An overview of the materials issues relating to the continued operation of the Magnox steel reactor pressure vessels

摘要

Magnox reactor steel pressure vessels are assured by multi-legged deterministic safety cases which include fracture mechanics arguments requiring a knowledge of steel mechanical properties using as appropirate, best estimate and bounding values.Surveillance specimens installed when the reactors were constructed permit tensile strength, Charpy impact energies and ductile to brittle transition temperatures to be assessed. Methods have been developed to derive fracture toughness, for serviceconditions, based upon surveillance data combined with start of life properties and a knowledge of temperature and neutron dose at given assessment locations. The indirect method of determining fracture toughness and validation of predicted properties by use of samples removed from a decommissioned vessel is described.