[Federal Register Volume 66, Number 198 (Friday, October 12, 2001)]
[Proposed Rules]
[Pages 52065-52066]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-25672]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 66, No. 198 / Friday, October 12, 2001 / 
Proposed Rules  

[[Page 52065]]



NUCLEAR REGULATORY COMMISSION

10 CFR Part 50

[Docket No. PRM-50-73]


Robert H. Leyse; Receipt of Petition for Rulemaking

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 
September 4, 2001, which was filed with the Commission by Robert H. 
Leyse. The petition was docketed by the NRC on September 4, 2001, and 
has been assigned Docket No. PRM-50-73. The petitioner requests that 
the NRC amend its regulations on the acceptance criteria for emergency 
core cooling systems for light-water nuclear power reactors to address 
the impact of crud on cooling capability during a fast-moving, large-
break, loss-of-coolant accident (LOCA).

DATES: Submit comments by December 26, 2001. Comments received after 
this date will be considered if it is practical to do so, but the 
Commission is able to assure consideration only for comments received 
on or before this date.

ADDRESSES: Submit written comments to the Secretary of the Commission, 
U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, 
Attention: Rulemakings and Adjudications Staff. Deliver comments to: 
11555 Rockville Pike, Rockville, Maryland, between 7:30 a.m. and 4:15 
p.m. Federal workdays.
    For a copy of the petition, write to Michael T. Lesar, Chief, Rules 
and Directives Branch, Division of Administrative Services, Office of 
Administration, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001.
    You may also provide comments via the NRC's interactive rulemaking 
website at http://ruleforum.llnl.gov. This site provides the capability 
to upload comments as files (any format), if your web browser supports 
that function. For information about the interactive rulemaking 
website, contact Ms. Carol Gallagher, 301-415-5905 (e-mail: 
[email protected]).
    The petition and copies of comments received may be inspected and 
copied for a fee at the NRC Public Document Room,11555 Rockville Pike, 
Public File Area O1F21, Rockville, Maryland. Copies of comments 
received are also available through the NRC's Agencywide Documents 
Access and Management System (ADAMS), which provides text and image 
files of NRC's public documents. These documents may be accessed 
through the NRC's Public Electronic Reading Room on the Internet at 
http://www.nrc.gov/NRC/ADAMS/index.html. If you do not have access to 
ADAMS or if there are problems in accessing the documents located in 
ADAMS contact the NRC Public Document Room (PDR) Reference staff at 1-
800-397-4209, 301-415-4737or by e-mail to [email protected].

FOR FURTHER INFORMATION CONTACT: Michael T. Lesar, Chief, Rules and 
Directives Branch, Division of Administrative Services, Office of 
Administration, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001, Telephone: 301-415-7163 or Toll Free: 800-368-5642.

SUPPLEMENTARY INFORMATION:

The Petitioners Request

    The petitioner requests that the NRC amend Sec. 50.46(a)(1)(i) and 
Appendix K to Part 50 to address the impact of crud on cooling 
capability during a fast-moving (large-break), LOCA.

Background

    The petitioner states that Sec. 50.46 and Appendix K to part 50 do 
not address the impact of crud on coolability during a fast-moving 
(large-break) LOCA. The petitioner states that a certain licensed power 
reactor has operated with unusually heavy crud deposits on many of the 
fuel pins. These crud deposits were identified and partially classified 
during a refueling outage. The petitioner states that if a fast-moving 
(large-break) LOCA had occurred before the shutdown for refueling, 
extensive blockage of the flow channels within the fuel bundles would 
have developed. The petitioner further states that, during blowdown, 
the redistribution of crud into any or all of the several restricted 
channels would result in the substantial flow blockage. The petitioner 
states that these restricted flow channels include at least the 
following items within the fuel bundles: the spacer grids, the mixing 
vanes attached to spacer grids, and the regions of ballooned and burst 
fuel cladding. The petitioner states that the consequent degradation of 
coolability would have resulted in a rapid deterioration of defense in 
depth. Under these conditions, the unusually heavy crud deposits on the 
fuel pins would have threatened the integrity of all of the barriers 
that in total comprise defense in depth.
    The petitioner believes that it could be argued that significant 
crud deposits would lead to an extensive amount of fuel failure during 
operation at [full] power. The petitioner believes that the amount of 
failed fuel would then lead to a decision to shut down the reactor as 
the inventory of radioactive material in the reactor coolant reached 
the limits that are allowed by the Technical Specifications. According 
to the petitioner, operating experience reveals that it is possible to 
operate a light-water reactor within the applicable Technical 
Specifications even though unusually heavy crud deposits are present on 
the fuel pins.

The Petitioner's Conclusions

    The petitioner believes that the deficiencies in Part 50 must be 
corrected to retain defense in depth. Accordingly, elements in 
Sec. 50.46 concerning comparisons to applicable experimental data must 
be revised to include the impact of crud on deposits on fuel pins.
    Also, the following paragraphs in Appendix K to part 50, should be 
revised to include the impact of crud deposits on fuel pins:

I.B.  Swelling and Rupture of the Cladding and Fuel Rod Thermal 
Parameters;
I.C.2  Frictional Pressure Drops;
I.C.4  Critical Heat Flux;
I.C.5  Post-CHF Heat Transfer Correlations;
I.C.7  Core Flow Distribution During Blowdown;
I.D.3  Calculation of Reflood Rate for Pressurized Water Reactors;
I.D.6  Convective Heat Transfer Coefficients for Boiling Water

[[Page 52066]]

Reactor Fuel Rods Under Spray Cooling; and
I.D.7  The Boiling-Water Reactor Channel Box Under Spray Cooling.
II.1.a  The documentation requirements in this paragraph should include 
a description of each evaluation model used for estimation of the 
effects of crud deposits on fuel pins.

    Dated at Rockville, Maryland, this 5th day of October, 2001.

    For the Nuclear Regulatory Commission.
Annette L. Vietti-Cook,
Secretary of the Commission.
[FR Doc. 01-25672 Filed 10-11-01; 8:45 am]
BILLING CODE 7590-01-P