[Federal Register Volume 77, Number 79 (Tuesday, April 24, 2012)]
[Notices]
[Pages 24541-24543]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-9803]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. 50-338, 50-339, 72-56, and 72-1030; NRC-2012-0084]


Virginia Electric and Power Company, North Anna Power Station 
Units 1 and 2, Independent Spent Fuel Storage Installation; Exemption

1.0 Background

    Virginia Electric and Power Company (Dominion, the licensee) is the 
holder of Facility Operating License Nos. NPF-4 and NPF-7, which 
authorize operation of the North Anna Power Station Units 1 and 2 in 
Louisa 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 North Anna 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 North Anna 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 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 DSC loading maps. This resulted in 
twelve fuel assemblies being loaded into seven DSCs with decay heat 
greater than the limits specified in the CoC. The seven DSCs are 
designated with serial numbers DOM-32PTH-004-C, -005-C, -007-C, -010-C, 
-013-C, -019-C and GBC-32PTH-011-C.
    In a letter dated July 21, 2011, as supplemented September 28, 2011 
(Agencywide Documents Access and Management System (ADAMS) Accession 
Nos. ML11208C453 and ML11286A143, respectively), Dominion requested a 
one-time exemption from the following requirements to allow storage of 
the seven DSCs, with serial numbers DOM-32PTH-004-C, -005-C, -007-C, -
010-C, -013-C, -019-C and GBC-32PTH-011-C, in their current, as-loaded, 
condition at the North Anna Power Station ISFSI:
    <bullet> 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.''
    <bullet> 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 seven 
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 North Anna 
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 seven 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 North Anna Power 
Station ISFSI.

[[Page 24542]]

    Currently, the twelve affected fuel assemblies have been in storage 
for a minimum of 1.3 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 
859 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 31.167 kW, the licensee states the model 
conservatively assumes a total 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 twelve fuel assemblies loaded into seven 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 seven 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 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 seven 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

[[Page 24543]]

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 seven DSCs in the current as-loaded configuration 
at the North Anna Power Station ISFSI.
    The NRC staff 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 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 20438, 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 TN 
NUHOMS[supreg] HD dry cask storage system with DSCs serial numbers DOM-
32PTH-004-C, -005-C,t -007-C, -010-C, -013-C, -019-C and GBC-32PTH-011-
C at the North Anna Power Station ISFSI.
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 12th day of April 2012.

    For the Nuclear Regulatory Commission.
Douglas Weaver,
Deputy Director, Division of Spent Fuel Storage and Transportation, 
Office of Nuclear Material Safety and Safeguards.
[FR Doc. 2012-9803 Filed 4-23-12; 8:45 am]
BILLING CODE 7590-01-P