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Instrument Sensing Lines

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Nuclear Regulatory Commission.


Draft regulatory guide; request for comment.


The U.S. Nuclear Regulatory Commission (NRC) is issuing for public comment draft regulatory guide (DG), DG-1352, “Instrument Sensing Lines.” DG-1352 describes an approach that is acceptable to the staff of the NRC to meet regulatory requirements for instrument sensing lines in nuclear power plants. The DG would endorse, with certain clarifications, standards that were updated and corrected subsequent to the last time the NRC endorsed them. More information on updates can be found in the “Additional Information” section below.


Submit comments by April 9, 2019. Comments received after this date will be considered if it is practical to do so, but the NRC is able to ensure consideration only for comments received on or before this date. Although a time limit is given, comments and suggestions in connection with items for inclusion in guides currently being developed or improvements in all published guides are encouraged at any time.


You may submit comments by any of the following methods:

  • Federal Rulemaking Website: Go to and search for: Docket ID: NRC-2019-0041. Address questions about NRC dockets to Krupskaya Castellon; telephone: 301-287-9122; email: For technical questions, contact the individual(s) listed in the FOR FURTHER INFORMATION CONTACT section of this document.
  • Mail comments to: Office of Administration, Mail Stop: TWFN-7A06M, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, ATTN: Program Management, Announcements and Editing Staff.

For additional direction on obtaining information and submitting comments, see “Obtaining Information and Submitting Comments” in the SUPPLEMENTARY INFORMATION section of this document.

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David Dawood, Telephone: 301-415-2389, email:, Yaguang, Yang, Telephone: 301-415-0655, email:, and Michael Eudy, Telephone: 301-415-3104, email: All are staff members of the Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.

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I. Obtaining Information and Submitting Comments

A. Obtaining Information

Please refer to Docket ID NRC-2019-0041 when contacting the NRC about the availability of information regarding this action. You may obtain publically-available information related to this action, by any of the following methods:

  • Federal Rulemaking Website: Go to and search for Docket ID: NRC-2019-0041.
  • 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/​adams.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 DG-1352 and the Regulatory Analysis are available in ADAMS under Accession No. ML18158A303 and ML18158A301 respectfully.
  • NRC's PDR: You may examine and purchase copies of public documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555 Rockville Pike, Rockville, Maryland 20852.

B. Submitting Comments

Please include Docket ID NRC-2019-0041 in your comment submission. The NRC cautions you not to include identifying or contact information that you do not want to be publicly disclosed in your comment submission. The NRC posts all comment submissions at as well as enters the comment submissions into ADAMS. The NRC does not routinely edit comment submissions to remove identifying or contact information.

If you are requesting or aggregating comments from other persons for submission to the NRC, then you should inform those persons not to include identifying or contact information that they do not want to be publicly disclosed in their comment submission. Your request should state that the NRC does not routinely edit comment submissions to remove such information before making the comment submissions available to the public or entering the comment submissions into ADAMS.

II. Additional Information

The NRC is issuing for public comment a DG 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 NRC's regulations, techniques that the staff uses in evaluating specific issues or postulated events, and data that the staff needs in its review of applications for permits and licenses.

The DG, entitled, “Instrument Sensing Lines,” is a proposed revision temporarily identified by its task number, DG-1352. DG-1352 is proposed revision 2 of RG 1.151, “Instrument Sensing Line.” DG-1352 describes an approach that is acceptable to the staff of the NRC to meet regulatory requirements for instrument sensing lines in nuclear power plants. It endorses, with certain clarifying regulatory positions, American National Standards Institute/International Society of Automation (ANSI/ISA)-67.02.01-2014, “Nuclear Safety-Related Instrument Sensing Line Piping and Tubing Standard for Use in Nuclear Power Plants.” The revision of ANSI/ISA-67.02.01 previously endorsed by the NRC was revised by ANSI/ISA in 2014. This DG also references the International Organization for Standardization (ISO) standard ISO 2186-2007, “Fluid Flow in Closed Conduits—Connections for Pressure Signal Transmissions between Primary and Secondary Elements.” In addition, this DG incorporates recent operating experience, as described in NRC Information Notice (IN) 2013-12, “Improperly Sloped Instrument Sensing Lines,” dated July 3, 2013.

III. Backfitting and Issue Finality

This DG may be applied to applications for operating licenses under title 10 of the Code of Federal Start Printed Page 2935Regulations (10 CFR) part 50 or combined licenses under 10 CFR part 52 docketed by the NRC as of the date of issuance of the final regulatory guide, as well as future applications submitted after the issuance of the regulatory guide. Such action would not constitute backfitting as defined in the 10 CFR 50.109 or be otherwise inconsistent with the applicable issue finality provision in 10 CFR part 52, inasmuch as such applicants or potential applicants, with certain exceptions, are not within the scope of entities that are the subject of the Backfit Rule or an issue finality provision in part 52. The exceptions are whenever an applicant references a part 50 or part 52 license (e.g., a construction permit) and/or regulatory approval (e.g., a design certification or a standard design approval) with specified backfitting or issue finality provisions.

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Dated at Rockville, Maryland, this 4th day of February, 2019.

For the Nuclear Regulatory Commission.

Thomas H. Boyce,

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

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[FR Doc. 2019-01556 Filed 2-7-19; 8:45 am]