[Federal Register Volume 77, Number 79 (Tuesday, April 24, 2012)]
[Notices]
[Pages 24539-24541]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-9802]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos.: 50-280, 50-281, 72-55, 72-1030; NRC-2012-0085]
Virginia Electric and Power Company; Surry Power Station Units 1
and 2; Independent Spent Fuel Storage Installation; Exemption
1.0 Background
Virginia Electric and Power Company (Dominion or licensee) is the
holder of Facility Operating License Nos. DRP-32 and DRP-37, which
authorize operation of the Surry Power Station Units 1 and 2 in Surry
County, Virginia, pursuant to Title 10 of the Code of Federal
Regulations (10 CFR), part 50. The licenses provide, among other
things, that the facility is subject to all rules, regulations, and
orders of the U.S. Nuclear Regulatory Commission (NRC or the
Commission) now or hereafter in effect.
Pursuant to 10 CFR part 72, Subpart K, a general license is issued
for the storage of spent fuel in an independent spent fuel storage
installation (ISFSI) at power reactor sites to persons authorized to
possess or operate nuclear power reactors under 10 CFR part 50.
Dominion 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 Surry Power Station ISFSI. Under the terms of its
general license, Dominion loaded spent fuel using the Transnuclear,
Inc, (TN) NUHOMS[supreg] HD Storage System (HD-32PTH) dry cask storage
system (Certificate of Compliance (CoC) No. 1030, Amendment No. 0) at
the Surry Power Station ISFSI.
2.0 Request/Action
The TN NUHOMS[supreg] HD dry cask storage system is designed for
zone loading based on decay heat. CoC No. 1030 specifies requirements,
conditions, and operating limits of the dry shielded canisters (DSCs)
in Appendix A of the Technical Specifications (TS). The TS restrict the
decay heat in lower Zone 1a locations to <=1.05 kW and the upper Zone
1b locations to <=0.8 kW. The licensee inadvertently reversed the upper
and lower zones while preparing the dry shielded canister (DSC) loading
maps. This resulted in five fuel assemblies being loaded into four DSCs
with decay heat greater than the limits specified in the CoC. The four
DSCs are designated with serial numbers DOM-32PTH-001-C, -002-C, -003-
C, and -009-C.
In a letter dated July 21, 2011, as supplemented September 28, 2011
(Agencywide Documents Access and Management System (ADAMS) Accession
Nos. ML11208B629 and ML11286A115, respectively), Dominion requested a
one-time exemption from the following requirements to allow storage of
the four DSCs, with serial numbers DOM-32PTH-001-C, -002-C, -003-C, and
-009-C, in their current, as-loaded, condition at the Surry Power
Station ISFSI:
10 CFR 72.212(b)(3), which states the 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.''
The portion of 10 CFR 72.212(b)(11), which states that
``[t]he licensee shall comply with the terms, conditions, and
specifications of the CoC * * *''
3.0 Discussion
Pursuant to 10 CFR 72.7, the Commission may, upon application by
any interested person or upon its own initiative, grant 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 licensee to continue to store four
DSCs (loaded with spent nuclear fuel assemblies having decay heat
exceeding the limits required by CoC No. 1030, Amendment No. 0, at the
time of loading) in their as-loaded configuration at the Surry Power
Station ISFSI. The provisions in 10 CFR part 72 from which Dominion is
requesting an exemption, require the licensee to comply with the terms,
conditions, and specifications of the CoC for the approved cask model
that it uses.
The Commission issued 10 CFR 72.7 under the authority granted to it
under Section 133 of the Nuclear Waste Policy Act of 1982, as amended,
42 U.S.C. 10153. Section 72.7 allows the NRC to grant exemptions from
the requirements of 10 CFR part 72. Granting the licensee's proposed
exemption provides adequate protection to public health and safety, and
the environment. 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
The provisions in 10 CFR 72.212(a) specifically state that the
general licensee is limited to spent fuel that the general licensee is
authorized to possess at the site under the specific license for the
site. Sections 72.212(b)(3) and 72.212(b)(11) require the general
licensee to store spent fuel in cask models approved under the
provisions of 10 CFR part 72 (which are listed in 10 CFR 72.214) and
require general licensees to comply with the terms and conditions of
the CoC for the approved cask model that is used. The requested
exemption would allow the licensee to continue to store four DSCs
(loaded with spent nuclear fuel assemblies having decay heat exceeding
the limits required by CoC No. 1030, Amendment No. 0 at the time of
loading) in their as-loaded configuration at the Surry Power Station
ISFSI.
