[Federal Register Volume 80, Number 188 (Tuesday, September 29, 2015)]
[Notices]
[Pages 58509-58512]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-24655]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos.: 72-1004, 72-40, 50-269, 50-270, 50-287; and NRC-2015-
0191]
Duke Energy Carolinas, LLC; Oconee Nuclear Station Units 1, 2,
and 3; Independent Spent Fuel Storage Installation
AGENCY: Nuclear Regulatory Commission.
ACTION: Exemption; issuance.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing an
exemption in response to a request submitted by Duke Energy Carolinas,
LLC., on August 28, 2014, from meeting Technical Specification (TS)
1.2.4a of Attachment A of CoC No. 1004, which limits the leak rate of
the inner seal weld to 1.0 X 10-7 reference cubic centimeters per
second (ref cc/s) at the highest DSC limiting pressure, for five (5)
dry shielded canisters (DSCs) at the Oconee Nuclear Station,
Independent Spent Fuel Storage Installation (ISFSI).
ADDRESSES: Please refer to Docket ID NRC-2015-0191 when contacting the
NRC about the availability of information regarding this document. You
may obtain publicly-available information related to this document
using any of the following methods:
Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2015-0191. Address
questions about NRC dockets to Carol Gallagher; telephone: 301-415-
3463; email: [email protected]. For technical questions, contact
the individual listed in the FOR FURTHER INFORMATION CONTACT section of
this document.
NRC's Agencywide Documents Access and Management System
(ADAMS): You may obtain publicly-available documents online in the
ADAMS Public Documents collection at http://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``ADAMS Public Documents'' and
then select ``Begin Web-based ADAMS Search.'' For problems with ADAMS,
please contact the NRC's Public Document Room (PDR) reference staff at
1-800-397-4209, 301-415-4737, or by email to [email protected]. The
ADAMS accession number for each document referenced (if it available in
ADAMS) is provided the first time that a document is referenced.
NRC's PDR: You may examine and purchase copies of public
documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555
Rockville Pike, Rockville, Maryland 20852.
FOR FURTHER INFORMATION CONTACT: John Vera, Office of Nuclear Material
Safety and Safeguards, U.S. Nuclear Regulatory Commission, Washington,
DC 20555-0001; telephone: 301-415-5790; email: [email protected].
SUPPLEMENTARY INFORMATION:
1.0 Background
Duke Energy Carolinas, LLC (the applicant) is the holder of
Facility Operating License Nos. DPR-38, DPR-47, and DPR-55, which
authorize operation of the Oconee Nuclear Station, Units 1, 2, and 3 in
Oconee County, South Carolina, pursuant to part 50 of Title 10 of the
Code of Federal Regulations (10 CFR), ``Domestic Licensing of
Production and Utilization Facilities.'' The licenses provide, among
other things, that the facility is subject to all rules, regulations,
and orders of the NRC now or hereafter in effect.
Consistent with 10 CFR part 72, subpart K, ``General License for
Storage of Spent Fuel at Power Reactor Sites,'' a general license is
issued for the storage of spent fuel in an ISFSI at power reactor sites
to persons authorized to possess or operate nuclear power reactors
under 10 CFR part 50. The applicant is authorized to operate a nuclear
power reactor under 10 CFR part 50, and holds a 10 CFR part 72 general
license for storage of spent fuel at the Oconee Nuclear Station ISFSI.
Under the terms of the general license, the applicant stores spent fuel
at its ISFSI using the Transnuclear, Inc. (TN) Standardized
NUHOMS[supreg] dry cask storage system Certificate of Compliance (CoC)
No. 1004, Amendment No. 9.
