ML23032A360

Issuance of Amendment Nos. 279 and 272 New Fuel Storage Vault and Spent Fuel Storage Pool Criticality Methodologies

ML23032A360
Person / Time
Site:	Dresden
Issue date:	03/22/2023
From:	Shilpa Arora Plant Licensing Branch III
To:	Rhoades D Constellation Energy Generation, Constellation Nuclear
Arora, S
References
EPID L-2022-LLA-0085
Download: ML23032A360 (19)

Text

March 22, 2023 Mr. David P. Rhoades Senior Vice President Constellation Energy Generation, LLC President and Chief Nuclear Officer Constellation Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3 - ISSUANCE OF AMENDMENT NOS. 279 AND 272 RE: NEW FUEL STORAGE VAULT AND SPENT FUEL STORAGE POOL CRITICALITY METHODOLOGIES (EPID L-2022-LLA-0085)

Dear Mr. Rhoades:

The U.S. Nuclear Regulatory Commission (the Commission) has issued the enclosed Amendment No. 279 to Renewed Facility Operating License No. DPR-19 and Amendment No. 272 to Renewed Facility Operating License No. DPR-25 for Dresden Nuclear Power Station, Units 2 and 3 (Dresden). The amendments consist of changes to the technical specifications (TSs) and Updated Final Safety Analysis Report in response to your application dated June 8, 2022 (Agencywide Documents Access and Management System (ADAMS)

Package Accession No. ML22159A309), as supplemented by your letter dated November 3, 2022 (ML22307A220).

Specifically, the amendment request is proposing a new criticality safety analysis (CSA) methodology for performing the criticality safety evaluation for legacy fuel types in addition to the Global Nuclear Fuel (GNF) fuel design GNF3 reload fuel in the spent fuel pool (SFP). The amendment initially proposed a change to the new fuel vault (NFV) CSA to utilize the GESTAR II methodology. An NRC staff audit of the GESTAR II CSA methodology revealed that there is not an NRC-approved GESTAR II CSA methodology. Subsequently, the licensee submitted a CSA for storing GNF3 fuel in the DNPS NFV.

D. Rhoades A copy of the safety evaluation is also enclosed. The Notice of Issuance will be included in the Commissions monthly Federal Register notice.

Sincerely,

/RA/

Surinder Arora, Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-237 and 50-249

Enclosures:

1. Amendment No. 279 to DPR-19

2. Amendment No. 272 to DPR-25

3. Safety Evaluation cc: Listserv

CONSTELLATION ENERGY GENERATION, LLC DOCKET NO. 50-237 DRESDEN NUCLEAR POWER STATION, UNIT 2 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 279 Renewed License No. DPR-19

1. The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A. The application for amendment by Constellation Energy Generation, LLC (the licensee) dated June 8, 2022, as supplemented by letter dated November 3, 2022, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act and the rules and regulations of the Commission; C. There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commissions regulations; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.

Enclosure 1

2. Accordingly, the license is amended (1) to authorize revision to the Updated Final Safety Analysis Report, as set forth in the application dated June 8, 2022, as supplemented by letter dated November 3, 2022, and (2) by changes to the Technical Specifications as indicated in the attachment to this license amendment. Paragraph 2.C.(2) of Renewed Facility Operating License No. DPR-19 is hereby amended to read as follows:

(2) Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 279, are hereby incorporated into this renewed operating license. The licensee shall operate the facility in accordance with the Technical Specifications.

3. This license amendment is effective as of the date of its issuance and shall be implemented within 60 days of the date of issuance. Implementation of the amendment shall also include revision of the Updated Final Safety Analysis Report as described in the licensees letters dated June 8, 2022 and November 3, 2022.

