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Plant-Specific Applicability of Transition Break Size Specified in 10 CFR 50.46a

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Nuclear Regulatory Commission.


Draft regulatory guide; discontinuation and withdrawal.


The U.S. Nuclear Regulatory Commission (NRC) is announcing the discontinuation of further regulatory action on Draft Regulatory Guide (DG) DG-1216, “Plant-Specific Applicability of Transition Break Size Specified in 10 CFR 50.46a,” and its withdrawal. Draft Regulatory Guide DG-1216 was a proposed new regulatory guide written to provide implementing guidance for a proposed rule “Risk-Informed Changes to Loss-of-Coolant Accident Technical Requirements,” (Emergency core cooling system (ECCS) rulemaking)) that provided a voluntary, alternate approach for evaluating the performance of an ECCS. The NRC is discontinuing further regulatory action on the DG and not publishing the DG in final form because the NRC has discontinued the underlying rulemaking.


The effective date for discontinuance and withdrawal of the DG is December 8, 2016.


Please refer to Docket ID NRC-2010-0229 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 Web site: Go to and search for Docket ID NRC-2010-0229. Address questions about NRC dockets to Carol Gallagher; telephone: 301-415-3463; 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/​adams.html. To begin the search, select “ADAMS Public Documents” and then 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 The ADAMS accession number for each document referenced in this document (if that document is available in ADAMS) is provided the first time that a document is referenced.
  • 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.
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Robert L. Tregoning, telephone: 301-415-2324; 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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The NRC is announcing the discontinuation of further NRC action on DG-1216, “Plant-Specific Applicability of Transition Break Size Specified in 10 CFR 50.46a, and its withdrawal. This draft guide describes a method that the NRC considered acceptable for demonstrating that the generic transition break size specified in the proposed 10 CFR 50.46a ECCS rule was applicable to a specific plant. The NRC provided an opportunity for public comment on DG-1216 in the Federal Register on June 28, 2010 (75 FR 36698). The DG package (ADAMS Accession No. ML100430352) consists of DG-1216 (ADAMS Accession No. ML100430356), a Federal Register notice (FRN) (ADAMS Accession No. ML100430445), and a regulatory analysis (ADAMS Accession No. ML101530472).

Draft Regulatory Guide DG-1216 was a proposed new regulatory guide written to provide implementing guidance for a proposed ECCS rulemaking which would have provided a voluntary, risk-informed alternative to the existing, deterministic requirements for evaluating ECCS performance. The proposed ECCS rule was published in the Federal Register on November 7, 2005 (70 FR 67597), with a supplemental proposed rule published on August 10, 2009 (74 FR 40006). In SECY-16-0009, “Recommendations Resulting from the Integrated Prioritization and Re-Baselining of Agency Activities,” dated January 31, 2016 (ADAMS Accession No. ML16028A189), the staff recommended that the ECCS rulemaking be discontinued. In the Staff Requirements Memorandum for SECY-16-0009, dated April 13, 2016 (ADAMS Accession No. ML16104A158), the Commission approved discontinuation of the ECCS rulemaking. The NRC published an FRN on October 6, 2016 (81 FR 69446), which provided a discussion of the discontinuation decision.

Because the NRC discontinued the ECCS rulemaking, further NRC action to develop and adopt DG-1216 as a final guidance document is not needed. Therefore, this notice announces the NRC's decision to discontinue further action on DG-1216 and documents the final NRC action on DG-1216.

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Dated at Rockville, Maryland, this 2nd day of December, 2016.

For the Nuclear Regulatory Commission.

Thomas H. Boyce,

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

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[FR Doc. 2016-29390 Filed 12-7-16; 8:45 am]