Document: NRC Regulatory Guide
Document ID: e16da529-b6b4-4fdf-bc3f-7490180363f3
Document Type: regulatory_guide
Title: Environmental Qualification of Certain Electric Equipment Important to Safety for Nuclear Power Plants (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2018/ML20183A423.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.89
CFR Part: 
CFR Title: 

Content:
ld be unnecessarily complex. DG-1361, Page 16 b. When replacing previously qualified components, or subcomponents with commercially procured equipment, no significant changes in form, fit, or function should have occurred to the subcomponents since performance of the original qualification testing. This would include any changes to materials, material formulations, or critical manufacturing processes. Visual examinations or material-type verifications alone may not be sufficient to determine that relevant changes have not occurred. In such cases, a combination of material testing along with partial requalification testing of the components may be necessary, since an assessment of manufacturing process changes is typically not practical for commercially procured components. Additional guidance on maintaining qualification when procuring commercially procured replacement components appears in EPRI 3002002982, “Plant Engineering: Guideline for the Acceptance of Commercial-Grade Items in Nuclear Safety-Related Applications: Revision 1 to EPRI NP-5652 and TR-102260,” published in September 2014 (Ref. 33), which the NRC endorsed in RG 1.164. c. RG 1.209 states that metal oxide semiconductor devices generally have a lower radiation threshold than bipolar devices and are very sensitive to ionizing doses but relatively insensitive to neutron fluence. Therefore, radiation qualification for electronic components may have a lower exposure threshold. (As stated in Chapter 3, “Design of Structures, Components, Equipment, and Systems,” of both NUREG-1503, “Final Safety Evaluation Report Related to the Certification of the Advanced Boiling Water Reactor Design,” issued July 1994 (Ref. 34); and NUREG-1793, “Final Safety Evaluation Report Related to the Certification of the AP1000 Standard Design,” issued September 2004 (Ref. 35), the staff considers a mild radiation environment for electronic equipment to be a total integrated dose less than 10 gray (Gy) (103 rad)