FOR THE NUCLEAR REGULATORY COMMISSION Digitally signed by Venkataiah Sreenivas Date: 2023.03.22 16:25:22 -04'00' V. Sreenivas, Acting Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Renewed Facility Operating License No. DPR-19 and Technical Specifications Date of Issuance: March 22, 2023

CONSTELLATION ENERGY GENERATION, LLC DOCKET NO. 50-249 DRESDEN NUCLEAR POWER STATION, UNIT 3 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 272 Renewed License No. DPR-25

1. The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A. The application for amendment by the Constellation Energy Generation, LLC (the licensee) dated June 8, 2022, as supplemented by letter dated November 3, 2022, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act and the rules and regulations of the Commission; C. There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commissions regulations; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.

Enclosure 2

2. Accordingly, the license is amended (1) to authorize revision to the Updated Final Safety Analysis Report, as set forth in the application dated June 8, 2022, as supplemented by letter dated November 3, 2022 and (2) by changes to the Technical Specifications as indicated in the attachment to this license amendment. Paragraph 3.B. of Renewed Facility Operating License No. DPR-30 is hereby amended to read as follows:

B. Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 272, are hereby incorporated into this renewed operating license. The licensee shall operate the facility in accordance with the Technical Specifications.

3. This license amendment is effective as of the date of its issuance and shall be implemented within 60 days of the date of issuance. Implementation of the amendment shall also include revision of the Updated Final Safety Analysis Report as described in the licensees letters dated June 8, 2022 and November 3, 2022.

FOR THE NUCLEAR REGULATORY COMMISSION Digitally signed by Venkataiah Sreenivas Date: 2023.03.22 16:26:00 -04'00' V. Sreenivas, Acting Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Renewed Facility Operating License No. DPR-25 and Technical Specifications Date of Issuance: March 22, 2023

ATTACHMENT TO LICENSE AMENDMENT NOS. 279 AND 272 RENEWED FACILITY OPERATING LICENSE NOS. DPR-19 AND DPR-25 DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3 DOCKET NOS. 50-237 AND 50-249 Replace the following pages of the Renewed Facility Operating Licenses and Appendix A, Technical Specifications, with the attached pages. The revised pages are identified by amendment number and contain marginal lines indicating the area of change.

Remove Insert License DPR-19 License DPR-19 Page 3 Page 3 License DPR-25 License DPR-25 Page 4 Page 4 TSs TSs 4.0-2 4.0-2

(2) Constellation Energy Generation, LLC, pursuant to the Act and 10 CFR Part 70, to receive, possess and use at any time special nuclear materials as reactor fuel, in accordance with the limitations for storage and amounts required for reactor operation, as described in the Updated Final Safety Analysis Report, as supplemented and amended; (3) Constellation Energy Generation, LLC, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess and use at any time any byproduct, source and special nuclear material as sealed neutron sources for reactor startup, sealed sources for reactor instrumentation and radiation monitoring equipment calibration, and as fission detectors in amounts as required; (4) Constellation Energy Generation, LLC, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; and (5) Constellation Energy Generation, LLC, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to possess, but not separate, such byproduct special nuclear materials as may be produced by the operation of the facility.

C. This renewed operating license shall be deemed to contain and is subject to the conditions specified in the Commissions regulations set forth in 10 CFR D. Chapter I; is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:

(1) Maximum Power Level The licensee is authorized to operate the facility at steady state reactor core power levels not in excess of 2957 megawatts thermal (100 percent rated power) in accordance with the conditions specified herein.

(2) Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 279, are hereby incorporated into this renewed operating license. The licensee shall operate the facility in accordance with the Technical Specifications.

(3) Operation in the coastdown mode is permitted to 40% power.

Renewed License No. DPR-19 Amendment No. 279

f. Surveillance Requirement 4.9.A.10 - Diesel Storage Tank Cleaning (Unit 3 and Unit 2/3 only)

Each of the above Surveillance Requirements shall be successfully demonstrated prior to entering into MODE 2 on the first plant startup following the fourteenth refueling outage (D3R14).

