Exelon Generation Company, LLC, Byron Station, Unit No. 2; Environmental Assessment and Finding of No Significant Impact, 20000-20002 [E9-9950]

Agencies

• NUCLEAR REGULATORY COMMISSION

[Federal Register Volume 74, Number 82 (Thursday, April 30, 2009)]
[Notices]
[Pages 20000-20002]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E9-9950]


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NUCLEAR REGULATORY COMMISSION

[Docket No. 50-455; NRC-2009-0182]


Exelon Generation Company, LLC, Byron Station, Unit No. 2; 
Environmental Assessment and Finding of No Significant Impact

    The U.S. Nuclear Regulatory Commission (NRC) is considering 
issuance of an exemption from Title 10 of the Code of Federal 
Regulations (10 CFR), Part 50, Section 50.46, ``Acceptance criteria for 
emergency core cooling systems for light-water nuclear power 
reactors,'' paragraph (a)(1)(i) for Facility Operating License No. NPF-
66, issued to Exelon Generation Company, LLC (Exelon, the licensee), 
for operation of the Byron Station, Unit No. 2 (Byron 2), located in 
Ogle County, Illinois. Therefore, as specified in 10 CFR 51.21, the NRC 
staff has performed an environmental assessment as described in this 
notice and has made a finding of no significant impact.

