French surveillance database

The surveillance program is specified in AFCEN RSE-M code (RSE-M, 2005,2010), and methods and practices are similar to those used in the US. The materials generally included in the surveillance capsules are those of 

Capsule - start-of-life position irradiation time (years) Equivaient time for the vessei (years) Selected base metal Weld metal HAZ Correlation monitor material 

Series Number of available locations Irradiated capsules at start-of-life Design lead factors 

In 900MWe units, the capsules are irradiated along the outer surface of the thermal shield assembly. In 1300 and 1450 MWe units, the capsules are directly attached to the core barrel. In the case of Chooz-A, the thermal shield assembly was removed in 1970 and the surveillance capsules were then located under the core. The capsules are equipped with neutron dosimeters and thermal monitors, with some variations according to the reactor series. In all cases, activation dosimeters of nickel, copper and cobalt, as well as fissile dosimeters of uranium-238 and neptunium-237 are used. This instrumentation is complemented by iron and cadmium-shielded cobalt dosimeters in most cases and, in the most recent plants, also by niobium dosimeters. Each capsule contains temperature detectors based on eutectic alloys with melting points generally of 304 and 310 °C. 

Dosimetry data are analyzed using the neutron transport code TRIPOLI in order to determine neutron fluences for energies over 1 MeV, parameter which indexes the aging results. The primary coolant temperatures are 286 °C for most 900 MWe units, 288 °C for 1300 MWe units and 293 °C for 1450 MWe units. The primary coolant temperature of Chooz-A increased from 257 to 265 °C due to a power uprate. 

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Abstract This chapter describes the surveillance database of the Western pressurized water reactor (PWR) reactor pressure vessel (RPV) beltline materials obtained from US, French and Japanese nuclear power plants (NPPs) and those from other countries, together with an overview of the characteristics of PWR RPVs. Trends of surveillance data which will be obtained in the near future and the possibility of new data from reconstituted and miniature specimen techniques are presented. 

Regarding the temperature effect, since the irradiation temperatures of French surveillance data are basically 288 °C, there is no need to include a temperature term in the correlation. Instead of using a temperature term, temperature correction, which is done by multiplying a factor, 1-0.0153(T-288), was performed on some limited data irradiated at lower temperatures than 288 °C before they were included in the database. 

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