2.0 Request/Action
The applicant has requested an exemption from the requirements of
10 CFR 72.212(b)(3), 10 CFR 72.212(b)(5)(i), and the portion of 10 CFR
72.212(b)(11) that requires compliance with the terms, conditions, and
specifications of CoC No. 1004, Amendment No. 9, for the Standardized
NUHOMS[supreg] Horizontal Modular Storage System, to the extent
necessary for the applicant to maintain 5 DSCs in their current
position at the ISFSI associated with the operation of Oconee, Units 1,
2, and 3. These regulations specifically require storage of spent
nuclear fuel under a general license in dry storage casks approved
under the provisions of 10 CFR part 72, and compliance with the terms
and conditions set forth in the CoC for each dry storage spent fuel
cask used by an ISFSI general licensee. Specifically, the exemption
would relieve the applicant from meeting TS 1.2.4a of Attachment A of
CoC No. 1004, which limits the leak rate of the inner seal weld to 1.0
x
[[Page 58510]]
10\-7\ reference cubic centimeters per second (ref cc/s) at the highest
DSC limiting pressure. As a result, granting this exemption will allow
for continued storage of DSCs numbers 93, 94, 100, 105, and 106 at the
Oconee Nuclear Station ISFSI.
In January 2014, the applicant identified a discrepancy on a test
report processed from the helium leak rate instrument vendor. The
discrepancy was that the temperature coefficient was stated as four (4)
percent per degree Celsius (%/[deg]C), when previously this value was
three (3) %/[deg]C. The applicant stated that the instrument vendor
confirmed that the three (3) %/[deg]C coefficient was incorrect for
this instrument, and that canisters loaded at ambient temperatures
greater than (>) 23[deg]C would have had a non-conservative temperature
coefficient applied to the helium leak rate measurement. The applicant
stated that the incorrect value had been used to calculate the leak
rates of forty-seven (47) DSCs.
According to the applicant, forty-two (42) of the forty-seven (47)
DSCs affected were verified to meet the TS. The applicant's re-
evaluation involved verifying the ambient temperature when the DSCs
were loaded and applying the appropriate temperature coefficient.
However, the applicant stated that the actual temperature correction
value datasheets could not be found for DSCs 93, 94, 100, 105, and 106,
and that these canisters were loaded in the summer months when ambient
conditions during helium leak testing would likely have exceeded
23[deg]C, so the revised temperature correction factor would have been
applicable. The applicant stated that for these DSCs, without evidence
of the actual ambient temperature or test value, confirmation that the
TS was met with the revised temperature coefficient was not possible.
In a letter dated August 28, 2014, (ADAMS Accession No.
ML14255A005), as supplemented December 8, 2014 (ADAMS Accession No.
ML14346A008), and June 12, 2015 (ADAMS Accession No. ML15169B103), the
applicant requested an exemption from certain parts of the following
requirements to allow storage of the 5 DSCs at the Oconee Nuclear
Station ISFSI:
10 CFR 72.212(b)(3), which states that ``[t]he general
licensee must [e]nsure that each cask used by the general licensee
conforms to the terms, conditions, and specifications of a CoC or an
amended CoC listed in Sec. 72.214.''
10 CFR 72.212(b)(5)(i), which requires that, ``The general
licensee perform written evaluations, before use and before applying
the changes authorized by an amended CoC to a cask loaded under the
initial CoC or an earlier amended CoC, which establish that [t]he cask,
once loaded with spent fuel or once the changes authorized by an
amended CoC have been applied, will conform to the terms, conditions,
and specifications of a CoC or an amended CoC listed in Sec. 72.214.''
10 CFR 72.212(b)(11), which states in part that ``[t]he
licensee shall comply with the terms, conditions, and specifications of
the CoC and, for those casks to which the licensee has applied the
changes of an amended CoC, the terms, conditions, and specifications of
the amended CoC. . . .''
Upon review, in addition to the requirements from which the
applicant requested exemption, the NRC staff determined exemptions from
the following requirements are also necessary in order to authorize the
applicant's request and added the following requirements to the
exemption for the proposed action pursuant to its authority under 10
CFR 72.7, ``Specific exemptions'':
10 CFR 72.212(a)(2), which states that ``[t]his general
license is limited to storage of spent fuel in casks approved under the
provisions of this part.''
10 CFR 72.214, which lists the approved spent fuel storage
casks.
