An Approach to Reducing Cost of an EQ Programme

Abstract

Environmental qualification of equipment in a nuclear power plant includes a requirement to preserve the status of all qualified components. This requirement adds a maintenance burden and an expense to ongoing operations. All qualified equipment has special purchase, storage and maintenance requirements, all of which add to operating costs. Thus, it is essential that only those components with credited safety functions, which require execution in harsh accident environments, are considered for environmental qualification. Every opportunity to reduce the number of components that are to be qualified should be taken. Review of the Safety Report can often lead to the identification of components which do not have a safety function but have been included on the EQ list for other reasons. These can be removed, leading to a shorter list of components requiring environmental qualification. The list is then culled to remove components that do not have to perform a safety function in a harsh accident environment or that do not have an adverse failure mode. All revisions to the room conditions manual should be reviewed because a component that was previously considered to be in a harsh environment could now be shown as being in a mild one. In that case it could be removed from the EQL. This paper also discusses the approach taken to perform an efficient reduction of components in an EQL (Environmental Qualification List) that was previously created using overly conservative considerations. Any removal has to be justified through auditable documentation. Since the same or similar justification can apply to many components in many systems, a generic procedure was prepared, with a spectrum of common reduction approaches. Using this generic procedure, in conjunction with the Safety Report and the Design Manuals, allowed efficient modification of the EQL development packages. Documenting the justification for removing a component was accomplished by simply identifying the relevant methods in the generic procedure. This also ensured that all possible reasons for removal were considered. Other possible means for reducing EQ related requirements are also mentioned.