[Federal Register Volume 91, Number 95 (Monday, May 18, 2026)]
[Notices]
[Pages 28624-28627]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2026-09887]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-259, 50-260, 50-296, and 72-052; NRC-2026-2509]
Tennessee Valley Authority; Browns Ferry Nuclear Power Plant;
Independent Spent Fuel Storage Installation; Exemption
AGENCY: Nuclear Regulatory Commission.
ACTION: Notice; issuance.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) issued a one-time
exemption to Tennessee Valley Authority (TVA), permitting Browns Ferry
Nuclear Power Plant (BFN) to allow use of the Vacuum Drying System
(VDS) for one Holtec FW (CoC-1032) system canister (MPC-0431), despite
exceeding the per assembly Region 2 decay heat limit per the
requirements of CoC 1032 Appendix B, Table 2.3-4, ``MPC-89 Heat Load
Data''. This exemption will allow BFN to complete the loading of the
MPC in the cask for ISFSI storage.
DATES: The exemption was issued on May 11, 2026.
ADDRESSES: Please refer to Docket ID NRC-2026-2509 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 website: Go to https://www.regulations.gov and search for Docket ID NRC-2026-2509. Address
questions about Docket IDs in Regulations.gov to Bridget Curran;
telephone: 301-415-1003; email: [email protected]. For technical
questions, contact the individual(s) 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 https://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``Begin ADAMS Public Search.''
For problems with ADAMS, please contact the NRC's Public Document Room
(PDR) reference staff at 1-800-397-4209, at 301-415-4737, or by email
to [email protected]. The ADAMS accession number for each document
referenced (if it is available in ADAMS) is provided the first time
that it is mentioned in this document.
NRC's PDR: The PDR, where you may examine and order copies
of publicly available documents, is open by appointment. To make an
appointment to visit the PDR, please send an email to
[email protected] or call 1-800-397-4209 or 301-415-4737, between 8
a.m. and 4 p.m. eastern time (ET), Monday through Friday, except
Federal holidays.
FOR FURTHER INFORMATION CONTACT: John-Chau Nguyen, Office of Nuclear
Material Safety and Safeguards, U.S. Nuclear Regulatory Commission,
Washington, DC 20555; telephone: 301-415-0262; email: [email protected].
SUPPLEMENTARY INFORMATION: The text of the exemption is attached.
Authority: 42 U.S.C. 2011 et seq.
Dated: May 14, 2026.
[[Page 28625]]
For the Nuclear Regulatory Commission.
Yoira Diaz Sanabria,
Chief, Storage and Transportation Licensing Branch, Division of Fuel
Management, Office of Nuclear Material Safety, and Safeguards.
Attachment--Exemption.
NUCLEAR REGULATORY COMMISSION
Docket Nos. 50-259, 50-260, 50-296, and 72-052; Tennessee Valley
Authority (TVA); Browns Ferry Nuclear Power Plant (BFN); Independent
Spent Fuel Storage Installation; Exemption
I. Background
TVA is the holder of Facility Operating Licenses Nos. DPR-33,
DPR-52, and DPR-68, which authorize operation of the Browns Ferry
Nuclear Power Plant (BFN), units 1, 2, and 3 in Tennessee, 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 U.S. Nuclear Regulatory
Commission (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 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. TVA is
authorized to operate nuclear power reactors under 10 CFR part 50
and holds a 10 CFR part 72 general license for storage of spent fuel
at the BFN ISFSI. Under the terms of the general license, TVA stores
spent fuel at its BFN ISFSI using the HI-STORM FW System in
accordance with Certificate of Compliance (CoC) No. 1032, Amendment
No. 0 Revision 1.
