Japanese surveillance database

In Japan, the Japan Electric Association Code, JEAC 4201, Method of Surveillance Tests for Structural Materials of Nuclear Reactors (JEAC 4201, 2007), specifies the design for a surveillance program to monitor radiation-induced changes in mechanical properties of beltline materials in light-water moderated nuclear power reactor vessels testing and evaluation of the test results. The JEAC 4201 was developed based on the ASTM E 185 for nuclear power RPVs for which the predicted maximum neutron fluence at the end of the operating period (usually 32 EFPY unless otherwise identified) exceeds 1 x 10 n/cm E IMeV) at the inside surface of the reactor vessels. 

The Code specifies that surveillance capsules shall be located within the reactor vessel so that the specimen history duplicates as closely as possible the neutron spectrum, the temperature history and the maximum neutron flux experienced by the reactor vessel. A sufficient number of surveillance capsules shall be provided to monitor the effect of neutron radiation on the reactor vessel materials, that is, the transition temperature shift, ARTndt and the decrease in USE throughout its operating period. A minimum number of capsules is specified depending on the predicted ARTndt value of each testing material at the inside surface of the beltUne of the reactor vessel. In this section, the Japanese surveillance tests program is reviewed. The details of the JEAC 4201 can be found elsewhere (Tomimatsu et al., 2006). Table 4.8 summarizes major revisions of the JEAC 4201. 

SA508 Class 3 forging, have been used for the shells of Japanese PWR vessels. The latter steel has been used for about 30 years in order to exclude weldments in the vessel beltline region. 

1970 Base metal taken from one of materials used in fabricating the RPV beltline Weld metal from one longitudinal weld 1980 Beltline base metal 

Base metal parallel to maximum principal stress 

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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. 

Table 4.12 Japanese PWR surveillance database (base metal)...

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