[Federal Register Volume 74, Number 82 (Thursday, April 30, 2009)]
[Notices]
[Pages 20000-20002]
From the Federal Register Online via the Government Publishing 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: http://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 [email protected].
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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