Measurement and Control of Combustible Gas Generation and Dispersal, 63039-63047 [2020-20708]

Agencies

• NUCLEAR REGULATORY COMMISSION

[Federal Register Volume 85, Number 194 (Tuesday, October 6, 2020)]
[Proposed Rules]
[Pages 63039-63047]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-20708]


=======================================================================
-----------------------------------------------------------------------

NUCLEAR REGULATORY COMMISSION

10 CFR Part 50

[Docket Nos. PRM-50-103; NRC-2011-0189]


Measurement and Control of Combustible Gas Generation and 
Dispersal

AGENCY: Nuclear Regulatory Commission.

ACTION: Petition for rulemaking; denial.

-----------------------------------------------------------------------

SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is denying a 
petition for rulemaking (PRM), dated October 14, 2011, submitted by Mr. 
Jordan Weaver (the petitioner) on behalf of the Natural Resources 
Defense Council, Inc. The petitioner requested that the NRC amend its 
regulations regarding the measurement and control of combustible gas 
generation and dispersal within a power reactor system. The petition 
was assigned Docket No. PRM-50-103 and the NRC published a

[[Page 63040]]

notice of docketing in the Federal Register on January 5, 2012. The NRC 
is denying the petition because the issues raised by the petitioner had 
been considered by the NRC in other NRC processes and the petitioner 
presented no sufficient new information or arguments to warrant the 
requested changes to the regulations.

DATES: The docket for the petition for rulemaking, PRM-50-103, is 
closed on October 6, 2020.

ADDRESSES: Please refer to Docket ID NRC-2011-0189 when contacting the 
NRC about the availability of information for this petition. You may 
obtain publicly-available information related to this petition by any 
of the following methods:
     Federal Rulemaking Website: Public comments and supporting 
materials related to this petition can be found at https://www.regulations.gov by searching on the petition Docket ID NRC-2011-
0189. Address questions about NRC dockets to Carol Gallagher; 
telephone: 301-415-3463; email: [email protected]. For technical 
questions, contact the individuals listed in the FOR FURTHER 
INFORMATION CONTACT section of this document.
     The NRC's Agencywide Documents Access and Management 
System (ADAMS): You may obtain publicly-available documents online in 
the ADAMS Public Document 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, at 301-415-4737, 
or by email to [email protected]. For the convenience of the reader, 
instructions about obtaining materials referenced in this document are 
provided in Section IV, ``Availability of Documents.''
     The NRC's PDR: You may examine and purchase copies of 
public documents at the NRC's PDR, O1-F21, One White Flint North, 11555 
Rockville Pike, Rockville, Maryland 20852.

FOR FURTHER INFORMATION CONTACT: Joseph Sebrosky, Office of Nuclear 
Reactor Regulation; telephone: 301-415-1132; email: 
[email protected]; or Edward M. Lohr, Office of Nuclear Material 
Safety and Safeguards; telephone: 301-415-0253; email: 
[email protected]. Both are staff of the U.S. Nuclear Regulatory 
Commission, Washington, DC 20555-0001.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. The Petition
II. Reasons for Denial
III. Availability of Documents
IV. Conclusion

I. The Petition

    Section 2.802 of title 10 of the Code of Federal Regulations (10 
CFR), ``Petition for rulemaking--requirements for filing,'' provides an 
opportunity for any interested person to petition the Commission to 
issue, amend, or rescind any regulation. The NRC received a petition 
for rulemaking, dated October 14, 2011, from Mr. Jordan Weaver on 
behalf of the Natural Resources Defense Council, Inc. The NRC published 
a notice of docketing in the Federal Register on January 5, 2012. The 
petitioner requested that the NRC amend its regulations regarding the 
measurement and control of combustible gas generation and dispersal 
within a power reactor system.
    When the NRC published the notice of docketing in 2012, the NRC 
elected not to seek public comment, because the staff was addressing 
the issues raised in the petition in the context of an ongoing effort 
at the time. Recommendations on that effort in response to the 
Fukushima Dai-ichi accident in Japan, SECY-11-0093, ``Near-Term Report 
and Recommendations for Agency Actions Following the Events in Japan,'' 
(Near-Term Task Force Report) had not yet been resolved.
    The NRC was in the process of holding public meetings on the Near-
Term Task Force Report recommendations and indicated in the notice of 
docketing for the petition that ``the NRC is not requesting public 
comment at this time but may do so in the future, if it decides public 
comment would be appropriate.'' Because the NRC held several public 
meetings on the Near-Term Task Force Report recommendations and on the 
subjects raised by the petitioner, the NRC determined that additional 
public input was not needed to resolve the issues raised in this 
petition.
    The NRC identified six issues in the petition. The petitioner 
raised various issues related to pressurized-water reactors (PWRs); 
boiling-water reactors (BWRs); or specific containment designs such as 
BWR Mark I, Mark II, or Mark III containments or PWR large dry 
containments, sub-atmospheric containments, and ice condenser 
containments.

II. Reasons for Denial

    The NRC is denying the petition because the issues raised by the 
petitioner had been considered by the NRC in other NRC processes and 
the petitioner did not present sufficient new information or arguments 
to warrant the requested changes to the NRC's regulations in light of 
the NRC's relevant past decisions and current policies. The NRC 
completed an assessment of potential regulatory changes related to 
hydrogen control following the March 2011 Fukushima accident in Japan. 
This assessment is summarized in SECY-16-0041, ``Closure of Fukushima 
Tier 3 Recommendations Related to Containment Vents, Hydrogen Control, 
and Enhanced Instrumentation.'' In SECY-16-0041, the NRC addressed 
recommendation 6 of the Near-Term Task Force Report involving hydrogen 
control and mitigation inside containment or in other buildings, and 
other recommendations from the report provided in connection with 
implementing lessons learned from the 2011 accident at the Fukushima 
Dai-ichi nuclear power plant.
    The NRC's response to Near-Term Task Force recommendation 6, as 
documented in SECY-16-0041, was based on a detailed holistic review of 
hydrogen control measures for power reactors. In SECY-16-0041, the NRC 
provided a high-level summary of the studies and evaluations related to 
hydrogen control, including studies issued in September of 2003 that 
supported requirements found in 10 CFR 50.44, ``Combustible gas control 
for nuclear power reactors.'' In SECY-16-0041, the NRC discusses 
hydrogen-related issues that have been addressed in major studies, such 
as those documented in NUREG-1150, ``Severe Accident Risks: An 
Assessment for Five U.S. Nuclear Power Plants,'' and NUREG-1935, 
``State-of-the-Art Reactor Consequence Analyses (SOARCA) Report.'' 
Additionally, the NRC has been participating in various international 
efforts, including a working group studying hydrogen generation, 
transport, and risk management organized by the Organisation for 
Economic Cooperation and Development/Nuclear Energy Agency.
    In SECY-16-0041, the NRC concluded that additional regulatory 
actions were not needed based on: (1) The evaluations of event 
frequencies, plant responses, the timing of barrier failures, and 
conditional release fractions, and; (2) the significant margin that 
exists between the NRC's quantitative health objectives as described in 
the NRC's ``Safety Goal Policy Statement,'' and estimated plant risks 
that might be reduced by improvement in hydrogen control.
    The NRC, in SECY-16-0041, documented that existing NRC