Environmental Assessment

    Identification of the Proposed Action:
    The proposed action would grant an exemption from the requirement 
of 10 CFR 46(a)(1)(i) related to fuel cladding material. The proposed 
action would allow a third cycle of irradiation (i.e., burnup) for up 
to 16 twice-burned fuel rods in Westinghouse AXIOM\TM\ cladding in a 
lead test assembly (LTA), with the remaining fuel rods in the LTA being 
fresh fuel rods in AXIOM\TM\ cladding. This third cycle of irradiation 
is expected to begin in the Cycle 16 core for Byron 2 in the spring of 
2010. Previously, by letter dated June 30, 2006 (Agencywide Documents 
Access and Management System (ADAMS) Accession No. ML061380518), the 
NRC staff approved the irradiation of four LTAs containing AXIOM\TM\ 
clad fuel rods in the Byron Station, Unit No. 1 (Byron 1) Cycle 15 
core. In the same letter, the NRC staff also approved the re-insertion 
of two of the four LTAs into the Byron 1 Cycle 16 core and the other 
two LTAs into the Byron 2 Cycle 15 core. Byron 1 is currently operating 
in Cycle 16; Byron 2 is currently operating in Cycle 15. Prior to re-
insertion of the LTAs into the Cycle 16 and Cycle 15 cores, 
respectively, for the second cycle of irradiation, the licensee 
performed post-irradiation examination (PIE) for the LTAs. During the 
spring 2010, Byron 2 refueling outage, the licensee plans to perform 
PIE for the two LTAs, then re-insert one LTA into the Byron 2 Cycle 16 
core to gain high burnup data. The LTA will consist of fresh fuel rods 
in AXIOM\TM\ cladding along with up to 16 twice-burned fuel rods in 
AXIOM\TM\ cladding selected from the irradiated LTAs. The licensee 
estimated that, at the beginning of this third cycle, the twice-burned 
fuel rods will have a burnup of approximately 50,000 megawatt days per 
metric ton uranium (MWD/MTU) and, at the end of this third cycle, the 
fresh fuel rods would reach an average burnup of approximately 27,500 
MWD/MTU and the twice-burned fuel rods could reach a peak rod average 
burnup of 75,000 MWD/MTU.
    The proposed action is in response to the licensee's exemption 
request dated March 24, 2008 (ADAMS Accession No. ML080850235). Also, 
information in the licensee's letter dated September 23, 2005 (ADAMS 
Accession No. ML060930560), that supported the exemption previously 
issued on June 30, 2006, has been considered in this action.
    The Need for the Proposed Action:
    Pursuant to 10 CFR 50.12, ``Specific exemptions,'' the licensee, in 
its letter dated March 24, 2008, requested an exemption from the 
requirements of 10 CFR 50.46 and 10 CFR Part 50, Appendix K for one LTA 
using AXIOM\TM\ cladding.
    As the licensee stated in its letter dated March 24, 2008, ``The 
purpose of irradiating the twice-burned AXIOM\TM\ clad fuel rods in a 
fresh LTA is to: (1) Evaluate the AXIOM\TM\ clad fuel rod performance 
at projected rod burnups between 72,000 to 75,000 MWD/MTU, (2) collect 
fuel clad profilometry data after one cycle for the fresh rods and 
after three cycles for the high burnup rods, and (3) evaluate AXIOM\TM\ 
clad integral fuel burnable absorber fuel rod performance.''
    The regulation at 10 CFR 50.46(a)(1)(i) requires that ``[e]ach 
boiling or pressurized light-water nuclear power reactor fueled with 
uranium oxide pellets within cylindrical zircaloy or ZIRLO cladding 
must be provided with an emergency core cooling system (ECCS) that must 
be designed so that its calculated cooling performance following 
postulated loss-of-coolant accidents conforms to the criteria set forth 
in paragraph (b) of this section.'' The regulation at 10 CFR 
50.46(a)(1)(ii) requires that, ``[a]lternatively, an ECCS evaluation 
model may be developed in conformance with the required and acceptable 
features of appendix K ECCS Evaluation Models.'' Appendix K of 10 CFR 
Part 50 requires, in paragraph I.A.5, that ``[t]he rate of energy 
release, hydrogen generation, and cladding oxidation from the metal/
water reaction shall be calculated using the Baker-Just equation 
(Baker, L., Just, L.C., ``Studies of Metal Water Reactions at High 
Temperatures, III. Experimental and Theoretical Studies of the 
Zirconium-Water Reaction,'' ANL-6548, page 7, May 1962).'' The 
regulations make no provisions for use of fuel rods clad in a material 
other than zircaloy or ZIRLO\TM\. As noted previously, the licensee 
plans to irradiate one LTA using fuel rods clad with AXIOM\TM\ alloy in 
Byron 2. Because the material specification of the AXIOM\TM\ alloy 
differs from the specification for zircaloy and ZIRLO\TM\, the licensee 
requested a plant-specific exemption from the requirements of 10 CFR 
50.46 and 10 CFR Part 50, Appendix K, to support the use of the LTA for 
Byron 2.
    As a result of the NRC staff's safety evaluation, the details of 
which will be provided as part of the letter to the licensee approving 
the exemption from 10 CFR 50.46(a)(1)(i), the NRC staff determined that 
an exemption from 10 CFR Part 50, Appendix K, is not necessary in this 
circumstance and, therefore, is not issuing an exemption from 10 CFR 
Part 50, Appendix K.
    Environmental Impacts of the Proposed Action:
    The proposed action would grant an exemption from a regulation for 
the acceptance and analytical criteria for emergency core cooling 
systems; the exemption is not an exemption from regulations directly 
governing offsite dose/exposure, occupational exposure, or the 
environment.
    The NRC staff has completed its evaluation of the proposed action 
and concludes that there are no significant environmental impacts 
associated with the use of one LTA using AXIOM\TM\ cladding for a third 
cycle of irradiation up to a burnup of 75,000 MWD/MTU. The following is 
a summary of the NRC staff's evaluation:
    In this environmental assessment, the NRC staff is relying, in 
addition to information submitted by the licensee, on the results of a 
study conducted for it by the Pacific Northwest National Laboratory 
(PNNL) entitled,

[[Page 20001]]

