Document: NUREG-0800
Document ID: feb81401-32fe-404e-84da-ff4b36e788bf
Document Type: srp
Title: RADIOLOGICAL CONSEQUENCES OF MAIN STEAM LINE FAILURE OUTSIDE
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350151.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.6.4
CFR Part: 
CFR Title: 

Content:
team line failure outside containment is done at the operating license (OL) stage when system parameters and accident analysis are fully developed. The review at the OL stage consists of the following steps: 1. Review of the applicant's description and dose analysis of the steam line failure accident. 2. Performance of an independent analysis by.the staff of the radiological consequences of the failure of the main steam line, using the assumptions of Regulatory Guide 1.5 (Ref. 2), except for the atmospheric dispersion factors. The following conservative assumptions are used to simplify the analysis: 315.6.4-2 Rev. 2 - July 1981 a. The mass of reactor coolant assumed to be released to the environment is 140,000 pounds for the "GESSAR 251" sized BWR and 100,000 pounds for the "GESSAR 238" sized BWR. Other BWRs should be evaluated on a case-by-case basis. The release is assumed to occur instantaneously. These assumptions are made unless notified otherwise by RSB. b. The iodine concentration in the primary coolant is assumed to corres- pond to the following two cases in the NSSS vendor's standard tech- nical specifications: (1) the concentration is the maximum value permitted and corresponds to the conditions of an assumed preaccident spike; and (2) the concentration is the maximum equilibrium value permitted for continued full power operation. As a result of the MSLB accident, fuel failures can occur releasing fission products into the reactor coolant and thus, making additional activity available for release to the atmosphere. The RSB reviews the effects of the MSLB on the core thermal margins and the asso- ciated amount of fuel failures. RSB, as a secondary review branch, will inform the AEB of the fuel failure- estimate. If the MSLB acci- dent is predicted to cause such fuel failure, a dose analysis will be performed with the corresponding iodine activity. No decontami- nation factor or other reductions in the concentrations are assumed in the staff's analysis. c.