[[Page 63041]]

requirements and programs undertaken by licensees addressed the risks 
to public health and safety from hydrogen generation during severe 
accidents; therefore, additional requirements would not provide a 
substantial safety improvement. For new reactors licensed after 2003, 
NRC regulations include more stringent hydrogen control and mitigation 
requirements. The NRC also documented in SECY-16-0041 that changes to 
NRC regulations related to hydrogen control and mitigation requirements 
for new reactors licensed after 2003 were not warranted.
    In PRM-50-103, the petitioner raised six issues and requested that 
the NRC address them in rulemaking. While the NRC's assessment in SECY-
16-0041 of Near-Term Task Force Report recommendation 6, is closely 
related to the issues raised in PRM-50-103, SECY-16-0041 does not 
specifically address every aspect of the six issues raised in the 
petition. The conclusions in SECY-16-0041 and other sources are 
referenced in addressing the specific issues raised in PRM-50-103. The 
following explains each issue raised in the petition, the NRC's 
detailed response, and as appropriate, supplemental information beyond 
that provided in SECY-16-0041.
    Issue 1: The petitioner requested that the NRC revise Sec.  50.44 
``to require that all PWRs (with large dry containments, sub-
atmospheric containments, and ice condenser containments) and [BWRs 
with Mark III containments] operate with systems for combustible gas 
control that would effectively and safely control the potential total 
quantity of hydrogen that could be generated in different severe 
accident scenarios. . . .'' The petitioner stated that the total 
quantity of hydrogen could exceed the amount generated from the metal-
water reaction of 100 percent of the fuel cladding because of 
contributions produced by the metal-water reaction with non-fuel 
components of the reactor.
    Response to Issue 1: The NRC has evaluated requirements related to 
hydrogen control for these containment types on several occasions. For 
example, hydrogen-related issues have been addressed in major studies, 
such as those documented in NUREG-1150 and NUREG-1935. In SECY-16-0041, 
the NRC provided a detailed assessment of whether additional hydrogen 
controls were warranted for large dry containments, ice condenser 
containments, and Mark III containments. The NRC concluded that the 
risks to public health and safety from hydrogen generation during 
severe accidents were addressed by existing NRC requirements and 
programs undertaken by licensees and that additional requirements for 
existing operating reactors would, therefore, not provide a substantial 
increase in the overall protection of the public health and safety and 
that changes to requirements were not warranted.
    For large dry and sub-atmospheric containments, Sec.  50.44 does 
not include a requirement to assume a particular percentage of hydrogen 
generated from metal-water reactions for existing operating reactors. 
The NRC's Federal Register notice for the final rule ``Combustible Gas 
Control in Containment,'' published on September 16, 2003, stated that 
combustible gas generated from severe accidents was not risk 
significant for large dry and sub-atmospheric containments ``because of 
the large volumes, high failure pressures, and likelihood of random 
ignition to help prevent the build-up of detonable hydrogen 
concentrations.''
    As documented in the draft report, ``State-of-the-Art Reactor 
Consequence Analysis Project--Uncertainty Analysis of the Unmitigated 
Short-Term Station Blackout of the Surry Power Station'' the MELCOR 
best-estimate computer program was used to model the progression of 
hypothetical severe accidents at Surry Power Station. Sandia National 
Laboratories developed the MELCOR computer program for the NRC to model 
the progression of severe accidents in nuclear power plants. The Surry 
Power Station MELCOR uncertainty analysis showed that the hydrogen that 
is produced in-vessel can vary between 250 kilograms (5th percentile) 
to 600 kilograms (95th percentile) with a mean of about 400 kilograms 
at 48 hours after the start of an accident. The corresponding fraction 
of cladding oxidized varies from 35 percent to 83 percent equivalent 
cladding mass with a mean of 55 percent. The typical timing for rapid 
initial hydrogen generation is about one to two hours after the start 
of hydrogen generation. None of the cases in the uncertainty analysis 
indicated early containment failure as a result of hydrogen combustion. 
In the hypothetical severe accident, any containment failure would 
occur later, as a result of continued heat up of the containment, due 
to core-concrete interaction if cooling to the containment were not 
restored. The analysis also did not predict late failure due to 
hydrogen combustion because after breach of the reactor pressure 
vessel, which would occur prior to containment failure, ignition 
sources would be available to burn the hydrogen at lower flammability 
levels.
    NUREG/CR-7110, ``State-of-the-Art Reactor Consequence Analyses 
Project,'' Volume 2, ``Surry Integrated Analysis'' considered hydrogen 
generated from non-cladding sources. That analysis showed that high-
steam concentrations are typically associated with scenarios that lead 
to large amounts of hydrogen generation from metal-water reactions. 
These high steam concentrations are sufficient to inert the containment 
and suppress hydrogen combustion in containments with large volumes.
    In reviewing the issues raised in the petition, the NRC also 
considered safety gains attributable to NRC Order EA-12-049, ``Order 
Modifying Licenses with Regard to Requirements for Mitigation 
Strategies for Beyond-Design-Basis External Events,'' (codified in 10 
CFR 50.155) which requires mitigation strategies for each operating 
reactor to reduce the risk of core damage from an extended loss of 
alternating current power event. Also, based on Commission direction in 
SRM-SECY-15-0065, ``Proposed Rulemaking: Mitigation of Beyond-Design-
Basis Events,'' the staff revised the Reactor Oversight Process to 
cover licensees' implementation and maintenance of severe accident 
management guidelines. The severe accident management guidelines 
address hydrogen generation in large dry and sub-atmospheric 
containments to minimize the potential for containment failure from 
hydrogen combustion events.
    For ice condenser and BWR Mark III containments, Sec.  
50.44(b)(2)(ii), (b)(3), and (b)(5) require the capability for 
controlling combustible gas (i.e., hydrogen igniters) and the 
performance of an evaluation of equipment survivability and an 
evaluation of the consequences of large amounts of hydrogen generated 
if there is an accident (hydrogen resulting from the metal-water 
reaction of up to and including 75 percent of the fuel cladding 
surrounding the active fuel region, excluding the cladding surrounding 
the plenum volume). As discussed in SECY-16-0041, the NRC performed 
additional analyses for these containments to determine if additional 
regulatory actions were warranted relative to hydrogen control. The NRC 
determined that such actions were not needed based on the underlying 
requirements in Sec.  50.44 as supplemented by additional guidance to 
include backup power supplies for hydrogen igniters under NRC Order EA-
12-049. The Order requirements have been made generically applicable in 
``Sec.  50.155, ``Mitigation of beyond-design-basis events.''

