DCL-25-029, License Amendment Request 25-01: Application to Utilize Optimize ZIRLO for Improved Fuel Rod Cladding Performance

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License Amendment Request 25-01: Application to Utilize Optimize ZIRLO for Improved Fuel Rod Cladding Performance
ML25085A409
Person / Time
Site: Diablo Canyon  Pacific Gas & Electric icon.png
Issue date: 03/26/2025
From: Rogers J
Pacific Gas & Electric Co
To:
Office of Nuclear Reactor Regulation, Document Control Desk
References
DCL-25-029
Download: ML25085A409 (1)
v • d • e


Text

Justin E. Rogers Station Director Diablo Canyon Power Plant Mail code 104/5/502 P.O. Box 56 Avila Beach, CA 93424 805.545.3088 Justin.Rogers@pge.com A member of the STARS Alliance Callaway

  • Diablo Canyon
  • Palo Verde
  • Wolf Creek PG&E Letter DCL-25-029 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Diablo Canyon Units 1 and 2 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 License Amendment Request 25-01 Application to Utilize Optimized ZIRLOTM for Improved Fuel Rod Cladding Performance

References:

1. NRC letter to Westinghouse, Final Safety Evaluation for Addendum 1 to Topical Report WCAP-12610-P-A and CENPD-404-P-A, Optimized ZIRLOTM, dated June 10, 2005 (ML051670403).
2. Westinghouse letter to NRC, LTR-NRC-06-45, Issuance of Approved Version of WCAP-12610-P-A & CENPD-404-P-A, Addendum 1-A (Proprietary) Optimized ZIRLOTM, dated July 10, 2006 (ML062080563).
3. WCAP-14342-A & CENPD-404-NP-A, Addendum 1-A, Optimized ZIRLOTM, dated July 2006 (ML062080569).

Dear Commissioners and Staff:

Pursuant to 10 CFR 50.90, Pacific Gas and Electric Company (PG&E) hereby requests approval of the enclosed proposed amendment to modify the Diablo Canyon Power Plant (DCPP) Units 1 and 2 Technical Specifications (TS) 4.2.1, Fuel Assemblies, and TS 5.6.5 Core Operating Limits Report (COLR), to allow the use of Optimized ZIRLOTM1 as an approved fuel rod cladding material.

This license amendment request is part of an advanced fuel feature strategy to optimize DCPPs fuel design and achieve superior fuel reliability, operating margins, and best in class fuel cycle cost resulting in safe, successful, economic operations.

Optimized ZIRLOTM provides improved cladding performance consistent with safely maintaining DCPP generation and thereby supporting electrical grid reliability in 1ZIRLO and Optimized ZIRLOTM are trademarks or registered trademarks of Westinghouse Electric Company LLC.

m Pacific Gas and Electric Company*

Document Control Desk PG&E Letter DCL-25-029 Page 2 A member of the STARS Alliance Callaway

  • Diablo Canyon
  • Palo Verde
  • Wolf Creek California. This application is standard practice in the nuclear industry and would be being implemented consistent with industry standards. This change is consistent with the Nuclear Regulatory Commission (NRC) safety evaluation that approved the use of Optimized ZIRLO' fuel cladding material (Reference 1) as documented in the Reference 2 and Reference 3 Proprietary and Non-Proprietary documents, respectively.

In support of this License Amendment Request (LAR), Enclosure 2 contains a corresponding exemption request in accordance with 10 CFR 50.12, Specific exemptions, from certain requirements of 10 CFR 50.46, Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors. This exemption request relates solely to the specific type of cladding material specified in these regulations for use in light water reactors. As written, the regulations presume use of either Zircaloy or ZIRLO fuel rod cladding. The exemption is required because Optimized ZIRLO' has a slightly different composition than Zircaloy or ZIRLO.

provides a description and technical evaluation of the proposed change, a regulatory evaluation, and a discussion of environmental considerations. to Enclosure 1 provides the existing respective DCPP Unit 1 and Unit 2 TS pages marked up to show the proposed changes. Attachment 2 to provides the revised (clean) respective DCPP Unit 1 and Unit 2 TS pages.

PG&E concludes that the proposed change does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of no significant hazards consideration is justified.

PG&E requests approval of this LAR in accordance with the complexity of the submittal and established precedents from other Licensees. Approval is requested no later than March 18, 2026, to allow for sufficient time for purchase and delivery of the new Optimized ZIRLO' cladding, and fuel manufacturing lead times to support loading of Optimized ZIRLO' in support of the DCPP Unit 2 Spring 2027 outage.

Once approved, the amendment shall be implemented during the Spring 2027 Unit 2 Refueling Outage 26 (2R26) and the Spring 2028 Unit 1 Refueling Outage 27 (1R27).

PG&E makes no regulatory commitments (as defined by NEI 99-04) in this letter.

This letter includes no revisions to existing regulatory commitments.

In accordance with site administrative procedures and the Quality Assurance Program, the proposed amendment has been reviewed by the Plant Staff Review Committee.

Document Control Desk PG&E Letter DCL-25-029 Page 3 A member of the STARS Alliance Callaway

  • Diablo Canyon
  • Palo Verde

If you have any questions or require additional information, please contact Mr. James Morris, Manager, Regulatory Services, at 805-545-4609.

I state under penalty of perjury that the foregoing is true and correct.

Sincerely, Justin E. Rogers Station Director Date MJR/51274077 Enclosures cc:

Diablo Distribution cc/enc: Anthony Chu, Branch Chief, California Dept of Public Health Mahdi O. Hayes, NRC Senior Resident Inspector Samson S. Lee, NRR Project Manager John D. Monninger, NRC Region IV Deputy Administrator 3/26/2025 PG&E Letter DCL-25-029 1

Evaluation of the Proposed Change

Subject:

Application to Utilize Optimized ZIRLO' for Improved Fuel Rod Cladding Performance.

1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION 2.1 Reason for the Proposed Changes 2.2 Description of the Proposed Changes

3.0 TECHNICAL EVALUATION

3.1 Review of the Conditions in the NRC Safety Evaluation

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 4.1.1 Regulations and Regulatory Guidance 4.1.2 General Design Criteria 4.2 Precedent 4.3 Significant Hazards Consideration 4.4 Conclusions

5.0 ENVIRONMENTAL CONSIDERATION

6.0 REFERENCES

ATTACHMENTS:

1.

Proposed Technical Specification Changes (Markups) 2.

Revised Technical Specification Pages (Clean)

PG&E Letter DCL-25-029 2

EVALUATION 1.0

SUMMARY

DESCRIPTION Pursuant to 10 CFR 50.90, Pacific Gas and Electric Company (PG&E) is submitting a License Amendment Request (LAR) for a change to Facility Operating License Nos.

