Exelon Generation Company, LLC; TMI-2 Solutions, LLC; Three Mile Island Nuclear Station, Units 1 and 2
| Published date | 16 March 2021 |
| Citation | 86 FR 14472 |
| Record Number | 2021-05396 |
| Section | Notices |
| Court | Nuclear Regulatory Commission |
Federal Register, Volume 86 Issue 49 (Tuesday, March 16, 2021)
[Federal Register Volume 86, Number 49 (Tuesday, March 16, 2021)]
[Notices]
[Pages 14472-14478]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-05396]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-289 and 50-320; NRC-2021-0069]
Exelon Generation Company, LLC; TMI-2 Solutions, LLC; Three Mile
Island Nuclear Station, Units 1 and 2
AGENCY: Nuclear Regulatory Commission.
ACTION: Exemptions; issuance.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) has issued
exemptions in response to a request to reduce the required level of
primary offsite liability insurance from $450 million to $100 million
and to eliminate the requirement to carry secondary financial
protection for Three Mile Island Nuclear Station, Unit 1 and to reduce
the required level of primary offsite liability insurance in the event
of an extraordinary nuclear occurrence from $200 million to $100
million for Three Mile Island Nuclear Station, Unit 2.
DATES: The exemptions were issued on March 9, 2021.
ADDRESSES: Please refer to Docket ID NRC-2021-0069 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-2021-0069. Address
questions about Docket IDs in Regulations.gov to Stacy Schumann;
telephone: 301-415-0624; 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 https://www.nrc.gov/reading-rm/adams.html. To begin the search, 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 is available in ADAMS) is provided the first
time that it is mentioned in this document.
Attention: The PDR, where you may examine and order copies
of public documents, is currently closed. You may submit your request
to the PDR via email at [email protected] or call 1-800-397-4209 or
301-415-4737, between 8:00 a.m. and 4:00 p.m. (EST), Monday through
Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Theodore Smith, Office of Nuclear
Material Safety and Safeguards, U.S. Nuclear Regulatory Commission,
Washington, DC 20555-0001; telephone: 301-415-6721, email:
[email protected].
SUPPLEMENTARY INFORMATION: The text of the exemptions is attached.
Dated: March 11, 2021.
For the Nuclear Regulatory Commission.
Bruce A. Watson,
Chief, Reactor Decommissioning Branch, Division of Decommissioning,
Uranium Recovery and Waste Programs, Office of Nuclear Material Safety
and Safeguards.
Attachment--Exemption
NUCLEAR REGULATORY COMMISSIOIN
Docket Nos. 50-289 and 50-320
Exelon Generation Company, LLC
TMI-2 Solutions, LLC
Three Mile Island Nuclear Station, Units 1 and 2 Exemptions
I. Background
By letter dated June 20, 2017 (Agencywide Documents Access and
Management System [ADAMS] Accession No. Main Library [ML] ML17171A151),
Exelon Generation Company, LLC (Exelon) certified to the U.S. Nuclear
Regulatory Commission (NRC, the Commission) that it planned to
permanently cease power operations at Three Mile Island Nuclear
Station, Unit 1 (TMI-1) on or about September 30, 2019. On September
20, 2019, Exelon permanently ceased power operations at TMI-1. By
letter dated September 26, 2019 (ADAMS Accession No. ML19269E480),
Exelon certified to the NRC that the fuel was permanently removed from
the TMI-1 reactor vessel and placed in the spent fuel pool (SFP) as of
September 26, 2019. Accordingly,
[[Page 14473]]
pursuant to Title 10 of the Code of Federal Regulations (10 CFR)
Section 50.82(a)(2), the TMI-1 renewed facility operating license no
longer authorizes operation of the reactor or emplacement or retention
of fuel in the reactor vessel. The facility is still authorized to
possess and store irradiated (i.e., spent) nuclear fuel. Spent fuel is
currently stored onsite at the TMI-1 facility in the SFP.
Three Mile Island Nuclear Station, Unit 2 (TMI-2) was a 2,770
megawatts thermal pressurized light-water reactor supplied by Babcock &
Wilcox that was issued an operating license on February 8, 1978 and
began commercial operations on December 30, 1978. On March 28, 1979,
TMI-2 experienced an accident that resulted in severe damage to the
reactor core. Subsequently, approximately 99 percent of the fuel and
damaged core material was removed from the TMI-2 reactor vessel and
associated systems and shipped to the U.S. Department of Energy Idaho
National Laboratory. After the completion of accident recovery
operations, TMI-2 was placed in a Post-Defueling Monitored Storage
(PDMS) state on September 14, 1993, with a possession only license that
authorizes the possession of byproduct and special nuclear materials
but not the operation of the reactor.