3. This renewed operating license shall be deemed to contain and is subject to the conditions specified in the following Commission regulations: 10 CFR Part 20, Section 30.34 of 10 CFR Part 30, Section 40.41 of 10 CFR Part 40, Sections 50.54 and 50.59 of 10 CFR Part 50, and Section 70.32 of 10 CFR Part 70; is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:

A. Maximum Power Level The licensee is authorized to operate the facility at steady state power levels not in excess of 2957 megawatts (thermal), except that the licensee shall not operate the facility at power levels in excess of five (5) megawatts (thermal), until satisfactory completion of modifications and final testing of the station output transformer, the auto-depressurization interlock, and the feedwater system, as described in the licensees telegrams; dated February 26, 1971, have been verified in writing by the Commission.

B. Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 272, are hereby incorporated into this renewed operating license. The licensee shall operate the facility in accordance with the Technical Specifications.

C. Reports The licensee shall make certain reports in accordance with the requirements of the Technical Specifications.

D. Records The licensee shall keep facility operating records in accordance with the requirements of the Technical Specifications.

E. Restrictions Operation in the coastdown mode is permitted to 40% power Renewed License No. DPR-25 Amendment No. 272

Design Features 4.0 4.0 DESIGN FEATURES (continued) 4.3 Fuel Storage 4.3.1 Criticality 4.3.1.1 The spent fuel storage racks are designed and shall be maintained with:

a. keff 0.95 if fully flooded with unborated water, which includes an allowance for uncertainties as described in Section 9.1.2 of the UFSAR; and

b. A nominal 6.30 inch center to center distance between fuel assemblies placed in the storage racks.

c. Fuel assemblies having a maximum kinf of 1.33 in the normal reactor core configuration at cold conditions.

4.3.2 Drainage The spent fuel storage pool is designed and shall be maintained to prevent inadvertent draining of the pool below elevation 589 ft 2.5 inches.

4.3.3 Capacity The spent fuel storage pool is designed and shall be maintained with a storage capacity limited to no more than 3537 fuel assemblies.

Dresden 2 and 3 4.0-2 Amendment No. 279/272

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 279 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-19 AND AMENDMENT NO. 272 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-25 CONSTELLATION ENERGY GENERATION, LLC DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3 DOCKET NOS. 50-237 AND 50-249

1.0 INTRODUCTION AND BACKGROUND

By letter to the U.S. Nuclear Regulatory Commission (NRC or Commission) dated June 8, 2022, (Agencywide Documents Access and Management System (ADAMS) Accession No. Package ML22159A309), Constellation Energy Generation, LLC (Constellation, or the licensee) submitted a request for amendments to Renewed Facility Operating License Nos. DPR-19 and DPR-25 for the Dresden Nuclear Power Station (DNPS), Units 2 and 3, respectively. On November 3, 2022, (ML22307A220), Constellation, supplemented its June 8, 2022, amendment request. Specifically, the amendment request is proposing a new criticality safety analysis (CSA) methodology for performing the criticality safety evaluation for legacy fuel types in addition to the Global Nuclear Fuel (GNF) fuel design GNF3 reload fuel in the spent fuel pool (SFP). The amendment initially proposed a change to the new fuel vault (NFV) CSA to utilize the GESTAR II methodology. An NRC staff audit of the GESTAR II CSA methodology revealed that there is not an NRC-approved GESTAR II CSA methodology. Subsequently, the licensee submitted a CSA for storing GNF3 fuel in the DNPS NFV.

2.0 REGULATORY EVALUATION

2.1 Regulatory Requirements DNPS, Units 2 and 3, were not licensed to the Title 10 of the Code of Federal Regulations (10 CFR), part 50, appendix A, General Design Criteria (GDC). The DNPS, Units 2 and 3, Updated Final Safety Analysis Report (UFSAR), section 3.1, Conformance with NRC General Design Criteria, provides an assessment against the 70 draft GDC published in 1967 and concluded that Dresden Station fully satisfies the intent of the criteria.