OL-DPR-80 and OL-DPR-82 for the Diablo Canyon Power Plant (DCPP) Units 1 and 2, respectively. Specifically, PG&E is requesting a license amendment to revise the DCPP Units 1 and 2 Technical Specification (TS) 4.2.1, Fuel Assemblies, to allow the use of Optimized ZIRLO' fuel rod cladding material.

The proposed LAR also revises DCPP Units 1 and 2 TS 5.6.5, Core Operating Limits Report (COLR), to add Westinghouse Electric Company LLC (Westinghouse) topical report WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A, Optimized ZIRLO',

(Reference 1) to the list of analytical methods used to determine the core operating limits approved by the Nuclear Regulatory Commission (NRC). Other editorial changes are to correct the spelling of the word Zircaloy and add a registered trademark designator to the word ZIRLO, all in TS 4.2.1 only. Editorial changes will also be proposed to remove the not-used references 6, 7, and 8 from the list of COLR references in TS 5.6.5.b.

In support of this LAR, Enclosure 2 contains a corresponding exemption request in accordance with 10 CFR 50.12, Specific exemptions, from certain requirements of 10 CFR 50.46, Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors. This exemption request relates solely to the specific type of cladding material specified in these regulations for use in light water reactors. As written, the regulations presume use of either Zircaloy or ZIRLO fuel rod cladding. The exemption is required because Optimized ZIRLO' has a slightly different composition than Zircaloy or ZIRLO.

PG&E currently plans to load Optimized ZIRLO' clad fuel rods during DCPP Unit 2 Refueling Outage Twenty-Six (2R26) and DCPP Unit 1 Refueling Outage Twenty-Seven (1R27), currently scheduled for Spring 2027 and Spring 2028, respectively.

PG&E Letter DCL-25-029 3

2.0 DETAILED DESCRIPTION 2.1 Reason for the Proposed Changes The proposed change allows loading of Optimized ZIRLO' fuel rod cladding material in support of the DCPP 2R26 (Unit 2) and 1R27 (Unit 1) refueling outages. Optimized ZIRLO' provides improved cladding performance.

2.2 Description of the Proposed Changes The following is a detailed description of the proposed DCPP Units 1 and 2 TS changes.

  • DCPP Units 1 and 2 TS 4.2.1, Fuel Assemblies, is revised to add Optimized ZIRLO', correct the spelling of the word Zircaloy, and add a registered trademark designator to the word ZIRLO as follows:

o The requirement that Each assembly shall consist of a matrix of Zircalloy or ZIRLO clad fuel rods with an initial composition of natural or slightly enriched uranium dioxide (UO2) as fuel material.

is revised to state, Each assembly shall consist of a matrix of Zircaloy, ZIRLO, or Optimized ZIRLO' clad fuel rods with an initial composition of natural or slightly enriched uranium dioxide (UO2) as fuel material.

is revised to delete TS 5.6.5.b references 6, 7, and 8 which are Not used, while moving current references 9, 10, and 11 to replace these references numbers.

Finally, the proposed change will add Westinghouse topical report WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A, Optimized ZIRLO' to the list of analytical methods in TS 5.6.5.b as follows:

o 9. WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A, Optimized ZIRLO'.

o Note that and is used rather than & in the title for reference 9 for readability.

  • An editorial change to add quotation marks to the titles of references 1 through 3 of TS 5.6.5.b is also included.

to this enclosure provides the existing respective DCPP Unit 1 and Unit 2 TS pages marked up to show the proposed changes. Attachment 2 to this enclosure provides the revised (clean) respective DCPP Unit 1 and Unit 2 TS pages.

PG&E Letter DCL-25-029 4

3.0 TECHNICAL EVALUATION

3.1 Review of the Conditions in the NRC Safety Evaluation Reference 1 of Enclosure 1 provides the details and test results of Optimized ZIRLO' compared to ZIRLO fuel rod cladding material. Reference 2 of Enclosure 1 is the non-proprietary version of Reference 1. Reference 1 also contains the material properties to be used in various models and methodologies when analyzing Optimized ZIRLO' fuel rod cladding. The NRC safety evaluation (SE) (Reference 3 of this Enclosure) for Reference 1 contains 10 conditions and limitations that are addressed below:

NRC Condition 1 Until rulemaking to 10 CFR Part 50 addressing Optimized ZIRLO' has been completed, implementation of Optimized ZIRLO' fuel clad requires an exemption from 10 CFR 50.46 and 10 CFR Part 50, Appendix K.

PG&E Response A request for the required exemption from 10 CFR 50.46 is provided in Enclosure 2.

It should be noted that the NRC Staff amended the requirements of 10 CFR 50.46 and Appendix K, ECCS Evaluation Models, in 1988 to permit the use of a realistic evaluation methodology (EM) to analyze the performance of the ECCS during a hypothetical loss-of-coolant accident (LOCA). Under the amended rules, best-estimate thermal-hydraulic models may be used in place of models with Appendix K features.

The use of these models in the DCPP Units 1 and 2 licensing basis was submitted by PG&E in References 18 and 19 and was approved by the NRC in Reference 20.

Therefore, the exemption from 10 CFR Part 50, Appendix K is not required for the proposed LAR.

NRC Condition 2 The fuel rod burnup limit for this approval remains at currently established limits: 62 gigawatt days per metric ton of uranium (GWd/MTU) for Westinghouse fuel designs and 60 GWd/MTU for Combustion Engineering (CE) fuel designs.

PG&E Letter DCL-25-029 5

PG&E Response For any fuel using Optimized ZIRLO' fuel rod cladding, the maximum fuel rod burnup limit for Westinghouse fuel designs will continue to be 62 GWd/MTU until such time that a new fuel rod burnup limit is approved for use. DCPP Units 1 and 2 use Westinghouse fuel designs. The fuel burnup limit will be confirmed as part of the normal reload design process.

NRC Condition 3 The maximum fuel rod waterside corrosion, as predicted by the best-estimate model, will [satisfy proprietary limits (included in the topical report and proprietary version of the NRC SE)] of hydrides for all locations of the fuel rod.

PG&E Response The maximum fuel rod waterside corrosion for fuel using Optimized ZIRLO' fuel rod cladding will be confirmed to be less than the specified proprietary limits for all locations of the fuel rod. Evaluations will be performed to confirm that the appropriate corrosion limits are satisfied as part of the normal reload design process.

NRC Condition 4 All the conditions listed in previous NRC SE approvals for methodologies used for standard ZIRLO and Zircaloy-4 fuel analysis will continue to be met, except that the use of Optimized ZIRLO' cladding in addition to standard ZIRLO and Zircaloy-4 cladding is now approved.