[[Page 63042]]

    As documented in SECY-16-0041, the NRC has performed assessments 
using best estimate simulations with MELCOR, consistent with the 
approach used in prior State-of-the-Art Consequence Analyses efforts. 
Additional assessments are documented in NUREG/CR-7245, ``State-of-the-
Art Consequence Analyses (SOARCA) Project--Sequoyah Integrated 
Deterministic and Uncertainty Analyses,'' dated November 2017. The 
NUREG/CR-7245 assessment included hydrogen generated from non-cladding 
sources. Based on the results of these studies, the NRC concluded that 
early containment failures could only occur on the first hydrogen burn 
for ice condenser containments in those cases where the hydrogen 
igniters were not credited. Subsequent hydrogen burns do not challenge 
ice condenser containment integrity because they occur closer to the 
lower flammability limit of hydrogen due to the presence of active 
ignition sources (e.g., hot gases from the primary system or ex-vessel 
debris). The total amount of hydrogen produced by the first 
deflagration varies between 5 to 50 percent of equivalent cladding mass 
oxidized. Therefore, the NRC concluded in SECY-16-0041 that the 
existing requirement to consider hydrogen generation from a 75 percent 
cladding mass oxidation for ice condenser containments is appropriate. 
In cases crediting hydrogen igniters, containment failure was delayed 
and only occurred as a result of overpressure if heat removal systems 
were not restored.
    For BWR Mark III containments, calculations were performed in 
resolving Near-Term Task Force recommendation 5.2 related to reliable 
hardened vents for containments other than BWR Mark I and Mark II. 
Further, analysis performed in response to Near-Term Task Force 
recommendation 6, associated with hydrogen control measures, showed 
that the total in-vessel hydrogen generation by the time of lower head 
failure is about 90 percent of equivalent cladding mass oxidized. The 
outcomes of these calculations indicate that containment failure by 
overpressure is significantly delayed in this scenario.
    Licensees with Mark III containments have extended reactor core 
isolation cooling system operation by cooling water in the suppression 
pool in compliance with NRC Order EA-12-049, made generically 
applicable in Sec.  50.155. This change decreases the likelihood of 
fission product barrier breaches.
    An assessment of event frequencies, plant responses, the timing of 
barrier failures, radioactive releases, and other factors show 
substantial margin to the quantitative health objectives of the 
Commission's Safety Goal Policy Statement. Therefore, even if hydrogen 
generation is assumed to be 90 percent of equivalent cladding mass 
oxidized, the NRC determined that additional regulatory actions are not 
warranted above those found in Sec.  50.44 and in response to NRC Order 
EA-12-049.
    The petitioner's request also applied to new reactors. Section 
50.44(c) sets forth combustible gas control requirements for water-
cooled nuclear power reactor designs licensed after 2003 with 
characteristics (e.g., type and quantity of cladding materials) such 
that the potential for production of combustible gases is comparable to 
light-water reactor designs licensed as of 2003. These requirements are 
more conservative than those for operating reactors.
    Section 50.44(c)(2) requires a system for hydrogen control that can 
safely accommodate hydrogen generated by the equivalent of a 100 
percent fuel clad metal-water reaction and that is capable of 
precluding uniformly distributed concentrations of hydrogen from 
exceeding 10 percent (by volume). If these conditions cannot be 
satisfied, an inerted atmosphere must be provided within the 
containment. As a result, new plants have design features such as 
hydrogen igniters for AP1000 design reactors and inerted containments 
and passive autocatalytic recombiners for the Economic Simplified 
Boiling-Water Reactors. As described in SECY-16-0041, the NRC assessed 
the potential for further hydrogen control enhancements and found that 
such measures would not be justified under the issue finality 
provisions of 10 CFR part 52, ``Licenses, certifications, and approvals 
for nuclear power plants'' (similar to the backfit requirements defined 
in Sec.  50.109, ``Backfitting''). In addition, based on the analyses 
for the various containment types, the NRC concludes that changing the 
existing Sec.  50.44(c) requirements is not warranted.
    The NRC also considered the petitioner's position that a hydrogen 
detonation inside containment can result in internally generated 
missiles that could damage structures, systems, and components used to 
maintain key safety functions of ensuring core cooling and containment 
integrity, as well as the petitioner's position that these types of 
events should be analyzed. While SECY-16-0041 does not specifically 
address this issue, the conclusions in that paper are based, in part, 
on the low risk associated with core damage events that could lead to 
the generation of large amounts of hydrogen. Given the low probability 
of missiles being generated from a hydrogen combustion event (which 
assumes the core is substantially degraded) the estimated plant risks 
that might be reduced by a proposed requirement to consider missiles 
generated from a hydrogen combustion event are not substantial.
    Therefore, the NRC concludes that the issues raised by the 
petitioner have been considered by the NRC in other NRC processes and 
the petitioner did not present sufficient new information or arguments 
to warrant the requested amendment in light of the NRC's relevant past 
decisions and current policies. The NRC determined that the analyses 
and plant changes requested by the petitioner in issue 1 of the 
petition for existing operating reactors would not provide substantial 
safety enhancements. For reactors licensed after 2003 (new reactors), 
the NRC determined that changes to the requirements in Sec.  
50.44(c)(2) are not warranted. The NRC continues to conclude that the 
current design and licensing requirements for operating and new 
reactors for the control of hydrogen provide adequate protection of 
public health and safety.
    Issue 2: The petitioner requested that the NRC revise Sec.  50.44 
to ``require that [BWRs with Mark I and Mark II containments] operate 
with systems for combustible gas control or inerted containments that 
would effectively and safely control the potential total quantity of 
hydrogen that could be generated in different severe accident 
scenarios.'' The petitioner stated that the total quantity of hydrogen 
could exceed the amount generated from the metal-water reaction of 100 
percent of the fuel cladding because of contributions produced by the 
metal-water reaction with non-fuel components of the reactor.
    Response to Issue 2: The NRC has evaluated requirements related to 
hydrogen control for BWRs with Mark I and Mark II containments on 
several occasions. In SECY-16-0041, the NRC provided a detailed 
assessment of whether additional hydrogen controls were warranted for 
these containment types. The NRC concluded that additional requirements 
or guidance beyond Sec.  50.44, those associated with NRC Order EA-13-
109, ``Order Modifying Licenses with Regard to Reliable Hardened 
Containment Vents Capable of Operation under Severe Accident 
Conditions,'' and the severe accident management guidelines were not 
warranted. For hydrogen combustion events outside primary containment, 
assessments performed