``Environmental Effects of Extending Fuel Burnup Above 60 GWD/MTU 
[gigawatt days per metric ton uranium],'' NUREG/CR-6703, PNNL-13257, 
January 2001. Although the study evaluated the environmental impacts of 
high burnup fuel up to 75,000 MWD/MTU, certain aspects of the review 
were limited to evaluating the impacts of extended burnup up to 62,000 
MWD/MTU because of the need for additional data about the effect of 
extended burn-up on gap-release fractions. During the study, all 
aspects of the fuel-cycle were considered, from mining, milling, 
conversion, enrichment and fabrication through normal reactor 
operation, transportation, waste management, and storage of spent fuel.
    The NRC staff has concluded that such changes would not adversely 
affect plant safety, and would have no adverse effect on the 
probability of any accident. For accidents that involve damage or 
melting of the fuel in the reactor core, fuel rod integrity has been 
shown to be unaffected by the extended burnup under consideration; 
therefore, the probability of an accident will not be affected. For 
accidents in which the core remains intact, the increased burnup may 
slightly change the mix of fission products that could be released in 
the event of a serious accident; however, the NRC staff concludes that 
the limited number of high burnup fuel rods in one LTA will not result 
in a significant change during core-wide events.
    Accidents that involve the damage or melting of the fuel in the 
reactor core and spent fuel handling accidents were also evaluated in 
NUREG/CR-6703. The accidents considered were a loss-of-coolant accident 
(LOCA), a steam generator tube rupture, and a fuel-handling accident 
(FHA).
    For LOCAs, the amount of radionuclides that would be released from 
the core (1) is proportional to the amount of radionuclides in the core 
and (2) is not significantly affected by the gap-release fraction. The 
gap-release fraction is a small contributor to the amount of 
radionuclides available for release when the fuel is severely damaged. 
Any increase in the amount of some longer-lived radionuclides available 
for release from the single LTA (1) will be small and (2) will not 
result in a significant increase in the overall core inventory of 
radionuclides. Therefore, there would be no significant increase in the 
previously calculated dose from a LOCA and the dose would remain below 
regulatory limits.
    The pressurized-water reactor steam generator tube rupture accident 
involves direct release of radioactive material from contaminated 
reactor coolant to the environment. No change is being requested by the 
licensee to the Byron Station technical specifications (TSs) pertaining 
to allowed cooling-water activity concentrations. The maximum coolant 
activity is regulated through TSs that are independent of fuel burnup. 
Therefore, the gap-release fraction does not significantly affect the 
amount of radionuclides available for release during a steam generator 
tube rupture. Therefore, there would be no significant increase in the 
previously-calculated dose from a steam generator tube rupture and the 
calculated dose would remain below regulatory limits.
    The scenario postulated to evaluate potential FHAs involves a 
direct release of gap activity to the environment. The assumptions 
regarding gap activity are based on guidance in Regulatory Guide 1.183, 
``Alternative Radiological Source Terms for Evaluating Design Basis 
Accidents at Nuclear Power Reactors,'' July 2000, and in NUREG/CR-5009, 
``Assessment of the Use of Extended Burnup Fuel in Light Water Power 
Reactors,'' February 1988. The gap activity consists primarily of noble 
gases and iodine. The isotopes that contribute significant fractions of 
the whole body and thyroid doses are \87\Kr and \131\I, respectively. 
The inventory of iodine and the primary dose contributor, decreases 
with increasing burnup. In addition, the single LTA will only 
contribute a small variation in the isotopic population of the entire 
Byron 2 core (193 fuel assemblies). In its letter dated March 24, 2008, 
the licensee discussed the conservatisms associated with the Byron FHA 
dose calculation, specifically: Use of the alternative source term 
methodology, the relative power for this particular LTA in Cycle 16, 
offloading time, containment isolation, and mechanical fuel damage due 
to impact. Based on the considerations discussed above, the NRC staff 
concludes (1) that the increase in the previously calculated dose 
resulting from a FHA involving the one LTA would not be significant, 
and (2) that the dose would remain below regulatory limits.
    Regulatory limits on radiological effluent releases are independent 
of burnup. The requirements of 10 CFR 50.36a, ``Technical 
specifications on effluents from nuclear power reactors,'' and 10 CFR 
Part 50, Appendix I, ``Numerical Guides for Design Objectives and 
Limiting Conditions for Operation to Meet the Criterion `As Low as is 
Reasonably Achievable' for Radioactive Material in Light-Water-Cooled 
Nuclear Power Reactor Effluents,'' ensure that any release of gaseous, 
liquid, or solid radiological effluents to unrestricted areas are kept 
``as low as reasonably achievable.'' Therefore, the NRC staff concludes 
that during routine operations, there will be no significant increase 
in the amount of gaseous radiological effluents released into the 
environment as a result of the proposed action, nor will there be a 
significant increase in the amount of liquid radiological effluents or 
solid radiological effluents released into the environment.
    No significant increase in the allowable individual or cumulative 
occupational radiation exposure will occur. The impacts to workers is 
expected to be reduced with higher irradiation due to the need for less 
frequent outages for fuel changes and less frequent fuel shipments to 
and from reactor sites.
    The use of extended irradiation will not change the potential 
environmental impacts of incident-free transportation of spent nuclear 
fuel or the accident risks associated with spent fuel transportation if 
the fuel is cooled for 5 years after discharge from the reactor. NUREG/
CR-6703 concluded that doses associated with incident-free 
transportation of spent fuel with burnup to 75 GWD/MTU are bounded by 
the doses given in 10 CFR 51.52, ``Environmental effects of 
transportation of fuel and waste--Table S-4,'' for all regions of the 
country if dose rates from the shipping casks are maintained within 
regulatory limits. Increased fuel burnup will decrease the annual 
discharge of fuel to the spent fuel pool, which will postpone the need 
to remove spent fuel from the pool.
    With regard to potential non-radiological environmental impacts of 
reactor operation with extended irradiation, the proposed changes 
involve systems located within the restricted area as defined in 10 CFR 
part 20, ``Standards For Protection Against Radiation.''
    Therefore, the proposed action does not result in any significant 
changes to land use or water use, or result in any significant changes 
to the quality or quantity of effluents. The proposed action does not 
affect nonradiological plant effluents, and no changes to the National 
Pollution Discharge Elimination System permit are needed. No effects on 
the aquatic or terrestrial habitat in the vicinity of the plant, or to 
endangered or threatened species, or to the habitats of endangered or 
threatened species are expected. The proposed action does not have a 
potential to affect any historical or archaeological sites.
    The proposed action will not change the method of generating 
electricity or the method of handling any influents

