Meeting the Qualified Life Challenge

It is proposed that use of a ´standard´ activation energy (in the range of 0.6 to 0.8 eV), selected by consensus, be adopted as an acceptable method of thermal aging analysis of safety-related equipment; the rationale for this proposal is given. Minor improvements of current practices for simulating the functional degradation of other stresses are suggested. It is recommended that utilities establish schedules for reevaluation of qualified life on the basis of operating experience and that such evaluations be documented. It is further recommended that more effort be placed on degradation monitoring. Adoption of these recommendations is expected to redistribute the cost of equipment qualification into more productive avenues. Ultimately, they are expected to provide increased assurance of plant safety coupled with increased reliability and availability and reduced operating costs.