Document: NRC Regulatory Guide
Document ID: da2e0703-3488-44b0-b6d0-089aac7cae3d
Document Type: regulatory_guide
Title: Format and Content of Plant-Specific Pressurized Thermal Shock Safety Analysis Reports for Pressurized Water Reactors
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740028.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.154
CFR Part: 
CFR Title: 

Content:
The s t a f f has determined t h a t t h i s DBA approach i s not appropriate f o r plant-specific PTS analyses because the t o t a l r i s k from a l l credible PTS events can be s i g n i f i c a n t even though each event i n d i v i d u a l l y i s less severe than the DBA. The NRC s t a f f therefore believes t h a t t h i s guide w i l l encourage licensees t o use the acceptable PRA approach and not waste time and resources on the more t r a d i t i o n a l DBA approach. 2. J u s t i f i c a t i o n o f This.Particular Guidance The NRC staff has performed prototype plant-specific analyses f o r three plants. They constitute the most detai 1 ed, thorough ana.lyses performed t o date, and the lessons learned i n t h e i r performance are r e f l e c t e d i n the guide. The NRC s t a f f has incorporated i n t o the guide descriptions o f the best methods found regarding how t o assemble d e t a i l s o f a p l a n t ' s design (and t o what level those d e t a i l s should be included), how t o use event t r e e methodologies t o i d e n t i f y and group potential PTS events, how t o calculate severity o f the events, how t o integrate the r e s u l t i n g r i s k , and many other subjects. The s t a f f believes t h a t the benefit o f t h i s experience i s presented i n t h i s guide, and i t s use by li- censees w i l l enable them t o avoid many o f the false s t a r t s and errors made by the s t a f f and t h e i r contractors i n performing the prototype analyses, thereby saving time! and resources. 3. J u s t i f i c a t i o n o f Acceptance C r i t e r i a The guide states that, i n judgi ng the acceptabi 1 i t y o f conti nued operation beyond the PTS screening c r i t e r i o n , the s t a f f w i l l accept any analyses performed w i t h acceptable methods such as those described i n the subject regulatory guide t h a t predict a through-wall crack penetration frequency less than 5 x per reactor year. The mean frequency o f reactor vessel