ML24112A002
| ML24112A002 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/21/2024 |
| From: | Richard Guzman NRC/NRR/DORL/LPL1 |
| To: | |
| References | |
| EPID L-2023-LLE-0013, NRC-2024-0102, 89 FR 46167;May 28, 2024 | |
| Download: ML24112A002 (14) | |
Text
[7590-01-P]
NUCLEAR REGULATORY COMMISSION
[Docket No. 50-423; NRC-2024-0102]
Dominion Energy Nuclear Connecticut, Inc.;
Millstone Power Station, Unit No. 3;
Exemption
AGENCY: Nuclear Regulatory Commission.
ACTION: Notice; issuance.
SUMMARY
- The U.S. Nuclear Regulatory Commission (NRC) has issued an exemption
in response to an exemption request from Dominion Energy Nuclear Connecticut, Inc.
(DENC, the licensee) submitted by letter dated May 2, 2023.
DATES: The exemption was issued on May 21, 2024.
ADDRESSES: Please refer to Docket ID NRC-2024-0102 when contacting the NRC
about the availability of information regar ding 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-2024-0102. Address questions about Docket IDs in
Regulations.gov to Stacy Schumann; telephone: 301-415-0624; email:
Stacy.Schumann@nrc.gov. For technical questions, contact the individual listed in the
For Further Information Contact section of this document.
- NRCs 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 NRCs Public Document Room (P DR) reference staff at 1-800-397-4209, at 301-415-4737, or by email to PDR.Resource@nrc.gov. 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. The request for the exemption was submitted by letter
dated May 2, 2023 (ADAMS Accession No. ML23123A279), as supplemented by letter
dated April 1, 2024 (ADAMS Accession No. ML24093A216).
- NRCs PDR: The PDR, where you may examine and order copies of publicly
available documents, is open by appointment. To make an appointment to visit the PDR,
please send an email to PDR.Resource@nrc.gov or call 1-800-397-4209 or 301-415-
4737, between 8 a.m. and 4 p.m. eastern time (ET), Monday through Friday, except
Federal holidays.
FOR FURTHER INFORMATION CONTACT: Richard Guzman, Office of Nuclear
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 20555-
0001, telephone: 301-415-1030; email: Richard.Guzman@nrc.gov.
SUPPLEMENTARY INFORMATION: The licensee is the holder of Renewed Facility
Operating License No. NPF-49, which authorizes operation of Millstone Power Station,
Unit No. 3 (Millstone 3), a pressurized-water reactor. The license provides, among other
things, that the facility is subject to all rules, regulations, and orders of the NRC now or
hereafter in effect. By letter dated May 2, 2023, as supplemented by letter dated April 1,
2024, DENC requested an exemption to section 50.46 of title 10 of the Code of Federal
Regulations (10 CFR), Acceptance criteria for emergency core cooling systems for light-
water nuclear power reactors, and 10 CFR part 50, appendix K, ECCS [Emergency
2 Core Cooling Systems] Evaluation Models, fo r Millstone 3. The text of the exemption is
attached.
Dated: May 21, 2024.
For the Nuclear Regulatory Commission.
/RA/
Richard V. Guzman, Senior Project Manager, Plant Licensing Branch 1, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation.
3 Attachment - Exemption.
NUCLEAR REGULATORY COMMISSION
Docket No. 50-423
Dominion Energy Nuclear Connecticut, Inc.,
Millstone Power Station, Unit No. 3
Exemption
I. Background.
Dominion Energy Nuclear Connecticut, Inc. (DENC, the licensee) is the holder of
Renewed Facility Operating License No. NPF-49, which authorizes operation of M illstone
Power Station, Unit No. 3 (Millstone 3), a pressurized-water reactor (PWR). The license
provides, among other things, that the facility is subject to all rules, regulations, and
orders of the U.S. Nuclear Regulatory Commission (NRC) now or hereafter in effect.
Millstone 3 shares the site with Millstone Power Station, Unit 1, a permanently
defueled boiling water reactor nuclear unit, and Millstone Power Station, Unit 2, a PWR.
