[Federal Register Volume 66, Number 73 (Monday, April 16, 2001)]
[Notices]
[Pages 19586-19588]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-9465]


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NUCLEAR REGULATORY COMMISSION

[Docket No. 50-331]


Nuclear Management Company, LLC; Duane Arnold Energy Center; 
Environmental Assessment and Finding of No Significant Impact

    The U.S. Nuclear Regulatory Commission (NRC) is considering 
issuance of an amendment to Facility Operating License No. DPR-49, 
issued to Nuclear Management Company, LLC (NMC, the licensed operator) 
and IES Utilities Inc., Central Iowa Power Cooperative, Corn Belt Power 
Cooperative (the licensed owners), for operation of the Duane Arnold 
Energy Center, located in Linn County, Iowa.

Environmental Assessment

Identification of the Proposed Action

    The proposed action would revise Facility Operating License No. 
DPR-49 to change the Technical Specifications (TS) for Duane Arnold 
Energy Center (DAEC and the facility) by relaxing operability 
requirements for secondary containment (aka, the reactor building), 
including associated isolation instrumentation, valves, dampers, and 
the standby gas treatment system, during core alterations and movement 
of irradiated fuel assemblies. The proposed action would also provide 
for a change in design and licensing bases for a selective application 
of the alternate radiological source term (AST) in accordance with 10 
CFR 50.67, ``Accident Source Term,'' and revised meteorology dispersion 
values, both being limited to evaluations of the consequences of a 
design-basis fuel handling accident (FHA).
    The proposed action is in accordance with a portion of NMC's 
application for amendment by letter dated October 19, 2000, as 
supplemented November 16, 2000, and April 9, 2001, and as limited in 
scope by NMC's letter dated March 23, 2001.

The Need for the Proposed Action

    Changing DAEC's TS to relax requirements for the operability of the 
secondary containment (including associated isolation instrumentation, 
isolation valves and dampers, and the standby gas treatment system) 
when core alterations are occurring or spent fuel is being moved 
provides increased flexibility to NMC in the scheduling and conduct of 
refueling activities. Changing the design and licensing bases regarding 
an AST for a FHA recognizes advances in understanding of the behavior 
of radiological releases resulting from the

[[Page 19587]]

accident, and is in accordance with 10 CFR 50.67. Changing the design 
and licensing bases regarding atmospheric dispersion values for use in 
evaluating the potential consequences of a radiological release due to 
a FHA is needed as a result of more recent data obtained from DAEC's 
meteorological program over the period of January 1, 1997, to December 
31, 1999. NMC states that DAEC's historical atmospheric dispersion data 
did not meet its current expectations for level of documentation and 
design bases, and was not sufficient for analysis of new transport 
pathways in the AST methodology.