[[Page 63043]]

with best estimate simulations (e.g., NUREG-1935) included hydrogen 
generated from non-cladding sources.
    In resolving issue 2, the NRC considered the international 
evaluations referenced by the petitioner in support of the request to 
modify the NRC's regulations. The NRC participated in the international 
working groups that developed these evaluations and used them in 
developing current NRC regulations and guidance.
    Under Sec.  50.44, BWRs with Mark I and Mark II containments have 
an inerted atmosphere within the primary containment that greatly 
reduces the possibility of hydrogen combustion.
    The analyses in NUREG/CR-7155, ``State-of-the-Art Reactor 
Consequence Analyses Project--Uncertainty Analysis of the Unmitigated 
Long-Term Station Blackout of the Peach Bottom Atomic Power Station,'' 
predicted that the hydrogen that is produced in-vessel during an 
unmitigated long-term station blackout at a BWR with a Mark I 
containment can vary between about 1,100 kilograms (5th percentile) and 
about 1,600 kilograms (95th percentile) with a mean of about 1,300 
kilograms. This corresponds to a fraction of equivalent cladding mass 
oxidized that varies from 62 percent to 90 percent, with a mean at 73 
percent. The more recent calculations in support of the NRC's 
evaluation of a potential rulemaking on containment protection and 
release reduction (NUREG-2206, ``Technical Basis for the Containment 
Protection and Release Reduction Rulemaking for Boiling Water Reactors 
with Mark I and Mark II Containments''), showed that equivalent 
cladding mass oxidation fraction varies between 60 percent and 77 
percent, with a typical timing for rapid initial hydrogen generation of 
about 2 to 3 hours after the start of hydrogen generation. The 
assessment in SECY-16-0041 concluded that adding hydrogen control 
measures beyond those already included in NRC regulations, Order EA-13-
109, and the severe accident management guidelines would not provide a 
substantial safety improvement, and therefore, were not warranted.
    In SRM-SECY-15-0085, ``Evaluation of the Containment Protection and 
Release Reduction for Mark I and Mark II Boiling Water Reactors 
Rulemaking Activities (10 CFR part 50) (RIN-3150-AJ26),'' the 
Commission directed the staff not to undertake rulemaking and to 
``leverage the draft regulatory basis to the extent applicable to 
support resolution of the post-Fukushima Tier 3 item related to 
containments of other designs.'' In SECY-16-0041, the NRC evaluated the 
technical analyses for Order EA-13-109, and the proposed Containment 
Protection and Release Reduction draft regulatory basis for rulemaking, 
``Draft Regulatory Basis for Containment Protection and Release 
Reduction for Mark I and Mark II Boiling Water Reactors (10 CFR part 
50).'' Order EA-13-109 and the Containment Protection and Release 
Reduction draft regulatory basis show that the threat of explosions 
from combustible gases outside primary containment is significantly 
reduced by effective venting strategies. Additionally, the 
implementation of Order EA-13-109 included the severe accident water 
addition/severe accident water management approaches to further control 
containment conditions in the event of a severe accident. In SECY-16-
0041, the NRC considered additional measures for hydrogen control and 
mitigation within containments and adjacent buildings that were being 
pursued in some countries. Examples of these measures include the 
installation of passive autocatalytic recombiners and venting 
capabilities to release hydrogen from BWR reactor buildings. The NRC 
concluded that these additional measures would not themselves directly 
support the cooling of core debris, but could help, for some selected 
scenarios, to maintain barriers to the release of radioactive material 
and prevent explosions that could hamper severe accident management 
activities. The potential benefits of the measures requested by the 
petitioner would be comparable or less than the alternatives analyzed 
in SECY-16-0041, which the NRC determined to be below the threshold for 
warranting further regulatory actions.
    Therefore, the NRC concludes that the issues raised by the 
petitioner have been considered by the NRC in other NRC processes and 
the petitioner did not present sufficient new information or arguments 
to warrant the requested requirement in light of the NRC's relevant 
past decisions and current policies. The NRC determined that the 
analyses and plant changes requested by the petitioner in issue 2 of 
the petition would not provide substantial safety enhancements. The NRC 
continues to conclude that the current design and licensing 
requirements for the control of hydrogen provide adequate protection of 
public health and safety.
    Issue 3: The petitioner requested that the NRC revise Sec.  50.44 
``to require that PWRs and [BWRs with Mark III containments] operate 
with systems for combustible gas control that would be capable of 
precluding local concentrations of hydrogen in the containment from 
exceeding concentrations that would support combustions, fast 
deflagrations, or detonations that could cause a loss of containment 
integrity or loss of necessary accident mitigating features.''
    Response to Issue 3: As discussed in the portion of this document 
entitled ``Response to Issue 1,'' additional hydrogen controls for 
large dry and sub-atmospheric containments do not yield a substantial 
safety benefit. The NRC provides additional insights on the basis for 
the removal of the requirements for hydrogen recombiners for these 
containment types in the Federal Register notice for the Sec.  50.44 
final rule, ``Combustible Gas Control in Containment,'' which 
references Attachment 2 to SECY-00-0198, ``Status Report on Study of 
Risk-Informed Changes to the Technical Requirements of 10 CFR part 50 
(Option 3) and Recommendations on Risk-Informed Changes to 10 CFR 50.44 
(Combustible Gas Control).'' Attachment 2 provides a discussion 
regarding why the large volumes and likelihood of spurious ignition in 
large dry and sub-atmospheric containment help prevent the build-up of 
detonable concentrations.
    The petitioner stated that the small volumes and confined spaces 
found in ice condenser and BWR Mark III containments make them 
susceptible to hydrogen pocketing. The NRC's analyses documented in 
SECY-16-0041 confirm that hydrogen accumulation and potential 
combustion could challenge the integrity of these containment types if 
igniters were not required.
    However, to meet the requirements of Sec.  50.44(b)(2)(ii), (b)(3), 
and (b)(5), ice condenser and BWR Mark III containments must have 
hydrogen igniters for combustible gas control. The hydrogen igniters 
address the threat from combustible gas buildup. In response to Order 
EA-12-049, as made generically applicable in 10 CFR 50.155, licensees 
with these containment types have taken action to ensure power is 
available to the igniter systems during station blackout conditions. 
These licensees follow the severe accident management guidelines to 
minimize the potential for containment failure from hydrogen combustion 
events. The location of the igniters prevents hydrogen (or any other 
combustible gas) from accumulating in large quantities.
    The petitioner's request also applied to new reactors. As discussed 
in the portion of this document entitled ``Response to Issue 1,'' Sec.  
50.44(c) sets forth combustible gas control

