Document: NRC Regulatory Guide
Document ID: c992c9f8-7405-4a7c-afdc-b3d2a6922aad
Document Type: regulatory_guide
Title: Assumptions Used for Evaluating the Potential Radiological Consequences of a Steam Line Break Accident for Boiling Water Reactors
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003739923.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.5
CFR Part: 
CFR Title: 

Content:
SAFETY GUIDE 5 ASSUMPTIONS USED FOR EVALUATING THE POTENTIAL RADIOLOGICAL CONSEQUENCES OF A STEAM LINE BREAK ACCIDENT FOR BOILING WATER REACTORS A. Introduction Section 50.34 of 10 CFR Part 50 requires that each applicant for a construction permit or op erating license provide an analysis and evalua tion of the design and performance of struc tures, systems, and components of the facility with the objective of assessing the risk to pub lic health and safety resulting from operation of the facility. The steam line break accident is one of the postulated accidents used to evaluate the adequacy of these structures, systems, and components with respect to the public health and safety. This safety guide gives aceeptable assumptions that may be used in evaluating the radiological consequences of this accident for a boiling water reactor. B. Discussion In the process of reviewing a large number of applications for construction permits and op erating licenses, the regulatory staff has de veloped, based on engineering judgment and on applicable experimental results from safety re search programs conducted by the AEC and the nuclear industry, a number of appropriately conservative assumptions which are used by the regulatory staff to evaluate the applicant's esti mate of the radiological consequences of various postulated accidents. This safety guide lists the assumptions I used by the regulatory staff to evaluate the steam line break accident for a boiling water reactor. C. Regulatory Position The assumptions related to the release of radioactive material are: 'In some cases, plant design conditions may exist which require special consideration and different as sumptions. 1. The steam line breaks I with the reactor at full power 3 and the reactor scrams. 2. The steam line isolation valves close in the maximum time incorporated or to be incorporated in the technical speci fications. This closure time will be veri fied by suitable periodic testing. 3. The total mass of coolant