Following the TMI-2 accident, in 1982, the NRC granted an exemption
from the requirements of 10 CFR 140.11(a)(4) for TMI-1 and TMI-2
(ML19141A211). The exemption allowed the licensees to provide two
endorsements to meet the financial protection requirements of
subsection 170 of the Atomic Energy Act of 1954, as amended. The first
endorsement, Endorsement No. 43, restored the limits of liability to
the amounts listed in other endorsements upon an ``extraordinary
nuclear occurrence'' (ENO) being declared by the NRC arising out of the
ownership, operation, maintenance, or use of TMI-1 and/or TMI-2. The
second endorsement, Endorsement No. 44, increased the TMI-1 liability
limit to the NRC limit in effect at the time for any bodily injury or
property damages caused by a nuclear energy hazard, but increased the
TMI-2 liability limit only in the event the NRC declared an ENO on or
after May 1, 1979. Subsequently, in 1994, the NRC granted TMI-2 an
exemption from participation in secondary financial protection (ADAMS
Accession No. 9408050260 [Legacy Library]). The exemptions herein do
not impact the exemptions already in place.
II. Request/Action
By letter dated January 3, 2020 (ADAMS Accession No. ML20003E096),
Exelon requested an exemption from 10 CFR 140.11(a)(4) to reduce the
required level of primary offsite liability insurance from $450 million
to $100 million and to eliminate the requirement to carry secondary
financial protection for TMI-1 and TMI-2 Solutions, LLC (TMI-2
Solutions) \1\ requested an exemption from 10 CFR 140.11(a)(4) to
reduce the required level of primary offsite liability insurance in the
event of an ENO \2\ from $200 million to $100 million for TMI-2.
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\1\ The TMI-2 license was transferred to TMI-2 Solutions on
December 18, 2020 (ADAMS Accession No. ML20352A381).
\2\ Pursuant to 10 CFR 140.83, if the Commission determines that
both of the criteria set forth in 10 CFR 140.84 and 140.85 have been
met, it will make the determination that there has been an ENO.
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The regulation at 10 CFR 140.11(a)(4) requires each licensee to
have and maintain primary financial protection in an amount of $450
million. In addition, the licensee is required to participate in an
industry retrospective rating plan (secondary financial protection)
that commits each licensee to pay into an insurance pool to be used for
damages that may exceed primary insurance coverage. Participation in
the industry retrospective rating plan will subject the licensee to
deferred premium charges up to a maximum total deferred premium of
$131,056,000 with respect to any nuclear incident at any operating
nuclear power plant and up to a maximum annual deferred premium of
$20,496,000 per incident.
Many of the accident scenarios postulated in the updated safety
analysis reports for operating power reactors involve failures or
malfunctions of systems, which could affect the fuel in the reactor
core and, in the most severe postulated accidents, would involve the
release of large quantities of fission products. With the permanent
cessation of power operations at TMI-1 and the permanent removal of the
fuel from the reactor vessel, and the PDMS state of TMI-2 with no fuel
assemblies in the TMI-2 reactor or the TMI-2 SFP, many accidents are no
longer possible. Similarly, the associated risk of offsite liability
damages that would require insurance or indemnification is
commensurately lower for such plants. Therefore, Exelon requested an
exemption from 10 CFR 140.11(a)(4) to permit a reduction in primary
offsite liability insurance and to withdraw from participation in the
industry retrospective rating plan for TMI-1. Additionally, TMI-2
Solutions requested an exemption from 10 CFR 140.11(a)(4) to permit a
reduction in primary offsite liability insurance to $100 million in the
event of an ENO for TMI-2.
III. Discussion
Pursuant to 10 CFR 140.8, ``Specific exemptions,'' the Commission
may, upon application of any interested person or upon its own
initiative, grant such exemptions from the requirements of the
regulations in 10 CFR part 140 when the exemptions are authorized by
law and are otherwise in the public interest. The NRC staff has
reviewed the licensees' request for exemptions from 10 CFR 140.11(a)(4)
and has concluded that the requested exemptions are authorized by law
and are otherwise in the public interest.
The Price Anderson Act of 1957 (PAA) requires that nuclear power
reactor licensees have insurance to compensate the public for damages
arising from a nuclear incident. Specifically, the PAA requires
licensees of facilities with a ``rated capacity of 100,000 electrical
kilowatts or more'' to maintain the maximum amount of primary offsite
liability insurance commercially available (currently $450 million) and
a specified amount of secondary insurance coverage (currently up to
$131,056,000 per reactor). In the event of an accident causing offsite
damages in excess of $450 million, each licensee would be assessed a
prorated share of the excess damages, up to $131,056,000 per reactor,
for a total of approximately $13 billion per nuclear incident. The
NRC's regulations at 10 CFR 140.11(a)(4) implement these PAA insurance
requirements and set forth the amount of primary and secondary
insurance each power reactor licensee must have.
As noted above, the PAA requirements with respect to primary and
secondary insurance and the implementing regulations at 10 CFR
140.11(a)(4) apply to licensees of facilities with a ``rated capacity
of 100,000 electrical kilowatts or more.'' In accordance with 10 CFR
50.82(a)(2), the license for a power reactor no longer authorizes
operation of the reactor or emplacement or retention of fuel into the
reactor vessel upon the docketing of the certifications for permanent
cessation of operations and permanent removal of fuel from the reactor
vessel, or when a final legally effective order to permanently cease
operations has come into effect. Therefore, the reactor cannot be used
to generate power.
Accordingly, a reactor that is undergoing decommissioning has no
``rated capacity.'' Thus, the NRC may take the reactor licensee out of
the category of reactor licensees that are required to maintain the
maximum available insurance and to participate in
[[Page 14474]]
the secondary retrospective insurance pool.
