Document: NUREG-0800
Document ID: 49aefb86-1adb-4b3c-826f-480e32947595
Document Type: srp
Title: Radiological Consequence Analyses Using Alternative Source Terms
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0037/ML003734190.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.0.1
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CFR Title: 

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nsee has been able to demonstrate that the existing analyses are bounding and would yield acceptable results if recalculated using the proposed AST. However, the design basis now incorporates the AST, and any future reanalysis or new analyses should be based on the AST, that is, the design basis source term. (2) A licensee has proposed a full implementation of an AST but is not requesting any plant modifications. The licensee submitted an evaluation of the offsite and control room doses due to a DBA LOCA in support of this request. On the basis of its review of analyses performed in the staff’s rebaselining study, the licensee has concluded that the existing LOCA analysis (based on the previous source term) remains bounding. In a sensitivity analysis, the licensee determined that multiplying the previous whole body result by a factor of 1.3 would yield a value that represents the TEDE dose. Is this an acceptable approach? Answer: The implementation of an AST is a significant change to the design basis that should be viewed as a replacement rather than a adaptation of the earlier assumptions and methods. Although sensitivity and scoping analyses may have a minor role, the staff should expect that the offsite and control room dose analysis will largely be recalculated using the guidance of RG-1.183. This position is taken to ensure that a clear, logical, and consistent design basis will be in place to support evaluations of future modifications, including safety evaluations under 10 CFR 50.59. f. For a full implementation, a complete DBA LOCA analysis as described in RG- 1.183, should be performed as a minimum. 4. The reviewer should evaluate the AST proposed by the licensee against the guidance in RG-1.183. Differences between the licensee’s proposal and the guidance should be resolved with the licensee. Although the licensee is allowed to propose alternatives to the guidance, large amounts of staff resources were expended in developing the revised source term