Document: NRC Regulatory Guide
Document ID: 0d99822b-1af0-41be-a088-75b961301b4f
Document Type: regulatory_guide
Title: Regulatory Guidance on the Alternate Pressurized Thermal Shock Rule + HISTORY - HISTORY 03/2015 – DG-1299 , Proposed Revision 0
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1405/ML14056A011.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.230
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CFR Title: 

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se and security, and special circumstances must be present. When addressing these exemption criteria, the licensee should demonstrate that the risk-significant factors controlling PTS for the plant in question are adequately addressed by the technical basis calculations that were performed to develop 10 CFR 50.61a. Factors to be considered in this evaluation should include the following: • The event sequences, which may lead to over-cooling of the RPV. • The thermal-hydraulic response of the nuclear steam supply system (NSSS) in response to such sequences. • Characteristics of the RPV design (e.g., vessel diameter, vessel wall thickness, operating pressure) that influence the stresses that develop in the beltline region of the vessel in response to the event sequences. o Note: As indicated in Section 1.2 of NUREG-2163, the “reactor vessel beltline” is defined as those reactor vessel shell materials with projected neutron fluence values equal to or greater than 1 x 1017 n/cm2 at the end of the design life. Fluence values should be determined in accordance with methodology consistent with that specified in Regulatory Guide 1.190, “Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence,” March 2001, or using methods otherwise acceptable to the staff. • Characteristics of the RPV material and its embrittlement behavior. DG-1299, Page 5 The technical details of how these factors were considered in the development of the Alternate PTS Rule are contained in NUREG-1806, “Technical Basis for Revision of the Pressurized Thermal Shock (PTS) Screening Limit in the PTS Rule (10 CFR 50.61)” (Ref. 6). 2. Criteria Relating to the Evaluation of Plant-Specific Surveillance Data This regulatory position describes a procedure by which licensees can assess their plant-specific material surveillance data using the three statistical tests required by Paragraph (f)(6) of 10 CFR 50.61a. If the criteria for all three statistical tests are