PROPOSED DETERMINISTIC SEVERE ACCIDENT CRITERIA FOR THE HEAVY-WATER REACTOR - NEW PRODUCTION REACTOR CONTAINMENT

This article summarizes the methodology developed by the Deterministic Severe Accident Criterion (DSAC) Development Project to assist the De partment of Energy's (DOE's) Office of Heavy Water Reactor (HWR) in fo rmulating containment design criteria for the New Production Reactor-H eavy Water Reactor (NPR-HWR). For a practical implementation of high-l evel programmatic goals, these DSACs represent a new approach because they address severe accidents early in the design phase of the nuclear plant. This article describes a process and an approach that consider s severe accidents in containment design by establishing practical des ign requirements based on calculations of stylized loads on the contai nment. The DSAC Development Project utilized a formal expert opinion p rocess to provide a quantitative specification of the severity of the loads and a reviewable technical basis. The goals for the project were to (1) generate specific proposals for quantitative criteria within t he specified project schedule; (2) minimize the phenomenological uncer tainty residing in the problem statements and success criteria so that the design's compliance with the criteria would not be the subject of protracted contention; (3) follow a formal plan consisting of well-de fined steps, each of which was scrutable and reviewable; (4) ensure th at the complete spectrum of credible severe accident threats was cover ed by the criteria; and (5) avoid over-constraining the design. As a r esult of the output of this process, the DOE's Office of Heavy Water R eactor was able to integrate the project recommendations with numerous other inputs to promulgate design criteria that were conservative, bu t not excessively so, and that could be technically reviewed and defen ded.