II. Request/Action
By letter dated May 10, 2026 (Agencywide Documents Access and
Management System [ADAMS] Accession No. ML26130A001), TVA requested
an expedited exemption from the requirements of 10 CFR 72.212(b)(3),
72.212(b)(5)(i), and 72.212(b)(11) that require BFN to comply with
the terms, conditions, and specifications of CoC No. 72-1032,
Amendment No. 0 Revision 1 (ML16112A306)(Package) and allow use of
Vacuum Drying System (VDS) for Multi-Purpose Canister (MPC)-0431
prior to loading into a HI-STORM FW storage cask. If approved, TVA's
exemption request would accordingly allow BFN to complete the
loading of the MPC in the cask for ISFSI storage, despite exceeding
the per assembly Region 2 decay heat limit per the requirements of
CoC 1032 Appendix B Table 2.3-4, ``MPC-89 Heat Load Data''. TVA uses
the Holtec HI-STORM FW MPC storage system (model MPC-89CBS),
certified under CoC No. 1032, Amendment 0, Revision 1, at the BFN
under its general license. During dry cask campaign 18, TVA
identified a failure of the Forced Helium Dehydration (FHD) system
while processing MPC-0431. Following completion of fuel loading, lid
installation, and hydrostatic testing, blowdown was performed as
expected; however, upon initiating drying operations, the FHD blower
experienced elevated differential pressure and sheath temperature,
resulting in repeated system trips. Subsequent borescope inspections
verified proper engagement of the vent and drain port plugs, and TVA
determined that the MPC drain line had become disengaged from the
lid coupling and had settled onto the baseplate. This condition
restricted airflow and prevented effective FHD drying and helium
backfill.
As an interim measure, TVA isolated MPC-0431 under a helium
blanket within the HI-TRAC VW transfer cask, placing the canister in
a temporary analyzed condition. TVA notes that this off-normal
configuration requires continuous monitoring of canister pressure
and temperature and could introduce additional operational risk,
including increased industrial hazards, radiological dose, and
dependence on temporary confinement boundaries such as valve seats
and O-rings. TVA consulted with the certificate holder, Holtec
International, which recommended the use of the VDS as an
alternative moisture-removal method. TVA notes that VDS applies
vacuum at each port and is capable of achieving drying and helium
backfill even in the presence of restricted flow through a single
port. As explained in the application for expedited review, VDS
equipment is expected to be available at BFN for moisture removal
beginning May 13, 2026. This equipment is provided by Holtec for a
limited time to support MPC processing.
Dry storage in the HI-STORM FW system is a passive design that
provides the required safety functions of heat removal, criticality
control, shielding, and confinement. TVA performed a site-specific,
steady-state thermal evaluation for MPC-0431 under VDS conditions
using the licensing-basis MPC-89 thermal model and the analytical
methodology described in the HI-STORM FW Final Safety Analysis
Report (FSAR).
For the evaluation, TVA applied a bounding heat-load
distribution consisting of 0.256 kW per cell in Region 1, 0.440 kW
per cell in Region 2, and 0.252 kW per cell in Region 3, for a total
canister heat load of 29.98 kW, which is conservative relative to
the actual configuration. The acceptance criteria required the peak
cladding temperature to remain below the applicable limit in FSAR
Table 2.2.3 for high-burnup fuel and all MPC component temperatures
to remain below their respective short-term operational limits.
The staff reviewed TVA's steady-state thermal evaluation for VDS
operation and finds that the calculated peak cladding temperature
and all MPC component temperatures remain below the corresponding
limits specified in Table 2.2.3 of the HI-STORM FW FSAR. Based on
these results, the staff concludes that VDS drying of MPC-0431 at
BFN can be conducted without imposed time restrictions. Therefore,
an exemption is warranted to allow BFN to use VDS for MPC-0431 prior
to loading into a HI-STORM FW storage cask, even though, the terms,
conditions and specifications of the CoC will not be met.
III. Discussion
Pursuant to 10 CFR 72.7, ``Specific exemptions,'' 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.
A. The Exemption Is Authorized by Law
This exemption would allow TVA to deviate from Holtec CoC No.
1032, Amendment No. 0 Revision 1, Appendix B, Table 2.3-4 (MPC-89
Heat Load Data) and allow use of VDS for MPC-0431 prior to loading
into a HI-STORM FW storage cask.
TVA is requesting an exemption from the provisions in 10 CFR
part 72 that 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. This authority to grant
exemptions is consistent with the Atomic Energy Act of 1954, as
amended, and is not otherwise inconsistent with NRC's regulations or
other applicable laws. Additionally, no other law prohibits the
activities that would be authorized by the exemption. Therefore, the
NRC concludes that there is no statutory prohibition on the issuance
of the requested exemption, and the NRC is authorized to grant the
exemption by law.
B. The Exemption Will Not Endanger Life or Property or the Common
Defense and Security
This exemption would allow TVA to deviate from Holtec CoC No.
