Document: NRC Regulatory Guide
Document ID: cf64153e-7623-469c-a3f9-b57ba0f5497d
Document Type: regulatory_guide
Title: Reactor Coolant Pump Flywheel Integrity + HISTORY - HISTORY 01/2006 – Periodic Review of Revision 1 – No Issues Identified
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003739936.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.14
CFR Part: 
CFR Title: 

Content:
the location of interest. Comparison of perhaps three or four cases in terms of KI/KIC, the ratio of the imposed stress intensity factor at some nominal speed to the material toughness, should locate to most severe sets of conditions. Evaluation of the critical speed for fracture, which may require techniques that go beyond linear elastic fracture mechanics, may then focus on one critical location. Excessive deformation during overspeed of the flywheel is of concern because damage could be caused by separation of the flywheel from the shaft. For the purpose of this guide, excessive deformation means any deformation such as an enlargement of the bore that could cause such separation directly or could cause an unbalance of the flywheel leading to structural failure or separation of the flywheel from the shaft. The calcula tion of deformation should employ elastic-plastic meth ods unless it can be shown that stresses remain within the elastic range. The geometry of the flywheel and pump motor design should facilitate preservice and inservice inspec tion of all high-stress regions (bore, keyway, and bolt hole regions) without the need for removal of the flywheel from its shaft and preferably without the need for removing the rotor from the motor assembly. The desired results of the analyses described in regulatory positions C.2.c, d, and e are quantitative estimates of the margins against fracture or excessive deformation during overspeed because such estimates, coupled with adequate provisions against overspeed, provide the best basis for assurance that the probability of failure under normal and transient conditions is sufficiently small that the consequences of failure need not be protected against. C. REGULATORY POSITION 1. Material and Fabrication a. The flywheel material should be of closely controlled quality. Plates' should conform to ASTM A20 and should be produced by the vacuum-melting and degassing process or the electroslag remelting process. Plate material