The financial protection limits of 10 CFR 140.11(a)(4) were
established to require a licensee to maintain sufficient insurance, as
specified under the PAA, to satisfy liability claims by members of the
public for personal injury, property damage, and the legal cost
associated with lawsuits as the result of a nuclear accident at an
operating reactor with a rated capacity of 100,000 kilowatts electric
or greater. Thus, the insurance levels established by this regulation,
as required by the PAA, were associated with the risks and potential
consequences of an accident at an operating reactor with a rated
capacity of 100,000 kilowatts electric or greater.
The legal and associated technical basis for granting exemptions
from 10 CFR part 140 is set forth in SECY-93-127, ``Financial
Protection Required of Licensees of Large Nuclear Power Plants During
Decommissioning,'' dated May 10, 1993 (ADAMS Accession No.
ML12257A628). The legal analysis underlying SECY-93-127 concluded that,
upon a technical finding that lesser potential hazards exist after
permanent cessation of power operations (and the reactor having no
``rated capacity''), the Commission has the discretion under the PAA to
reduce the amount of insurance required of a licensee undergoing
decommissioning.
As a technical matter, the fact that a reactor has permanently
ceased power operations is not itself determinative as to whether a
licensee may cease providing the offsite liability coverage required by
the PAA and 10 CFR 140.11(a)(4). In light of the presence of freshly
discharged irradiated fuel in the SFP at a recently shut down reactor,
the potential for an offsite radiological release from a zirconium fire
with consequences comparable in some respects to an operating reactor
accident remains. That risk is very low at the time of reactor shut
down because of design provisions that prevent a significant reduction
in coolant inventory in the SFP under normal and accident conditions
and becomes no longer credible once the continual reduction in decay
heat provides ample time to restore coolant inventory and permits air-
cooling in a drained SFP. After that time, the probability of a large
offsite radiological release from a zirconium fire is negligible for
permanently shut down reactors, but the SFP is still operational and an
inventory of radioactive materials still exists onsite. Therefore, an
evaluation of the potential for offsite damage is necessary to
determine the appropriate level of offsite insurance post shut down, in
accordance with the Commission's discretionary authority under the PAA
to establish an appropriate level of required financial protection for
such permanently shut down facilities.
The NRC staff has conducted an evaluation and concluded that, aside
from the handling, storage, and transportation of spent fuel and
radioactive materials for a permanently shut down and defueled reactor,
no reasonably conceivable potential accident exists that could cause
significant offsite damage. During normal power reactor operations, the
forced flow of water through the reactor coolant system (RCS) removes
heat generated by the reactor. The RCS transfers this heat away from
the reactor core by converting reactor feedwater to steam, which then
flows to the main turbine generator to produce electricity. Most of the
accident scenarios postulated for operating power reactors involve
failures or malfunctions of systems that could affect the fuel in the
reactor core, which in the most severe postulated accidents would
involve the release of large quantities of fission products. With the
permanent cessation of reactor operations at the TMI site and the
permanent removal of the fuel from the reactor core, such accidents are
no longer possible. The reactor, RCS, and supporting systems no longer
operate and have no function related to the storage of the irradiated
fuel. Therefore, postulated accidents involving failure or malfunction
of the reactor, RCS, or supporting systems are no longer applicable.
During reactor decommissioning, the principal radiological risks
are associated with the storage of spent fuel onsite. On a case-by-case
basis, licensees undergoing decommissioning have been granted
permission to reduce the required amount of primary offsite liability
insurance coverage from $450 million to $100 million and to withdraw
from the secondary insurance pool. One of the technical criteria for
granting the exemption is that the possibility of a design-basis event
that could cause significant offsite damage has been eliminated.
In its exemption request, Exelon described both design-basis and
beyond-design-basis events involving irradiated fuel stored in the TMI-
1 SFP. Exelon stated, and the NRC staff agrees, that while spent fuel
remains in the SFP, the only postulated design-basis accident that
would remain applicable to TMI-1 in the permanently defueled condition
that could contribute a significant dose is a fuel handling accident
(FHA) in the Reactor Building, where the SFP is located. For
completeness, the NRC staff also evaluated the applicability of other
design-basis accidents documented in the TMI-1 Updated Final Safety
Analysis Report (UFSAR) (ADAMS Package Accession No. ML18117A343) to
ensure that these accidents would not have consequences that could
potentially exceed the 10 CFR 50.67 dose limits and Regulatory Guide
1.183, ``Alternative Radiological Source Terms for Evaluating Design
Basis Accidents at Nuclear Power Reactors,'' dose acceptance criteria
or approach the U.S. Environmental Protection Agency (EPA) early phase
protective action guides (PAGs).
