[Federal Register Volume 74, Number 197 (Wednesday, October 14, 2009)]
[Pages 52822-52823]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-24719]




Draft Regulatory Guide: Issuance, Availability

AGENCY: Nuclear Regulatory Commission.

ACTION: Notice of Issuance and Availability of Draft Regulatory Guide, 
DG-1199, ``Alternative Radiological Source Terms for Evaluating Design 
Basis Accidents at Nuclear Power Reactors.''


Regulatory Commission, Washington, DC 20555-0001, telephone: (301) 415-
1083 or e-mail [email protected].


I. Introduction

    The U.S. Nuclear Regulatory Commission (NRC) is issuing for public 
comment a draft regulatory guide in the agency's ``Regulatory Guide'' 
series. This series was developed to describe and make available to the 
public such information as 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 problems or postulated 
accidents, and data that the staff needs in its review of applications 
for permits and licenses.
    The draft regulatory guide (DG), titled, ``Alternative Radiological 
Source Terms for Evaluating Design Basis Accidents at Nuclear Power 
Reactors,'' is temporarily identified by its task number, DG-1199, 
which should be mentioned in all related correspondence. DG-1199 is 
proposed Revision 1 of Regulatory Guide 1.183, dated July 2000. This 
regulatory guide describes a method that the staff of the NRC considers 
acceptable in complying with alternative source term (AST) regulations 
for design basis accident dose consequence analysis. This guidance for 
light-water reactor designs includes the scope, nature, and 
documentation of associated analyses, evaluations; consideration of 
impacts on analyzed risk; and content of submittals. This guide 
establishes the AST based on NUREG-1465, ``Accident Source Terms for 
Light-Water Nuclear Power Plants,'' and identifies significant 
attributes of other accident source terms that may be acceptable. This 
guide also identifies acceptable radiological analysis assumptions for 
use in conjunction with the AST. In some cases, unusual site 
characteristics, plant design features, or other factors may require 
different assumptions, which will be considered on an individual case 
    The draft guide references Regulatory Guide 1.89, ``Environmental 
Qualification of Certain Electric Equipment Important to Safety for 
Nuclear Power Plants,'' regarding environmental qualification analyses 
that may be affected by implementing alternate source terms. This 
guidance will be available in the forthcoming revision of Regulatory 
Guide 1.89 and is currently available in Appendix I of Regulatory Guide 
1.183, Revision 0.

II. Further Information

    The Commission invites advice and recommendations on the content of 
DG-1199. Specifically, comments are solicited for the following 
questions. Each comment should include supporting basis or rationale to 
enable the staff to fully understand the point of view being provided.
    1. The alternative source term methodology described in the draft 
regulatory guide permits the assumption that the release of radioactive 
effluent to the environment occurs at some time period following the 
onset of the accident within the plant facility. Section 5.3, 
Meteorology Assumptions, provides guidance on pairing atmospheric 
dispersion factors ([chi]/Q values) with the periods of maximum 
postulated release of radioactive effluent to the environment.
    a. Is it equally or more appropriate to include consideration of 
engineering factors such as time of control room isolation and 
initiation of filtration, in addition to the time sequence release of 
radiological effluent to the environment, when assessing the limiting 
dose to control room operators?
    2. Table 3 of DG-1199 provides revised non-loss of coolant accident 
fission product gap inventories applicable to all current fuel designs. 
The purpose of revising Table 3 was to expand its applicability by 
replacing the prior footnote 11 limitation (i.e., 6.3 kw/ft beyond 54 
GWd/MTU) with bounding fuel rod power envelopes.
    a. Does the bounding fuel rod power envelopes depicted in Figure 1 
of DG-1199 provide sufficient fuel management flexibility such that 
current and anticipated fuel loading patterns will be able to utilize 
the Table 3 fission product gap fractions?
    b. Fission gas release and the resulting fission product gap 
inventory are sensitive to fuel rod design and rod power history. To 
maintain consistency with current regulatory guidance, the revised 
Table 3 remains applicable to all current pressurized water reactor 
(PWR) and boiling water reactor (BWR) fuel rod designs (limited only by 
the bounding power envelope). Significant reductions in fission product 
gap inventories are achievable with specific fuel rod design 
calculations (e.g., PWR 17x17 versus PWR 14x14) and/or less bounding 
rod power histories. Should RG 1.183 provide alternate versions of 
Table 3, each with its own set of applicability criteria?
    3. Reference 18 of DG-1199 documents the expanded fission gas 
release empirical database and methods used to calculate the revised 
Table 3 and Table 4 fission product gap inventories. Are any further 
fission gas measurements available which would help enhance the gap 
inventories listed in Table 3 and 4?
    Comments should mention DG-1199 in the subject line. Comments 
submitted in writing or in electronic form will be made available to 
the public in their entirety through the NRC's Agencywide Documents 
Access and Management System (ADAMS).
    Personal information will not be removed from the comments. 
Comments may be submitted by any of the following methods:
    1. Mail comments to: Rulemaking and Directives Branch, Division of 
Administrative Services, Mail Stop: TWB-05-B01M, Office of 
Administration, U.S. Nuclear Regulatory

[[Page 52823]]

Commission, Washington, DC 20555-0001.
    2. Federal e-Rulemaking Portal: Go to http://www.regulations.gov 
and search for documents filed under Docket ID [NRC-2009-0453]. Address 
questions about NRC dockets to Carol Gallagher, 301-492-3668; e-mail 
[email protected].
    3. Fax comments to: Rulemaking and Directives Branch, Division of 
Administrative Services, Office of Administration, U.S. Nuclear 
Regulatory Commission at (301) 492-3446.
    Requests for technical information about DG-1199 may be directed to 
Mark Blumberg at (301) 415-1083 or e-mail to [email protected].
    Comments would be most helpful if received by December 11, 2009. 
Comments received after that 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.
    Electronic copies of DG-1199 are available through the NRC's public 
Web site under Draft Regulatory Guides in the ``Regulatory Guides'' 
collection of the NRC's Electronic Reading
    Room at http://www.nrc.gov/reading-rm/doc-collections/. Electronic 
copies are also available in ADAMS (http://www.nrc.gov/reading-rm/adams.html), under Accession No. ML090960464. In addition, regulatory 
guides are available for inspection at the NRC's Public Document Room 
(PDR) located at 11555 Rockville Pike, Rockville, Maryland. The PDR's 
mailing address is USNRC PDR, Washington, DC 20555-0001. The PDR can 
also be reached by telephone at (301) 415-4737 or (800) 397-4205, by 
fax at (301) 415-3548, and by e-mail to [email protected].
    Regulatory guides are not copyrighted, and Commission approval is 
not required to reproduce them.

    Dated at Rockville, Maryland, this 6th day of October 2009.

    For the Nuclear Regulatory Commission.
Andrea D. Valentin,
Chief, Regulatory Guide Development Branch, Division of Engineering, 
Office of Nuclear Regulatory Research.
[FR Doc. E9-24719 Filed 10-13-09; 8:45 am]