Enclosure 3

Draft GDC 66 Criterion, Prevention of fuel storage criticality is the one most similar to the final 10 CFR, part 50, GDC 62, Prevention of Criticality in Fuel Storage and Handling. Draft GDC 66 Criterion states Criticality in new and spent fuel storage shall be prevented by physical systems or processes. Such means as geometrically safe configurations shall be emphasized over procedural controls. For practical purposes this is essentially identical to GDC 62, which states, Criticality in the fuel storage and handling system shall be prevented by physical systems or processes, preferably by use of geometrically safe configurations.

Paragraph 50.68(a) of 10 CFR part 50 requires, Each holder of a construction permit or operating license for a nuclear power reactor issued under this part or a combined license for a nuclear power reactor issued under part 52 of this chapter, shall comply with either 10 CFR 70.24 of this chapter or the requirements in paragraph (b) of this section. The licensee has chosen to comply with paragraph 50.68(b) of 10 CFR part 50.

Paragraph 50.68(b)(2) of 10 CFR part 50 requires, The estimated ratio of neutron production to neutron absorption and leakage (k-effective) of the fresh fuel in the fresh fuel storage racks shall be calculated assuming the racks are loaded with fuel of the maximum fuel assembly reactivity and flooded with unborated water and must not exceed 0.95, at a 95 percent probability, 95 percent confidence level. This evaluation need not be performed if administrative controls and/or design features prevent such flooding or if fresh fuel storage racks are not used.

Paragraph 50.68(b)(3) of 10 CFR part 50 requires, If optimum moderation of fresh fuel in the fresh fuel storage racks occurs when the racks are assumed to be loaded with fuel of the maximum fuel assembly reactivity and filled with low-density hydrogenous fluid, the k-effective corresponding to this optimum moderation must not exceed 0.98, at a 95 percent probability, 95 percent confidence level. This evaluation need not be performed if administrative controls and/or design features prevent such moderation or if fresh fuel storage racks are not used.

Paragraph 50.68(b)(4) of 10 CFR part 50 requires, in part, If no credit for soluble boron is taken, the k-effective of the spent fuel storage racks loaded with fuel of the maximum fuel assembly reactivity must not exceed 0.95, at a 95 percent probability, 95 percent confidence level, if flooded with unborated water.

The DNPS SFP nuclear criticality safety (NCS) analysis does not contain soluble boron, so the 10 CFR 50.68(b)(4) requirements regarding soluble boron do not apply.

In addition, paragraph 50.36(c)(4) of 10 CFR part 50 requires, Design features to be included

[in the TSs] are those features of the facility such as materials of construction and geometric arrangements, which, if altered or modified, would have a significant effect on safety and are not covered in categories described in paragraphs (c) (1), (2), and (3) of this section.

2.2 Regulatory Guidance Regulatory Guide (RG) 1.240, Fresh and Spent Fuel Pool Criticality Analyses (ML20356A127) describes an approach that the NRC staff considers acceptable to demonstrate that NRC regulatory requirements are met for subcriticality of fuel assemblies stored in fresh fuel vaults and spent fuel pools at light-water reactor (LWR) power plants. It endorses, with clarifications and exceptions, the Nuclear Energy Institute (NEI) guidance document NEI 12-16, Guidance for Performing Criticality Analyses of Fuel Storage at Light-Water Reactor Power Plants, Revision 4, (ML19269E069). The licensee used NEI 12-16, Revision 4, in preparing its licensee amendment request (LAR).

2.3 Description of Proposed Technical Specification/License Changes The licensee does not have technical specifications (TSs) for its NFV. The licensees June 8, 2028, letter stated the licensee was changing the NFV CSA to utilize the GESTAR II methodology. In its November 3, 2022, letter, the licensee stated that a previously submitted CSA is applicable to storing GNF3 fuel in its NFV. The licensees June 8, 2022, letter states 10 CFR 50.68(b)(3) concerning optimum moderation in the NFV is not applicable to DNPS. The licensee also proposed a change to its TS 4.3.1.1.c to change the SFP storage criteria from a SFP k-infinity of 0.8895 to a maximum k-infinity of 1.33 in the normal reactor core configuration at cold condition (standard cold core geometry (SCCG) k-infinity). The June 8, 2022, letter contained a CSA supporting the requested TS change for TS 4.3.1.1.c.