PG&E Response The Optimized ZIRLO' fuel rod analysis will continue to meet all conditions associated with approved methods. Confirmation of these conditions is required as part of the normal reload design process.

NRC Condition 5 All methodologies will be used only within the range for which ZIRLO and Optimized ZIRLO data were acceptable and for which the verifications discussed in Addendum 1 and responses to requests for additional information (RAl) were performed.

PG&E Letter DCL-25-029 6

PG&E Response The application of ZIRLO and Optimized ZIRLO' will use approved methodologies consistent with the approach accepted in Reference 1. Confirmation of these conditions is required as part of the normal reload design process.

NRC Condition 6 The licensee is required to ensure that Westinghouse has fulfilled the following commitment: Westinghouse shall provide the NRC staff with a letter(s) containing the following information (based on the schedule described in response to RAI #3 of Reference 4):

Optimized ZIRLO' lead test assembly (LTA) data from Byron, Calvert Cliffs, Catawba, and Millstone.

i.

Visual ii.

Oxidation of fuel rods iii.

Profilometry iv.

Fuel rod length

v.

Fuel assembly length

a. Using the standard and Optimized ZIRLO' database including the most recent LTA data, confirm applicability with currently approved fuel performance models (e.g., measured versus predicted).

Confirmation of the approved models' applicability up through the projected end of cycle burnup for the Optimized ZIRLO' fuel rods must be completed prior to their initial batch loading and prior to the startup of subsequent cycles. For example, prior to the first batch application of Optimized ZIRLO', sufficient LTA data may only be available to confirm the models' applicability up through 45 GWd/MTU. In this example, the licensee would need to confirm the models up through the end of the initial cycle. Subsequently, the licensee would need to confirm the models, based upon the latest LTA data, prior to re-inserting the Optimized ZIRLO' fuel rods in future cycles. Based upon the LTA schedule, it is expected that this issue may only be applicable to the first few batch implementations, since sufficient LTA data up through the burnup limit should be available within a few years.

PG&E Response Westinghouse has provided the NRC with information related to test data and models.

The NRC has confirmed that this condition has been satisfied as stated in Reference 5.

No further information is necessary in response to this Condition.

PG&E Letter DCL-25-029 7

NRC Condition 7 The licensee is required to ensure that Westinghouse has fulfilled the following commitment: Westinghouse shall provide the NRC staff with a letter containing the following information (based on the schedule in response to RAI #11 of Reference 4):

a. Vogtle growth and creep data summary reports.
b. Using the standard ZIRLO and Optimized ZIRLO' database including the most recent Vogtle data, confirm applicability with currently approved fuel performance models (e.g., level of conservatism in Westinghouse rod pressure analysis, measured versus predicted, predicted minus measured versus tensile and compressive stress).

Confirmation of the approved models' applicability up through the projected end of cycle burnup for the Optimized ZIRLO' fuel rods must be completed prior to their initial batch loading and prior to the startup of subsequent cycles. For example, prior to the first batch application of Optimized ZIRLO', sufficient LTA data may only be available to confirm the models' applicability up through 45 GWd/MTU. In this example, the licensee would need to confirm the models up through the end of the initial cycle. Subsequently, the licensee would need to confirm the models, based upon the latest LTA data, prior to re-inserting the Optimized ZIRLO' fuel rods in future cycles. Based upon the LTA schedule, it is expected that this issue may only be applicable to the first few batch implementations since sufficient LTA data up through the burnup limit should be available within a few years.

PG&E Response Westinghouse has provided the NRC with information related to test data and models.

The NRC has confirmed that this condition has been satisfied as stated in Reference 5.

No further information is necessary in response to this condition.

NRC Condition 8 The licensee shall account for the relative differences in unirradiated strength (yield strength (YS) and ultimate tensile strength (UTS)) between Optimized ZIRLO' and standard ZIRLO in cladding and structural analyses until irradiated data for Optimized ZIRLO' has been collected and provided to the NRC staff.

a. For the Westinghouse fuel design analyses:
i.

The measured, unirradiated Optimized ZIRLO' strengths shall be used for beginning of life (BOL) analyses.

ii.

Between BOL up to a radiation fluence of 3.0E21 neutrons/centimeter2 (n/cm2) [E > 1 (million electron volts (MeV)], pseudo-irradiated Optimized PG&E Letter DCL-25-029 8

ZIRLO' strength set equal to linear interpolation between the following two strength level points: at zero fluence, strength of Optimized ZIRLO' equal to measured strength of Optimized ZIRLO' and at a fluence of 3.0E21 n/cm2 (E

> 1 MeV), irradiated strength of standard ZIRLO at the fluence of 3.0E21 n/cm2 (E > 1 MeV) minus 3 kilopound per square inch (ksi).

iii.

During subsequent irradiation from 3.0E21 n/cm2 up to 12E21 n/cm2, the differences in strength (the difference at a fluence of 3.0E21 n/cm2 due to tin content) shall be decreased linearly such that the pseudoirradiated Optimized ZIRLO' strengths will saturate at the same properties as standard ZIRLO at 12.0E21 n/cm2.

b. For the CE fuel design analyses, the measured, unirradiated Optimized ZIRLO' strengths shall be used for all fluence levels (consistent with previously approved methods).

PG&E Response The Optimized ZIRLO' fuel rod analysis for DCPP will use the YS and UTS as modified per conditions and limitations 8.a.i., 8.a.ii., and 8.a.iii. Confirmation of this condition is required as part of the reload design process.

Condition 8.b does not apply because DCPP uses a Westinghouse fuel design and not a CE fuel design.

NRC Condition 9 As discussed in response to RAI 21 of Reference 3, for plants introducing Optimized ZIRLO' that are licensed with LOCBART or STRIKIN-11 and have a limiting peak cladding temperature (PCT) that occurs during blowdown or early reflood, the limiting LOCBART or STRIKIN-11 calculation will be rerun using the specified Optimized ZIRLO' material properties. Although not a condition of approval, the NRC strongly recommends that, for future evaluations, Westinghouse update all computer models with Optimized ZIRLO' specific material properties.

PG&E Response Condition 9 does not apply because DCPP is not licensed to use the LOCBART or STRIKIN-11 codes.

PG&E Letter DCL-25-029 9

NRC Condition 10 Due to the absence of high temperature oxidation data for Optimized ZIRLO', the Westinghouse coolability limit on PCT during the locked rotor event shall be [proprietary limits included in topical report and proprietary version of safety evaluation].

PG&E Response Confirmation of this condition is required as part of the normal reload design process.

