[Federal Register Volume 66, Number 143 (Wednesday, July 25, 2001)]
[Notices]
[Pages 38755-38756]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-18520]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. STN 50-454, STN 50-455, STN 50-456 and STN 50-457]


Exelon Generation Company, LLC Byron Station, Units 1 and 2 
Braidwood Station, Units 1 and 2; Environmental Assessment and Finding 
of No Significant Impact

    The U.S. Nuclear Regulatory Commission (NRC) is considering 
issuance of an exemption from the requirements of Title 10 of the Code 
of Federal Regulations (10 CFR) part 50, Section 50.60(a) for Facility 
Operating License Nos. NPF-37, NPF-66, NPF-72 and NPF-77, issued to 
Exelon Generation Company, LLC, (the licensee), for operation of the 
Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 
located in Ogle County in Illinois and Will County in Illinois, 
respectively. Therefore, as required by 10 CFR 51.21, the NRC is 
issuing this environmental assessment and finding of no significant 
impact.

Environmental Assessment

Identification of the Proposed Action

    The proposed action would exempt Byron and Braidwood from 
application of specific requirements of 10 CFR part 50, Section 
50.60(a) as it applies to Appendix G, and substitute with the use of 
ASME Code Cases N-588 and N-640. 10 CFR part 50, Appendix G, requires 
that pressure-temperature (P-T) limits be established for reactor 
pressure vessels (RPVs) during normal operating and hydrostatic or leak 
rate testing conditions. Specifically, 10 CFR part 50, Appendix G, 
states, ``The appropriate requirements on both the pressure-temperature 
limits and the minimum permissible temperature must be met for all 
conditions.'' Appendix G of 10 CFR Part 50 specifies that the 
requirements for these limits are the American Society of Mechanical 
Engineers (ASME) Boiler and Pressure Vessel Code (Code), Section XI, 
Appendix G Limits.
    The proposed action is in accordance with the licensee's 
application for exemption dated July 5, 2000, as supplemented by letter 
dated December 8, 2000.

The Need for the Proposed Action

    The proposed action (i.e., granting the exemption) is needed 
because utilization of Code Case N-588 and Code Case N-640 will widen 
the current narrow P-T operating window, especially in the region of 
low temperature operations. The two primary safety benefits that would 
be realized are a reduction in the challenges to the low-temperature 
over pressure protection (LTOP) system, resulting in an inadvertent 
opening of a power-operated relief valve (PORV) and a reduction in the 
risk of damaging the reactor coolant pump seals due to pump operation, 
under conditions where it is difficult to maintain adequate seal 
differential pressure to ensure proper pump operation.
    Code Case N-588 permits the postulation of a circumferentially-
oriented flaw (in lieu of an axially-oriented flaw) for the evaluation 
of the circumferential welds in RPV P-T limit curves. Code Case N-640 
permits the use of an alternate reference fracture toughness 
(KIC fracture toughness curve instead of Kla 
fracture toughness curve) for reactor vessel materials in determining 
the P-T limits. Since the pressure stresses on a circumferentially-
oriented flaw are lower than the pressure stresses on an axially-
oriented flaw by a factor of 2, using Code Case N-588 for establishing 
the P-T limits would be less conservative than the methodology 
currently endorsed by 10 CFR Part 50, Appendix G and, therefore, an 
exemption to apply the Code Case would be required by 10 CFR 50.60. 
Likewise, since the KIC fracture toughness curve shown in 
ASME Section XI, Appendix A, Figure G-2200-1 (the KIC 
fracture toughness curve) provides greater allowable fracture toughness 
than the corresponding Kla fracture toughness curve of ASME 
Section XI, Appendix G, Figure G-2210-1 (the Kla fracture 
toughness curve), using Code Case N-640 for establishing the P-T limits 
would be less conservative than the methodology currently endorsed by 
10 CFR Part 50, Appendix G and, therefore, an exemption to apply the 
Code Case would also be required by 10 CFR 50.60. It should be noted 
that, although Code Case N-640 was incorporated into the ASME Code 
recently, an exemption is still needed because the proposed P-T limits 
(excluding Code Cases N-588 and

[[Page 38756]]

N-640) are based on the 1989 edition of the ASME Code.

Environmental Impacts of the Proposed Action

    The NRC has completed its evaluation of the proposed action and 
concludes granting the exemption would provide an adequate margin of 
safety against brittle failure of the Byron and Braidwood reactor 
vessels. The proposed action (i.e., granting the exemption) will not 
significantly increase the probability or consequences of accidents, no 
changes are being made in the types of any effluents that may be 
released off site, and there is no significant increase in occupational 
or public radiation exposure. Therefore, there are no significant 
radiological environmental impacts associated with the proposed action.
    With regard to potential non-radiological impacts, the proposed 
action does not have a potential to affect any historic sites. It does 
not affect non-radiological plant effluents and has no other 
environmental impact. Therefore, there are no significant non-
radiological environmental impacts associated with the proposed action.
    Accordingly, the NRC concludes that there are no significant 
environmental impacts associated with the proposed action.

Environmental Impacts of the Alternatives to the Proposed Action

    As an alternative to the proposed action, the staff considered 
denial of the proposed action (i.e., the ``no-action'' alternative). 
Denial of the application would result in no change in current 
environmental impacts. The environmental impacts of the proposed action 
and the alternative action are similar.

Alternative Use of Resources

    This action does not involve the use of any different resource than 
those previously considered in the Final Environmental Statement for 
the Byron and Braidwood stations dated April 1982 and June 1984 
respectively.

Agencies and Persons Consulted

    On June 22, 2001, the staff consulted with the Illinois State 
official, Mr. Frank Niziolek of the Illinois Department of Nuclear 
Safety, regarding the environmental impact of the proposed action. The 
State official had no comments.

Finding of No Significant Impact

    On the basis of the environmental assessment, the NRC concludes 
that the proposed action will not have a significant effect on the 
quality of the human environment. Accordingly, the NRC has determined 
not to prepare an environmental impact statement for the proposed 
action.
    For further details with respect to the proposed action, see the 
licensee's letter dated July 5, 2000, as supplemented by letter dated 
December 8, 2000. Documents may be examined, and/or copied for a fee, 
at the NRC's Public Document Room, located at One White Flint North, 
11555 Rockville Pike (first floor), Rockville, Maryland. Publicly 
available records will be accessible electronically from the Agencywide 
Documents Access and Management Systems (ADAMS) Public Electronic 
Reading Room on the Internet at the NRC web site, 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-
415-4737 or by e-mail to [email protected].

    Dated at Rockville, Maryland, this 19th day of July 2001.

For the Nuclear Regulatory Commission.
Mahesh Chawla,
 Project Manager, Section 2, Project Directorate III, Division of 
Licensing Project Management, Office of Nuclear Reactor Regulation.
[FR Doc. 01-18520 Filed 7-24-01; 8:45 am]
BILLING CODE 7590-01-P