[Federal Register Volume 84, Number 223 (Tuesday, November 19, 2019)]
[Proposed Rules]
[Pages 63816-63819]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-25018]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
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  Federal Register / Vol. 84, No. 223 / Tuesday, November 19, 2019 / 
Proposed Rules  

[[Page 63816]]



NUCLEAR REGULATORY COMMISSION

10 CFR Part 50

[Docket No. PRM-50-111; NRC-2015-0124]


Power Reactor In-Core Monitoring

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 March 13, 2015, submitted by Mark 
Edward Leyse (petitioner). The petition was docketed by the NRC on 
April 24, 2015, and assigned Docket No. PRM-50-111. The petitioner 
requested that the NRC require all holders of operating licenses for 
nuclear power plants to operate them with in-core temperature-
monitoring devices (e.g., thermoacoustic sensors or thermocouples) 
located at different elevations and radial positions throughout the 
reactor core. The NRC is denying the petition because current 
regulations provide a sufficient level of safety, such that additional 
requirements for in-core temperature-monitoring devices as specified in 
the petition are not needed.

DATES: The docket for the petition for rulemaking, PRM-50-111, is 
closed on November 19, 2019.

ADDRESSES: Please refer to Docket ID NRC-2015-0124 when contacting the 
NRC about this petition. You may obtain publicly-available information 
related to this action by any of the following methods:
     Federal Rulemaking Website: Go to https://www.regulations.gov and search for Docket ID NRC-2015-0124. Address 
questions about NRC dockets to Carol Gallagher; telephone: 301-415-
3463; 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, 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 III, ``Availability of Documents,'' of this 
document.
     NRC's PDR: You may examine and purchase copies of public 
documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555 
Rockville Pike, Rockville, Maryland 20852.

FOR FURTHER INFORMATION CONTACT: James O'Driscoll, Office of Nuclear 
Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, 
Washington, DC 20555-0001; telephone: 301-415-1325; email: 
James.O'[email protected].

SUPPLEMENTARY INFORMATION:

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 
dated March 13, 2015, from Mark Edward Leyse and assigned it Docket No. 
PRM-50-111. The NRC published a notice of docketing in the Federal 
Register on July 16, 2015 (80 FR 42067). The NRC did not request public 
comment on PRM-50-111 because the staff had sufficient information to 
review the issues raised in the petition.
    The NRC identified three issues that provide the bases for the 
request in PRM-50-111:
    1. Measurement of the temperatures at various locations within the 
reactor core would enable nuclear power plant operators to better 
understand the condition of the core under normal and transient 
conditions and to more clearly foresee incipient or impending damage to 
the reactor core.
    2. The use of in-core temperature-monitoring devices is needed in 
boiling-water reactors.
    3. The use of in-core temperature-monitoring devices would satisfy 
recommendations regarding enhanced reactor instrumentation made in the 
near-term task force report, ``Recommendations for Enhancing Reactor 
Safety in the 21st Century: The Near-Term Task Force Review of Insights 
from the Fukushima Dai-ichi Accident,'' dated July 12, 2011 (ADAMS 
Accession No. ML111861807).
    The petitioner requested that the NRC amend its regulations at 10 
CFR part 50, ``Domestic Licensing of Production and Utilization 
Facilities,'' to require all holders of operating licenses for nuclear 
power plants to operate them with in-core temperature-monitoring 
devices (e.g., thermoacoustic sensors or thermocouples) located at 
different elevations and radial positions throughout the reactor core. 
The petitioner stated that the use of the devices would enable nuclear 
power plant operators to accurately measure in-core temperatures, 
thereby providing crucial information to help them track the 
progression of core damage and manage an accident (e.g., by indicating 
the correct time to transition from emergency operating procedures to 
implementing severe accident management guidelines).
    The petitioner stated that installing in-core temperature-
monitoring devices would satisfy the recommendations in the near-term 
task force report, ``Recommendations for Enhancing Reactor Safety in 
the 21st Century,'' dated July 12, 2011, regarding enhanced reactor 
instrumentation. Specifically, the petitioner referenced the following 
from the report:
    [A] new and dedicated portion of the regulations would allow the 
Commission to recharacterize its expectations for safety features 
beyond design basis more clearly and more positively as `extended 
design-basis' requirements.
    The petitioner asserted that a new regulation is needed, requiring 
that a wide range of in-core temperatures be accurately measured in the 
event of a severe accident.