Currently, the five affected fuel assemblies have been in storage
for a minimum of 2.5 years and have decayed to meet the required decay
heat limits of the CoC. The licensee submitted TN Calculation No.
10494-174, which performed a bounding thermal analysis using ANSYS
finite element software to evaluate the misloading events. The ANSYS
analysis consists of a half-symmetric, three-dimensional model of a
32PTH DSC with a number of conservative assumptions. First, the modeled
fuel assembly loading pattern is based on the configuration that
resulted in the maximum fuel cladding temperature presented in the
UFSAR analysis dated October 2, 2009, with the exception that the two
fuel assemblies in Zone 1b were set to 860 W. The licensee states this
configuration bounds the design zone limits as listed in TS, Section
2.1, which are based on each Zone 1b fuel assemblies being 800 W. It
also bounds the as-loaded configurations, where one or both fuel
assemblies in Zone 1b exceeded a decay heat of 800 W, up to a value of
806 W. The remaining DSC fuel assembly decay heats were within the
design basis. Therefore, since the as-loaded configuration had a total
DSC decay heat of 33.31 kW, the licensee states the model
conservatively assumes a total
[[Page 24540]]
DSC decay heat of 34.92 kW. Secondly, the licensee applies a storage
condition ambient temperature of 115 [deg]F, which is above the maximum
normal storage ambient temperature of 100 [deg]F. The NRC staff finds
the assumed 115 [deg]F boundary condition provides a reasonably
conservative ambient temperature choice, considering that summer
temperatures often are greater than 90 [deg]F and can reach 100 [deg]F
(per weather almanac, www.NOAA.gov). The NRC staff further finds that
applying a higher ambient temperature boundary condition also mitigates
the thermal effects of other ambient weather conditions, such as wind
direction relative to the DSC's inlet and outlet openings.
Using the conservative assumptions stated above, the TN Calculation
No. 10494-174 analysis presented by the licensee indicates a maximum
cladding temperature of 689 [deg]F for the as-loaded DSC with the
reversed heat load zoning for storage conditions. This is 5 [deg]F
higher than the previously calculated cladding temperature found in
Table 4-2 of the UFSAR. The temperatures of other DSC components
increased by less than 5 [deg]F. The temperature increases due to the
misloaded fuel assemblies are essentially unchanged for transfer
conditions. By applying an additional 5 [deg]F to the previously
calculated temperature for transfer conditions listed in Table 4-1 of
the UFSAR, the licensee estimates that the maximum fuel cladding
temperature for the as-loaded DSC with the reversed heat load zoning
for transfer conditions to be 724 [deg]F. As a result, the licensee
concluded that the maximum cladding temperatures for both normal
storage and transfer conditions were below the 752 [deg]F maximum
allowable cladding temperature limit noted in the UFSAR analysis. The
NRC staff has reviewed the analysis presented by Dominion and finds the
thermal effect of the misloaded fuel assemblies to be minimal, and that
the thermal margins were sufficient to mitigate the effects of the
misloaded fuel assemblies so as to provide adequate heat removal
capabilities when the DSC fuel assembly arrangement was not within the
design basis. This thermal evaluation provides reasonable assurance
that the TN NUHOMS[supreg] HD Storage System (HD-32PTH) loaded with
fuel assemblies exceeding the decay heat limits allowed by the CoC will
allow for continued safe storage of the spent fuel.
The licensee also discusses structural and pressure considerations
due to the increased decay heat of the Zone 1b fuel assemblies. The
licensee concludes that the increased decay heat did not have an effect
on the structural evaluation since the DSC fuel compartment and basket
rails are at temperatures below those considered in the design basis
analysis. The submitted analysis finds that the 5 [deg]F higher
temperature, due to the larger as-loaded decay heat, would result in a
DSC pressure increase of 0.1 psig. The resulting 6 psig and 6.5 psig
DSC pressures for the normal storage and transfer conditions were less
than the 15 psig design basis pressure. The NRC staff has reviewed the
analysis submitted in the exemption request and finds that there were
no structural implications on the cask system resulting from the
misloaded fuel assemblies.
