Development of a Generic Procedure for Thermal Annealing an Embrittled Reactor Vessel Using a Dry-Annealing Method

摘要

The feasibility and methodology for thermal annealing an embrittled reactor vessel was investigated with the primary goal being to develop an in-situ thermal annealing procedure which would maximize fracture toughness recovery, minimize re-exposure sensitivity, and minimize reactor downtime. The feasibility was assessed by evaluating whether plant design and system limitations (reactor vessel design, metallurgical, reactor vessel insulation, primary shield concrete, RCS piping and associated equipment support, and reactor vessel internals and fuel storage) would be exceeded by an imposed localized 850 exp 0 F heat source. In addition, health physics problems were also considered. Finally, a conceptual thermal annealing apparatus was developed and a general thermal annealing procedure was established. The results of this work indicate that an anneal temperature of 850 exp 0 F for a holding period of 168 hours, obtained by using resistance-type heating elements attached to a support apparatus, could be used in an effort to restore the fracture toughness properties of ferritic materials of the reactor vessel as required by 10CFR Part 50 Appendix G. (ERA citation 07:053711)