[[Page 63044]]

requirements for water-cooled nuclear power reactor designs licensed 
after 2003, which are more stringent than those for existing operating 
reactors. As a result, new plants have design features such as hydrogen 
igniters for AP1000 design reactors and inerted containments and 
passive autocatalytic recombiners for the Economic Simplified Boiling-
Water Reactors. As described in SECY-16-0041, the NRC assessed the 
potential for further hydrogen control enhancements for existing 
operating reactors and found that such measures would not be justified 
under the issue finality provisions of 10 CFR part 52 (similar to 
backfit requirements defined in Sec.  50.109, ``Backfitting'').
    Therefore, as it relates to issue 3 of the petition, the NRC 
concludes that the petitioner did not present sufficient new 
information or arguments to warrant the requested requirement in light 
of the NRC's relevant past decisions and current policies. Although 
SECY-16-0041 did not specifically consider this issue, the NRC's 
assessments in SECY-16-0041 did consider the contributions to the risk 
to public health and safety from severe accidents and related hydrogen 
generation and concluded that those contributions were not substantial. 
The NRC determined that the analyses and plant changes requested by the 
petitioner in issue 3 of the petition for existing operating reactors 
would not provide substantial safety enhancements and therefore, they 
were not warranted. For reactors licensed after 2003, the NRC also 
determined that changes to the requirements in Sec.  50.44(c)(2) are 
not warranted. The NRC continues to conclude that the current design 
and licensing requirements for the control of hydrogen for operating 
and new reactors provide adequate protection of public health and 
safety.
    Issue 4: The petitioner stated that ``[t]he current requirement 
that hydrogen monitors be functional within 90-minutes after the 
initiation of safety injection is inadequate for protecting public and 
plant worker safety.'' To correct this issue, the petitioner requested 
that the NRC revise Sec.  50.44 to ``require that PWRs and [BWRs with 
Mark III containments] operate with combustible gas and oxygen 
monitoring systems that are qualified in accordance with 10 CFR 
50.49.'' The petitioner also requested that NRC revise Sec.  50.44 ``to 
require that after the onset of a severe accident, combustible gas 
monitoring systems be functional within a timeframe that enables the 
proper monitoring of quantities of hydrogen indicative of core damage 
and indicative of a potential threat to the containment integrity.''
    Response to Issue 4: Hydrogen monitoring in containment in Sec.  
50.44 includes requirements that hydrogen monitors be functional. 
Functional requirements are also provided in Item II.F.1, Attachment 6, 
of NUREG-0737, ``Clarification of TMI Action Plan Requirements,'' which 
states that hydrogen monitors are to be functioning within 30 minutes 
of the initiation of safety injection. This requirement was imposed by 
confirmatory orders in 1983 following the accident at Three Mile Island 
Unit 2.
    Since NUREG-0737 was issued, the NRC has determined that the 30-
minute requirement can be unnecessarily stringent. This is documented 
in the Federal Register notice for the Sec.  50.44 final rule and in 
Regulatory Guide 1.7, Revision 3, ``Control of Combustible Gas 
Concentrations in Containment.'' Through a confirmatory order, 
``Confirmatory Order Modifying Post-TMI Requirements Pertaining to 
Containment Hydrogen Monitors for Arkansas Nuclear One, Units 1 and 2 
(TAC NOS. MA1267 and 1268),'' the NRC developed a method for licensees 
to adopt a risk-informed functional requirement in lieu of the 30-
minute requirement. As described in the confirmatory order, an 
acceptable functional requirement would meet the following 
requirements:
    (1) Procedures shall be established for ensuring that indication of 
hydrogen concentration in the containment atmosphere is available in a 
sufficiently timely manner to support the role of information in the 
emergency plan (and related procedures) and related activities such as 
guidance for the severe accident management plan.
    (2) Hydrogen monitoring will be initiated on the basis of the 
following considerations:
    a. The appropriate priority for establishing indication of hydrogen 
concentration within containment in relation to other activities in the 
control room.
    b. The use of the indication of hydrogen concentration by decision-
makers for severe accident management and emergency response.
    c. Insights from experience or evaluation pertaining to possible 
scenarios that result in significant generation of hydrogen that would 
be indicative of core damage or a potential threat to the integrity of 
the containment building.
    The NRC has determined that adoption of this risk-informed 
functional requirement by licensees results in the hydrogen monitors 
being functional within 90 minutes after the initiation of safety 
injection.
    Subsequent to the issuance of the confirmatory order, the NRC 
issued a notice of availability of a model in the Federal Register 
titled, ``Notice of Availability of Model Application Concerning 
Technical Specification Improvement to Eliminate Hydrogen Recombiner 
Requirement, and Relax the Hydrogen and Oxygen Monitor Requirements for 
Light Water Reactors Using the Consolidated Line Item Improvement 
Process.'' The notice stated that this model was available for 
referencing in license amendment applications for licensees wanting to 
relax safety classifications and the licensee commitments to certain 
design and qualification criteria for hydrogen monitors. This allowed 
licensees to choose to remove containment hydrogen monitoring 
requirements from their license through a license amendment process. 
One such license amendment was approved for Arkansas Nuclear One, Unit 
1 in August 2004. The NRC based its approval of the license amendment 
request on the conclusion that the hydrogen monitors were not risk-
significant. However, because the monitors are needed to diagnose the 
course of beyond-design-basis accidents, each licensee choosing this 
approach should verify that it has a hydrogen monitoring system capable 
of diagnosing beyond-design-basis accidents and make a regulatory 
commitment to maintain the system.
    Section 50.44 requires that equipment used for monitoring hydrogen 
in containment is functional, reliable, and capable of continuously 
measuring the concentration of hydrogen in the containment atmosphere 
following a significant beyond-design-basis accident. The Federal 
Register notice for the Sec.  50.44 final rule states that the NRC 
determined that the monitoring equipment need not be qualified in 
accordance with Sec.  50.49 because the requirements found in Sec.  
50.44 address beyond-design-basis combustible gas control. As a result 
of the Fukushima lessons learned, the NRC also reviewed whether 
enhancements to reactor and containment instrumentation to withstand 
beyond-design-basis accident conditions were warranted. As documented 
in Enclosure 2 to SECY-16-0041, the NRC concluded that regulatory 
actions to require enhancements to reactor and containment 
instrumentation to support the response to severe accidents would not 
provide a substantial safety enhancement and, therefore, were not 
warranted.