[[Page 20002]]

from the environment or non-radiological effluents to the environment. 
Therefore, no changes or different types of non-radiological 
environmental impacts are expected as a result of the exemption.
    Accordingly, the NRC staff concludes that there are no significant 
environmental impacts associated with the proposed action.
    For more detailed information regarding the environmental impacts 
of extended fuel burnup, please refer to NUREG/CR-6703.
    The details of the NRC staff's safety evaluation will be provided 
in the exemption that will be issued as part of the letter to the 
licensee approving the exemption to the regulation.
    Environmental Impacts of the 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 exemption request would result in no change in current 
environmental impacts. The environmental impacts of the proposed 
exemption and this alternative are similar.
    Alternative Use of Resources:
    The action does not involve the use of any different resources than 
those previously considered in the ``Final Environmental Statement 
Related to the Operation of Byron Station, Units 1 and 2,'' NUREG-0848, 
dated April 1982.
    Agencies and Persons Consulted:
    In accordance with its stated policy, on February 27, 2009, the NRC 
staff consulted with the Illinois State official, Mr. Frank Niziolek of 
the Illinois Emergency Management Agency, 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 staff 
concludes that the proposed action will not have a significant effect 
on the quality of the human environment. Accordingly, the NRC staff 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 March 24, 2008 (ADAMS Accession No. 
ML080850235). Documents may be examined, and/or copied for a fee, at 
the NRC's Public Document Room (PDR), located at One White Flint North, 
1555 Rockville Pike, Rockville, Maryland 20852. Publicly available 
records will be accessible electronically from the ADAMS Public 
Electronic Reading Room on the Internet at the NRC Web site: https://www.nrc.gov/reading-rm/adams.html. Persons who do not have access to 
ADAMS or who encounter problems in accessing the documents located in 
ADAMS should contact the NRC PDR Reference staff by telephone at 1-800-
397-4209 or 301-415-4737, or send an e-mail to pdr@nrc.gov.

    Dated at Rockville, Maryland, this 23rd day of April 2009.

    For The Nuclear Regulatory Commission
Christopher Gratton,
Senior Project Manager, Plant Licensing Branch III-2, Division of 
Operating Reactor Licensing, Office of Nuclear Reactor Regulation.
[FR Doc. E9-9950 Filed 4-29-09; 8:45 am]
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