In the TMI-1 UFSAR, the licensee has determined that 365 days after
shut down, the FHA doses would decrease to a level that would not
warrant protective actions under the EPA early phase PAG framework,
notwithstanding meeting the dose limit requirements under 10 CFR 50.67
and dose acceptance criteria under Regulatory Guide 1.183. The NRC
staff notes that the doses from an FHA are dominated by the isotope
Iodine-131. TMI-1 permanently ceased power operations on September 20,
2019. With 488 days of decay, the thyroid dose from an FHA would be
negligible and the only isotope remaining in significant amounts, among
those postulated to be released in a design-basis FHA, would be
Krypton-85. Since Krypton-85 primarily decays by beta emission, the
calculated skin dose from an FHA analysis would make an insignificant
contribution to the total effective dose equivalent, which is the
parameter of interest in the determination of the EPA early phase PAGs
for sheltering or evacuation. The NRC staff concludes that the dose
consequence from an FHA for the permanently shut down TMI-1 would not
approach the EPA early phase PAGs. Therefore, any offsite consequence
from a design-basis radiological release is highly unlikely and, thus,
a significant amount of offsite liability insurance coverage is not
required.
The only beyond design-basis event that has the potential to lead
to a significant radiological release at a permanently shut down and
defueled reactor is a zirconium fire. The zirconium fire scenario is a
postulated, but highly unlikely, accident scenario that involves the
loss of water inventory from the SFP resulting in a significant heat up
of the spent fuel and culminating in substantial zirconium cladding
oxidation and fuel damage. The probability of a zirconium fire scenario
is related to the decay heat of the irradiated fuel stored in the SFP.
Therefore, the risks from a zirconium
[[Page 14475]]
fire scenario continue to decrease as a function of the time that TMI-1
has been permanently shut down.
In the analysis provided in Attachment 2, ``Three Mile Island
Nuclear Station Zirconium Fire Analysis for Drained Spent Fuel Pool
(Calculation C-1101-202-E410-476, Revision 1),'' to the letter dated
July 1, 2019 (ADAMS Accession No. ML19182A104), the licensee compared
the conditions for the hottest fuel assembly stored in the SFP to a
criterion proposed in SECY-99-168, ``Improving Decommissioning
Regulations for Nuclear Power Plants,'' dated June 30, 1999 (ADAMS
Accession No. ML12265A598), applicable to offsite emergency response
for the unit in the decommissioning process. This criterion considers
the time for the hottest assembly to heat up from 30 degrees Celsius
([deg]C) to 900 [deg]C adiabatically. If the heat up time is greater
than 10 hours, then offsite emergency preplanning involving the plant
is not necessary. Based on the limiting fuel assembly for decay heat
and adiabatic heat up analysis presented in Attachment 2, at 488 days
(approximately 16 months) after permanent cessation of power
operations, the time for the hottest fuel assembly to reach 900 [deg]C
is 10 hours after the assemblies have been uncovered. As stated in
NUREG-1738, ``Technical Study of Spent Fuel Pool Accident Risk at
Decommissioning Nuclear Power Plants,'' dated February 2001 (ADAMS
Accession No. ML010430066), 900 [deg]C is an acceptable temperature to
use for assessing onset of fission product release under transient
conditions to establish the critical decay time for determining the
availability of 10 hours for deployment of mitigation equipment and, if
necessary, for offsite agencies to take appropriate action to protect
the health and safety of the public if fuel and cladding oxidation
occurs in air.
The NRC staff reviewed the calculation to verify that important
physical properties of materials were within acceptable ranges and the
results were accurate. The NRC staff determined that physical
properties were appropriate and completed independent confirmatory
calculations that produced similar results. Therefore, the NRC staff
found that after 488 days of decay, at least 10 hours would be
available before a significant offsite release could begin. The NRC
staff concluded that the adiabatic heat up calculation provided an
acceptable method for determining the minimum time available for
deployment of mitigation equipment and, if necessary, implementing
measures under a comprehensive general emergency plan.
In this regard, one technical criterion for relieving
decommissioning reactor licensees from the insurance obligations
applicable to an operating reactor is a finding that the heat generated
by the SFP has decayed to the point where the possibility of a
zirconium fire is highly unlikely. This was addressed in SECY-93-127,
where the NRC staff concluded that there was a low likelihood and
reduced short-term public health consequences of a zirconium fire once
a decommissioning plant's spent fuel has sufficiently decayed. In its
Staff Requirements Memorandum, ``Financial Protection Required of
Licensees of Large Nuclear Power Plants during Decommissioning,'' dated
July 13, 1993 (ADAMS Accession No. ML003760936), the Commission
approved a policy that authorized, through the exemption process,
withdrawal from participation in the secondary insurance layer and a
reduction in commercial liability insurance coverage to $100 million
when a licensee is able to demonstrate that the spent fuel could be
air-cooled if the SFP was drained of water.
The NRC staff has used this technical criterion to grant similar
exemptions to other decommissioning reactors (e.g., Maine Yankee Atomic
Power Station, published in the Federal Register (FR) on January 19,
1999 (64 FR 2920); Zion Nuclear Power Station, published in the Federal
Register on December 28, 1999 (64 FR 72700); Kewaunee Power Station,
published in the Federal Register on March 24, 2015 (80 FR 15638);
Crystal River Unit 3 Nuclear Generation Plant, published in the Federal
Register on May 6, 2015 (80 FR 26100); Oyster Creek Nuclear Generating
Station, published in the Federal Register on December 28, 2018 (83 FR
67365); and Pilgrim Nuclear Power Station, published in the Federal
Register on January 13, 2020 (85 FR 1827)).