1032, Amendment No. 0, Revision 1, Appendix B, Table 2.3-4 (MPC-89
Heat Load Data) and allow use of VDS for MPC-0431 prior to loading
into a HI-STORM FW storage cask. In support of this exemption
request, TVA asserts that issuance of the exemption would not
endanger life or property or the common defense and security because
the safety assessment demonstrates that the TVA's proposed use of
the VDS provides adequate thermal control, maintains confinement
integrity, and does not pose an undue risk to the safe processing of
the loaded cask.
For these reasons, the NRC staff has determined that under the
requested exemption, the storage system will continue to meet the
safety requirements of 10 CFR part 72 and the offsite dose limits of
10 CFR part 20, ``Standards for Protection Against Radiation'', and,
therefore, will not endanger life or property or the common defense
and security.
The staff reviewed TVA's exemption request and concluded, as
discussed below, that the proposed exemption from certain
requirements of 10 CFR part 72 will not cause CoC No. 1032 to
encounter conditions beyond those for which it has already been
evaluated and demonstrated to meet the applicable safety
requirements in 10 CFR part 72.
The staff's evaluation focused on the application and those
calculations and
[[Page 28626]]
analyses submitted with the application. The staff followed the
guidance in NUREG-2215 to complete its safety evaluation. The NRC's
staff evaluation includes thermal and materials safety areas, which
are the relevant technical disciplines affected by this exemption.
Thermal Evaluation
The licensee conducted a comprehensive thermal analysis of the
current cask configuration, utilizing a loading pattern designed to
encompass the BFN MPC-0431 cask. This approach ensured that the
analysis would address a most challenging operational scenario,
relevant to the cask's performance.
The NRC staff reviewed the applicant's thermal models used
throughout the analysis. As part of this evaluation, the staff
examined the code inputs to verify the selection of appropriate
material properties and boundary conditions. This step was crucial
in ensuring the models reflected realistic conditions and accurately
represented the thermal behavior of the storage system.
The staff also reviewed the suitability of the code models and
underlying assumptions. The staff's evaluation focused on whether
the models and assumptions could reliably capture the heat transfer
characteristics inherent to the HI-STORM FW storage system's
geometry, as well as the specific scenario of vacuum drying.
To further validate the applicant's analysis, the staff
performed energy and mass balance checks. These checks were
complemented by an assessment of the convergence of the thermal
analysis under vacuum drying conditions, ensuring the reliability
and accuracy of the results.
Additional sensitivity analyses were performed by adjusting
critical assumptions within the model. This procedure was
instrumental in confirming the correct characterization of heat
transfer mechanisms and supported the robustness of the overall
analysis.
Based on the comprehensive review and verification procedures,
the staff concludes that the maximum temperatures reported in the
exemption request are acceptable. This finding demonstrates
compliance with regulatory requirements and confirms the thermal
safety of the cask configuration under the analyzed conditions.
Materials Evaluation
As noted in II. Request/Action, the applicant stated that 16 of
the high burnup fuel assemblies have decay heats that exceed the
limits for vacuum drying under HI-STORM FW Amendment 0 Revision 1
Technical Specifications Appendix B, Table 2.3-4. Subsequently, the
applicant provided a specific analysis for the vacuum drying of MPC
0431 that showed the maximum fuel cladding temperature would be
below the 400 [deg]C temperature limit for the high burnup fuel
specified in Table 2.2.3 of the HI-STORM FW FSAR. In addition, the
supplemental analysis showed that all during the vacuum drying
operation, all MPC components remain below the short-term operation
temperature limits specified in Table 2.2.3 of the HI-STORM FW FSAR.
The staff reviewed the information provided by the applicant and
compared the operations conducted and planned for MPC 0431 against
the approved HI-STORM FW FSAR and Technical Specifications and the
guidance in NUREG-2215, ``Standard Review Plan for Spent Fuel Dry
Storage Systems and Facilities.'' The staff determined that the
results of the supplemental analysis provided by the applicant
showed that the peak cladding temperature limits and MPC component
temperature limits were below the maximum temperatures listed in the
HI-STORM FW FSAR and Technical Specifications.
The staff also reviewed the guidance in NUREG-2215 on spent fuel
and loading operations. Specifically, the staff reviewed the
following guidance in NUREG-2215 Chapter 8, ``Materials
Evaluation,'' and Chapter 11, ``Operation Procedures and Systems
Evaluation.''
Section 8.5.15.2.4, ``Maximum (Peak) Cladding
Temperature,'' which states that the maximum calculated fuel
cladding temperature should not exceed 400[deg]C (752 [deg]F) for
normal conditions of storage and short-term loading operations
including drying, backfilling with inert gas, and transfer of the
cask to the storage pad.
