[Federal Register Volume 65, Number 182 (Tuesday, September 19, 2000)]
[Notices]
[Pages 56602-56603]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-24020]
-----------------------------------------------------------------------
NUCLEAR REGULATORY COMMISSION
Commonwealth Edison Company; Dresden Nuclear Power Station, Units 2
and 3; Environmental Assessment and Finding of No Significant
Impact
[Docket Nos. 50-237 and 50-249]
The U.S. Nuclear Regulatory Commission (NRC) is considering
issuance of an exemption from certain
[[Page 56603]]
requirements of 10 CFR 50.60(a) for Facility Operating Licenses Nos.
DPR-19 and DPR-25, issued to Commonwealth Edison Company (ComEd, or the
licensee) for operation of the Dresden Nuclear Power Station, Units 2
and 3, located in Grundy County, Illinois.
Environmental Assessment
Identification of the Proposed Action
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.
To address provisions of amendments to the technical specifications
(TS) P-T limits, the licensee requested in its submittal dated February
23, 2000, that the staff exempt ComEd from application of specific
requirements of 10 CFR Part 50, Section 50.60(a) and Appendix G, and
substitute use of ASME Code Cases N-588 and N-640.
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 KIa
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 two, 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(b). Likewise, since the KIC fracture toughness
curve shown in ASME Section XI, Appendix A, Figure A-2200-1 (the
KIC fracture toughness curve) provides greater allowable
fracture toughness than the corresponding KIa fracture
toughness curve of ASME Section XI, Appendix G, Figure G-2210-1 (the
KIa 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(b).
The Need for the Proposed Action
The proposed exemption is needed to allow the licensee to implement
ASME Code Case N-588 and Code Case N-640 in order to revise the
method used to determine the reactor coolant system (RCS) P-T limits,
because continued use of the present curves unnecessarily restricts the
P-T operating window. Since the RCS P-T operating window is defined by
the P-T operating and test limit curves developed in accordance with
the ASME Section XI, Appendix G procedure, continued operation of
Dresden with these P-T curves without the relief provided by ASME Code
Case N-640 would unnecessarily require the RPV to maintain a
temperature exceeding 212 degrees Fahrenheit in a limited operating
window during the pressure test. Consequently, steam vapor hazards
would continue to be one of the safety concerns for personnel
conducting inspections in primary containment. Implementation of the
proposed P-T curves, as allowed by ASME Code Cases N-588 and N-640,
does not significantly reduce the margin of safety and would eliminate
steam vapor hazards by allowing inspections in primary containment to
be conducted at a lower coolant temperature.
In the associated exemption, the staff has determined that,
pursuant to 10 CFR 50.12(a)(2)(ii), the underlying purpose of the
regulation will continue to be served by the implementation of these
Code Cases.
Environmental Impacts of the Proposed Action
The Commission has completed its evaluation of the proposed action
and concludes that there are no significant adverse environmental
impacts associated with the proposed action.
The proposed action 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 offsite, 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 nonradiological environmental impacts, the
proposed action does not involve any historic sites. It does not affect
nonradiological plant effluents and has no other environmental impact.
Therefore, there are no significant nonradiological impacts associated
with the proposed action.
Accordingly, the Commission concludes that there are no significant
environmental impacts associated with the proposed action.
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 resources not
previously considered in the Final Environmental Statement for the
Dresden Nuclear Power Station, Units 2 and 3, dated November 1973.
Agencies and Persons Consulted
In accordance with its stated policy, on July 19, 2000, the staff
consulted with the Illinois State official, 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 Commission 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 February 23, 2000, which is available for
public inspection at the NRC Public Document Room, The Gelman Building,
2120 L Street, NW., Washington, DC. Publicly available records will be
accessible electronically from the ADAMS Public Library component on
the NRC Web site, http://www.nrc.gov (the Electronic Reading Room).
Dated at Rockville, Maryland, this 17th day of August 2000.
For the Nuclear Regulatory Commission.
Anthony J. Mendiola,
Chief, Section 2, Project Directorate III, Division of Licensing
Project Management, Office of Nuclear Reactor Regulation.
[FR Doc. 00-24020 Filed 9-18-00; 8:45 am]
BILLING CODE 7590-01-U