Additional discussions of other decommissioning reactor licensees
that have received exemptions to reduce their primary insurance level
to $100 million are provided in SECY-96-256, ``Changes to the Financial
Protection Requirements for Permanently Shutdown Nuclear Power
Reactors, 10 CFR 50.54(w) and 10 CFR 140.11,'' dated December 17, 1996
(ADAMS Accession No. ML15062A483). These prior exemptions were based on
the licensee demonstrating that the SFP could be air-cooled consistent
with the technical criterion discussed above.
The NRC staff has evaluated the issue of zirconium fires in SFPs
and presented an independent evaluation of an SFP subject to a severe
earthquake in NUREG-2161, ``Consequence Study of a Beyond-Design-Basis
Earthquake Affecting the Spent Fuel Pool for a U.S. Mark l Boiling
Water Reactor,'' dated September 2014 (ADAMS Accession No.
ML14255A365). This evaluation concluded that, for a representative
boiling-water reactor, fuel in a dispersed high-density configuration
would be adequately cooled by natural circulation air flow within
several months after discharge from a reactor if the pool was drained
of water.
In its exemption request, Exelon compared TMI-1 fuel storage
parameters with those used in NRC generic evaluations of fuel cooling
included in NUREG/CR-6451, ``A Safety and Regulatory Assessment of
Generic BWR [Boiling-Water Reactor] and PWR [Pressurized-Water Reactor]
Permanently Shut down Nuclear Power Plants,'' dated August 1997 (ADAMS
Accession No. ML082260098). The analysis described in NUREG/CR-6451
determined that natural air circulation would adequately cool fuel that
has decayed for 17 months after operation in a typical PWR, which is a
slightly longer decay time than the zirconium fire period of 488 days
on which the TMI-1 exemption request is based. In order to evaluate if
the TMI-1 decay period was conservative, Exelon examined the decay heat
at TMI-1 and determined that the average fuel assembly decay heat for
the most recently offloaded TMI-1 spent fuel at 488 days after shut
down will be approximately 3 percent less than the decay heat for the
average fuel assembly at 519 days for the representative PWR plant in
NUREG/CR-6451.
A comparison of the parameters for the fuel assembly power, power
density, and hydraulic resistance of the 15x15 fuel assemblies at TMI-1
indicated that these parameters are less than those of the 17x17 fuel
assemblies modeled in NUREG/CR-6451. Therefore, the NUREG/CR-6451 fuel
assembly model is conservative for TMI-1. The SFP rack configuration
was also evaluated and found to be conservative for TMI-1. The
configuration/hydraulic resistance of the TMI-1 downcomers and plenum
underneath the SFP storage racks is bounded by that modeled in NUREG/
CR-6451. Additionally, the hydraulic resistance of the SFP rack loaded
cells is less than that of the SFP rack configuration modeled in NUREG/
CR-6451. The bottom orifices on all TMI-1 SFP racks are equal to or
larger than those modeled in NUREG/CR-6451, which also makes the
estimates for TMI-1 more conservative.
[[Page 14476]]
As a result of the comparison, Exelon concluded that the TMI-1 SFP
conditions are bounded by the NUGREG/CR-6451 benchmark and that the
TMI-1 spent fuel would be air-coolable at 488 days after permanent shut
down. Therefore, at 16 months after permanent shut down, the NRC staff
has reasonable assurance that fuel stored in the TMI-1 SFP would be
adequately air-cooled in the unlikely event the SFP completely drained.
In SECY-00-0145, ``Integrated Rulemaking Plan for Nuclear Power
Plant Decommissioning,'' dated June 28, 2000, and SECY-01-0100,
``Policy Issues Related to Safeguards, Insurance, and Emergency
Preparedness Regulations at Decommissioning Nuclear Power Plants
Storing Fuel in Spent Fuel Pools,'' dated June 4, 2001 (ADAMS Accession
Nos. ML003721626 and ML011450420, respectively), the NRC staff
discussed additional information concerning SFP zirconium fire risks at
decommissioning reactors and associated implications for offsite
insurance. Analyzing when the spent fuel stored in the SFP is capable
of adequate air-cooling is one measure that demonstrates when the
probability of a zirconium fire would be exceedingly low.
In addition, the licensee performed adiabatic heat up analyses to
determine a dose rate curve at the Exclusion Area Boundary (EAB) and
Control Room. Although the analysis described above demonstrated that a
significant release of radioactive material from the spent fuel in the
absence of water cooling is not possible after 488 days following
permanent cessation of power operations, the potential exists for
radiation exposure to an offsite individual in the event that shielding
of the fuel is lost. The site-specific offsite and Control Room
radiological impacts of a postulated complete loss of SFP water were
assessed in TMI-1 Technical Evaluation 623073, ``TMI Spent Fuel Pool
Draindown Shine Dose Rate Evaluation, Revision 0.'' With a decay of 365
days from shut down, the dose rate at the EAB would be 4.04 x
10-1mrem/hour not crediting the shielding from
the Fuel Handling Building (FHB) roof. Crediting the FHB roof
structure, the dose rate at the EAB would be 4.6 x
10-10 mrem/hour.