II. Reasons for Denial

    As discussed in this document, the NRC is denying PRM-50-111 
because the petitioner does not demonstrate the need for a regulation 
that requires the use of in-core temperature-monitoring devices in 
nuclear power plants. The

[[Page 63817]]

NRC addressed a substantial portion of the request in this petition in 
its response to a previous petition. PRM-50-105 was submitted on 
February 28, 2012, and the NRC published a notice of receipt and 
request for comment in the Federal Register on May 23, 2012 (77 FR 
30435). In PRM-50-105, the petitioner requested that the NRC require 
all holders of operating licenses for nuclear power plants to have in-
core thermocouples at different elevations and radial positions 
throughout the reactor core to enable the operators to accurately 
measure a large range of in-core temperatures in nuclear power plant 
steady-state and transient conditions. The NRC limited the scope of the 
review of PRM-50-105 to only the use of in-core thermocouples in 
pressurized-water reactors because that was the primary focus of that 
petition, although the petitioner also mentioned boiling-water 
reactors. The NRC denied PRM-50-105 on September 12, 2013 (78 FR 
56174).

NRC's Response to Issue 1

    In its denial of PRM-50-105, the NRC evaluated the petitioner's 
claims that, in the event of a severe accident, in-core thermocouples 
would enable nuclear power plant operators to accurately measure in-
core temperatures better than core exit thermocouples, and would 
provide crucial information to help operators manage the accident. In 
PRM-50-111, the petitioner reiterated the same assertions and updated 
the previous request by including other instrument types that might be 
used in the measurement of in-core temperatures (e.g., thermoacoustic 
sensors).
    The NRC denied PRM-50-105 because the NRC concluded that knowledge 
of core temperatures at various elevations and radial positions would 
not enhance safety or change operator action. Core-exit thermocouples, 
despite known limitations, are sufficient to allow nuclear power plant 
operators to take timely and effective action in the event of an 
accident. In pressurized-water reactors, they provide an indication of 
initial core damage during accident conditions and provide the 
necessary indication to make operational decisions with respect to the 
approach to imminent core damage.
    The current suite of instrumentation used in pressurized-water 
reactors, which includes core-exit thermocouples, provides sufficient 
information to determine the need for operator action well before the 
onset of significant core damage. Other indications include reactor 
coolant system level and containment pressure. A more comprehensive 
description of the applications of core-exit thermocouples is provided 
in NRC's denial of PRM-50-105, Issue 1. In its denial of PRM-50-105, 
the NRC concluded that there is no need for more accurate measurement 
of temperatures throughout the core in pressurized-water reactors. The 
NRC concludes that the reasons for that decision remain valid and are 
applicable to PRM-50-111.
    In PRM-50-111, the petitioner discussed core temperature 
measurement devices other than thermocouples. The NRC evaluated this 
information and concludes that the nature of the device is not relevant 
to the decision of whether or not to require the use of in-core 
temperature instrumentation.
    As in the denial of PRM-50-105, the NRC has determined that precise 
in-core temperatures would not provide information that would enable 
nuclear power plant operators to better respond to and manage a reactor 
accident.
    The NRC therefore concludes that more accurate and precise 
temperature distribution information within the reactor core that would 
be provided by such instrumentation is not necessary to provide 
adequate protection to the health and safety of the public or nuclear 
power plant staff, nor would it provide a substantial safety 
enhancement at nuclear power plants. Therefore, installation of such 
instrumentation need not be required by regulation.

NRC's Response to Issue 2

    The petitioner asserted that in the event of a severe accident at a 
boiling-water reactor, in-core temperature-monitoring devices would be 
more accurate and immediate for detecting inadequate core cooling and 
core uncovery than readings of the reactor water level, reactor 
pressure, containment pressure, or wetwell water temperature. The 
petitioner also asserted that, after the onset of core damage, water 
level indicators in boiling-water reactors are unreliable.
    The NRC determined that the current means to detect and respond to 
inadequate core cooling is already anticipatory in nature, and 
emergency operator actions would be no different if in-core 
temperature-monitoring devices were present. Therefore, no safety 
benefit would result from the availability of such devices.
    Existing boiling-water reactor emergency operating procedures 
(EOPs) do not require operator assessment of core cooling. Instead, 
operators use specific parametric data, such as the water level, 
containment pressure, containment radiation, and reactor pressure, in 
conjunction with the EOP actions to respond to the event. Under 
accident conditions, reactor vessel water level is an acceptable 
indication of conditions relating to imminent core damage, and drywell 
radiation monitors are typically the primary method for determining the 
presence of core damage and severe accident management guideline entry 
conditions. For boiling-water reactors, severe accident management 
guideline entry conditions are also tied to parameters such as water 
level, containment hydrogen concentration, and component failures. If 
reactor water level is unknown or conditions render water level 
instrumentation unreliable, then the EOPs require the operators to 
proactively flood the reactor vessel. In addition, the EOPs for 
boiling-water reactors describe steam cooling as a method of cooling 
the core when there is insufficient water to cover the core, typically 
available when water level is at or above two-thirds of core height. 
This method allows additional time to restore reactor coolant injection 
and reduce the likelihood of emergency reactor depressurization, which 
would be necessary for the injection of low pressure sources.
    The intent of the NRC's regulations is to prevent or minimize 
significant core damage. The detection of inadequate core cooling and 
actual core uncovery is not necessary for managing emergency and 
accident scenarios. Nuclear power plant operators are directed by EOPs 
to take proactive emergency operating actions based on the indication 
of parameters that are anticipatory to actual inadequate core cooling 
conditions, while the instruments reading those parameters are still 
functioning within their acceptably-accurate performance ranges. If 
significant core damage were to occur, water level instrumentation and 
in-core temperature instrumentation (if installed) would no longer be 
relied upon for operator action.
    The NRC has determined that boiling-water reactor operators do not 
need in-core temperature-monitoring devices to safely navigate 
emergency and accident scenarios. Because the use of water level 
instrumentation is sufficient to inform operator actions prior to 
significant core damage, the NRC finds that the information 
representing the temperature within specific core locations would not 
provide an improvement in the prevention of an accident or the 
mitigation of the consequences of an accident. The NRC