3.0 TECHNICAL EVALUATION

There is no comprehensive NRC-approved generic methodology for performing NCS analyses for fuel storage and handling. The CSA analysis for storing GNF3 in the DNPS SFP is described in GNF NEDC-33938P, Dresden Nuclear Power Station Fuel Storage Criticality Safety Analysis, Revision 0, April 2022, Attachment 3/6 to the licensees June 8, 2022, letter, and supplemented by the November 3, 2022, letter. The CSA analysis for storing GNF3 in the DNPS NFV is described in GE Hitachi Nuclear Energy (GEH) 003N7421-P, Generic Criticality Safety Analysis of GE New Fuel Storage Racks for GNF3 Fuel, Revision 1, September 2022 (ML22278A150). GEH 003N7421-P, Revision 1, was submitted as Attachment 3/4 to the licensees October 5, 2022, letter supporting the LAR for Quad Cities Nuclear Power Station, Units 1 and 2 (ML22278A149), which is referenced in the licensees November 3, 2022, letter.

3.1 Code Versions and Applications The licensees submittal uses TGBLA06 for in core calculations and MCNP-05P for in-rack calculations. TGBLA06 is a lattice physics code that calculates the exposure dependent pin-by-pin isotopic specifications used in developing the design basis lattice for the SFP CSA, but also has application to many other GEH/GNF analysis methods. Letter MFN-035-99, S. Richards (NRC) to G. Watford (GE), Amendment 26 to GE licensing Topical Report NEDE-24011-P-A, GESTAR II - Implementing Improved GE Steady State Methods (TAC No. MA6481), dated November 10, 1999 (ML993230184) documents the NRCs original acceptance of TGBLA06

and its associated application methodology. NRC letter dated March 21, 2019, Final Safety Evaluation for NEDC-33173P Supplement 5 - Applicability of GE Methods To Expanded Operating Domains - Supplement for GNF3 Fuel (EPID: L-2017-TOP-0033) (ML19064A229) documents the NRCs acceptance of using TBGLA06 to model GNF3 fuel. NRC letter dated September 25, 1999, Final Safety Evaluation for Proposed Administrative Amendment 49 to NEDE-24011-P-A-27, GENERAL ELECTRIC STANDARD APPLICATION FOR REACTOR FUEL (GESTAR II) (EPID L-2018-TOP-0039) (ML19267A051) documents the NRCs acceptance of adding NEDC-33173P Supplement 5 to GESTAR II. Based on the prior NRC review and approval of TGBLA06 for depletion and reactivity calculations, the NRC staff found the use of this code for the purpose described in the analysis reports to be acceptable.

The MCNP, Monte Carlo N-Particle, code can be used for general-purpose transport of many particles including neutrons, photons, electrons, ions, and many other elementary particles.

MCNP is developed, maintained, and distributed by the Los Alamos National Laboratory.

MCNP-05P, is the GEH/GNF proprietary version of MCNP5. MCNP-05P is a Monte Carlo program for solving the linear neutron transport equation for a fixed source or an eigenvalue problem. The code implements the Monte Carlo process for neutron, photon, electron, or coupled transport involving all these particles, and computes the eigenvalue for neutron-multiplying systems. For the DNPS NFV and SFP CSAs only neutron transport is considered.

Based on the generally accepted use of MCNP for neutron transport calculations, as discussed in letter from M. OBanion (U. S. NRC) to Entergy Operations, Inc., River Bend Station, Unit 1 -

Issuance of Amendment No. 201 RE: Change to the Neutron Absorbing Material Credited in Spent Fuel Pool for Criticality Control (EPID L-2018-LLA-0298), dated December 31, 2019 (ML19357A009), and the CSA specific validation described below, the NRC staff found this code to be acceptable for use in the CSAs.

