Document: NRC Regulatory Guide
Document ID: 74c49394-8dbf-46e7-b62a-b85de93b47d8
Document Type: regulatory_guide
Title: Initial Test Programs for Water-Cooled Nuclear Power Plants + HISTORY - HISTORY 11/2012 – DG-1259 , Proposed Revision 4 11/2006 – DG-1166 , Proposed Revision 3 (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1229/ML12298A071.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.68
CFR Part: 
CFR Title: 

Content:
rods should be retested a sufficient number of times (e.g., three times) to reasonably ensure proper performance during subsequent plant operations. For facilities using more than one type of control element or control rod drive design, scram times should be compared with identical designs (e.g., two control rods attached to a single drive mechanism). Additionally, the proper operation of decelerating devices used to prevent mechanical damage to the control rods should be demonstrated during this testing. Reactor coolant system flow tests should include loss-of-flow tests to measure flow coast down. Differential pressure measurements across the fully loaded core and major components need not be repeated for plants using calculation models and designs identical to prototype plants. Appendix A to DG-1259, Page A-22 A-3. Initial Criticality Licensees should conduct the initial approach to criticality in a deliberate and orderly manner using the same rod withdrawal sequences and patterns that will be used during subsequent startups. Neutron flux levels should be continuously monitored and periodically evaluated. A neutron count rate of at least 1/2 counts per second should register on the startup channels before startup begins, and the signal to noise ratio should be known to be greater than 2. All systems required for startup or protection of the plant, including the reactor protection system and emergency shutdown system, should be operable, and in a state of readiness. The control rod or poison removal sequence should be accomplished using detailed procedures approved by personnel or groups designated by the licensee. For reactors that will achieve initial criticality by boron dilution, control rods should be withdrawn before dilution begins. The control rod insertion limits defined in the TS should be observed and followed. Criticality predictions for boron concentration (PWRs) and control rod positions should be provided, and criteria and actions to be taken if