[[Page 63818]]

has further determined that having the core temperature data would not 
provide any additional safety margins in managing post accident or 
severe accident conditions. Therefore, the NRC concludes that more 
accurate and precise temperature distribution within the reactor core 
that would be provided by such instrumentation is not necessary to 
provide adequate protection of the health and safety of the public or 
nuclear power plant staff, nor would it provide a substantial safety 
enhancement at nuclear power plants. Therefore, installation of such 
instrumentation need not be required by regulation.

NRC's Response to Issue 3

    The petitioner stated that in-core temperature-monitoring devices 
would satisfy the July 12, 2011, near-term task force report 
recommendations for enhanced reactor instrumentation. To support this 
claim, the petitioner cited Recommendation 8, in Section 4.2.5 of the 
report, which recommends strengthening and integrating onsite emergency 
response capabilities such as emergency operating procedures, severe 
accident management guidelines and extensive damage mitigation 
guidelines. The petitioner also cited Volume 10 of NUREG-1635, ``Review 
and Evaluation of the Nuclear Regulatory Commission Safety Research 
Program: A Report to the U.S. Nuclear Regulatory Commission,'' dated 
October 31, 2012. The petitioner quoted sections from pages 11 and 12 
of this report, in which the Advisory Committee on Reactor Safeguards 
stated that the NRC recognized the need for enhanced reactor 
instrumentation, that such instrumentation would help clarify the 
transition points of various onsite emergency response capabilities, 
and that the NRC was in the process of adding this to the 
implementation of the near-term task force report recommendations. The 
petitioner gave, as an example of a transition point, the point at 
which nuclear power plant operators should transition from EOPs to 
implementing severe accident management guidelines.
    The staff proposed plans to the Commission for resolving open near-
term task force recommendations in SECY-15-0137, ``Proposed Plans for 
Resolving Open Fukushima Tier 2 and 3 Recommendations,'' dated October 
29, 2015. In SECY-15-0137, the staff described how remaining open 
recommendations from the near-term task force report should be 
resolved. The staff specifically assessed the need for enhanced reactor 
instrumentation for beyond-design-basis conditions in Enclosure 5 of 
SECY-15-0137. The staff recommended that the Commission not pursue 
additional regulatory action beyond the current requirements, including 
those imposed by orders EA-12-049, ``Order Modifying Licenses with 
Regard to Requirements for Mitigation Strategies for Beyond-Design-
Basis External Events,'' and EA-12-051, ``Order Modifying Licenses with 
Regard to Reliable Spent Fuel Pool Instrumentation.'' In SRM-SECY-15-
0137, dated February 8, 2016, the Commission approved the staff's 
closure plan for these items. On January 24, 2019, in SRM-M190124A, the 
Commission directed agency staff to publish a final rule based on 
lessons learned from the March 2011 accident at Japan's Fukushima 
Daiichi plant; the final rule was published in the Federal Register on 
August 9, 2019 and became effective on September 9, 2019 (84 FR 39684). 
That final rule made generically applicable the requirements from 
orders EA-12-049 and EA-12-051, taking into account lessons learned in 
the implementation of the orders and feedback received from 
stakeholders.
    As discussed under Issues 1 and 2, the NRC evaluated the potential 
contribution that more accurate and precise temperature information 
would have on improving nuclear power plant safety for both boiling-
water reactor and pressurized-water reactor plants. The NRC has 
determined that the availability of such information would not improve 
operator actions to prevent or mitigate a reactor accident. The NRC 
finds that the Commission's conclusions in SRM-SECY-15-0137 apply to 
the instrumentation proposed by the petitioner. The NRC concludes that 
more accurate and precise temperature distribution information that 
would be provided by such instrumentation is not necessary to provide 
adequate protection to the health and safety of the public or nuclear 
power plant staff, nor would it provide a substantial safety 
enhancement at nuclear power plants. Therefore, installation of such 
instrumentation need not be required by regulation.