[[Page 63045]]

    Additionally, the NRC has revised the Reactor Oversight Process to 
address licensees' implementation and maintenance of severe accident 
management guidelines. The severe accident management guidelines are 
based on the concept of using available resources (including 
instrumentation) to mitigate a severe accident, such that if a key 
instrument is not available for any reason, alternate instruments are 
used. The instrumentation available that might be used before, during, 
and after a severe accident is discussed in Regulatory Guide 1.97, 
Revision 3, ``Instrumentation for Light-Water Cooled Nuclear Power 
Plants to Assess Plant and Environs Conditions During and Following an 
Accident,'' licensing documents, severe accident management guidelines, 
and supporting technical guidance documents. The severe accident 
management guidelines include guidance to address hydrogen generation 
from metal-water reactions and actions to take to minimize the 
potential for containment failure from hydrogen combustion events.
    The petitioner stated that effective and safe use of hydrogen 
igniters in ice condenser and BWR Mark III containments is a complex 
issue that requires thorough analysis, including consideration of the 
safety of using the igniters at certain times in a severe accident. The 
severe accident management guidelines for ice condenser and Mark III 
containments include guidelines for the use of the igniters.
    Therefore, as it relates to issue 4 of the petition, the NRC 
concludes that the petitioner did not present sufficient new 
information or arguments to warrant the requested requirement in light 
of the NRC's relevant past decisions and current policies. The NRC 
determined that the analyses and plant changes requested by the 
petitioner in issue 4 of the petition would not provide substantial 
safety enhancements.
    Issue 5: The petitioner requested that the NRC revise Sec.  50.44 
to ``require that licensees of PWRs and [BWRs with Mark III 
containments] perform analyses that demonstrate containment structural 
integrity would be retained in the event of a severe accident.'' 
Additionally, the petitioner requested that the NRC revise Sec.  50.44 
to require licensees of Mark Is and Mark IIs to perform analyses 
``using the most advanced codes, which demonstrate containment 
structural integrity would be retained in the event of a severe 
accident.''
    Response to Issue 5: For large dry and sub-atmospheric PWR 
containments, Sec.  50.44 does not require that containment structural 
integrity analysis is performed for hydrogen combustion events. 
Studies, including ``Feasibility Study for a Risk-Informed Alternative 
to 10 CFR 50.44 `Standards for Combustible Gas Control System in Light-
water cooled Power Reactors''' (Attachment 2 to SECY-00-0198), NUREG-
1935, SECY-16-0041 evaluations, and ``State-of-the-Art Reactor 
Consequence Analysis Project--Uncertainty Analysis of the Unmitigated 
Short-Term Station Blackout of the Surry Power Station'' (draft 
report), have indicated that these containments have very large 
internal volumes and are not predicted to fail until they reach about 
three times their design pressure. These studies also have determined 
that these containments have significant capacity for withstanding the 
pressure load associated with hydrogen deflagrations. Detonations of 
sufficient magnitude to cause failure of these types of containments 
were determined to have a low probability of occurrence.
    In SECY-16-0041, the NRC determined that the longer times to over-
pressurize large dry containments in long-term station blackout 
scenarios provides additional opportunities for emergency responders to 
restore key safety functions prior to the containment being breached. 
The low latent cancer fatality risks estimated in NUREG-1935 reflect 
the ability of large dry containments to limit the release of 
radioactive material for many hours. These estimates confirm the NRC's 
assessment of the adequacy of containment performance and finding that 
additional regulatory actions, such as requiring improved containment 
vents, are not warranted for large dry containments. Therefore, the 
staff concludes requiring licensees to perform detailed structural 
analysis of the containment using different or advanced codes (as the 
petitioner requested) to demonstrate that containment structural 
integrity would be retained in the event of a severe accident is not 
warranted.
    For ice condenser and BWRs with Mark III containments, Sec.  
50.44(b)(5)(v)(A) requires demonstration of containment structural 
integrity by use of an analytical technique accepted by the NRC for 
hydrogen combustion events. The demonstration must include sufficient 
supporting justification to show that the technique describes the 
containment response to the structural loads involved. In SECY-16-0041, 
additional analyses performed by the NRC confirmed that hydrogen 
accumulation and potential combustion could challenge the integrity of 
these containments and showed the benefit of igniters to address this 
concern. Therefore, the NRC continues to find that the structural 
analysis associated with hydrogen deflagration events regarding the use 
of the igniters that is required by Sec.  50.44(b)(5)(v)(A) is 
appropriate.
    Further, the NRC concludes that the additional requirements 
proposed by the petitioner to use the most advanced codes, such as 
computational fluid dynamic codes, to model hydrogen distribution in 
the containment and loads from flame acceleration, are not required. In 
SECY-16-0041, the NRC assessed whether additional regulatory 
requirements, such as a hardened containment vent or additional 
hydrogen control and mitigation, were warranted for these containment 
types. The assessments, which used the best-estimate computer program 
MELCOR, concluded that sufficient safety margins exist between 
estimated plant risks that might be influenced by improvements in 
containment performance or hydrogen control and the NRC's quantitative 
health objectives described in the NRC's ``Safety Goal Policy 
Statement.'' Therefore, because the requirements for existing 
structural analysis for these containment designs provide sufficient 
margin to ensure safety, the staff concluded that requiring licensees 
to continually update this structural evaluation using updated codes 
would not provide a substantial safety benefit and that no regulatory 
action is warranted.
    For BWRs with Mark I and Mark II containments, Sec.  50.44 does not 
require that containment structural integrity analysis be performed for 
hydrogen combustion events. Under Sec.  50.44, BWR Mark I and Mark II 
primary containments are inerted. Because the primary containments are 
inerted, hydrogen combustion inside the primary containment is highly 
unlikely, rendering performance of primary containment structural 
analysis associated with hydrogen combustion events unnecessary. In 
addition, for BWR Mark I and Mark II containments, Order EA-13-109 
requires the installation of reliable hardened containment vents 
capable of operation under severe accident conditions. In SECY-16-0041, 
the technical analyses for Order EA-13-109 and NUREG-2206 show that the 
threat of explosions from combustible gasses in secondary containment 
is significantly reduced by effective venting strategies and that 
severe accident water addition/severe accident water management 
approaches are used as part of the implementation of Order EA-13-109.

