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:
d heat transfer regimes. 4.5 Thermal-Hydraulic Analysis Results This section should present graphs o f the best-estimate downcomer pressures, f 1 u i d temperatures, and heat transfer coefficients and t h e i r associated uncer- t a i n t y ranges as a function o f time a t the c r i t i c a l weld areas. This includes the results o f the detailed thermal-hydraulic model, the simplified model, and mixing analysis calculations. The duration assumed f o r each overcooling scenario should be j u s t i f i e d . It i s assumed t h a t a scenario duration o f 2 hours may be reasonable f o r many cases since the overcool ing transient would probably be i d e n t i f i e d and m i ti gated p r i o r t o t h a t time. However, there may be scenarios requiring lengthier evaluation periods because the control 1 i ng phenomena delay the scenario's evolution. I Also provide a discussion o f the accuracy o f the results, including a demonstration t h a t nodalization and error estimation methods chosen are appro- p r i a t e , and how the predicted p l a n t behavior compared t o p l a n t h i s t o r y and oper- ating experience. Time-dependent uncertainty estimates f o r the downcomer pres- sure, f l u i d temperature, and heat transfer coefficients a t the c r i t i c a l welds should be provided f o r each scenario. These uncertainties are often l i m i t e d by physical phenomena. For example, the pressurizer power-operated r e l i e f valve (PORV) setpoints w i l l l i m i t the system pressure f o r certain high-pressure sce- narios. Therefore, the uncertainty i s l i m i t e d by PORV operating character- i s t i c s . References 16 and 18 describe some uncertainty analysis techniques. 5. FRACTURE MECHANICS ANALYSIS For each sequence identified in Chapter 3, "Determination of Detailed PTS Sequences for Analyses," calculate (or for unimportant sequences, estimate using bounding conditions) the conditional probabi 1 i ty of through-wal 1 crack penetra- tion given the