ML23115A241

NRR E-mail Capture - Preliminary RAIs Related to L-2022-LLA-0131 - Byron, Unit 2, Reinsertion of an Accident Tolerant Fuel Lead Test Assembly

ML23115A241
Person / Time
Site:	Byron
Issue date:	01/20/2023
From:	Joel Wiebe NRC/NRR/DORL/LPL3
To:	Steinman R Exelon Generation Co
References
L-2022-LLA-0131
Download: ML23115A241 (4)

Text

From: Joel Wiebe Sent: Friday, January 20, 2023 3:00 PM To: Rebecca.Steinman@constellation.com

Subject:

Preliminary RAIs Related to L-2022-LLA-0131 - Byron, Unit 2, Reinsertion of an Accident Tolerant Fuel Lead Test Assembly

Hi Rebecca,

Here are the preliminary RAIs for the subject amendment request. The RAIs are identified as preliminary to allow Constellation to review for proprietary information and to ensure that the RAIs are clear and understandable. No other RAIs are expected at this point. We request a clarification call to be held about a week from the date of this email to verify understanding of the RAIs.

Joel

REQUEST FOR ADDITIONAL INFORMATION RELATED TO CHANGES TO TECHNICAL SPECIFICATIONS 2.1.1 AND 4.2.1 TO ALLOW A PREVIOUSLY IRRADIATED ATF LTA TO BE FURTHER IRRADIATED AT BYRON STATION, UNIT 2, DURING CYCLE 25 DOCKET NO. 50-455 EPID: L-2022-LLA-0131

INTRODUCTION

By letter dated August 31, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22242A094), Constellation Energy Generation, LLC, (CEG, the licensee) submitted a license amendment request (LAR) to request revisions to Technical Specification 2.1.1, "Reactor Core SLs," and 4.2.1, "Fuel Assemblies," to allow a previously irradiated Accident Tolerant Fuel (ATF) Lead Test Assembly (LTA) to be further irradiated during Byron Station Unit 2, Cycle 25. Byron Station plans to reinsert a previously irradiated LTA containing test rods with Westinghouse ADOPTTM fuel pellets and chromium-coated cladding in Unit 2 during the Fall 2023 refueling outage. The subject LTA would remain in the Unit 2 core for one additional cycle, i.e., Cycle 25; and will then be discharged during the Spring 2025 refueling outage.

After reviewing the LAR (Reference 1), the NRC staff has developed the following requests for additional information (RAIs).

REGULATORY BASES AND RAIs

SNSB RAI 1:

REGULATORY BASIS:

10 CFR 50.67 which establishes radiation dose limits for individuals at the boundary of the exclusion area and at the outer boundary of the low population zone.

RAI:

In section 3.4 of attachment 6 to the LAR, the licensee indicates that, for the Condition III and IV accident analysis performed using the current approved methods for Cycle 25, fuel rods in the reinserted LTA are not predicted to fail. The licensee states that this was confirmed for the locked rotor and rod ejection analysis.

Please provide a discussion on the analysis methodology and the results from evaluations performed for the limiting case(s) to show that high burnup ATF LTA does not experience DNBR or exceed other applicable fuel integrity acceptance criteria during:

a) the locked rotor event &

b) the rod ejection event.

SNSB RAI 2:

REGULATORY BASIS:

10 CFR 50.46(b)(4), Coolable geometry, which states

Calculated changes in core geometry shall be such that the core remains amenable to cooling.

RAI:

In section 3.4 of attachment 6 to the LAR, the licensee states that the LTA will have a significant reduction of power and peaking factors relative to the core lead such that the LTA being reinserted for higher burnup does not pose any additional fuel dispersal risk. The licensee further states in section 4.1 of the attachment 6 to the LAR that no cladding rupture has been demonstrated for the LTA, which would preclude concerns associated with fuel dispersal under high burnup conditions. During an audit conducted over December 12-16, 2022, the licensee discussed further information supporting these statements in its LAR.

To demonstrate no cladding rupture and preclude any concerns associated with fuel dispersal, drawing as necessary upon materials discussed during the audit, please provide the following:

(a) A comparison of rod internal pressures at the proposed higher burnups for the ATF LTA to a comparable standard reload fuel assembly, along with brief discussion of the methodology behind the comparison.

(b) An evaluation of margin to rupture for the limiting LTA rod for the LOCA event along with an assessment of the effect of significant factors that would influence the margin to rupture at the proposed higher burnups for the LTA. Please consider the following specific questions in addressing the available margin:

i. A quantification of the margin to rupture for the analytical rod in the Full Spectrum LOCA analysis for Byron, Unit 2, that the licensee considers most representative of the LTA proposed for reinsertion during Cycle 25.

ii. A comparison of the limiting fuel rod for the LTA proposed for reinsertion to the most representative analytical rod in the Full Spectrum LOCA analysis with respect to the propensity to rupture. The NRC staff observes that there are multiple differences between these two rods that were not directly included in the analysis that could affect the propensity for rupture, including at least the following: (1) a difference in linear power density, (2) a burnup-driven difference in rod internal pressure, and (3) a burnup-driven difference in fuel stored energy. Please clarify the magnitude of the differences with respect to these factors, and any other key factors identified by the licensee, along with their expected net impact on the limiting cladding rupture margin for the LTA.

REFERENCES

Letter from Constellation Energy Generation, LLC, (CEG) to NRC, dated August 31, 2022, License Amendment Request for Changes to Technical Specification 2.1.1 and 4.2.1 To Reinsert an Accident Tolerant Fuel Lead Test Assembly at Byron Station Unit 2 (ADAMS Accession No. ML22242A094)

Hearing Identifier: NRR_DRMA Email Number: 2050

Mail Envelope Properties (MN2PR09MB49714D525B193C0B9E3B5DB58BC59)

Subject:

Preliminary RAIs Related to L-2022-LLA-0131 - Byron, Unit 2, Reinsertion of an Accident Tolerant Fuel Lead Test Assembly Sent Date: 1/20/2023 2:59:59 PM Received Date: 1/20/2023 2:59:00 PM From: Joel Wiebe

Created By: Joel.Wiebe@nrc.gov

Recipients:

"Rebecca.Steinman@constellation.com" <rebecca.steinman@constellation.com>

Tracking Status: None

Post Office: MN2PR09MB4971.namprd09.prod.outlook.com

Files Size Date & Time MESSAGE 5420 1/20/2023 2:59:00 PM

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