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###### Nuclear Regulatory Commission

          - 10 CFR Part 50
          - [Docket No. PRM-50-93; NRC-2009-0554]

# AGENCY: 

Nuclear Regulatory Commission.

# ACTION: 

Petition for rulemaking; notice of receipt.

# SUMMARY: 

The Nuclear Regulatory Commission (NRC) is publishing for public comment a notice of receipt of a petition for rulemaking, dated November 17, 2009, which was filed with the NRC by Mark Edward Leyse. The petition was docketed by the NRC on November 23, 2009, and has been assigned Docket No. PRM-50-93. The petitioner requests that the NRC amend its regulations regarding the domestic licensing of production and utilization facilities. Specifically, the petitioner requests that the NRC revise its regulations based on data from multi-rod (assembly) severe fuel damage experiments. The petitioner also requests that the NRC promulgate a regulation that will stipulate minimum allowable core reflood rates in the event of a loss-of-coolant accident.

# DATES: 

Submit comments by April 12, 2010. Comments received after this date will be considered if it is practical to do so, but the NRC is able to assure consideration only for comments received on or before this date.

# ADDRESSES: 

You may submit comments by any one of the following methods. Please include Docket ID NRC-2009-0554 in the subject line of your comments. Comments submitted in writing or in electronic form will be posted on the NRC Web site and on the Federal rulemaking Web site Regulations.gov. Because your comments will not be edited to remove any identifying or contact information, the NRC cautions you against including any information in your submission that you do not want to be publicly disclosed.

The NRC requests that any party soliciting or aggregating comments received from other persons for submission to the NRC inform those persons that the NRC will not edit their comments to remove any identifying or contact information, and therefore, they should not include any information in their comments that they do not want publicly disclosed.

*Federal Rulemaking Web site:*                         Go to                         *http://www.regulations.gov*                         and search for documents filed under Docket ID NRC-2009-0554. Address questions about NRC dockets to Carol Gallagher, 301-492-3668, e-mail                         *Carol.Gallagher@nrc.gov.*

*Mail comments to:*                         Secretary, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001,                         *Attn:*                         Rulemakings and Adjudications Staff.                    

*E-mail comments to: Rulemaking.Comments@nrc.gov.*                         If you do not receive a reply e-mail confirming that we have received your comments, contact us directly at (301) 415-1677.                    

*Hand-deliver comments to:*                         11555 Rockville Pike, Rockville, Maryland 20852, between 7:30 am and 4:15 pm Federal workdays (telephone (301) 415-1677).                    

*Fax comments to:*                         Secretary, U.S. Nuclear Regulatory Commission at (301) 415-1101.                    

You can access publicly available documents related to this petition, including the incoming petition for rulemaking, using the following methods:

*NRC's Public Document Room (PDR):*                         The public may examine and have copied for a fee publicly available documents the NRC's PDR, Room O1 F21, One White Flint North, 11555 Rockville Pike, Rockville, Maryland.                    

*NRC's Agencywide Documents Access and Management System (ADAMS):*                         Publicly available documents created or received at the NRC, including the incoming petition for rulemaking (ADAMS Accession No. ML093290250) are available electronically at the NRC's Electronic Reading Room at                         *http://www.nrc.gov/​reading-rm/​adams.html*. From this page, the public can gain entry into ADAMS, which provides text and image files of NRC's public documents. If you do not have access to ADAMS or if there are problems in accessing the documents located in ADAMS, contact the NRC's PDR Reference staff at 1-800-397-4209, 301-415-4737 or by e-mail to                         *pdr.resource@nrc.gov.*

                        Federal Rulemaking Web site: Public comments and supporting materials related to this petition, including the incoming petition for rulemaking, can be found at                         *http://www.regulations.gov*                         by searching on Docket ID NRC-2009-0554.                    

# FOR FURTHER INFORMATION CONTACT: 

                        Michael T. Lesar, Chief, Rulemaking and Directives Branch, Division of Administrative Services, Office of Administration, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001,                         *Telephone:*                         301-492-3663 or Toll Free: 800-368-5642.                    

# SUPPLEMENTARY INFORMATION:

## Background

Mark Edward Leyse (petitioner) submitted a petition for rulemaking dated November 17, 2009. The petitioner states that he is aware that data from multi-rod (assembly) severe fuel damage experiments indicates that the current regulations at 10 CFR Part 50 are non-conservative in their peak cladding temperature limit of 2200 °F, and that the Baker-Just and Cathcart-Pawel equations are also non-conservative for calculating the metal-water reaction rates that would occur in the event of a LOCA. As a result, the petitioner requests that the NRC revise its regulations at 10 CFR 50.46(b)(1) and Appendix K to 10 CFR Part 50 based on this data. The petitioner also requests that the NRC promulgate a regulation that will stipulate minimum allowable core reflood rates in the event of a LOCA. The NRC has determined that the petition meets the threshold sufficiency requirements for a petition for rulemaking under 10 CFR 2.802. The petition has been docketed as PRM-50-93. The NRC is requesting public comment on the petition for rulemaking.

## Discussion of the Petition

                    The petitioner believes that data from multi-rod (assembly) severe fuel damage experiments indicates that the current peak cladding temperature limit contained in 10 CFR 50.46(b)(1) is non-conservative. The petitioner also believes that data from such experiments as the LOFT LP-FP-2 experiment also indicates that the Baker-Just and Cathcart-Pawel equations                           ( print page 3877)                        are both non-conservative for calculating the temperature at which an autocatalytic (runaway) oxidation reaction of Zircaloy would occur in the event of a LOCA. The petitioner states that these experiments demonstrate that the autocatalytic oxidation reaction of Zircaloy cladding occurs at temperatures far below those predicted by the Baker-Just and Cathcart-Pawel equations. The petitioner concludes that this, in turn, indicates that the Baker-Just and Cathcart-Pawel equations are both non-conservative for calculating the metal-water reaction rates that would occur in the event of a LOCA. The petitioner requests that the NRC revise its regulations at 10 CFR 50.46(b)(1) to require that the calculated maximum fuel element cladding temperature not exceed a limit based on data from multi-rod (assembly) severe fuel damage experiments.                

The petitioner also requests that the NRC revise Appendix K to 10 CFR Part 50 to require that the rates of energy release, hydrogen generation, and cladding oxidation from the metal-water reaction considered in emergency core cooling system (ECCS) evaluation calculations be based on data from multi-rod (assembly) severe fuel damage experiments. The petitioner believes that these same requirements also need to apply to any NRC-approved best-estimate ECCS evaluation models used in lieu of calculations made under Appendix K to 10 CFR Part 50.

Lastly, the petitioner requests that the NRC promulgate a regulation that will stipulate minimum allowable core reflood rates in the event of a LOCA. The petitioner believes that it can be extrapolated from experimental data that in the event of a LOCA, a constant core reflood rate of approximately one inch per second or lower would not, with high probability, prevent Zircaloy fuel cladding from exceeding the peak cladding temperature limit of 2200 °F if, at the onset of reflood, the cladding temperature was 1200 °F or higher.

The petitioner believes that, if implemented, the amendments proposed in the petition would improve public and plant-worker safety. Therefore, the petitioner requests that the NRC amend its regulations regarding the domestic licensing of production and utilization facilities.

Dated at Rockville, Maryland, this 19th day of January 2010.

For the Nuclear Regulatory Commission.

Annette Vietti-Cook,

Secretary of the Commission.

[FR Doc. 2010-1317 Filed 1-22-10; 8:45 am]

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