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:
istribution 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 examination procedures have not been adequate for detecting and sizing flaws. Discussions and undesirable licensing delays were frequently the result. As more plants begin producing power and existing plants grow older, more flaws may be expected irk the weld areas. These flaws may be generated as a result of fatigue, stress corrosion, or other unanticipated factors. It is imperative that the guide recommendations for supplementary UT examination procedures be used in the future to maintain an acceptable level of safety at these welds. The second alternative was therefore selected for applying this guide to the preservice and inservice examination of RPV welds. It is expected that inservice UT examinations will detect flaws generated during plant operation, whereas preservice examinations will provide UT examination data for sub- sequent comparisons. First, a radiographic examination is performed of all the vessel welds under Section III of the ASME Code. After this examination, a UT preservice exam- ination of welds is performed to serve as a supplementary volumetric examination. Because of the above, these pre- service examinations are not as important as inservice exam- inations. It was therefore decided that the guide recommenda- tions should apply to judging the inservice examination results for those examinations performed immediately after the issuance of the guide; however, the guide recommendations should apply to preservice examinations. beginning 6 months after the issuance date. The NRC staff considered this approach best because of the difficulties being experienced in reviewing inservice UT examination data from the different plants. 1.150-23 UNh.:') S': : ES NUCLEAR REGULA OR)( C,:;iMISSION WASHINGTON, D.C. 20555 I FIRST CLASS MAIL POSTAGE & FEES PAID