Section 8.5.15.2.5, ``Thermal Cycling during Drying
Operations,'' which states that repeated thermal cycling (repeated
heatup or cooldown cycles) during loading operations is limited to
less than 10 cycles, where cladding temperature variations during
each cycle do not exceed 65 [deg]C (117 [deg]F).
Section 8.5.15.2.6, ``Cover Gas,'' which provides
options for evaluating cladding oxidation including the option to
maintain the fuel rods in an inerted environment such as argon,
nitrogen gas, or helium to prevent oxidation.
Section 11.5.2.6, ``Draining and Drying,'' which states
that the container should be drained of as much water as practicable
and evacuated to less than or equal to 4.0x10-4 MPa (4 millibar, 3.0
millimeters of mercury or Torr). After evacuation, adequate moisture
removal should be verified by maintaining a constant pressure over a
period of about 30 minutes without vacuum pump operation (or the
vacuum pump is running but is isolated from the container with its
suction vented to atmosphere).
The staff determined that the HI-STORM FW FSAR, Technical
Specifications, and the specific analysis for the vacuum drying of
MPC 0431 are consistent with the NRC guidance. Therefore, the staff
determined that the applicant's exemption request is acceptable.
C. The Exemption Is Otherwise in the Public Interest
TVA requests exemption from meeting the requirements of 10 CFR
72.212(b)(3), 72.212(b)(5)(i), and 72.212(b)(11) that require BFN to
comply with the terms, conditions, and specifications of CoC No. 72-
1032, Amendment No. 0, Revision 1 (ML16112A306)(package) and allow
use of VDS for MPC-0431 prior to loading into a HI-STORM FW storage
cask.
According to TVA, the exemption is in the public interest
because it would allow for safe storage of spent nuclear fuel at the
BFN ISFSI. TVA indicates that the current condition at BFN involves
non-safety equipment maintaining stable temperature and pressure for
the loaded MPC. There is no redundancy to this equipment, so 24-hour
continuous monitoring is necessary, which over an extended period of
time adds risk of additional radiological dose to personnel. TVA
also identified that the only alternative to obtaining the exemption
(defueling the MPC-0431) would introduce substantially more risk
than the proposed action. Defueling the canister has not been
previously performed at BFN and would require additional handling of
the loaded storage system, removal of the canister lid, creation of
contaminated waste, and exposure of the spent fuel to additional
thermal cycles. Additionally, defueling the canister would introduce
the risk of dropping a fuel assembly in the spent fuel pool. These
activities would subject personnel to increased radiation exposure
and potentially further limit operational flexibility at BFN.
Delaying resolution of MPC-0431 condition could affect the
licensee's broader ability to manage spent fuel handling activities.
Upon staff's review, staff concludes that approving the
exemption is in the public interest.
Environmental Consideration
The NRC staff also considered whether there would be any
significant environmental impacts associated with the exemption. The
staff has determined that this action is categorically excluded
under 10 CFR 51.22(d)(7), and there are no extraordinary
circumstances present that would preclude reliance on this
exclusion. The NRC staff have made this finding because granting the
exemption would result in no changes other than a change in process
operations or equipment, and as such, will not cause any ground
disturbance, effluent changes, increased additional exposure or
increased accident consequences. Therefore, pursuant to 10 CFR
51.22, no environmental impact statement or environmental assessment
need be prepared in connection with granting an exemption to allow
BFN to complete the loading of the MPC in the cask for ISFSI
storage.
IV. Conclusion
Based on these considerations, the NRC 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
TVA an exemption from the requirements of Sec. Sec. 10 CFR
72.212(b)(3), 72.212(b)(5)(i), and 72.212(b)(11) to deviate from
Holtec CoC No. 1032, Amendment No. 0, Revision 1, Appendix B, Table
2.3-4 (MPC-89 Heat Load Data) and allow use of VDS for MPC-0431
prior to loading into a HI-STORM FW storage cask.
This exemption is effective upon issuance.
Dated: May 11, 2026.
For the Nuclear Regulatory Commission.
/RA/
Shana Helton,
[[Page 28627]]
Director, Division of Fuel Management, Office of Nuclear Material
Safety, and Safeguards.
[FR Doc. 2026-09887 Filed 5-15-26; 8:45 am]
BILLING CODE 7590-01-P