The facility is located in Waterford, Connecticut, approximately 3.2 miles west southwest
of New London, Connecticut. This exemption applies to Millstone 3 only. The other units,
Units 1 and 2, are not covered by this exemption.
II. Request/Action.
By letter dated May 2, 2023 (Agencywide Documents Access and Management
System (ADAMS) Accession No. ML23123A279), as supplemented by letter dated
April 1, 2024 (ML24093A216), DENC, requested an exemption to title 10 of the Code of
4 Federal Regulations (10 CFR), part 50, section 50.46, Acceptance criteria for
emergency core cooling systems for light-water nuclear power reactors, and part 50,
Appendix K, ECCS [Emergency Core Cooling Systems] Evaluation Models, for
Millstone 3.
This exemption request relates solely to the specific types of cladding materials
for which 10 CFR 50.46 and 10 CFR part 50, Appendix K, are expressly applicable,
namely zircaloy and ZIRLO'. Since these regula tions specifically apply only to zircaloy
and ZIRLO', an exemption would be required to apply them to fuel clad with other
materials, in this case Framatome M5 TM. Therefore, the licensee has requested such an
exemption to support the introduction of Framatome GAIA fuel with the M5 TM cladding.
The proposed request would not exempt Millst one 3 from other requirements of 10 CFR
50.46 or 10 CFR part 50, appendix K, such as acceptance criteria, evaluation model
features and documentation, and reporting of changes or errors.
This exemption request is specific to the M5 TM cladding material exemption
request only. The technical analysis necessary to support the use of M5 TM cladding in
the Millstone 3 GAIA Small Break and Large Break Loss-of-Coolant Accident (SBLOCA
and RLBLOCA) evaluations under Framatome methods is documented in a separate
safety evaluation for the related license amendment request (ML24109A003).
III. Discussion.
Pursuant to 10 CFR 50.12, the licensee requested an exemption from the
requirements of 10 CFR 50.46, and appendix K to 10 CFR part 50. The proposed
exemption request would permit application of the requirements of 10 CFR 50.46 and
appendix K to 10 CFR part 50 to fuel assemblies containing fuel rods fabricated with
5 M5TM cladding material at Millstone 3.
The technical basis for the use of fuel clad with M5 TM in PWRs is documented in
Topical Report (TR) BAW-10227P-A, Revision 1, Evaluation of Advanced Cladding and
Structural Material (M5) in PWR Reactor Fuel, dated June 2003 (ADAMS Package No.
This TR describes Framatomes evaluation for the use of the M5 TM alloy in PWR fuel
assemblies as a replacement for Zircaloy-4. This TR discusses material properties of
M5TM, as well as its behavior under normal operation, anticipated transients, and
postulated accident conditions.
The regulation in 10 CFR 50.46(a)(1)(i) requires, in part, that each boiling or
pressurized light-water nuclear power reactor fueled with uranium oxide pellets within
cylindrical zircaloy or ZIRLOTM cladding must be provided with an ECCS that must be
designed so that its calculated cooling performance following postulated loss-of-coolant
accidents conforms to the criteria set forth in 10 CFR 50.46(b). Since 10 CFR 50.46
specifically refers to fuel with zircaloy or ZIRLO' cladding, the use of fuel with M5'
cladding requires an exemption from this section of the regulations.
Paragraph I.A.5, Metal - Water Reaction Rate, of appendix K to 10 CFR part 50
requires the Baker-Just equation be used in the ECCS evaluation model to determine
the rate of energy release, hydrogen generation, and cladding oxidation. The
requirement for using the Baker-Just equation in appendix K conformant loss-of-coolant
accident (LOCA) evaluation models presume use of zircaloy-or ZIRLO'-clad fuel rods.
Therefore, application of 10 CFR part 50, appendix K to cladding materials other than
zircaloy or ZIRLO' also requires an exemption. Pursuant to 10 CFR 50.12, the NRC
may, upon application by any interested person or upon its own initiative, grant
exemptions from the requirements of 10 CFR part 50 when: (1) the exemptions are
6 authorized by law, will not present an undue risk to the public health or safety, and are
consistent with the common defense and secu rity; and (2) when special circumstances
are present. Under 10 CFR 50.12(a)(2)(ii), special circumstances include, among other
things, when application of the specific regulation in the particular circumstances would
not serve, or is not necessary to achieve, the underlying purpose of the rule.
