Engineering judgement and bridging the fire safety gap in existing nuclear facilities

Canadian nuclear power plants were constructed in the 1960's through the 1980's. Fire safety considerations were largely based on guidance from general building and fire codes in effect at the time. Since then, nuclear specific fire safety standards have been developed and adopted by the Regulator, increasing the expected level of fire safety in the process. Application of the standards to existing plants was largely limited to operational requirements viewed as retroactive. However, as existing facilities undergo modifications or refurbishment for the purpose of life extension, the expectation is that the design requirements of these fire safety standards also be satisfied. This creates considerable challenges for existing nuclear power plants as fire safety requirements such as those intended to assure means for safe egress, prevention of fire spread and protection of redundancy rely upon fire protection features that are inherent in the physical infrastructural design. This paper focuses on the methodology for conducting fire safety gap analyses on existing plants, and the integral role that engineering judgement plays in the development of viable and cost effective solutions to achieve the objectives of the current fire safety standards. (author)