3.0 Discussion
Pursuant to 10 CFR 72.7, the Commission may, upon application by
any interested person or upon its own initiative, grant such exemptions
from the requirements of the regulations of 10 CFR part 72 as it
determines are authorized by law and will not endanger life or property
or the common defense and security and are otherwise in the public
interest.
Authorized by Law
This exemption would allow the applicant to continue storage of
DSCs numbers 93, 94, 100, 105, and 106 in their as-loaded
configurations at the Oconee ISFSI by relieving the applicant of the
requirement to meet the inner seal weld leak rate limit as required by
TS 1.2.4a of Attachment A of CoC No. 1004. The provisions in 10 CFR
part 72 from which the applicant is requesting exemption, as well as
provisions determined to be applicable by the NRC staff, require the
licensee to comply with the terms, conditions, and specifications of
the CoC for the approved cask model it uses. Section 72.7 allows the
NRC to grant exemptions from the requirements of 10 CFR part 72.
Granting the licensee's proposed exemption is not otherwise
inconsistent with NRC regulations or other applicable laws. As
explained below, the proposed exemption will not endanger life or
property, or the common defense and security, and is otherwise in the
public interest. Therefore, the exemption is authorized by law.
Will Not Endanger Life or Property or the Common Defense and Security
This exemption would relieve the applicant from meeting TS 1.2.4a
of Attachment A of CoC No. 1004, which limits the leak rate of the
inner seal weld to less than or equal to 1.0 X 10-7 ref cc/s
at the highest DSC limiting pressure, allowing for continued storage of
DSCs numbers 93, 94, 100, 105, and 106 in their as loaded conditions at
the Oconee Nuclear Station ISFSI. This exemption only addresses the 5
DSCs for which the ambient temperature at time of loading could not be
confirmed by the applicant. Because the temperature at the time of
loading cannot be confirmed, the applicant cannot demonstrate that the
leak rate of the inner seal weld would be less than or equal to 1.0 x
10-7 ref cc/s at the highest DSC limiting pressure. As
detailed below, NRC staff reviewed the exemption request to determine
whether granting of the exemption would cause potential for danger to
life, property, or common defense and security.
Review of the Requested Exemption
Background: The NUHOMS[supreg] system provides for the horizontal
dry storage of canisterized spent fuel assemblies in a concrete
horizontal storage module (HSM). The cask storage system components for
NUHOMS[supreg] consist of a reinforced concrete HSM and a DSC vessel
with an internal basket assembly that holds the spent fuel assemblies.
The HSM is a low-profile, reinforced concrete structure designed to
withstand all normal condition loads, as well as abnormal condition
loads created by natural phenomena such as earthquakes and tornados. It
is also designed to withstand design basis accident conditions. The
Standardized NUHOMS[supreg] Horizontal Modular Storage System has been
approved for storage of spent fuel under the conditions of Certificate
of Compliance No. 1004. The DSCs under consideration for exemption were
loaded under Certificate of Compliance No. 1004, Amendment No. 9.
The NRC has previously approved the Standardized NUHOMS[supreg]
Horizontal Modular Storage System storage system. The requested
exemption does not change the fundamental design, components, contents,
or safety features
[[Page 58511]]
of the storage system. The NRC staff evaluated the applicable potential
safety impacts of granting the exemption to assess the potential for
danger to life or property or the common defense and security. The
potential impacts identified for this exemption request were in the
areas of structural integrity and confinement capability.
Structural Review for the Requested Exemption: The two objectives
of TS 1.2.4a are to (1) demonstrate that the top cover is ``leak
tight'' as defined in ANSI N14.5--1997, ``American National Standard
for Leakage Tests on Packages for Shipment of Radioactive Materials,''
and (2) to retain helium cover gases within the DSC to provide heat
dissipation and minimize oxidation of the fuel cladding. There are two
tests used to verify the ``leak tight'' condition of the inner top
cover seal weld. The first is a dye penetrant test (PT) and the second
is a helium leak test (LT).
The applicant stated that the dye penetrant tests conducted met the
limits of TS 1.2.5 for the population of forty-seven (47) canisters for
which the helium leak rates were calculated with the incorrect
temperature coefficient.