3.2 Computer Code Validation The purpose of the computer code validation is to ensure that appropriate code bias and bias uncertainty are determined for use in the criticality calculation. The licensee followed NEI 12-16, Revision 4, guidance for determining the depletion uncertainty for TGBLA06. The licensee followed NUREG/CR-6698, Guide for Validation of Nuclear Criticality Safety Calculational Methodology (ML010170125) to validate and determine a code bias and bias uncertainty for MCNP-05P. Using NUREG/CR-6698 to validate the Monte Carlo code is consistent with NEI 12-16, Revision 4. Both are consistent with RG 1.240s endorsement of NEI 12-16, Revision 4, and, therefore, the NRC staff found the validation to be acceptable.

3.3 New Fuel Vault Regulation 10 CFR 50.68(b) has two paragraphs that specifically address storage of fuel in the new fuel vault. Both are accident driven as the NFV is dry/unmoderated. Paragraph 50.68(b)(2) addresses the scenario should the NFV become fully flooded. Paragraph 50.68(b)(3) addresses the scenario should the NFV be the subject of an optimum moderation condition. Typically, the source of the optimum moderation is thought to be firefighting water or aqueous foam from

firefighting efforts in the building holding the NFV. If the building housing the NFV is susceptible to environmental damage, that could be another source of moderating medium.

With respect to the fully flooded scenario, the licensee stated in its June 8, 2022, letter that the DNPS NFV CSA methodology was being changed to that in GESTAR II and cited references.

The LAR also stated there was a GNF3 GESTAR II [NFV CSA] validation report, again citing references. However, the cited references did not contain a NFV GESTAR II methodology or GNF3 GESTAR II NFV CSA validation report. To expedite the review, the NRC staff conducted a virtual audit of GESTAR IIs NFV criticality coverage. That audit was held from August 4, 2022, until September 2, 2022, (ML22300A253). The audit revealed that there is no NRC-approved GESTAR II NFV or SFP CSA methodology. The audit also revealed that there is a generic GNF3 NFV CSA covering storage of GNF3 in GE designed NFV racks, but that CSA previously hadnt been made available to the NRC staff. The licensee cited GEH 003N7421-P, Revision 1, as applicable to its NFV storage.

The CSA analysis for storing GNF3 in the DNPS NFV is described in GEH 003N7421-P, Revision 1, September 2022. The analysis is generic as it is based on demonstrating that GNF3 fuel with a maximum cold, uncontrolled peak in-core (otherwise known as SCCG) k-infinity of 1.31 will satisfy 10 CFR 50.68(b)(2) when stored in either of two GE Rack Types. So long as a particular licensee has one of the two GE Rack Types and meets the Cell Pitch listed in 003N7421-P, Table 1-1, New Fuel Vault Rack Dimensions, then the analysis would be representative of their NFV.

The NFV CSA is a fresh fuel analysis with the SCCG calculated using TGBLA06. As a fresh fuel analysis, core depletion impact is not a factor. With the fuel design set as GNF3, the SCCG is essentially set by a combination of Uranium-235 (U-235) enrichment and gadolinia loading. The fuel design identified by TGBLA06 is then modeled in the NFV storage racks with MCNP-05P to calculate the in-rack k-infinity. It is the in-rack k-infinity that is used to demonstrate compliance with paragraph 50.68(b)(2). The licensee checks each fuel assemblys peak lifetime reactivity against the SCCG k-infinity of 1.31. Therefore, establishing the relationship between the fuel assemblys maximum cold, uncontrolled peak in-core k-infinity and its in-rack k-infinity is required. 003N7421-P, Revision 1, establishes that relationship by calculating a rack efficiency for each fuel design.

Revision 1 of 003N7421-P calculated an in-rack k-infinity of 0.93919 at a 95 percent probability, 95 percent confidence level for a fresh GNF3 fuel assembly with a SCCG k-infinity of 1.31. This represents 0.01 k-effective of margin to the regulatory limit in paragraph 50.68(b)(2). The NRC staff considered this margin in its review to apply engineering judgement to the depth of the review on items unlikely to challenge the margin.