[[Page 63046]]

    Severe accident management guidelines also include specific 
measures to monitor and vent BWR Mark I and Mark II containments to 
address containment over-pressurization events and hydrogen issues. 
This provides further risk reduction by improving the control of 
hydrogen in BWR Mark I and Mark II containments. Using different or 
advanced codes (as the petitioner requested) to demonstrate that 
containment structural integrity would be retained in the event of a 
severe accident, is not necessary for these containment designs 
because: (1) Hydrogen combustion events are highly unlikely in the 
primary containment given the inerted containment, (2) the severe 
accident hardened containment vents being installed in these primary 
containments reduce the already low likelihood of containment failure 
to levels below the levels where additional regulatory actions are 
warranted, and (3) as documented in SECY-16-0041, reduction of pressure 
in the primary containment using the severe accident capable hardened 
vents reduces the already low likelihood of secondary containment 
failure due to hydrogen combustion events to levels below where 
additional regulatory actions are warranted.
    For new reactors, Sec.  50.44(c) sets forth combustible gas control 
requirements for water-cooled nuclear power reactor designs licensed 
after 2003 with characteristics (e.g., type and quantity of cladding 
materials) such that the potential for production of combustible gases 
is comparable to light-water reactor designs licensed as of 2003. These 
requirements are more stringent than those for existing operating 
reactors. Section 50.44(c)(5) requires a structural analysis that 
demonstrates containment structural integrity. This demonstration must 
use an analytical technique accepted by the NRC and must include 
sufficient supporting justification to show that the technique 
describes the containment response to the structural loads involved. 
The analysis must address an accident that releases hydrogen generated 
from a 100 percent fuel clad coolant reaction accompanied by hydrogen 
burning. Systems necessary to ensure containment integrity must also be 
demonstrated to perform their function under these conditions. 
Therefore, for reactors licensed after 2003 with similar 
characteristics to current pressurized water reactors and Mark III 
boiling water reactors, the kind of structural analysis requested by 
the petitioner is already required.
    Therefore, as it relates to issue 5 of the petition, the NRC 
concludes that the petitioner did not present sufficient new 
information or arguments to warrant the requested amendments in light 
of the NRC's relevant past decisions and current policies. The NRC 
determined that the analyses and plant changes for operating reactors 
requested by the petitioner in issue 5 of the petition would not 
provide substantial safety enhancements. For reactors licensed after 
2003, for reasons stated in previous paragraphs, the NRC determined 
that changes to the requirements in Sec.  50.44(c)(5) are not 
warranted. The NRC continues to conclude that the current design and 
licensing requirements for the control of hydrogen for operating and 
new reactors provide adequate protection of public health and safety.
    Issue 6: The petitioner requested that the NRC revise Sec.  50.44 
to ``require that licensees of PWRs with ice condenser containments and 
[BWRs with Mark III containments] (and any other NPPs that would 
operate with hydrogen igniter systems) perform analyses that 
demonstrate hydrogen igniter systems would effectively and safely 
mitigate hydrogen in different severe accident scenarios.''
    Response to Issue 6: In SECY-16-0041, the NRC's assessment 
concluded that hydrogen igniters would likely delay containment 
failures in ice condenser and BWR Mark III containments. The NRC 
determined that additional improvements beyond those already included 
in NRC regulations and Order EA-12-049 would not provide a substantial 
safety improvement.
    The NRC concluded that compliance with Order EA-12-049, as made 
generically applicable in 10 CFR 50.155, ensures that additional 
mitigation strategies are available for each operating reactor to 
reduce the risk of core damage from an extended loss of alternating 
current power event. The NRC has revised the reactor oversight process 
to cover licensees' implementation and maintenance of severe accident 
management guidelines. The severe accident management guidelines 
include guidance to address hydrogen generation in these containment 
designs and the use of the igniters to minimize the potential for 
containment failure from hydrogen detonation.
    For new reactors, Sec.  50.44(c) sets forth combustible gas control 
requirements for water-cooled nuclear power reactor designs licensed 
after 2003 that are more stringent than those requirements for existing 
operating reactors. As a result, new plants have design features such 
as hydrogen igniters for AP1000 design reactors. As described in SECY-
16-0041, the NRC assessed potential further hydrogen control 
enhancements and found that such measures were not warranted. The NRC 
further notes that development of severe accident management 
guidelines, which include guidance for the use of the igniters to 
minimize the potential for containment failure for hydrogen detonation, 
is addressed by combined license holders for the AP1000 design in 
accordance with the AP1000 design certification.
    Therefore, the NRC determined that the analyses and plant changes 
requested by the petitioner in issue 6 of the petition for existing 
operating reactors would not provide substantial safety enhancements. 
For reactors licensed after 2003, the NRC determined that changes to 
the requirements in Sec.  50.44(c) are not needed for the reasons 
discussed. The NRC concludes that the current design and licensing 
requirements for the control of hydrogen for both operating and new 
reactors provide adequate protection of public health and safety.