The licensee verified the design basis shielding analysis remained
bounding for the as-loaded DSCs. The licensee concluded the design
basis shielding analysis assumes a DSC loading of 32 assemblies all
having source terms applicable to assemblies generating 1.5 kW of decay
heat and therefore bounds the as-loaded DSCs. The NRC staff has
reviewed the design basis shielding analysis and concludes that the
design remains bounding for the as-loaded DSCs and the radiation
protection system of the NUHOMS[supreg] HD-32PTH dry cask storage
system remains in compliance with 10 CFR part 72.
The NRC staff has reviewed Dominion's exemption request and finds
that the five fuel assemblies loaded into four DSCs with decay heat
greater than specified in the CoC do not affect the heat removal
capabilities, the structural integrity, or the radiation protection
system of the cask systems. Therefore, the NRC staff concludes that the
exemption to allow the licensee to store the four DSCs in their as-
loaded configuration does not pose an increased risk to public health
and safety or the common defense or security.
Otherwise in the Public Interest
The information Dominion submitted with its exemption request and
the TN analysis documented in TN Calculation No. 10494-174 demonstrate
that the as-loaded DSCs are not compromised due to the misloaded fuel
assemblies. Dominion has also considered an alternative action to
correct the condition by reloading the affected DSCs to be in
compliance with CoC No. 1030. This would involve retrieving each of the
DSCs from their Horizontal Storage Modules (HSM), unloading the spent
fuel assemblies from the DSC, performing inspections of various DSC
components, reloading the spent fuel assemblies into the used DSC or a
new DSC (if there was damage noted on the used DSC) in accordance with
CoC No. 1030, performing the DSC closing procedures, and transferring
the DSC back to the ISFSI for re-insertion into the HSM.
The licensee estimates this alternative action of loading and
unloading operations would increase personnel exposures by 250 mRem per
affected DSC. In addition, the licensee also states the alternative to
the proposed action would generate radioactive contaminated material
and waste during loading and unloading operations and disposal of the
used DSCs (if the DSCs were damaged during the unloading process). The
licensee estimates the alternative to the proposed action would cost an
estimated $300,000 for unloading and reloading operations of each
affected DSC and also necessitate additional fuel handling operations.
If the DSC was damaged during unloading, the licensee estimates an
additional $1,000,000 for purchase of a new DSC and $200,000 for
disposal of the used DSC.
The exemption, by allowing the four affected DSCs to remain in
their as-loaded condition, is consistent with NRC's mission to protect
public health and safety. Approving the DSCs to remain in their as-
loaded condition results in less of an opportunity for a release of
radioactive material than the alternative to the proposed action.
Therefore, the exemption is in the public interest.
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. The
proposed action is the approval of a request for a one-time exemption
from the requirements of 10 CFR 72.212(b)(3) and the portion of
72.212(b)(11), which requires compliance with the terms, conditions,
and specifications of a CoC, but only to the extent necessary to allow
Dominion to store the four DSCs in the current as-loaded configuration
at the Surry Power Station ISFSI.
The NRC staff performed an environmental assessment and determined
that the proposed action will not significantly impact the quality of
the human environment. The NRC staff concludes that there are no
changes being made 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 as a result of
[[Page 24541]]
the proposed action. In addition the proposed action only affects the
requirements associated with the fuel assemblies already loaded into
the casks and does not affect non-radiological plant effluents, or any
other aspects of the environment. The Environmental Assessment and the
Finding of No Significant Impact are documented in the Federal Register
(77 FR 20440, dated April 4, 2012).
4.0 Conclusion
Based on the foregoing considerations, the NRC has determined
pursuant to 10 CFR 72.7, that 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 Dominion
a one-time exemption from the requirements in 10 CFR 72.212(b)(3) and
from the portion of 10 CFR 72.212(b)(11) that states the licensee shall
comply with the terms, conditions, and specifications of the CoC for
the TN NUHOMS[supreg] HD dry cask storage system with DSCs serial
numbers DOM-32PTH-001-C, -002-C, -003-C, and -009-C, at the Surry Power
Station ISFSI.
This exemption is effective upon issuance.
For the Nuclear Regulatory Commission.
Dated: Dated at Rockville, Maryland, this 12th day of April
2012.
Doug Weaver,
Deputy Director, Division of Spent Fuel Storage and Transportation,
Office of Nuclear Material Safety and Safeguards.
[FR Doc. 2012-9802 Filed 4-23-12; 8:45 am]
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