for gas-cooled reactors (GCR) and fast breeder reactors (FBR). However, in collaboration with Belgium, a PWR-designed nuclear reactor is being built at the _Chooz-A_ nuclear power plant, very close to the border between the two countries [29]. Its construction began in 1961, and in 1967, the operation of the first commercial PWR nuclear reactor in Europe began. In the 1970s, several series of the PWR design [30; 31]--all of them 3-loop and 900 MWe electrical output--were developed in stages in France. These new series based on the PWR design were named CP0, CP1 and CP2. The CP0 series, fully under Westinghouse license, was only implemented during the 1970s, in the aforementioned Units 1 and 2 of _Fesenheim_ and Units 2, 3, 4, and 5 of the _Bugey_ nuclear power plant. Instead, the CP1 and CP2 series were implanted throughout the 1970s and 1980s, totaling 28 built nuclear reactors. These CP1 and CP2 series benefited from the feedback obtained from the design, construction, and operation studies of the CP0 reactors. Unlike the design studies for the CP0 series, which were conducted separately for each site, the design studies for the CP1 and CP2 series were standardized. As a result, the CP1 and CP2 series differ from the CP0 series in (i) the design of the containment building--which was modified to facilitate operations inside, (ii) the location of the designed security systems--which were modified to increase the independence of the trains from the systems and increase their reliability, and (iii) more flexible reactor control--thanks to the use of control rods and the addition of control rods with less neutron absorption capacity. Subsequently, it advanced to the plants of four primary circuits, which meant an increase in the generation capacity, reaching 1300 MWe. These new plants were called the P4 and P'4 series. The initial design of the plants named P4 was based on a Westinghouse license, of which 8 units were built throughout the 1980s. However, in the face of such an ambitious and protectionist national nuclear program, the Framatome company developed its own \"Frenchified\" version of Westinghouse's P4 series, called P'4, from which 12 units were built. The increase in power in these series P4 and P'4 was achieved by increasing the size of the reactor. To eliminate the increase in thermal power for the initial series CP0, CP1 and CP2, it was necessary to install an additional loop (thus changing from 3-loop for the CP0, CP1 and CP2 reactors from 900 MWe to 4-loop for the series P4 and P'4 of 1300 MWe). The components of each loop--mainly Reactor Coolant Pump and Generator Steam--are also larger than those of the previous series. Regarding the location of the buildings, the new series are single-unit plants, while the previous series were double-unit plants. The designed security systems and auxiliary systems are located in specific buildings of each unit to improve the safety of its operation. Additionally, each containment vessel has a double concrete wall  
Figure 9: Combustion Engineering PWR design. (one pre-stressed concrete interior wall and one reinforced concrete exterior wall) in place of the single steel-lined pre-stressed concrete wall in the 900 MWe reactors. New microprocessor-based control and instrumentation technologies using programmable memory are used. The P'4 series differs from the P4 series in that the installation of buildings and structures was optimized with the main objective of reducing costs. The result is a more complex plant design and smaller buildings and structures [32; 33]. Finally, during the eighties, the Framatome company came to implement a French design for the PWR plant: the N4 design, four new plants were built with this N4 design: two new units in _Chooz_ and another two units in _Civeaux_.