PG&E Letter DCL-25-029 10

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 10 CFR 50.36, Technical Specifications, requires that design features be included that described the facility in terms of materials of construction and geometric arrangement, which, if altered or modified, would have a significant effect on safety.

4.1.1 Regulations and Regulatory Guidance NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition (SRP), Section 4.2, Fuel System Design, provides regulatory guidance to the NRC staff for the review of fuel rod cladding materials and fuel system. In addition, the SRP provides guidance for compliance with the applicable General Design Criteria (GDC) of 10 CFR Part 50, Appendix A.

According to SRP Section 4.2, the fuel system safety review provides assurance that:

  • Fuel system damage is never so severe as to prevent control rod insertion when it is required.
  • The number of fuel rod failures is not underestimated for postulated accidents.
  • Coolability is always maintained.

In Reference 3, the NRC approved Addendum 1 to WCAP-12610-P-A and CENPD-404-P-A for the use of Optimized ZIRLO' as an acceptable fuel rod cladding material for Westinghouse fuel designs.

10 CFR 50.46 requires, in part, that each boiling or pressurized light-water nuclear power reactor fueled with uranium oxide pellets within cylindrical Zircaloy or ZIRLO cladding must be provided with an emergency core cooling system (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). Appendix K to 10 CFR Part 50 establishes the regulations for conservative ECCS evaluation models.

contains an exemption request from 10 CFR 50.46.

4.1.2 General Design Criteria As noted in the DCPP Final Safety Analysis Report Update (UFSAR) Section 3.1, DCPP was designed to comply with the Atomic Energy Commission (AEC) (now the Nuclear Regulatory Commission, or NRC) General Design Criteria (GDC) for Nuclear Power Plant Construction Permits, published in July 1967. The DCPP design basis is PG&E Letter DCL-25-029 11 the 1967 GDCs. Subsequent commitments to GDCs issued later are noted in the discussion of each GDC in the UFSAR and as applicable below.

Criterion 10 - Reactor Design The reactor core and associated coolant, control, and protection systems shall be designed with appropriate margin to assure that specified acceptable fuel design limits are not exceeded during any condition of normal operation, including the effects of anticipated operational occurrences.

GDC 10, 1971 supersedes GDC 6, 1967 with respect to the design of the reactor core.

Compliance with GDC 10 is described in UFSAR Section 3.1.3.1.1.

Criterion 27 - Combined Reactivity Control Systems Capability The reactivity control systems shall be designed to have a combined capability, in conjunction with poison addition by the ECCS, of reliably controlling reactivity changes to assure that under postulated accident conditions and with appropriate margin for stuck rods the capability to cool the core is maintained.

Compliance with GDC 27, 1971 is described in Appendix 3.1A of the DCPP UFSAR. It should be noted that the DCPP UFSAR Section 3.1.6.1 states that Criterion 27, 1967, is no longer part of the DCPP license basis and has been replaced by GDC 26, 1971.

However, Appendix 3.1A provides information to show the degree to which the DCPP design conforms to the intent of the 1971 GDCs and establishes additional DCPP licensing basis which must be reviewed when evaluating facility changes. Therefore, GDC 27, 1971, is included for completeness.

Criterion 35 - Emergency Core Cooling A system to provide abundant emergency core cooling shall be provided. The system safety function shall be to transfer heat from the reactor core following any loss of reactor coolant at a rate such that (1) fuel and clad damage that could interfere with continued effective core cooling is prevented and (2) clad metal-water reaction is limited to negligible amounts.

Suitable redundancy in components and features, and suitable interconnections, leak detection, isolation, and containment capabilities shall be provided to assure that for onsite electric power system operation (assuming offsite power is not available) and for offsite electric power system operation (assuming onsite power is not available) the system safety function can be accomplished, assuming a single failure.

Compliance with GDC 35, 1967, is described in the DCPP UFSAR Section 3.1.7.3 while compliance with GDC 35, 1971, is described in Appendix 3.1A of the DCPP UFSAR.

PG&E Letter DCL-25-029 12 There will be no changes to the DCPP design such that compliance with any of the regulatory requirements above would come into question. Therefore, DCPP Units 1 and 2 will continue to comply with the applicable regulatory requirements.

4.2 Precedent This proposed change is similar in nature to the following LARs and associated Requests for Exemption from 10 CFR 50.46 approved by the NRC that authorized the use of Optimized ZIRLO' fuel rod cladding:

  • Watts Bar Nuclear Plant Units 1 and 2 (References 6 and 7)
  • Beaver Valley Power Station, Units 1 and 2 (References 8 and 9)
  • Wolf Creek Generating Station (References 10 and 11)
  • Palo Verde Nuclear Generating Station, Units 1, 2, and 3 (References 13 and 14)
  • Seabrook Station, Unit 1 (References 16 and 17)

PG&E also reviewed the related RAI responses associated with the Palo Verde Nuclear Generating Station, Units 1, 2, and 3 LAR (Reference 15) and the Wolf Creek Generating Station LAR (Reference 12) and incorporated the requested information as appropriate.

4.3 Significant Hazards Consideration PG&E proposes to revise the DCPP Units 1 and 2 TS to allow the use of Optimized ZIRLO' fuel rod cladding material. The current acceptable fuel rod cladding material is identified in DCPP Units 1 and 2 TS 4.2.1, Fuel Assemblies.

The proposed amendment would revise DCPP Units 1 and 2 TS 4.2.1 to add Optimized ZIRLO' to the approved fuel rod cladding materials. The proposed amendment also revises DCPP Units 1 and 2 TS 5.6.5, Core Operating Limits Report (COLR), to add Westinghouse Electric Company LLC (Westinghouse) topical report WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A, Optimized ZIRLO', to the list of analytical methods used to determine the core operating limits reviewed and approved by the NRC. Other editorial changes are to correct the spelling of the word Zircaloy and add a registered trademark designator to the word ZIRLO (TS 4.2.1 only). Editorial changes will also be proposed to remove the not-used references 6, 7, and 8 from the list of COLR references in TS 5.6.5.b.

PG&E has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, Issuance of amendment, as discussed below:

PG&E Letter DCL-25-029 13

1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The proposed amendment will allow the use of Optimized ZIRLO' clad nuclear fuel at DCPP Units 1 and 2. The NRC approved topical report WCAP-12610-P-A and CENPD 404-P-A, Addendum 1-A, which addresses Optimized ZIRLO' fuel rod cladding and demonstrates that Optimized ZIRLO' fuel rod cladding has essentially the same properties as currently licensed ZIRLO fuel rod cladding. The use of Optimized ZIRLO' fuel rod cladding material will not result in adverse changes to the operation or configuration of the facility. The fuel cladding itself is not an accident initiator and does not affect accident probability. Use of Optimized ZIRLO' meets the fuel design acceptance criteria and hence does not significantly affect the consequences of an accident.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed change create the possibility of a new or different accident from any accident previously evaluated?