The NRC staff used RG 1.240, Fresh and Spent Fuel Pool Criticality Analyses, to review the analysis in 003N7421-P, Revision 1. RG 1.240 provides guidance for salient aspects of a NFV CSA such as: determining the reactivity effects of fuel assembly manufacturing tolerances and rack tolerances; evaluating potential biases such as fuel assembly eccentricity within the rack

storage cells; and selecting representative fuel assembly designs for the licensees total inventory. The information provided in 003N7421-P, Revision 1, indicates these topics were treated in a manner consistent with the guidance. The margin in the analysis of 0.01 k-effective provided reasonable assurance the licensee will meet paragraph 50.68(b)(2).

With respect to the 10 CFR 50.68(b)(3) optimum moderation scenario, the licensee stated in its June 8, 2022, letter that the [t]he optimum moderation case is not applicable to the DNPS NFV as it is a moderation-controlled area, as stated in DNPS UFSAR, Section 9.1.1.3 (Reference 6.7). The optimum moderation scenario was determined to be out of scope for this LAR.

However, the NRC staff notes that even if a licensee has administrative controls and/or design features [to] prevent such moderation 10 CFR 50.68(b)(3) will still apply. However, the method of compliance changes from an analysis and operation in accordance with that analysis that demonstrates sufficient sub-critical margin to maintenance of the administrative controls and/or design features and operation within those.

The 003N7421-P contains analyses for a fully flooded and optimum moderated NFV. As noted, the optimum moderated scenario was considered out of scope for this LAR. Therefore, the NRC staff did not review that portion of 003N7421-P and makes no determination regarding the optimum moderation scenario. As discussed above, the NRC staff found the CSA for the fully flooded NFV to be acceptable to demonstrate compliance with the applicable 10 CFR 50.68(b)(2) regulations based on consistency with NRC regulatory guidance and a technically justified approach.

3.4 Spent Fuel Pool Regulation 10 CFR 50.68(b) has one paragraph that specifically addresses storage of fuel in the SFP. Paragraph 50.68(b)(4) of 10 CFR, part 50, requires, in pertinent part, If no credit for soluble boron is taken, the k-effective of the spent fuel storage racks loaded with fuel of the maximum fuel assembly reactivity must not exceed 0.95, at a 95-percent probability, 95-percent confidence level, if flooded with unborated water. The DNPS SFP NCS analysis does not contain soluble boron, so the 10 CFR 50.68(b)(4) requirements regarding soluble boron do not apply. There is no optimum moderation paragraph for SFPs since TS 4.3.2, Drainage, ensures a minimum water level in the SFP providing reasonable assurance an optimum moderation will not occur.

The CSA analysis for storing GNF3 in the DNPS SFP is described in GNF NEDC-33938P, Dresden Nuclear Power Station Fuel Storage Criticality Safety Analysis, Revision 0, April 2022, Attachment 3/6 to the licensees June 8, 2022, letter, as supplemented by the November 3, 2022, letter. The analysis is specific to the DNPS SFP demonstrating that GNF3 fuel with a maximum cold, uncontrolled peak in-core (SCCG) k-infinity of 1.33 will satisfy 10 CFR 50.68(b)(4). The analysis includes consideration for DNPS legacy fuel, stating the legacy fuel is bounded by the analysis in NEDC-33938P, Revision 0.

The SFP CSA is an irradiated fuel analysis with the SCCG calculated using TGBLA06. As an irradiated fuel analysis, the core depletion impact is a significant factor. In addition to the fuel design, U-235 enrichment, and gadolinia loading, the reactor operating conditions while the fuel is being used will impact its reactivity. The fuel design with a specified U-235 enrichment and gadolinia loading is modeled by TGBLA06 over a range of reactor operating parameters. The irradiated fuel assembly is then modeled with MCNP-05P to calculate the in-rack k-infinity. This can be an iterative process until the licensee finds a solution that meets the regulatory requirement and any other needs it might have. Only the final set of analyses is provided in the LAR.

