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:
i t h each i n i t i a t o r would be reviewed t o i d e n t i f y those operator actions t h a t 7 would have an impact on downcomer temperature. 2. I d e n t i f y time constraint - I n the case o f each operator action, the transient would be reviewed assuming no operator action t o i d e n t i f y the time- frame available f o r successful comp~etion' o f the operator action. 3. Assign screening f a i l u r e p r o b a b i l i t i e s - I n t h i s step a conservative value f o r the f a i l u r e o f the operator action would be identified. For operator actions required by procedures- t o be performed w i t h i n the f i r s t 5 minutes o f the transient, the t i m e - r e l i a b i l i t y curve as presented i n NUREGKR-2815 (Ref. 7) could be used t o i d e n t i f y a screening value. After 5 minutes, a value o f 0.9 f o r success and 0.1 f o r f a i l u r e would be assumed f o r a l l operator actions. The e n t i r e PTS analysis would then be completed using these screening values. 4. I d e n t i f y dependency factors - I n some instances, there may be coupled f a i l u r e s associated w i t h operator actions j u s t as there were coupled f a i l u r e s associated with equipment failures. I n many instances, the potential failure of an operator action may be linked, t o various degrees, to the success or fail- ure of a previous operator action. Thus, i t is recommended that each operator action be reviewed w i t h respect to dependency. T h i s can be accomplished using the dependency tables as presented i n the human reliability handbook (Ref. 8). 5. If any of the dominant sequences involve the failure of an operator action, a more comprehensive evaluation of the failure would be performed for that operator action. When necessary, the comprehensive evaluation should be performed using a human reliability methodology. The acceptability of this methodology for the purpose should be justified by the licensee (Refs. 9 through 13). 3.5 Event Tree Col