The licensee's adiabatic heat up analyses demonstrate that 16
months after the permanent cessation of operations, there would be at
least 10 hours to take mitigative actions in response to events that
could lead to a zirconium fire. In addition, the TMI-1 SFP conditions
were determined to be bounded by the analysis of the NUREG/CR-6451
benchmark demonstrating that the SFP would be air-coolable at 488 days
after permanent cessation of operations.
In its exemption request, Exelon furnished the following
information: ``Because of the length of time it would take for the
adiabatic heat up to occur, there is ample time to respond (>=10 hours)
to any drain down event that might cause such an occurrence by
restoring [SFP] cooling or makeup or providing [SFP] spray. As a
result, the likelihood that such a scenario would progress to a
zirconium fire is not deemed credible.''
In the NRC staff's evaluation contained in SECY-20-0041, ``Request
by Exelon Generation Company, LLC for Exemptions from Certain Emergency
Planning Requirements for the Three Mile Island Nuclear Station,''
dated May 5, 2020 (ADAMS Accession No. ML19311C763), the NRC staff
assessed the Exelon accident analyses associated with the radiological
risks from a zirconium fire at a permanently shut down and defueled TMI
site. For the highly unlikely beyond design-basis accident scenario
where the SFP coolant inventory is lost in such a manner that all
methods of heat removal from the spent fuel are no longer available,
the NRC staff found that there will be a minimum of 10 hours from the
initiation of the accident until the cladding reaches a temperature
where offsite radiological release might occur. The NRC staff finds
that 10 hours is sufficient time to support deployment of mitigation
equipment, consistent with plant conditions, to prevent the zirconium
cladding from reaching a point of rapid oxidation.
The NRC staff has determined that the licensee's proposed reduction
in primary offsite liability coverage to a level of $100 million and
the licensee's proposed withdrawal from participation in the secondary
insurance pool for offsite financial protection are consistent with the
policy established in SECY-93-127 and subsequent insurance
considerations resulting from zirconium fire risks, as discussed in
SECY-00-0145 and SECY-01-0100. The NRC has previously determined in
SECY-00-0145 that the minimum offsite financial protection requirement
may be reduced to $100 million and that secondary insurance is not
required once it is determined that the spent fuel in the SFP is no
longer thermal-hydraulically capable of sustaining a zirconium fire
based on a plant-specific analysis. In addition, the NRC staff notes
that similar exemptions from these insurance requirements have been
granted to other permanently shut down and defueled power reactors upon
satisfactory demonstration that zirconium fire risk from the irradiated
fuel stored in the SFP is of negligible concern.
As provided in SECY-93-127, the NRC staff included in its
recommendations that using the standards set forth in SECY-93-127,
primary financial protection could be reduced to $100 million for
nuclear power plants that have had the requisite spent fuel cooling
period. However, as specifically mentioned in SECY-93-127 (Note 5), for
TMI-2 ``primary financial protection covering the site will remain at
$200 million [the full required regulatory value at the time of the
issuance of SECY-93-127] because there is at least one other operating
reactor on [the] site.'' Since TMI-1 is no longer authorized to
operate, there is no longer at least one other operating reactor on the
TMI site. Therefore, TMI-2 Solutions requested a corresponding
exemption from 10 CFR 140.11(a)(4) for TMI-2 to permanently reduce the
required level of primary offsite liability insurance for ENOs from
$200 million to $100 million. As discussed above, TMI-2 is maintained
in a PDMS state with a possession only license that authorizes the
possession of byproduct and special nuclear materials but not the
operation of the reactor.
The NRC staff evaluated the applicability of a waste gas tank
rupture as documented in the TMI-1 UFSAR, and the applicability of any
unanticipated releases as documented in the Unanticipated Events
Analysis in the TMI-2 Post-Defueling Monitored Storage Safety Analysis
Report (ADAMS Package Accession No. ML17236A295), to ensure that these
accidents would not have consequences that could potentially exceed the
10 CFR 50.67 dose limits and Regulatory Guide 1.183 dose acceptance
criteria or approach the EPA early phase PAGs. Exelon stated that the
bounding event for TMI-2 is a fire in the Reactor Building with the
Reactor Building Purge System in operation. The NRC staff reviewed the
assumptions, inputs, and methods used by Exelon to assess the
radiological impacts of the requested exemption. The NRC staff
concludes that Exelon has demonstrated that the dose consequences for
postulated accidents at the permanently defueled TMI facility would not
have consequences that could potentially exceed the applicable dose
limits in 10 CFR 100.11, ``Determination of exclusion area, low
population zone, and population center distance,'' and 10 CFR 50.67,
and the dose acceptance criteria in Regulatory Guide 1.183. The
analysis demonstrates
[[Page 14477]]
that 365 days after permanent cessation of power operations, the
radiological consequences of the analyzed design-basis accidents will
not exceed the limits of the EPA early phase PAGs at the EAB.
Therefore, the NRC staff finds the requested exemption to be acceptable
from a dose consequence perspective.
