NPP Life Management_vs02

Hydrogen and NPP Life Management: Doel 3 and Tihange 2

Potential Effects of Process-generated Hydrogen on Reactor

Pressure Vessel Walls affected by Hydrogen Flaking

ABSTRACT – Three years after its first detection, the problem of (hydrogen-related) cracks in RPV- steels is still imminent in the Belgian nuclear power reactors Doel 3 and Tihange 2. This report briefly elaborates on some reported findings and identifies possible mechanisms for the detected flaws in the reactor pressure vessel wall and the risks for further growth of these defects. The study shows that – despite a number of counter-arguments – there are significant potential risks or uncertainties for process-generated hydrogen problems; enough to raise concerns about the fitness-for-service of the affected reactors, and also about similar reactors world-wide. Just one example are the recent findings in Swiss nuclear power plants. From a safety point of view, it should at least be recommended that meticulous inspection and continuous monitoring or surveillance programs be set up and implemented when keeping the reactors into operation.