Status of “Low Power and Shutdown PRA Methodology Standard ANSI/ANS-58.22”

The American Nuclear Society is developing a standard titled “Low Power and Shutdown PRA Methodology, ANSI/ANS-58.22.” It has been under development for more than 10 years now. During this time, drafts of the standard have been balloted by the ANS American Nuclear Society (ANS) Risk-Informed Safety Committee (RISC) on three different occasions; i.e., in 2005, 2006, and 2008. The most recent of these ballots occurred in November 2008; i.e., Reference 1. Each ballot failed to achieve a consensus for approval and numerous comments were received for improvement. Since the completion of the ballot on Version 8C in 2008, the Low Power and Shutdown (LPSD) writing group has been working on a volunteer basis to respond to the approximately 600 comments received and to revise the Standard for future ballot. A revised standard was completed in early November 2009. This latest draft was submitted in November 2009 to the ANS RISC pending a formal ballot for informal review. The intention of this informal review is to ascertain if members of the balloting RISC committee could support the revised standard and if not, to identify those issues for further work by the writing group. For approval of ANS standards, a consensus for approval must be received among all stakeholder groups, rather than a simple majority to approve.