Response: No.

The use of Optimized ZIRLO' fuel rod cladding material will not result in adverse changes to the operation or configuration of the facility. WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A demonstrated that the material properties of Optimized ZIRLO' fuel rod cladding are similar to those of ZIRLO fuel rod cladding. Therefore, Optimized ZIRLO' fuel rod cladding will perform similarly to ZIRLO fuel rod cladding, thus precluding the possibility of the fuel rod cladding becoming an accident initiator and causing a new or different kind of accident.

Therefore, the proposed change does not create the possibility of a new or different accident from any accident previously evaluated.

3. Does the proposed change involve a significant reduction in a margin of safety?

Response: No.

WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A, demonstrated that the material properties of the Optimized ZIRLO' fuel rod cladding are similar to those of ZIRLO fuel rod cladding. Optimized ZIRLO' fuel rod cladding is expected to perform similarly to ZIRLO fuel rod cladding for normal operating and accident scenarios, including both loss-of-coolant accident (LOCA) and non-LOCA scenarios. The use of PG&E Letter DCL-25-029 14 Optimized ZIRLO' fuel rod cladding will not result in adverse changes to the operation or configuration of the facility. The proposed change does not alter the permanent plant design, nor does it change the assumptions contained in the UFSAR Safety Analyses.

There is no reduction in capability or change in operation, design or configuration of any accident mitigating system as a result of the proposed change. Therefore, the plants ability to respond to a design basis accident is unaffected. The proposed change also does not alter any design basis or safety limit.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above evaluation, PG&E concludes that the proposed change does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and accordingly, a finding of no significant hazards consideration is justified.

4.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by the proposed change, (2) such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

PG&E Letter DCL-25-029 15

5.0 ENVIRONMENTAL CONSIDERATION

PG&E has evaluated the proposed amendment and has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.

Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

6.0 REFERENCES

1.

Westinghouse letter to NRC, LTR-NRC-06-45, Issuance of Approved Version of WCAP-12610-P-A & CENPD-404-P-A, Addendum 1-A (Proprietary) Optimized ZIRLOTM, dated July 10, 2006 (ML062080563).

2.

WCAP-14342-A & CENPD-404-NP-A, Addendum 1-A, Optimized ZIRLOTM, dated July 2006 (ML062080569).

3.

NRC letter to Westinghouse, Final Safety Evaluation for Addendum 1 to Topical Report WCAP-12610-P-A and CENPD-404-P-A, Optimized ZIRLOTM, dated June 10, 2005 (ML051670403).

4.

Westinghouse letter to NRC, LTR-NRC-04-44, Westinghouse Responses to NRC Request for Additional Information (RAIs) on Optimized ZIRLO' Topical - Addendum 1 to WCAP-12610-P-A, dated August 4, 2004 (ML042240411).

5.

NRC letter to Westinghouse, Satisfaction of Conditions 6 and 7 of the U. S. Nuclear Regulatory Commission Safety Evaluation for Westinghouse Electric Company Addendum 1 to WCAP-12610-P-A &

CENP-404-P-A, Optimized ZIRLO', Topical Report, dated August 3, 2016 (ML16173A354).

6.

Letter from NRC to J. Shea, Watts Bar Nuclear Plant, Units 1 and 2 -

Issuance of Amendment Nos. 127 and 30 regarding the use of Optimized ZIRLOTM Fuel Rod Cladding (EPID L-2018-LLA-0197),

dated July 25, 2019 (ML19112A004).

7.

Letter from NRC to J. Shea, Watts Bar Nuclear Plant, Units 1 and 2 -

Exemption from the Requirements of 10 CFR Section 50.46 and PG&E Letter DCL-25-029 16 Appendix K to 10 CFR part 50 to Allow the Use of Optimized ZIRLOTM Fuel Rod Cladding (EPID L-2018-LLE-0012), dated July 25, 2019 (ML19112A011).

8.

Letter from NRC to R. Bologna, Beaver Valley Power Station, Unit Nos. 1 and 2 -Issuance of Amendment Nos. 302 and 191 Regarding the Use of Optimized ZIRLOTM Fuel Rod Cladding (CAC Nos. MF9580 and MF9581; EPID L-2017-LLA-0201), dated March 1, 2018 (ML18022B116).

9.

Letter from NRC to R. Bologna, Beaver Valley Power Station, Unit Nos. 1 and 2 -Exemption from the Requirements of 10 CFR 50.46 and Appendix K to 10 CFR Part 50 to Allow the Use of Optimized ZIRLOTM Fuel Rod Cladding (CAC Nos. MF9582 and MF9583; EPID L-2017-LLE-0011), dated March 1, 2018 (ML17313A550).

10.

Letter from NRC to A. Heflin, Wolf Creek Generating Station -

Issuance of Amendment RE: Use of Optimized ZIRLOTM Fuel Rod Cladding (CAC No. MF7285), dated August 3, 2016 (ADAMS Accession No. ML16179A293).

11.

Letter from NRC to A. Heflin, Wolf Creek Generating Station -

Exemption from the Requirements of 10 CFR 50.46 and Appendix K of 10 CFR Part 50 to allow the use of Optimized ZIRLOTM Clad Fuel Rods (CAC No. MF7286), dated August 2, 2016 (ADAMS Accession No. ML16179A440).

12.

Wolf Creek Nuclear Operating Corporation letter to NRC, Docket No.

50-482: Response to Request for Additional Information Regarding License Amendment Request to Allow Use of Optimized ZIRLOTM, dated May 19, 2016 (ML16161A509).

13.

NRC letter to Arizona Public Service Company, Palo Verde Nuclear Generating Station, Units 1, 2, and 3 - Issuance of Amendments to Revise Technical Specifications to Support the Implementation of Next Generation Fuel (CAC Nos. MF8076, MF8077, and MF8078; EPID L-2016-LLA-0005), dated January 23, 2018 (ML17319A103 (Proprietary) and ML17319A107).

14.

NRC letter to Arizona Public Service Company, Palo Verde Nuclear Generating Station, Units 1, 2, and 3 - Exemption from the Requirements of 10 CFR Part 50, Section 50.46 and Appendix K (CAC Nos. MF8079, MF8080, and MF8081; EPID L-2016-LLE-0001), dated January 23, 2018 (ML17319A207 (Proprietary) and ML17319A214).

15.