A. The Exemption is Authorized by Law.
In accordance with 10 CFR 50.12, the NRC may grant an exemption from the
requirements of 10 CFR part 50 if the exempt ion is authorized by law. The exemption
requested in this instance is authorized by law, because no other prohibition of law
exists to preclude the activities which would be authorized by the exemption.
This exemption would allow the use of M5 TM cladding at Millstone 3 for GAIA
SBLOCA and RLBLOCA analyses performed using Framatome (FRM) methods, instead
of zircaloy or ZIRLOTM cladding. Selection of a specific cladding material in 10 CFR 50,
appendix K was at the discretion of the Commission consistent with its statutory
authority. No statute required the NRC to adopt this specification. As stated above, 10
CFR 50.12 allows the Commission to grant exemptions from the requirements of 10
CFR part 50. The NRC staff has determined that granting of an exemption from 10 CFR
part 50, appendix K related to M5TM cladding, which is neither Zircaloy nor ZIRLO, will
not result in a violation of the Atomic Energy Act of 1954, as amended, or the
Commission's regulations. Therefore, the exemption is authorized by law.
B. The Exemption Presents no Undue Risk to Public Health and Safety.
The 10 CFR 50.46 requirements establish acceptance criteria for ECCS
performance for reactors fueled with zircaloy or ZIRLO cladding during a LOCA. The
technical basis for the use of fuel clad with M5 TM in PWRs is documented in NRC-
7 approved TR BAW-10227P-A, Revision 1, Evaluation of Advanced Cladding and
Structural Material (M5) in PWR Reactor Fuel, dated June 2003 (ADAMS Package No.
ML15162B043). In this TR, Framatome demonstrated that the effectiveness of the
ECCS will not be affected by a change from zircaloy or ZIRLO fuel rod cladding to M5 TM
fuel rod cladding. The analysis described in the TR demonstrated that the ECCS
acceptance criteria applied to reactors fueled with zircaloy or ZIRLO clad fuel are also
applicable to reactors fueled with M5 TM fuel rod cladding.
Paragraph I.A.5 of appendix K to 10 CFR 50 requires that the Baker-Just
equation be used in the ECCS evaluation models to determine the rate of energy
release, cladding oxidation, and hydr ogen generation. In the NRC-approved TR BAW-
10227-P-A, Revision 1, Framatome demonstrated that the Baker-Just model is
conservative in the postulated LOCA scenarios with respect to the use of the M5 TM alloy
as a fuel rod cladding material. The Baker-Just equation is used to calculate cladding
oxidation for the SBLOCA methodologies in the NRC-approved TR EMF-2328-P-A,
Revision 0 (ML011410383) for fuel with M5 TM cladding. The SBLOCA analysis
(Attachments 3 and 4 in the licensees May 2, 2023, letter) using the methodologies in
TR EMF-2328-P-A, Revision 0 for Millstone 3 demonstrated that the amount of hydrogen
generated in an M5-clad core meets the 10 CFR 50.46 criteria.
The NRC staff has reviewed the SBLOCA and RLBLOCA analyses in
Attachments 3 through 6 in the licensees May 2, 2023, letter, and concluded in a safety
evaluation (ML24109A003) that the LOCA analyses meet the applicable acceptance
criteria, confirming that the use of M5 TM fuel cladding at Millstone 3 would not result in an
increase in the consequences of postulated LOCAs beyond the required limits. Based on
these reviews, the NRC staff concludes t hat the exemption presents no undue risk to
public health and safety.