Environmental Impacts of the Proposed Action

    In December 1999, the NRC issued 10 CFR 50.67, which provides a 
mechanism for licensees of power reactors to replace the traditional 
radiological source term used in the design-basis accident (DBA) 
analyses with an AST. The NRC also issued Regulatory Guide (RG) 1.183, 
``Alternative Radiological Source Terms for Evaluating Design-Basis 
Accidents at Nuclear Power Reactors,'' to provide guidance for 
implementing these ASTs. Section 50.67 provides that a licensee who 
seeks to revise its current accident source term in design basis 
radiological consequence analyses shall submit an application for a 
license amendment containing an evaluation of the consequences of 
applicable DBAs previously analyzed in the safety analysis report. By 
letter dated October 19, 2000, Nuclear Management Company, LLC (NMC and 
the licensee) requested a license amendment to apply the AST to a 
spectrum of DBAs. NMC's evaluation of the radiological consequences for 
the spectrum of DBAs applied the AST consistent with NMC's application 
for amendment, by letter dated November 16, 2000, to increase the 
maximum power level from 1658 thermal megawatts (MWt) to 1912 MWt. In a 
subsequent letter dated March 23, 2001, NMC requested that the portion 
of the October 19, 2000, application addressing a design-basis FHA be 
reviewed separately and in an expedited manner to facilitate an 
upcoming refueling outage. By letter dated April 9, 2001, NMC forwarded 
typed TS replacement pages reflecting certain TS changes proposed in 
the March 23, 2001, letter.
    Accordingly, as requested in NMC's letter dated March 23, 2001, 
this environmental assessment addresses only the following portions of 
the original October 19, 2000, application for license amendment: (1) 
Implementing the AST in the radiological consequence analysis of a 
design-basis FHA performed to show compliance with 10 CFR 50.67(b)(2); 
(2) using revised atmospheric dispersion factors for radiological 
releases related to release points and human receptors associated with 
an FHA; and (3) eliminating TS requirements for operability of 
secondary containment (TS 3.6.4.1), its isolation instrumentation (TS 
3.3.6.2), isolation valves and dampers (TS 3.6.4.2), and the standby 
gas treatment system (TS 3.6.4.3) during core alterations and movement 
of irradiated fuel assemblies.
    The application for amendment describes NMC's radiological analysis 
of the design-basis FHA implementing the AST for a reactor core 
designed to operate at up to 1912 MWt. The accident analysis postulates 
that a spent fuel assembly is dropped from 30 feet above the top of the 
reactor core during refueling operations, resulting in the breaching of 
the cladding for 151 fuel rods. The drop over the reactor core is more 
limiting (damages more fuel rods) than any drops that could occur over 
the fuel pool. The assumption of 151 damaged fuel rods is more 
conservative than the existing design and licensing basis value of 125 
fuel rods. Consistent with DAEC refueling procedures, a post-shutdown 
period of 60 hours is credited for radioactive decay in determining the 
release activity inventory, which is greater than the existing design 
and licensing basis of 24 hours. All the activity in the gap between 
the fuel pellets and the cladding of the damaged fuel rods is assumed 
to be released instantaneously into the pool. A pool water iodine 
decontamination factor of 200 is used, which is higher than the value 
of 100 used in the existing licensing basis analysis. NMC assumed no 
decontamination for noble gases released in the pool and full retention 
of all aerosol and particulate fission products by the pool water. Any 
activity leaving the pool enters the reactor building. All of the FHA 
activity is assumed to be released within 2 hours from the reactor 
building as a ground release, with no credit for holdup or dilution by 
the reactor building, and no credit for operation of the standby gas 
treatment system. Not crediting any dilution, holdup, or cleanup by the 
standby gas treatment system of the activity released from the pool 
represents a more conservative basis than that used in the existing 
licensing basis FHA analysis. NMC used atmospheric dispersion values 
derived from additional meteorology data from DAEC's meteorological 
program over the period of January 1, 1997, to December 31, 1999. The 
new atmospheric dispersion values are more conservative (e.g., provide 
higher offsite doses) than the previous values. The NRC staff finds 
that these assumptions and input parameters for the design-bases FHA 
are consistent with NMC's application to (1) change the TS to relax 
requirements for the operability of the secondary containment 
(including associated isolation instrumentation, isolation valves and 
dampers, and the standby gas treatment system) when core alterations 
are occurring or spent fuel is being moved, (2) change the design and 
licensing bases to apply an AST for a FHA, and (3) change the design 
and licensing bases to apply the updated atmospheric dispersion values 
for the FHA consequence analysis.
    The results of NMC's analyses indicate that the dose at the 
exclusion area boundary would be no more than 0.94 rem total effective 
dose equivalent (TEDE) \1\ and the dose at the low-population zone 
would be no more than 0.23 rem TEDE. These results are less than the 
TEDE criterion of 6.3 rem set forth in RG 1.183 (Table 6) and, 
therefore, are acceptable. Therefore, the proposed action to change the 
TS and the licensing and design bases regarding the design-basis FHA 
does not represent a significant offsite radiological impact to the 
human environment.
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    \1\ As part of the implementation of the AST, the TEDE 
acceptance criterion of 10 CFR 50.67(b)(2) replaces the previous 
whole body and thyroid dose guidelines of 10 CFR 100.11, ``Reactor 
Site Criteria--Determination of Exclusion Area, Low Population Zone, 
and Population Center Distance,'' and General Design Criterion 
(GDC)-19 of 10 CFR part 50, appendix A, which (based upon NMC's 
selective application) is limited to the FHA only.
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    Using the above AST and the updated atmospheric dispersion values, 
NMC evaluated the dose to operators in the control room assuming that 
operators manually actuate control room isolation within 10 minutes. 
NMC evaluated the dose to personnel in the technical support center 
(TSC), which was assumed to be isolated manually after a 30-minute 
delay. These delay times are consistent with NMC's proposed TS change 
to relax the operability requirements for isolation of the control room 
and TSC. The analyses also assumed 1000 cubic feet per minute of 
unfiltered inleakage into the control room and TSC, even though both 
areas are designed to be pressurized to preclude such inleakage after 
an accident. The control room and TSC doses were analyzed over a 30-day 
period. The results indicate that the control room operators would 
receive no more than 3.16 rem TEDE and TSC personnel would receive no 
more than

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2.83 rem TEDE. These doses are less than the TEDE limit of 5 rem 
contained in 10 CFR 50.67 and are, therefore, acceptable. Therefore, 
the proposed action would not result in a significant onsite 
radiological impact to the human environment.
    The proposed action to change the TS and to change the licensing 
and design bases with respect to the FHA will not increase the 
probability or consequences of accidents, no significant changes are 
being made in the types or amounts of any effluents that may be 
released offsite, and there is no significant increase in occupational 
or public radiation exposure. Therefore, the NRC concludes that there 
are no significant radiological environmental impacts associated with 
the proposed action.
    With regard to potential nonradiological impacts, the proposed 
action does not involve any historic sites. The proposed action does 
not involve any physical features of the plant or procedure changes 
involving a potential nonradiological release. Thus, the proposed 
action does not affect nonradiological plant effluents and has no other 
environmental impact. Therefore, there are no significant 
nonradiological environmental impacts associated with the proposed 
action.
    Accordingly, the NRC 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 NRC staff considered 
denial of the proposed action (i.e., the ``no action'' alternative). 
Denial of the application would not result in a significant improvement 
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 Relating 
to the Operation of Duane Arnold Energy Center,'' dated March 1973.

Agencies and Persons Consulted

    In accordance with its stated policy, the NRC staff consulted with 
the Iowa State official, Mr. D. Fleeter of the Department of Public 
Health, 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 
application dated October 19, 2000, as supplemented by letters dated 
November 16, 2000, and April 9, 2001, and as limited in scope by letter 
dated March 23, 2001. 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 
ADAMS Public Library component on the NRC Web site, http://www.nrc.gov 
(the Electronic Reading Room).


    Dated at Rockville, Maryland, this 11th day of April 2001.
    For the Nuclear Regulatory Commission.
Darl S. Hood,
Senior Project Manager, Section 1, Project Directorate III, Division of 
Licensing Project Management, Office of Nuclear Reactor Regulation.
[FR Doc. 01-9465 Filed 4-13-01; 8:45 am]
BILLING CODE 7590-01-P