Arizona Public Service Company letter to NRC, Palo Verde Nuclear Generating Station (PVNGS) Units 1, 2, and 3 Docket Nos. STN 50-528/529/530 Renewed Operating License Nos. NPF-41, NPF-51, NPF-74 Response to NRC Staff Request for Additional Information PG&E Letter DCL-25-029 17 Regarding License Amendment and Exemption Requests Related to the Implementation of Next Generation Fuel (NGF), dated June 2, 2017 (ML17153A373).

16.

NRC letter to NextEra Energy Seabrook LLC, Seabrook Station, Unit No. 1 - Issuance of Amendment Regarding the Use of Optimized ZIRLO' Fuel Rod Cladding Material (TAC No. MF2410), dated March 5, 2014 (ML13213A143).

17.

NRC letter to NextEra Energy Seabrook LLC, Seabrook Station, Unit 1 - Exemption from the Requirements of 10 CFR Section 50.46 and Appendix K to10 CFR Part 50 to Allow the Use of Optimized ZIRLO' Clad Fuel Rods (TAC No. MF2411), dated March 5, 2014 (ML13213A074).

18.

Pacific Gas and Electric Company letter to NRC, License Amendment Request 18-02, License Amendment Request to Revise Technical Specification 5.6.5b Core Operating Limits Report (COLR) for Full Spectrum Loss-of-Coolant Accident Methodology, dated December 26, 2018 (ML19003A196).

19.

Pacific Gas and Electric Company letter to NRC, Diablo Canyon, Units 1 and 2 - Supplement to License Amendment Request 18-02, License Amendment Request to Revise Technical Specification 5.6.5b, Core Operating Limits Report (COLR) for Full Spectrum Loss-of-Coolant Accident Methodology, dated October 24, 2019 (ML19297H634).

20.

NRC letter to Pacific Gas and Electric Company, Diablo Canyon Power Plant, Units 1 and 2 - Issuance of Amendment Nos. 234 and 236 to Revise Technical Specification 5.6.5b, Core Operating Limits Report (COLR), for Full Spectrum Loss-of-Coolant Accident Methodology (EPID L-2018-LLA-0730), dated January 9, 2020 (ML19316A109).

PG&E Letter DCL-25-029 1

Proposed Technical Specification Changes (Markups)

Design Features 4.0 DIABLO CANYON - UNITS 1 & 2 4.0 DESIGN FEATURES 4.1 Site Location The DCPP site consists of approximately 750 acres which are adjacent to the Pacific Ocean in San Luis Obispo County, California, and is approximately twelve (12) miles west-southwest of the city of San Luis Obispo.

4.2 Reactor Core 4.2.1 Fuel Assemblies The reactor shall contain 193 fuel assemblies. Each assembly shall consist of a matrix of Zircalloy, or ZIRLOZIRLO, or Optimized ZIRLO' clad fuel rods with an initial composition of natural or slightly enriched uranium dioxide (UO2) as fuel material. Limited substitutions of zirconium alloy or stainless steel filler rods for fuel rods, in accordance with approved applications of fuel rod configurations, may be used. Fuel assemblies shall be limited to those fuel designs that have been analyzed with applicable NRC staff approved codes and methods and shown by tests or analyses to comply with all fuel safety design bases. A limited number of lead test assemblies that have not completed representative testing may be placed in nonlimiting core locations.

4.2.2 Control Rod Assemblies The reactor core shall contain 53 control rod assemblies. The control rod material shall be silver, indium, and cadmium, as approved by the NRC.

4.3 Fuel Storage 4.3.1 Criticality 4.3.1.1 The permanent spent fuel pool storage racks are designed and shall be maintained with:

a.

Fuel assemblies having a maximum U-235 enrichment of 5.0 weight percent; b.

keff < 1.0 if fully flooded with unborated water, which includes an allowance for uncertainties as described in Section 9.1.2.3 of the FSAR; c.

keff 0.95 if fully flooded with water borated to 806 ppm, which includes an allowance for uncertainties as described in Section 9.1.2.3 of the FSAR; d.

A nominal 11 inch center to center distance between fuel assemblies placed in the fuel storage racks; (continued) 4.0-1 Unit 1 - Amendment No. 135,154,183, Unit 2 - Amendment No. 135,154,185,

Reporting Requirements 5.6 DIABLO CANYON - UNITS 1 & 2 5.6 Reporting Requirements 5.6.5 CORE OPERATING LIMITS REPORT (COLR) (continued) b.

The analytical methods used to determine the core operating limits shall be those previously reviewed and approved by the NRC, specifically those described in the following documents:

1.

WCAP-10216-P-A, "Relaxation of Constant Axial Offset Control FQ Surveillance Technical Specification, (Westinghouse Proprietary),

2.

WCAP-9272-P-A, "Westinghouse Reload Safety Evaluation Methodology," (Westinghouse Proprietary),

3.

WCAP-8385, "Power Distribution Control and Load Following Procedures," (Westinghouse Proprietary),

4.

WCAP-16996-P-A, Revision 1, "Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FULL SPECTRUM LOCA Methodology),"

5.

WCAP-17661-P-A, Revision 1, Improved RAOC and CAOC FQ Surveillance Technical Specifications, 6.

Not used.WCAP-8567-P-A, "Improved Thermal Design Procedure,"

7.

Not used.WCAP-16045-P-A, "Qualification of the Two Dimensional Transport Code PARAGON,"

8.

Not used.WCAP-16045-P-A, Addendum 1-A, "Qualification of the NEXUS Nuclear Data Methodology," and 9.

WCAP-8567-P-A, "Improved Thermal Design Procedure,"WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A, Optimized ZIRLO'."

10.

WCAP-16045-P-A, "Qualification of the Two Dimensional Transport Code PARAGON," and 11.

WCAP-16045-P-A, Addendum 1-A, "Qualification of the NEXUS Nuclear Data Methodology."

(continued) 5.0-20 Unit 1 - Amendment No. 135,136,191,195,198,224,234,239, Unit 2 - Amendment No. 135,136,192,196,199,226,236,240, Remove 135 to 234, and 135 to 236 A

r------,

PG&E Letter DCL-25-029 1

Revised Technical Specification Pages (Clean)

Remove Page Insert Page 4.0-1 4.0-1 5.0-20 5.0-20

Design Features 4.0 DIABLO CANYON - UNITS 1 & 2 4.0 DESIGN FEATURES 4.1 Site Location The DCPP site consists of approximately 750 acres which are adjacent to the Pacific Ocean in San Luis Obispo County, California, and is approximately twelve (12) miles west-southwest of the city of San Luis Obispo.