The most significant accident sequence for a permanently defueled
and shut down reactor involves the complete loss of water from the
spent fuel pool. As the NRC previously recognized when issuing an
exemption for TMI-2 from the requirement to participate in secondary
financial protection, this accident scenario is not credible or
reasonably conceivable at TMI-2 since the spent fuel pool is drained
and no spent fuel is stored in the pool. Since TMI-2 is being
maintained in a PDMS state with the reactor defueled and no fuel in the
TMI-2 SFP, TMI-2 meets the criterion established in SECY-93-127 for
relief from the requirements to maintain primary offsite liability
insurance for ENOs at a level above $100 million. As discussed
previously, TMI-2 has already received an exemption from participation
in the secondary retrospective insurance pool. Because the criteria
presented in SECY-93-127 for removal from the secondary financial
protection requirement are identical to those for reducing the primary
offsite liability insurance, there is precedent for allowing the
reduction of offsite liability insurance for TMI (as a site), once TMI-
1 has met the criteria in SECY-93-127. In addition, the NRC staff notes
that similar exemptions from these insurance requirements have been
granted to other permanently shut down and defueled power reactors,
upon satisfactory demonstration that zirconium fire risk from the
irradiated fuel stored in the SFP is of negligible concern.
A. The Exemptions Are Authorized by Law
The PAA and its implementing regulations in 10 CFR 140.11(a)(4)
require licensees of nuclear reactors that have a rated capacity of
100,000 kilowatts electric or more to have and maintain $450 million in
primary financial protection and to participate in a secondary
retrospective insurance pool. In accordance with 10 CFR 140.8, the
Commission may grant exemptions from the regulations in 10 CFR part 140
as the Commission determines are authorized by law. The legal and
associated technical basis for granting exemptions from 10 CFR part 140
are set forth in SECY-93-127. The legal analysis underlying SECY-93-127
concluded that, upon a technical finding that lesser potential hazards
exist after permanent cessation of operations, the Commission has the
discretion under the PAA to reduce the amount of insurance required of
a licensee undergoing decommissioning.
Based on its review of the exemption requests, the NRC staff
concludes that the technical criteria for relieving Exelon and TMI-2
Solutions from their existing primary and/or secondary insurance
obligations have been met. As explained above, the NRC staff found that
no reasonably conceivable design-basis accident exists that could cause
an offsite release greater than the EPA PAGs and, therefore, that any
offsite consequence from a design-basis radiological release is highly
unlikely and the need for a significant amount of offsite liability
insurance coverage is unwarranted. Additionally, the NRC staff
determined that, after 16 months decay, the fuel stored in the TMI-1
SFP will be capable of being adequately cooled by air in the highly
unlikely event of pool drainage. Moreover, in the highly unlikely
beyond design-basis accident scenario where the SFP coolant inventory
is lost in such a manner that all methods of heat removal from the
spent fuel are no longer available, the NRC staff has determined that
at least 10 hours would be available and is sufficient time to support
deployment of mitigation equipment, consistent with plant conditions,
to prevent the zirconium cladding from reaching a point of rapid
oxidation. Thus, the NRC staff concludes that the fuel stored in the
TMI-1 SFP will have decayed sufficiently by the requested effective
date for the exemptions of 16 months after permanent cessation of power
operations to support a reduction in the required insurance consistent
with SECY-00-0145. Moreover, since the criteria presented in SECY-93-
127 for removal from the secondary financial protection requirement are
identical to those for reducing the primary offsite liability
insurance, there is precedent for allowing the reduction of offsite
liability insurance for TMI (as a site), once TMI-1 has met the
criteria in SECY-93-127.
The NRC staff has determined that granting the licensees' proposed
exemptions will not result in a violation of the Atomic Energy Act of
1954, Section 170, or other laws, as amended, which require licensees
to maintain adequate financial protection. Accordingly, consistent with
the legal standard presented in SECY-93-127, under which
decommissioning reactor licensees may be relieved of the requirements
to carry the maximum amount of insurance available and to participate
in the secondary retrospective premium pool where there is sufficient
technical justification, the NRC staff concludes that the requested
exemptions are authorized by law.
B. The Exemptions Are Otherwise in the Public Interest
The financial protection limits of 10 CFR 140.11 were established
to require licensees to maintain sufficient offsite liability insurance
to ensure adequate funding for offsite liability claims following an
accident at an operating reactor. However, the regulation does not
consider the reduced potential for and consequence of nuclear incidents
at permanently shut down and decommissioning reactors.
The basis provided in SECY-93-127, SECY-00-0145, and SECY-01-0100
allows licensees of decommissioning plants to reduce their primary
offsite liability insurance and to withdraw from participation in the
retrospective rating pool for deferred premium charges. As discussed in
these documents, once the zirconium fire concern is determined to be
negligible, possible accident scenario risks at permanently shut down
and defueled reactors are greatly reduced when compared to the risks at
operating reactors and the associated potential for offsite financial
liabilities from an accident are commensurately less. The licensee
analyzed and the NRC staff confirmed that the risks of accidents that
could result in an offsite radiological risk are minimal, thereby
justifying the proposed reductions in offsite primary liability
insurance and withdrawal from participation in the secondary
retrospective rating pool for deferred premium charges.
