Doel 3 & Tihange 2 - Some Peer-reviewed Scientific Papers & Reports

Hydrogen-induced Damage in PWR Reactor Pressure Vessels

W.F. Bogaerts (1) , J.H. Zheng (2) , A.S. Jovanovic (3) & D.D. Macdonald (4)

(1) University of Leuven – Dept. of Materials Engineering & Center for Nuclear Technology (Belgium) (2) Technologica Group – INS, Intelligent Nuclear Solutions Div. (Belgium) (3) Eu-VRi – European Virtual Institute for Integrated Risk Management (Germany) (4) University of California, Berkeley – Dept. of Nuclear Engineering, Berkeley, CA 94720 (USA) Recently, the potential problem of (hydrogen-related) cracks in RPV-steels has become imminent in the Belgian nuclear power reactors Doel 3 and Tihange 2. This communication briefly elaborates on some reported findings and identifies possible mechanisms for the detected flaws in the reactor pressure vessel walls. Stress corrosion cracking, pitting corrosion, and other materials degradation mechanisms in reactor coolant system components have cost the nuclear industry billions of dollars, due to forced and extended outages, component repair and replacement, and increased inspection requirements and regulatory scrutiny. Materials aging effects must be effectively managed to ensure that safe and reliable functionality is maintained throughout the life of the plant, especially if life extension of nuclear power plants (NPP) is contemplated. In this respect, specific R&D activities on plant integrity and materials reliability have been launched in recent years 1 . Since mid-2012, however, the situation for a number of PWR plants may have dramatically changed. Ultrasonic inspections of the Reactor Pressure Vessels (RPV) at the Belgian PWR nuclear power plants Doel 3 and Tihange 2 (1000 MWe), which started operation in 1982-1983, have revealed a large number of (small) cracks in the RPV wall 2 , causing the operator and the national regulatory authority FANC (Federal Agency for Nuclear Control) to shut down the reactors and commence further testing. Other plants around the world, both in the US and Europe, are operating reactor pressure vessels manufactured by the same company or using steels from the same producer (at least 22 in total). Introduction

Figure 1: Illustration translated from FANC, showing the original forged steel ring sections of the RPV separated for clarity. These rings are welded together and cladded internally with a stainless steel lining to form the reactor pressure vessel.

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