Summary report on new regulatory codes and criteria and guidelines: IAEA guidelines for WWER reactor coolant system integrity assessment

In the frame of the nuclear safety programme to assist the countries of Cen tral and Eastern Europe, the IAEA identified and ranked in total 263 safety issues for WWER-440/230, WWER-440/213 and WWER-1000/320 nuclear power plan ts. related to both design and operation. In the area of reactor coolant sy stem integrity, 24 safety issues were identified and 15 of them ranked as o f high safety significance. These include: reactor pressure-vessel integrit y and related aspects? primary and secondary high-energy piping integrity, steam generator integrity and reliability of the non-destructive testing fo r in-service inspection. In addition to obtaining international consensus o n possible solutions to address the safety issues identified and to reviewi ng completeness of proposed safety improvements, the IAEA initiated develop ment of guidelines to address the issues of highest safety concern. In the area of the reactor coolant system integrity, guidelines for the leak befor e break concept application, for the pressurized thermal shock analysis and for the in-service inspection systems qualification a ere developed. Furth er activities of the IAEA were focused on the implementation of guidelines developed in the Member States concerned. With this objective, a Go-ordinat ed Research Programme 'Round-robin Exercise on WWER-440 Reactor Pressure Ve ssel Embrittlement, Annealing and Re-embrittlement', a 'WWER-440/213 Pressu rized Thermal Shock Analysis Benchmark Exercise' and a pilot study to imple ment the qualification approach to a real power plant component have been i nitiated by the IAEA and are well under way at present. In this paper, an o verview of these IAEA activities related to reactor coolant system integrit y is provided and the main principles and elements of guidelines developed discussed. (C) 2000 Elsevier Science S.A. All rights reserved.