Additionally, participation in the secondary retrospective rating
pool could potentially have adverse consequences on the safe and timely
completion of decommissioning. If a nuclear incident sufficient to
trigger the secondary insurance layer occurred at another nuclear power
plant, the licensee could incur financial liability of up to
$131,056,000. However, because TMI is permanently shut down, it cannot
produce revenue from electricity generation sales to cover such a
liability. Therefore, such liability if subsequently incurred could
significantly affect the ability of the facility to conduct and
complete timely radiological decontamination and decommissioning
activities. In addition, as SECY-93-127 concluded, the shared financial
risk exposure to the licensee is greatly disproportionate to the
[[Page 14478]]
radiological risk posed by TMI when compared to operating reactors. The
reduced overall risk to the public at decommissioning power plants does
not warrant that the licensee be required to carry full operating
reactor insurance coverage after the requisite spent fuel cooling
period has elapsed following final reactor shut down. The licensee's
proposed financial protection limits will maintain a level of liability
insurance coverage commensurate with the risk to the public. These
changes are consistent with previous NRC policy as discussed in SECY-
00-0145 and exemptions approved for other decommissioning reactors.
Thus, the underlying purpose of the regulations will not be adversely
affected by the reductions in insurance coverage. Accordingly, an
exemption from participation in the secondary insurance pool (for TMI-
1) and a reduction in the primary insurance to $100 million (for TMI-1
and TMI-2), a value more in line with the potential consequences of
accidents, would be in the public interest in that this ensures that
there will be adequate funds to address any of those consequences and
helps to ensure the safe and timely decommissioning of the reactor.
Therefore, the NRC staff has concluded that the requested
exemptions from 10 CFR 140.11(a)(4) at the requested effective date of
16 months after the permanent cessation of power operations, are in the
public interest.
C. Environmental Considerations
The NRC's approval of an exemption from insurance or indemnity
requirements belongs to a category of actions that the Commission, by
rule or regulation, has declared to be a categorical exclusion after
first finding that the category of actions does not individually or
cumulatively have a significant effect on the human environment.
Specifically, the exemption is categorically excluded from the
requirement to prepare an environmental assessment or environmental
impact statement in accordance with 10 CFR 51.22(c)(25).
Under 10 CFR 51.22(c)(25), granting of an exemption from the
requirements of any regulation of Chapter I to 10 CFR is a categorical
exclusion provided that: (i) There is no significant hazards
consideration; (ii) there is no significant change in the types or
significant increase in the amounts of any effluents that may be
released offsite; (iii) there is no significant increase in individual
or cumulative public or occupational radiation exposure; (iv) there is
no significant construction impact; (v) there is no significant
increase in the potential for or consequences from radiological
accidents; and (vi) the requirements from which an exemption is sought
involve surety, insurance, or indemnity requirements.
As the Director, Division of Decommissioning, Uranium Recovery, and
Waste Programs, Office of Nuclear Material Safety and Safeguards, I
have determined that approval of the exemption request involves no
significant hazards consideration, as defined in 10 CFR 50.92, because
reducing a licensee's offsite liability requirements at TMI does not:
(1) Involve a significant increase in the probability or consequences
of an accident previously evaluated; (2) create the possibility of a
new or different kind of accident from any accident previously
evaluated; or (3) involve a significant reduction in a margin of
safety. The exempted financial protection regulation is unrelated to
the operation of TMI or site activities. Accordingly, there is no
significant change in the types or significant increase in the amounts
of any effluents that may be released offsite and no significant
increase in individual or cumulative public or occupational radiation
exposure. The exempted regulation is not associated with construction
so there is no significant construction impact. The exempted regulation
does not concern the source term (i.e., potential amount of radiation
in an accident) nor any activities conducted at the site. Therefore,
there is no significant increase in the potential for, or consequences
of, a radiological accident. In addition, there would be no significant
impacts to biota, water resources, historic properties, cultural
resources, or socioeconomic conditions in the region resulting from
issuance of the requested exemptions. The requirement for offsite
liability insurance involves surety, insurance, or indemnity matters
only.
Therefore, pursuant to 10 CFR 51.22(b) and 51.22(c)(25), no
environmental impact statement or environmental assessment need be
prepared in connection with the approval of this exemption request.
IV. Conclusions
Accordingly, the Commission has determined that, pursuant to 10 CFR
140.8, the requested exemptions are authorized by law and are otherwise
in the public interest. Therefore, the Commission hereby grants Exelon
and TMI-2 Solutions exemptions from the requirements of 10 CFR
140.11(a)(4) for the TMI site. TMI-1 permanently ceased power
operations on September 20, 2019. The exemptions from 10 CFR
140.11(a)(4) permit TMI-1 to reduce the required level of primary
financial protection from $450 million to $100 million and to withdraw
from participation in the secondary layer of financial protection 16
months after the permanent cessation of power operations. Further, the
exemptions permit TMI-2 relief from the requirements to maintain
primary offsite liability insurance for ENOs at a level above $100
million.
The exemptions are effective as of 16 months after permanent
cessation of power operations.
Dated, this 9th day of March, 2021.
For the Nuclear Regulatory Commission.
Patricia K. Holahan,
Director, Division of Decommissioning, Uranium Recovery, and Waste
Programs, Office of Nuclear Material Safety and Safeguards.
[FR Doc. 2021-05396 Filed 3-15-21; 8:45 am]
BILLING CODE 7590-01-P