III. Availability of Documents

    The documents identified in the following table are available to 
interested persons as indicated. For more information on accessing 
ADAMS, see the ADDRESSES section of this document.

------------------------------------------------------------------------
                                                        ADAMS Accession
                                                          No./website/
               Date                     Document        Federal Register
                                                            citation
------------------------------------------------------------------------
Petition Documents:
    March 13, 2015...............  PRM-50-111--Petiti  ML15113B143.
                                    on for Rulemaking
                                    from Mark E.
                                    Leyse Regarding
                                    In-Core
                                    Temperature
                                    Monitoring at
                                    Nuclear Power
                                    Plants.
    July 16, 2015................  Federal Register    80 FR 42067.
                                    notice: Petition
                                    for Rulemaking,
                                    Notice of
                                    Docketing, Power
                                    Reactor In-Core
                                    Monitoring.
    February 28, 2012............  Petition for        ML12065A215.
                                    Rulemaking
                                    submitted Mark
                                    Edward Leyse, on
                                    PRM-50-105,
                                    Request NRC
                                    Require all
                                    Holders of
                                    Operating
                                    Licenses for
                                    Nuclear Power
                                    Plants to Operate
                                    with In-Core
                                    Thermocouples at
                                    Different
                                    Elevations and
                                    Radial Positions.
    May 23, 2012.................  Federal Register    77 FR 30435.
                                    notice: Petition
                                    for Rulemaking;
                                    Receipt and
                                    Request for
                                    Comment, In-core
                                    Thermocouples at
                                    Different
                                    Elevations and
                                    Radial Positions
                                    in Reactor Core.
    September 12, 2013...........  Federal Register    78 FR 56174.
                                    notice: Petition
                                    for rulemaking;
                                    Denial, In-core
                                    Thermocouples at
                                    Different
                                    Elevations and
                                    Radial Positions
                                    in Reactor Core.
Other Documents:
    October 30, 1979.............  The Need for        https://
                                    Change, the         tmi2kml.inl.gov/
                                    Legacy of TMI:      Documents/Common/
                                    Report of the       PresidentsCommis
                                    President's         sion,(MainReport
                                    Commission on the   )TheNeedForChang
                                    Accident at Three   e,The
                                    Mile Island.        LegacyofTMI-
                                                        2(1979-10-
                                                        30).pdf.

[[Page 63819]]

 
    July 12, 2011................  SECY-11-0093--Encl  ML111861807.
                                    osure: The Near
                                    Term Task Force
                                    Review of
                                    Insights from the
                                    Fukushima Dai-
                                    Ichi Accident.
    October 31, 2012.............  NUREG-1635, Volume  ML12311A417.
                                    10, ``Review and
                                    Evaluation of the
                                    Nuclear
                                    Regulatory
                                    Commission Safety
                                    Research Program:
                                    A Report to the
                                    U.S. Nuclear
                                    Regulatory
                                    Commission''.
    October 29, 2015.............  SECY-15-0137,       ML15254A006.
                                    ``Proposed Plan
                                    for Resolving
                                    Open Fukushima
                                    Tier 2 and 3
                                    Recommendations''.
    March 12, 2012...............  EA-12-049 ``Order   ML12054A735.
                                    Modifying
                                    Licenses with
                                    Regard to
                                    Requirements for
                                    Mitigation
                                    Strategies for
                                    Beyond-Design-
                                    Basis External
                                    Events''.
    March 12, 2012...............  EA-12-051, ``Order  ML12056A044.
                                    Modifying
                                    Licenses with
                                    Regard to
                                    Reliable Spent
                                    Fuel Pool
                                    Instrumentation''.
    February 8, 2016.............  SRM-SECY-15-0137--  ML16039A175.
                                    Proposed Plans
                                    for Resolving
                                    Open Fukushima
                                    Tier 2 and 3
                                    Recommendations.
    January 24, 2019.............  SRM-M190124A:       ML19024A073.
                                    Affirmation
                                    Session-SECY-16-
                                    0142: Final Rule:
                                    Mitigation of
                                    Beyond-Design-
                                    Basis Events (RIN
                                    3150-AJ49).
------------------------------------------------------------------------

IV. Conclusion

    For the reasons cited in Section II of this document, the NRC is 
denying PRM-50-111. The NRC finds that the existing regulations provide 
a sufficient level of safety such that additional requirements are not 
necessary. Therefore, installation of in-core temperature monitoring 
devices need not be required by regulation.

    Dated at Rockville, Maryland, this 14th day of November, 2019.

    For the Nuclear Regulatory Commission.
Annette L. Vietti-Cook,
Secretary of the Commission.
[FR Doc. 2019-25018 Filed 11-18-19; 8:45 am]
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