Document: NUREG-0800
Document ID: 1734e678-943d-4e2c-a9a5-1e89a00a9865
Document Type: srp
Title: UNCONTROLLED CONTROL ROD ASSEMBLY WITHDRAWAL FROM A
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0636/ML063600413.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.4.1
CFR Part: 
CFR Title: 

Content:
withdrawal procedures, a single rod of maximum worth available in a normal configuration should be used. In many cases this will be a rod near the 50% rod density configuration. (More recent modes of BWR control such as group withdrawal may require that other configurations be examined.) 15.4.1-5 Revision 3 - March 2007 3. The exact analysis of the transient would ideally involve a three dimensional, coupled neutron kinetics-thermal hydraulics calculation. However, acceptable results may be obtained with a neutron point-kinetics analysis and a coupled or separate hot fuel rod thermal analysis, if conservative input data are used. The reviewer determines whether the applicant's analytical methods are acceptable by using one or more of the following procedures: A. Determine whether the method has been reviewed and approved previously, by considering past safety evaluation reports and reports prepared in response to technical assistance requests. B. Perform a de novo review of the method (usually described in a separate licensing topical report, and frequently handled outside the scope of the review for a particular facility). C. Perform auditing-type calculations with methods available to the staff. D. Require additional, bounding calculations by the applicant to cover portions of the applicant's analytical methods that have not been fully reviewed or approved. 4. The input to the neutron kinetics analysis model should be examined to assure that the input is appropriately conservative both for the state of the reactor and for the particular way it is used in the analysis. The power distribution or peaking factors used in the neutron kinetics and hot pin thermal calculations must provide a conservative representation of the control rod configuration under consideration. The Doppler feedback coefficient should be related conservatively to the values accepted in the review under SRP Section 4.3, considering the time in cycle and temperature conditions of the fuel.