The structural acceptance criteria for both the inner top cover
weld and the outer top cover weld is predicated on the successful
results of the dye penetrant test in accordance with Interim Staff
Guidance (ISG)--15 ``Materials Evaluation'' (ADAMS Accession No.
ML010100170). The NRC staff finds that because the dye penetrant tests
were acceptable, the staff finds that welds are structurally
acceptable. There are no structural implications with the inner top
cover seal weld as a result of the helium leak test having been
conducted with an incorrect temperature correction coefficient. The NRC
staff finds that the structural properties of the five (5) CoC No.
1004, Amendment No. 9 DSCs addressed in the exemption request remain in
compliance with 10 CFR part 72 and the applicable design and acceptance
criteria have been satisfied.
Confinement Review for the Requested Exemption: For canisters
affected by use of an incorrect temperature coefficient for leakage
rate, the licensee was unable to verify compliance with the technical
specifications and thus performed a bounding leak rate calculation
based on the maximum bounding temperature (40.6[deg]C) expected during
the loading of the DSCs. The NRC staff finds that this temperature is
bounding based on publicly published values for the maximum temperature
for the area surrounding Oconee (ADAMS Accession No. ML15218A297). This
calculation resulted in a calculated leak rate limit of 1.02 x
10-7 ref cc/s (air), or a 2% increase. This does not mean
that an actual leakage rate of 1.02 x 10-7 ref cc/s (air) is
expected but that the licensee asserts it is a reasonable estimate of
the worst case leakage rate that can be derived in the absence of an
actual recorded temperature data at the time of leak testing.
The NRC staff finds that the assumption of a maximum bounding
temperature, as described above, is appropriate, because the actual
ambient temperature is unknown. Use of this assumption demonstrated
that the calculated revised leakage rate limit cannot be greater than
reported (1.02 x 10-7 ref cc/s (air)). The ambient
temperature in part determines the maximum size of the equivalent hole
for leak rate calculations, and since the maximum likely temperature
value was used, the NRC staff determined that it is reasonable for the
license to conclude that a bounding leak rate would be achieved with a
maximum equivalent hole size.
The NRC staff reviewed the applicant's calculation method for
determining the equivalent leak rate hole size and the estimated
leakage rate corrected for assumed gas mixtures (i.e., air: helium).
The NRC staff determined that, based on this calculation, even if
significant uncertainty in the physical parameters used in the
calculation were considered, the maximum equivalent hole size was the
main driver that would account for any large change in a calculated
leak rate criteria. Accordingly, the NRC staff determined that the
revised calculated leakage rate with a bounding maximum temperature
could not also result in large changes in the calculated leakage rate
depending on the geometric or other physical parameters, such as
pressure, which are used in the calculation. Therefore, the NRC staff
concludes that consideration of the maximum expected temperature
provides a reasonable best estimate of the maximum leakage rate that
could be expected for the subject DSCs. Inspection of the revised
bounding leak rate calculation demonstrates that even if the package
was leaking at the revised leakage rate, there would still be no
significant release of radioactive material to the environment nor
would this leakage rate result in a depletion of the inert helium
environment necessary to ensure spent fuel cladding integrity.
The NRC staff finds that the confinement functions of the five (5)
CoC No. 1004, Amendment No. 9 DSCs addressed in the exemption request
remain in compliance with 10 CFR part 72.
The NRC staff considered the potential impacts of granting the
exemption on the common defense and security. The requested exemption
is not related to any security or common defense aspect of the Oconee
Nuclear Station ISFSI, therefore granting the exemption would not
result in any potential impacts to common defense and security.
Based on its review, the NRC staff has reasonable assurance that in
granting the exemption, the storage system will continue meet the
thermal, structural, criticality, retrievability and radiation
protection requirements of 10 CFR part 72 and the offsite dose limits
of 10 CFR part 20 and, therefore, will not endanger life or property.
The NRC staff also finds that there is no threat to the common defense
and security.