4.2 Reactor Core 4.2.1 Fuel Assemblies The reactor shall contain 193 fuel assemblies. Each assembly shall consist of a matrix of Zircaloy, ZIRLO, or Optimized ZIRLO' clad fuel rods with an initial composition of natural or slightly enriched uranium dioxide (UO2) as fuel material.

Limited substitutions of zirconium alloy or stainless steel filler rods for fuel rods, in accordance with approved applications of fuel rod configurations, may be used. Fuel assemblies shall be limited to those fuel designs that have been analyzed with applicable NRC staff approved codes and methods and shown by tests or analyses to comply with all fuel safety design bases. A limited number of lead test assemblies that have not completed representative testing may be placed in nonlimiting core locations.

4.2.2 Control Rod Assemblies The reactor core shall contain 53 control rod assemblies. The control rod material shall be silver, indium, and cadmium, as approved by the NRC.

4.3 Fuel Storage 4.3.1 Criticality 4.3.1.1 The permanent spent fuel pool storage racks are designed and shall be maintained with:

a.

Fuel assemblies having a maximum U-235 enrichment of 5.0 weight percent; b.

keff < 1.0 if fully flooded with unborated water, which includes an allowance for uncertainties as described in Section 9.1.2.3 of the FSAR; c.

keff 0.95 if fully flooded with water borated to 806 ppm, which includes an allowance for uncertainties as described in Section 9.1.2.3 of the FSAR; d.

A nominal 11 inch center to center distance between fuel assemblies placed in the fuel storage racks; (continued) 4.0-1 Unit 1 - Amendment No. 135,154,183, Unit 2 - Amendment No. 135,154,185,

Reporting Requirements 5.6 DIABLO CANYON - UNITS 1 & 2 5.6 Reporting Requirements 5.6.5 CORE OPERATING LIMITS REPORT (COLR) (continued) b.

The analytical methods used to determine the core operating limits shall be those previously reviewed and approved by the NRC, specifically those described in the following documents:

1.

WCAP-10216-P-A, "Relaxation of Constant Axial Offset Control FQ Surveillance Technical Specification, " (Westinghouse Proprietary),

2.

WCAP-9272-P-A, "Westinghouse Reload Safety Evaluation Methodology," (Westinghouse Proprietary),

3.

WCAP-8385, "Power Distribution Control and Load Following Procedures," (Westinghouse Proprietary),

4.

WCAP-16996-P-A, Revision 1, "Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FULL SPECTRUM LOCA Methodology),"

5.

WCAP-17661-P-A, Revision 1, Improved RAOC and CAOC FQ Surveillance Technical Specifications, 6.

WCAP-8567-P-A, "Improved Thermal Design Procedure,"

7.

WCAP-16045-P-A, "Qualification of the Two Dimensional Transport Code PARAGON,"

8.

WCAP-16045-P-A, Addendum 1-A, "Qualification of the NEXUS Nuclear Data Methodology," and 9.

WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A, "Optimized ZIRLO'."

(continued) 5.0-20 Unit 1 - Amendment No. 239, Unit 2 - Amendment No. 240, PG&E Letter DCL-25-029 1

Exemption Request

Subject:

Request for Exemption from 10 CFR 50.46 to Allow for the Use of Optimized ZIRLO' Fuel Rod Cladding Material for Diablo Canyon Nuclear Plant Units 1 and 2.3 1.0 PURPOSE

2.0 BACKGROUND

3.0 TECHNICAL JUSTIFICATION OF ACCEPTABILITY 4.0 JUSTIFICATION OF EXEMPTION

5.0 CONCLUSION

6.0 REFERENCES

3 3ZIRLO and Optimized ZIRLOTM are trademarks or registered trademarks of Westinghouse Electric Company LLC.

PG&E Letter DCL-25-029 2

1.0 PURPOSE Pursuant to 10 CFR 50.12, Specific exemptions, Pacific Gas and Electric Company (PG&E) requests an exemption from the provisions of 10 CFR 50.46, Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors for the Diablo Canyon Nuclear Power Plant (DCPP) Units 1 and Unit 2. The requested exemption would permit the use of Optimized ZIRLO' fuel rod cladding. The regulations in 10 CFR 50.46 contain acceptance criteria for the emergency core cooling system (ECCS) for reactors that have fuel rods fabricated either with zircaloy or ZIRLO fuel rod cladding material.

Therefore, an exemption is required from 10 CFR 50.46 to support the use of Optimized ZIRLO' fuel rod cladding at DCPP Units 1 and 2. This exemption request relates solely to the specific cladding material identified in this regulation (fuel rods with zircaloy or ZIRLO cladding) and will provide for the application of 10 CFR 50.46 acceptance criteria to fuel assembly designs utilizing Optimized ZIRLO' fuel rod cladding at DCPP Units 1 and 2.

2.0 BACKGROUND

Optimized ZIRLO' will provide more robust fuel. Optimized ZIRLO' was developed to be more resistant to corrosion, than ZIRLO, while providing enhanced strength at higher burnups. In addition, fuel rod internal pressure (resulting from the increased fuel duty, use of integral fuel burnable absorbers, and corrosion and temperature feedback effects) have become more limiting with respect to fuel rod design criteria. Reducing the associated corrosion buildup, and thus, minimizing the temperature feedback effects, provides additional margin to the fuel rod internal pressure design limit.

Optimized ZIRLO' provides enhanced corrosion resistance in more adverse in-reactor primary chemistry environments and at higher fuel duties with higher burnups. A Technical Specification (TS) amendment for DCPP Units 1 and 2 is required to allow the use of Optimized ZIRLO' fuel rod cladding. The amendment request is provided in to this submittal.

3.0 TECHNICAL JUSTIFICATION OF ACCEPTABILITY Westinghouse topical report WCAP-12610-P-A & CENDP-404-P-A, Addendum 1-A, has been reviewed and approved by the NRC (References 1 to 5). The NRC staff approved Optimized ZIRLO' fuel cladding based on: 1) similarities with standard ZIRLO, 2) demonstrated material performance; and 3) a commitment to provide irradiated data and validated fuel performance models ahead of burnups achieved in batch application.

The NRC Safety Evaluation (Reference 3) included 10 Limitation and Conditions. The first condition requires an exemption from 10 CFR 50.46 before implementing Optimized PG&E Letter DCL-25-029 3

ZIRLO'. This exemption request fulfills this condition. The remainder of the Limitations and Conditions are addressed in Enclosure 1 to this submittal. There are no additional commitments necessary to support NRC approval of this exemption request.

Future reload evaluations will ensure that acceptance criteria are met for the insertions of assemblies with Optimized ZIRLO'. These assemblies will be evaluated using NRC-approved methods and models to address the use of Optimized ZIRLO'.