8 C. The Exemption is Consistent with the Common Defense and Security.
The proposed exemption will allow the licensee to use M5 TM fuel rod cladding
material, an improved fuel rod cladding material relative to the zircaloy material for
which the requirements of 10 CFR 50.46 and 10 CFR Part 50, appendix K were
originally established. In its letter dated May 2, 2023, the licensee stated that the M5 TM
fuel rod cladding material is similar in design to the current cladding material used in
Millstone 3. The change in cladding material will not result in any changes to the
security aspects associated with control of special nuclear material and is unrelated to
other security issues. In addition to its re view of the exemption request, the NRC staffs
technical analysis necessary to support the use of M5 TM cladding in the Millstone 3
GAIA SBLOCA and RLBLOCA evaluations under Framatome methods is documented
in a separate safety evaluation for the related license amendment request
(ML24109A003). Based on these reviews, the NRC staff concludes that the use of
M5TM fuel rod cladding at Millstone 3 will not significantly affect plant operations and is
therefore consistent with the common defense and security.
D. Special Circumstances
Special circumstances, in accordance with 10 CFR 50.12(a)(2)(ii), are present
whenever application of the regulation in t he circumstances would not serve the purpose
of the rule or is not necessary to achieve the purpose of the rule.
The underlying purpose of 10 CFR 50.46 and appendix K to 10 CFR part 50 is to
establish acceptance criteria for ECCS performance to provide reasonable assurance of
safety in the event of a LOCA. Although the regulations in 10 CFR 50.46 and appendix K
to 10 CFR part 50 are not expressly applicable to M5 TM fuel rod cladding, the evaluations
9 described in the above section show that the purpose of the regulations are met by this
exemption; specifically, the NRC-approved t opical report (TR) BAW-10227-A, Revision 1
demonstrated that the effectiveness of the ECCS will not be affected by a change from
zircaloy or ZIRLO fuel rod cladding to M5 TM fuel rod cladding and that that the ECCS
acceptance criteria applied to reactors fueled with zircaloy or ZIRLO clad fuel are also
applicable to reactors fueled with M5 TM fuel rod cladding.
Paragraph I.A.5 of appendix K to 10 CFR 50 requires that the Baker-Just
equation be used in the ECCS EMs to determine the rate of energy release, cladding
oxidation, and hydrogen generation. The NRC-approved TR BAW-10227-P-A, Revision
1 demonstrated that the Baker-Just model is conservative in the postulated LOCA
scenarios with respect to the use of the M5 TM alloy as a fuel rod cladding material.
Neither 10 CFR 50.46 acceptance criteria nor the 10 CFR 50 appendix K
requirements for use of the Baker-Just equation in the ECCS EMs allows the use of
M5TM fuel rod cladding material, even though the analysis demonstrated that applying
the zircaloy or ZIRLO criteria to M5 TM fuel produces acceptable results. Application of the
regulatory requirements of 10 CFR 50.46 and 10 CFR 50 appendix K in this
circumstance is not necessary to achieve the purpose of the rule. The purpose of these
regulations is achieved through the application of the requirements to the use M5 TM fuel
rod cladding material. Therefore, the NRC staff determines that special circumstances
for granting of an exemption, defined in 10 CFR 50.12(a)(2)(ii), exist.
E. Environmental Considerations
With respect to its impact on the qualit y of the human environment, the NRC has
determined that the issuance of the exemption discussed herein meets the eligibility
criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9) because it is related to a
10 requirement concerning the installation or use of a facility component located within the
restricted area, as defined in 10 CFR Part 20, and issuance of this exemption involves:
(i) no significant hazards consideration; (ii) no significant change in the types or a
significant increase in the amounts of any effluents that may be released offsite; and (iii)
no significant increase in individual or cumulative occupational radiation exposure.
Therefore, in accordance with 10 CFR 51.22( b), no environmental impact statement or
environmental assessment need be prepared in connection with the NRCs
consideration of this exemption request. The basis for the NRC staffs determination is
discussed as follows with an evaluation against each of the requirements in 10 CFR
51.22(c)(9)(i) - (iii).
Requirements in 10 CFR 51.22(c)(9)(i)
The NRC evaluated whether the exemption involves no significant hazards
consideration using the standards described in 10 CFR 50.92(c), as presented below:
- 1. Does the proposed exemption involve a significant increase in the probability
or
consequences of an accident previously evaluated?
Response: No.