Therefore, the NRC staff concludes that the exemption to relieve
the applicant from meeting TS 1.2.4a of Attachment A of CoC No. 1004,
which limits the leak rate of the inner seal weld to less than or equal
to 1.0 x 10-7 ref cc/s at the highest DSC limiting pressure,
allowing for continued storage of DSCs numbers 93, 94, 100, 105, and
106 at the Oconee Nuclear Station ISFSI, will not endanger life or
property or the common defense and security.
Otherwise in the Public Interest
In considering whether granting the exemption is in the public
interest, the NRC staff considered the alternative of not granting the
exemption. If the exemption were not granted, in order to comply with
the CoC, the five DSCs which are subject to the exemption request would
have to be unloaded from the storage module, transported back to the
cask handling area, opened, rewelded, retested, transported back to the
HSM, and reloaded. This would entail a higher risk of a cask handling
accident and additional personnel exposure. This alternative would also
generate additional radioactive contaminated material and waste from
operations.
The proposed exemption to permit the continued storage of DSCs
numbers 93, 94, 100, 105, and 106 at the Oconee Nuclear Station ISFSI
is consistent with NRC's mission to protect public health and safety.
Approving the requested exemption produces less of an opportunity for a
release of radioactive material than the alternative to the proposed
action because there will be no operations involving opening the DSCs
which confine the spent nuclear fuel. Therefore, the exemption is in
the public interest.
[[Page 58512]]
Environmental Consideration
The NRC staff also considered in the review of this exemption
request whether there would be any significant environmental impacts
associated with the exemption. For this proposed action, the NRC staff
performed an environmental assessment pursuant to 10 CFR 51.30,
``Environmental assessment.'' The proposed action is the approval of an
exemption from the requirements of 10 CFR 72.212(a)(2), 72.212(b)(3),
72.212(b)(5)(i), 72.214, and the portion of 72.212(b)(11) that states
the licensee shall comply with the terms, conditions, and
specifications of the CoC. This exemption would relieve the applicant
from meeting Technical Specification (TS) 1.2.4a of Attachment A of CoC
No. 1004, allowing for continued storage of DSCs numbers 93, 94, 100,
105, and 106 at the Oconee Nuclear Station ISFSI.
The environmental assessment concluded that the proposed action
would not significantly impact the quality of the human environment.
The NRC staff concludes that the proposed action will not result in any
changes in the types or amounts of any radiological effluents that may
be released offsite, and there is no significant increase in
occupational or public radiation exposure because of the proposed
action. The proposed action only affects the requirements associated
with Technical Specification (TS) 1.2.4a of Attachment A of CoC No.
1004, which limits the leak rate of the inner seal weld to 1.0 x
10-7 ref cc/s at the highest DSC limiting pressure, and does
not affect plant effluents, or any other aspects of the environment,
for DSCs numbers 93, 94, 100, 105, and 106 at the Oconee Nuclear
Station ISFSI.
The Environmental Assessment and the Finding of No Significant
Impact was published on September 3, 2015; 80 FR 53350.
4.0 Conclusion
Based on the foregoing considerations, the NRC staff has determined
that, pursuant to 10 CFR 72.7, the exemption is authorized by law, will
not endanger life or property or the common defense and security, and
is otherwise in the public interest. Therefore, the NRC grants the
applicant an exemption from the requirements of 10 CFR 72.212(a)(2),
72.212(b)(3), 72.212(b)(5)(i), 72.214, and the portion of 72.212(b)(11)
that states the licensee shall comply with the terms, conditions, and
specifications of the CoC, only with regard to meeting Technical
Specification (TS) 1.2.4a of Attachment A of CoC No. 1004. This
exemption approval is limited to authorizing continued storage of DSCs
numbers 93, 94, 100, 105, and 106 in the TN Standardized NUHOMS[supreg]
dry cask storage system at the Oconee Nuclear Station ISFSI.
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 17 day September, 2015.
For the Nuclear Regulatory Commission.
Michele Sampson,
Branch Chief, Spent Fuel Licensing Branch, Division of Spent Fuel
Management, Office of Nuclear Material Safety and Safeguards.
[FR Doc. 2015-24655 Filed 9-28-15; 8:45 am]
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