4.0 JUSTIFICATION OF EXEMPTION 10 CFR 50.12, Specific exemptions, states that the Commission may grant exemptions from the requirements of the regulations of this part provided two criteria are met. These criteria are: (1) the exemption authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common defense and security; and (2) the Commission will not consider granting an exemption unless special circumstances are present. The requested exemption to allow the use of Optimized ZIRLO' fuel rod cladding material at DCPP satisfies these criteria as described below.

It should be noted that the NRC Staff amended the requirements of 10 CFR 50.46 and Appendix K, ECCS Evaluation Models, in 1988 to permit the use of a realistic evaluation methodology to analyze the performance of the ECCS during a hypothetical LOCA. Under the amended rules, best-estimate thermal-hydraulic models may be used in place of models with Appendix K features. The use of these models in the DCPP Units 1 and 2 licensing basis was submitted by PG&E in References 6 and 7 and was approved by the NRC in Reference 8. Therefore, the exemption from 10 CFR Part 50, Appendix K is not required for the proposed license amendment request (LAR).

Criterion 1

a. This exemption is authorized by law. The selection of a specified cladding material in 10 CFR 50.46 was adopted at the discretion of the Commission consistent with its statutory authority. No statute required the NRC to adopt this specification.

Additionally, the NRC has the authority under 10 CFR 50.12 to grant exemptions from the requirements of Part 50 upon showing proper justification. Diablo Canyon is not seeking an exemption from the acceptance and analytical criteria of 10 CFR 50.46. The intent of this request is solely to allow the use of the Optimized ZIRLO' fuel rod cladding material in lieu of ZIRLO cladding as it is currently not explicitly covered by 10 CFR 50.46.

b. This exemption will not present an undue risk to public health and safety. Reload evaluations ensure that acceptance criteria are met for future reload cores after the transition to fuel rods clad with Optimized ZIRLO' material. Due to similarities in the PG&E Letter DCL-25-029 4

composition of the Optimized ZIRLO' and standard ZIRLO alloys, fuel assemblies using Optimized ZIRLO' fuel rod cladding are evaluated using plant-specific models to address the changes in the cladding material properties. The LOCA safety analyses for DCPP are supported by the applicable site-specific Technical Specifications (TS).

Reload cores are required to be operated in accordance with the operating limits specified in the TS. Thus, the granting of this exemption request will not pose an undue risk to public health and safety.

c. This exemption is consistent with the common defense and security. As noted above, this exemption request is only to allow the application of the aforementioned regulations to Optimized ZIRLO', an improved fuel rod cladding material. All the requirements and acceptance criteria will be maintained. Use of Optimized ZIRLO' fuel rod cladding will not affect plant operations and is consistent with common defense and security.

Criterion 2 Special circumstances support the issuance of an exemption. 10 CFR 50.12(a)(2) states that the NRC will not consider granting an exemption to the regulations unless special circumstances are present. This exemption request meets the special circumstance criteria of 10 CFR 50.12(a)(2)(ii), Application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule. For DCPP, application of the subject regulations is not necessary to achieve the underlying purpose of the rule.

10 CFR 50.46 identifies acceptance criteria for ECCS performance at nuclear power plants. Westinghouse has performed an evaluation using LOCA methods as described in Enclosure 1 of this submittal to ensure that assemblies with Optimized ZIRLO' fuel rod cladding material meet all LOCA safety criteria.

5.0 CONCLUSION

For DCPP, the 10 CFR 50.46 regulations are currently limited to the use of fuel rods with zircaloy or ZIRLO cladding. 10 CFR 50.46 does not apply to the proposed use of Optimized ZIRLO' fuel rod cladding material because Optimized ZIRLO' has a slightly different composition than zircaloy or ZIRLO. With the approval of this exemption request, these regulations will be applied to Optimized ZIRLO' fuel rod cladding at DCPP.

Pursuant to 10 CFR 50.12, the requested exemption is authorized by law, does not present undue risk to public health and safety, and is consistent with common defense and security. Approval of this exemption request does not violate the underlying purpose of the rule. In addition, special circumstances exist to justify the approval of an PG&E Letter DCL-25-029 5

exemption from the subject requirements. This exemption request meets the special circumstance criteria of 10 CFR 50.12(a)(2)(ii), Application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule. For DCPP, application of the subject regulations is not necessary to achieve the underlying purpose of the rule.

6.0 REFERENCES

1. Westinghouse letter to NRC, LTR-NRC-06-45, Issuance of Approved Version of WCAP-12610-P-A & CENPD-404-P-A, Addendum 1-A (Proprietary) Optimized ZIRLOTM, dated July 10, 2006 (ML062080563).
2. WCAP-14342-A & CENPD-404-NP-A, Addendum 1-A, Optimized ZIRLOTM, July 2006 (ML062080569).
3. NRC letter to Westinghouse, Final Safety Evaluation for Addendum 1 to Topical Report WCAP-12610-P-A and CENPD-404-P-A, Optimized ZIRLOTM, dated June 10, 2005 (ML051670403).
4. Westinghouse letter to NRC, LTR-NRC-04-44, Westinghouse Responses to NRC Request for Additional Information (RAIs) on Optimized ZIRLO' Topical -

Addendum 1 to WCAP-12610-P-A, dated August 4, 2004 (ML042240411).

5. NRC letter to Westinghouse, Satisfaction of Conditions 6 and 7 of the U. S.

Nuclear Regulatory Commission Safety Evaluation for Westinghouse Electric Company Addendum 1 to WCAP-12610-P-A & CENP-404-P-A, Optimized ZIRLO', Topical Report, August 3, 2016 (ML16173A354).

6. Pacific Gas and Electric Company letter to NRC, License Amendment Request 18-02, License Amendment Request to Revise Technical Specification 5.6.5b Core Operating Limits Report (COLR) for Full Spectrum Loss-of-Coolant Accident Methodology, dated December 26, 2018 (ML19003A196).
7. Pacific Gas and Electric Company letter to NRC, Diablo Canyon, Units 1 and 2 -

Supplement to License Amendment Request 18-02, License Amendment Request to Revise Technical Specification 5.6.5b, 'Core Operating Limits Report (COLR)' for Full Spectrum Loss-of-Coolant Accident Methodology, dated October 24, 2019 (ML19297H634).

8. NRC letter to Pacific Gas and Electric Company, Diablo Canyon Nuclear Power Plant, Units 1 and 2 - Issuance of Amendment Nos. 234 and 236 to Revise Technical Specification 5.6.5b, Core Operating Limits Report (COLR), for Full Spectrum Loss-of-Coolant Accident Methodology (EPID L-2018-LLA-0730),

dated January 9, 2020 (ML19316A109).

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