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Plant-Specific, Risk-Informed Decisionmaking for Inservice Inspections of Piping

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Nuclear Regulatory Commission.


Regulatory guide; issuance.


The U.S. Nuclear Regulatory Commission (NRC) is issuing Revision 2 to Regulatory Guide (RG) 1.178, “Plant-Specific, Risk-Informed Decisionmaking for Inservice Inspection of Piping.” Revision 2, incorporates information to be consistent with the terminology and defense-in-depth philosophy provided in RG 1.174, “An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis,” as well as to reference the American Society of Mechanical Engineers Code Case N-716-1, “Alternative Classification and Examination Requirements, Section XI, Division 1.”


Revision 2 to RG 1.178 is available on April 23, 2021.


Please refer to Docket ID NRC-2020-0256 when contacting the NRC about the availability of information regarding this document. You may obtain publicly available information related to this document using any of the following methods:

  • Federal Rulemaking Website: Go to and search for Docket ID NRC-2020-0256. Address questions about Docket IDs in to Stacy Schumann; telephone: 301-415-0624; email: . For technical questions, contact the individuals listed in the FOR FURTHER INFORMATION CONTACT section of this document.
  • NRC's Agencywide Documents Access and Management System (ADAMS): You may obtain publicly available documents online in the ADAMS Public Documents collection at​reading-rm/​Start Printed Page 21773adams.html. To begin the search, select “Begin Web-based ADAMS Search.” For problems with ADAMS, please contact the NRC's Public Document Room (PDR) reference staff at 1-800-397-4209, 301-415-4737, or by email to
  • Attention: The PDR, where you may examine, and order copies of public documents, is currently closed. You may submit your request to the PDR via email at or call 1-800-397-4209 or 301-415-4737, between 8:00 a.m. and 4:00 p.m. (EST), Monday through Friday, except Federal holidays.

Revision 2 to RG 1.178 and the regulatory analysis may be found in ADAMS under Accession Nos. ML21036A105 and ML20210M044, respectively.

Regulatory guides are not copyrighted, and NRC approval is not required to reproduce them.

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Zeechung Wang, telephone: 301-415-1686, email:, or Harriet Karagiannis, telephone: 301-415-2493, email: Both are staff of the Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.

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I. Discussion

The NRC is issuing a revision to an existing guide in the NRC's “Regulatory Guide” series. This series was developed to describe and make available to the public information regarding methods that are acceptable to the NRC staff for implementing specific parts of the agency's regulations, techniques that the NRC staff uses in evaluating specific issues or postulated events, and data that the NRC staff needs in its review of applications for permits and licenses.

Revision 2 of RG 1.178 was issued with a temporary identification of Draft Regulatory Guide, DG-1288. It addresses new information identified since the previous revision of this guide was issued.

II. Additional Information

The NRC published a notice of the availability of DG-1288 (ADAMS Accession No. ML20210M047), in the Federal Register on December 14, 2020 (85 FR 80825), for a 30-day public comment period. The public comment period closed on January 13, 2021. The NRC has not received any comments on DG-1288.

III. Congressional Review Act

This RG is a rule as defined in the Congressional Review Act (5 U.S.C. 801-808). However, the Office of Management and Budget has not found it to be a major rule as defined in the Congressional Review Act.

IV. Backfitting, Forward Fitting, and Issue Finality

Revision 2 of RG 1.178 describes methods acceptable to the NRC staff for complying with the NRC's regulations for inservice inspections of piping.

Issuance of RG 1.178, would not constitute backfitting as defined in section 50.109 of title 10 CFR of the Code of Federal Regulations (10 CFR), “Backfitting,” and as described in NRC Management Directive (MD) 8.4, “Management of Backfitting, Forward Fitting, Issue Finality, and Information Requests”; constitute forward fitting as that term is defined and described in MD 8.4; or affect the issue finality of any approval issued under 10 CFR part 52. As explained in RG 1.178, applicants and licensees would not be required to comply with the positions set forth in RG 1.178.

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Dated: April 19, 2021.

For the Nuclear Regulatory Commission.

Meraj Rahimi,

Chief, Regulatory Guidance and Generic Issues Branch, Division of Engineering, Office of Nuclear Regulatory Research.

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[FR Doc. 2021-08446 Filed 4-22-21; 8:45 am]