The proposed exemption would allow the use of M5 TM cladding at Millstone 3 for
GAIA SBLOCA and RLBLOCA analyses performed using FRM methods. The NRC
approved topical reports cited above demonstrate that M5 TM cladding has similar
properties as the currently licensed Zircaloy. The fuel cladding itself is not a postulated
initiator of previously evaluated accidents; thus, fuel cladding material does not affect the
probability of occurrence of any accident. The consequences of none of the previously
11 evaluated accidents were affected by fuel cladding material, and M5 TM fuel cladding,
likewise, is not expected to have any effe ct on the consequences of any previously
evaluated accidents.
Therefore, the proposed exemption does not involve a significant increase in the
probability or consequences of an accident previously evaluated.
- 2. Does the proposed exemption create the possibility of a new or different kind
of
accident from any accident previously evaluated?
Response: No.
The use of M5TM fuel rod cladding material will not result in changes in the
operation or configuration of the facility. The above cited topical reports demonstrated
that the material properties of M5TM cladding are similar to those of standard Zircaloy.
Therefore, M5TM fuel cladding material will perform similarly to those fabricated from
standard Zircaloy. The fuel cladding itself is not a postulated initiator of previously
evaluated accidents and does not create the possibility of a new or different kind of
accident.
Therefore, the proposed exemption does not create the possibility of a new or
different kind of accident from any previously evaluated.
- 3. Does the proposed exemption involve a significant reduction in a margin of
safety.
Response: No.
The proposed exemption will not involve a significant reduction in the margin of
safety because it has been demonstrated that the material properties of the M5 TM
12 cladding is not significantly different from those of the standard Zircaloy. M5 TM fuel
cladding material is expected to perform similarly to standard Zircaloy for all normal
operating and accident scenarios. Use of M5 TM cladding does not require changing any
of the current regulatory acceptance criteria, or relaxation of the methods of analysis.
Therefore, the proposed exemption does not involve a significant reduction in a
margin of safety.
Based on the above evaluation of the standards set forth in 10 CFR 50.92(c), the
NRC staff concludes that the proposed exem ption involves no significant hazards
consideration. Accordingly, the requirements of 10 CFR 51.22(c)(9)(i) are met.
Requirements in 10 CFR 51.22(c)(9)(ii)
The proposed exemption would allow the use of M5 TM cladding at Millstone 3 for
GAIA SBLOCA and RLBLOCA analyses performed using FRM methods. M5 TM cladding
has similar properties and performance characte ristics as the currently licensed Zircaloy
cladding. Thus, the use of M5 TM fuel cladding material will not significantly increase the
amount of effluents that may be released offsite. Therefore, the requirements of 10 CFR
51.22(c)(9)(ii) are met.
Requirements in 10 CFR 51.22(c)(9)(iii)
The proposed exemption would allow the use of M5 TM cladding at Millstone 3 for
GAIA SBLOCA and RLBLOCA analyses performed using FRM methods. M5 TM cladding
has similar properties and performance characte ristics as the currently licensed Zircaloy
cladding. Thus, the use of M5 TM fuel cladding material will not significantly increase
individual occupational radiation exposure, or significantly increase cumulative
occupational radiation exposure. Therefore, the requirements of 10 CFR 51.22(c)(9)(iii)
13 are met.
Based on the above, the NRC staff conc ludes that the proposed exemption
meets the eligibility criteria for the categoric al exclusion set forth in 10 CFR 51.22(c)(9).
Therefore, in accordance with 10 CFR 51.22( b), no environmental impact statement or
environmental assessment need be prepared in connection with the NRCs issuance of
this exemption.
IV. Conclusions.
Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12,
the exemption is authorized by law, will not present an undue risk to the public health
and safety, and is consistent with the common defense and security. Also, special
circumstances are present. Therefore, the Commission hereby grants DENC an
exemption from the requirements of 10 CFR 50.46 and 10 CFR part 50, appendix K. The
proposed exemption request would permit application of the requirements of 10 CFR
50.46 and appendix K to fuel rod cladding with M5 TM at Millstone 3. As stated above, this
exemption relates solely to the cladding material specified in these regulations.
Dated at Rockville, Maryland, this 21 st day of May, 2024
For the Nuclear Regulatory Commission.
/RA/
Jamie Pelton, Deputy Director, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation.
14