WWER surveillance programmes

Rules and requirements for surveillance specimen programmes are summarized in two documents, which were issued in 1990 by Russian Gosatonmadzor, that are practically identical to an older document from 

4 Results of surveillance tests of weld metal with 1.7 mass % of nickel evaluated with the use of a power law and taking into account the late blooming effect. 

A comparison of the requirements for WWER- and LWR-type reactors leads to the following conclusions. Both codes and requirements have the following similarities  

The real design of individual reactors usually differs from these requirements, although in most instances no reason for such a decision has been documented. 

5 Typical containers for WWER standard surveillance programmes in WWER-440A/-213 reactor. Dimensions in mm. 

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In the Czech Republic, modification of the surveillance programme for WWER-1000/V-320C RPVs was designed and realised. The main principles of this design include the following ... 

Photograph of a surveillance container of the WWER-1000/V-320C Modified Surveillance Programme. 

For plants under construction, a modification of the surveillance programme is considered. Specimen containers will be located in positions representative of vessel wall conditions at Temelin NPP. Based on the fracture mechanics analysis, it was recommended to heat up the accumulator water to 5S°C and to prevent injection of ECCS water with temperatures below 20°C for all the plants. The use of low leakage core loading patterns in WWER-1000 reactors would reduce RPV wall fluence by approximately 30%. It was planned to introduce partial low leakage loading patterns at some plants during 1994 (fuel assemblies with high bumup to be placed at the core periphery). 

Abstract This chapter describes the embrittlement processes in WWER reactor pressure vessel (RPV) materials during operation - radiation embrittlement and thermal ageing. Current trend curves for both types of WWER RPV materials are given and explained. Surveillance specimen programmes are shown, as their results are used for RPV integrity and lifetime evaluation. Finally, anneahng of the RPV is proposed as the most efficient mitigation measure. 

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