III. Availability of Documents

    The documents identified in the following table are available to 
interested persons through one or more of the following methods, as 
indicated.

 
----------------------------------------------------------------------------------------------------------------
                                                                        ADAMS Accession No./web link/Federal
                             Document                                            Register citation
----------------------------------------------------------------------------------------------------------------
Petition for rulemaking from the Natural Resources Defense         ML11301A094
 Council, Inc., October 14, 2011.
Federal Register notice, ``Measurement and Control of Combustible  77 FR 441
 Gas Generation and Dispersal,'' January 5, 2012.

[[Page 63047]]

 
SECY-16-0041, ``Closure of Fukushima Tier 3 Recommendations        ML16049A079 (Package)
 Related to Containment Vents, Hydrogen Control, and Enhanced
 Instrumentation,'' March 31, 2016.
SECY-11-0093, ``Near-Term Report and Recommendations for Agency    ML11186A950 (Package)
 Actions Following the Events in Japan,'' July 12, 2012.
Federal Register notice for the final rule, ``Combustible Gas      68 FR 54123
 Control in Containment,'' September 16, 2003.
NUREG-1150, ``Severe Accident Risks: An Assessment for Five U.S.   ML120960691
 Nuclear Power Plants,'' December 1990.
NUREG-1935, ``State-of-the-Art Reactor Consequence Analyses        ML12332A053 (Package)
 (SOARCA) Report,'' November 2012.
``Safety Goals for the Operations of Nuclear Power Plants; Policy  ML011210381
 Statement Correction and Republication,'' August 21, 1986.
Draft report ``State-of-the-Art Reactor Consequence Analysis       ML15224A001
 Project--Uncertainty Analysis of the Unmitigated Short-Term
 Station Blackout of the Surry Power Station,'' August 2015.
NUREG/CR-7245, ``State-of-the-Art Reactor Consequence Analyses     ML17340B209
 (SOARCA) Project--Sequoyah Integrated Deterministic and
 Uncertainty Analyses,'' November 2017.
NUREG/CR-7110, Vol. 2, ``State-of-the-Art Reactor Consequence      ML120260681
 Analyses Project--Volume 2: Surry Integrated Analysis,'' January
 2012.
Order EA-12-049, ``Order Modifying Licenses With Regard to         ML12054A735
 Requirements for Mitigation Strategies for Beyond-Design-Basis
 External Events,'' March 12, 2012.
Order EA-13-109, ``Order Modifying Licenses with Regard to         ML13130A067
 Reliable Hardened Containment Vents Capable of Operation Under
 Severe Accident Conditions,'' June 6, 2013.
SRM-SECY-15-0065, ``Proposed Rulemaking: Mitigation of Beyond-     ML15239A767
 Design-Basis Events (RIN 3150-AJ49),'' August 27, 2015.
SRM-SECY-16-0142, ``Final Rule: Mitigation of Beyond-Design-Basis  ML19023A038
 Events (RIN 3150-AJ49),'' January 24, 2019.
Federal Register notice, ``Policy Statement on Severe Reactor      50 FR 32138
 Accidents Regarding Future Designs and Existing Plants,'' August
 8, 1985.
NUREG/CR-7155, ``State-of-the-Art Reactor Consequence Analyses     ML16133A461
 Project--Uncertainty Analysis of the Unmitigated Long-Term
 Station Blackout of the Peach Bottom Atomic Power Station,'' May
 2016.
NUREG-2206, ``Technical Basis for the Containment Protection and   ML18065A048
 Release Reduction Rulemaking for Boiling Water Reactors with
 Mark I and Mark II Containments,'' March 2018.
``Draft Regulatory Basis for Containment Protection and Release    ML15022A214
 Reduction for Mark I and Mark II Boiling Water Reactors (10 CFR
 Part 50),'' May 2015.
SRM-SECY-15-0085, ``Evaluation of the Containment Protection and   ML15231A471
 Release Reduction for Mark I and Mark II Boiling Water Reactors
 Rulemaking Activities (10 CFR Part 50) (RIN-3150-AJ26),'' August
 19, 2015.
SECY-00-0198, ``Status Report on Study of Risk-Informed Changes    ML003747725 (Package)
 to the Technical Requirements of 10 CFR PART 50 (Option 3) and
 Recommendations on Risk-Informed Changes to 10 CFR 50.44
 (Combustible Gas Control),'' September 14, 2000.
NUREG-0737, ``Clarification of TMI Action Plan Requirements,''     ML051400209
 November 1980.
Regulatory Guide 1.7, Revision 3, ``Control of Combustible Gas     ML070290080
 Concentrations in Containment,'' March 2007.
``Confirmatory Order Modifying Post-TMI Requirements Pertaining    ML021270103
 to Containment Hydrogen Monitors for Arkansas Nuclear One, Units
 1 and 2 (TAC NOS. MA1267 and 1268),'' September 28, 1998.
Federal Register notice, ``Notice of Availability of Model         68 FR 55416
 Application Concerning Technical Specification Improvement to
 Eliminate Hydrogen Recombiner Requirement and Relax the Hydrogen
 and Oxygen Monitor Requirements for Light Water Reactors Using
 the Consolidated Line Item Improvement Process,'' September 25,
 2003.
License amendment, ``Arkansas Nuclear One, Unit 1, License         ML042290464 (Package)
 Amendment 222 regarding Elimination of Requirements for Hydrogen
 Recombiners and Hydrogen Monitors,'' August 12, 2004.
Regulatory Guide 1.97, Revision 3, ``Instrumentation for Light-    ML003740282
 Water-Cooled Nuclear Power Plants to Assess Plant and Environs
 Conditions During and Following an Accident,'' May 1983.
----------------------------------------------------------------------------------------------------------------

IV. Conclusion

    For the reasons cited in this document, the NRC is denying PRM-50-
103. The petitioner did not present sufficient new information or 
arguments to warrant the requested requirements. The NRC continues to 
conclude that the current design and licensing requirements for the 
control of hydrogen for operating and new reactors provide adequate 
protection of public health and safety.

    Dated at Rockville, Maryland, this 15th day of September, 2020.

    For the Nuclear Regulatory Commission.
Annette L. Vietti-Cook,
Secretary of the Commission.
[FR Doc. 2020-20708 Filed 10-5-20; 8:45 am]
BILLING CODE 7590-01-P