Similar to the NFV analyses, the SFP in-rack k-infinity is used to demonstrate compliance with 10 CFR 50.68(b)(4). The licensee checks each fuel assemblys peak lifetime reactivity against the SCCG k-infinity of 1.33. Therefore, establishing the relationship between the fuel assemblys maximum cold, uncontrolled peak in-core k-infinity and its in-rack k-infinity is required.

NEDC-33938P, Revision 0, establishes that relationship by calculating a rack efficiency for each fuel design.

NEDC-33938P, Revision 0, calculated an in-rack k-infinity of 0.93410, for DNPS, Units 2 and 3, at a 95 percent probability, 95 percent confidence level for an irradiated GNF3 fuel assembly with a SCCG k-infinity of 1.33. This represents 0.0159 k-effective of margin to the regulatory limit in 10 CFR 50.68(b)(4). The NRC staff considered this margin in its review to apply engineering judgment to the depth of the review on items unlikely to challenge the margin.

The NRC staff used RG 1.240, Fresh and Spent Fuel Pool Criticality Analyses, to review the analysis in NEDC-33938P, Revision 0. RG 1.240 provides guidance for salient aspects of a SFP CSA such as: modeling depletion parameters and uncertainty; determining the reactivity effects of fuel assembly manufacturing tolerances and rack tolerances; evaluating potential biases such as fuel assembly eccentricity within the rack storage cells; and selecting representative fuel assembly designs for the licensees total inventory. Several of the general steps are the same between an unirradiated and irradiated CSA, but the irradiated CSA is typically more detailed due to additional complexity of the fuels depletion in the reactor during operation. The information provided in NEDC-33938P, Revision 0, indicates these topics were treated in a manner consistent with the guidance. The margin in the analysis of 0.0159 k-effective provided reasonable assurance that the licensee will continue to meet paragraph 50.68(b)(4).

The proposed TS 4.3.1.1.c reflects the above SFP analysis that the NRC staff has determined provides reasonable assurance that 10 CFR 50.68(b)(4) will be met. The textual change of the SFP keff limit to a maximum SCCG k-infinity limit is therefore acceptable. Since the SFP keff limit is not included elsewhere in the licensees license, it is appropriate to be in the TS Design Features in accordance with 10 CFR 50.36(c)(4) as a feature of the facility that if altered or modified, would have a significant effect on safety and is not covered by a TS under 10 CFR 50.36(c)(1), (2), or (3).

3.5 Technical Evaluation Conclusion

The licensee has provided reasonable assurance that a GNF3 fuel assembly with a peak SCCG of 1.31 k-infinity will comply with 10 CFR 50.68(b)(2).

The licensee has provided reasonable assurance that a GNF3 fuel assembly with a peak SCCG of 1.33 k-infinity will comply with 10 CFR 50.68(b)(4).

Compliance with 10 CFR 50.68(b)(2) and 10 CFR 50.68(b)(4) also ensures conformance with Draft GDC Criterion 66.

The licensees proposed change to TS 4.3.1.1.c complies with 10 CFR 50.36(c)(4).

The difference in the two peak SCCG k-infinity numbers means that fuel that is acceptable for storage in the SFP is not acceptable for storage in the NFV unless it also meets the peak SCCG of 1.31 k-infinity for the NFV.

4.0 STATE CONSULTATION

In accordance with the Commissions regulations on, the Illinois State official was notified of the proposed issuance of the amendment on January 23, 2023. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendments change the requirements with respect to installation or use of a facilitys components located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration on October 4, 2022 (87 FR 60224), and there has been no public comment on such finding. Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

6.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor: Kent Wood, NRR Date of Issuance: March 22, 2023

ML23032A360 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DSS/STSB/BC NRR/DSS/SFNB/BC NAME SArora SRohrer VCusumano SKrepel DATE 1/30/2023 2/2/2023 2/8/2023 1/18/2023 OFFIC OGC NRR/DORL/LPL3/BC NRR/DORL/LPL3/PM NAME MASpencer VSreenivas SArora DATE 3/20/2023 3/21/2023 3/22/2023