Document: NRC Regulatory Guide
Document ID: c55ba6c5-aa2d-4ad6-aba2-2001e16524ab
Document Type: regulatory_guide
Title: Ultrasonic Testing of Reactor Vessel Welds During Preservice and Inservice Examinations (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1221/ML12216A015.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.150
CFR Part: 
CFR Title: 

Content:
NTATION It should be noted that the recommendations of this guide are not intended to apply to those preservfce examination tests already completed. However, the licensees may consider repeating their preservice examination tests or using the recommendations of this guide any time at their option to avoid possible flaw interpretation problems at a later date. Flaw interpretation problems may occur if traveling indications identified as significant according to the recommendations of this guide do not correlate with preservice volumetric NDE results and hence would be assumed to have been service induced. It would be difficult to show that these indications arose from fabrication flaws. Therefore, licensees would be well advised to consider the above possibilities. 8.1 Alternatives The following alternatives were considered in applying the recommendations of this guide. 1. To apply the recommendations of the guide to all the preservice and inservice examinations that have already been performed. 2. To apply the recommendations of the guide to all future preservice and inservice examinations per- formed after the issuance of the guide. 8.2 Discussion of Alternatives 8.2.1 First Alternative Alternative 1 would infer that all RPV welds examined as per the current code requirements are at a quality level that would not ensure an acceptable safety performance. This approach would also mean that all the plants would have to repeat, in accordance with the recommendations of this guide, those inservice and preservice examinations performed in the past. Such a policy would tend to be overly conservative and would put a heavy burden on all plant owners. Although UT examinations have missed some flaws in the past, there appears to be no immediate danger from the estimated flaw distribution probability to warrant such a strong action. Therefore, this alternative was not adopted. 8.2.2 Second Alternative In the past, several instances have been noted where the ,minimal Code UT