ML20137B931

Application for Amend to License NPF-42,revising TS Section 5.3.1,fuel Assemblies to Allow Use of Alternate Zr Based Fuel Cladding Matl ZIRLO

ML20137B931
Person / Time
Site:	Wolf Creek
Issue date:	03/18/1997
From:	Muench R WOLF CREEK NUCLEAR OPERATING CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20137B934	List: ML20137B931 ML20137B937
References
ET-97-0020, ET-97-20, NUDOCS 9703240105
Download: ML20137B931 (13)

Text

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i WedLF CREEK NUCLEAR OPERATING CORPORATION 2 Richard A. Muench Vice President Engineering 4

March 18, 1997 ET 97-0020 i

U. S. Nuclear Regulatory Commission -

1 ATTN: Document Control Desk - '

, Mail Station P1-137 Washington, D. C. 20555 '

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Subject:

Docket No. 50-482: Proposed Revision to Technical a

Specification Section 5.3.1, Fuel Assemblies l Gentlemen: l This letter transmits an application for amendment to Facility Operating License 1 No. NPF-42 for Wolf Creek Generating Station (WCGS). This license amendment '

request revises Technical Specification Section 5.3.1, Fuel Assemblien, to allow j the use of an alternate zirconium-based fuel cladding material, ZIRLO. l

' l Wolf Creek Nuclear Operating Corporation is planning to insert Westinghouse fuel l assemblies containing ZIRLO fuel rod cladding during the ninth refueling outage, 1

which is currently scheduled to begin in late September 1997. Therefore, WCNOC respectfully requests that the NRC Staff review and approve this license  ;

amendment request no later than August 20, 1997, so that the amendment may be j implemented prior to the beginning of the refueling outage. 1 A Safety Evaluation for the proposed change is provided in Attachment I, and  !

Attachment II provides a No Significant Hazards Consideration Determination.  ;

Attachment III is the Environmental Impact Determination for the proposed  !

, change, and the marked-up technical specification page for this request is provided in Attachment IV.

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9703240105 970318 g0 '

PDR ADOCK 05000482 P PDR \

l l@EjEEElElE!E,EE!U$ I PO. Box 411/ Burlington, KS 66839 / Phone. (316) 364-8831 An Equal Opportunity Employer M F HC' VET

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.ET 97-0020

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.In accordance with 10 CFR 150. 91, a copy of this application,.with attachments, 11s being provided to the designated-Kansas State Official.

If you. have any questions concerning this matter, please contact me at

_(316) 364-8831, extension.4034, or Mr. Richard D. Flannigan, at extension 4500. l i

Very truly yours, Richard A. Muench j

. RAM /jad Attachments I - Safety Evaluation-II - No Significant Hazards Consideration Determination-III - Environmental Impact. Determination IVx -. Proposed Technical Specification Change j

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cc: V. L. Cooper ~.(KDHE), w/a E. W. Merschoff-(NRC), w/a W. D. Johnson (NRC), w/a J. F. Ringwald (NRC), w/a- -

'J. C. Stone (NRC), w/a  !

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-STATE OF KANSAS )

) SS COUNTY OF COFFEY )

Richard A. Muench, of lawful age; being first duly sworn upon oath says that he is Vice President Engineering of Wolf Creek Nuclear Operating Corporation;

~ that he has read the foregoing document and knows the content thereof; that

'he has executed that same for and on behalf of said Corporation with full "

power and. authority to do so; and that the facts therein stated are true'and" correct to the best of his knowledge,'information and belief.

By Richard At Muench Vice President Engineering SUBSCRIBEDandsworntobefore.methisj/fN day of.' /y/d ,.1997.

&llJYn. D 1.oDLk.

Notary P lic ANGELA E.WESSEL IgNotaryPub5e Stateof Kansas yy Appt. Expires O 7/a3/9 9 '

Expiration Date O '/* C3 " 9 7

4 Att: chm:nt I to ET 97-0020 Paga 1 of 4 1

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ATTACHMENT I i

1 SAFETY EVALUATION l

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Attachm nt I to ET 97-0020 Paga 2 of 4 Safety Evaluation Proposed chance This license amendment request proposes revising Technical Specification Section 5.3.1, " Fuel Assemblies," to allow the use of an alternate zirconium based fuel cladding material, ZIRLO, for the Wolf Creek Generating Station (WCGS). Wolf Creek Nuclear Operating Corporation (WCNOC) is planning to insert Westinghouse fuel assemblies containing ZIRLO fuel rod cladding during the ninth refueling outage, which is currently scheduled to begin in late September 1997.

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Background

WCGS is currently operating with Westinghouse VANTAGE SH (V5H) fuel with IFMs and fuel cladding fabricated with Zircaloy-4. Changing to ZIRLO cladding will provide additional operational benefit from the alloy's improved corrosion resistance and dimensional stability under irradiation.

As discharge burnups, coolant temperatures, and cycle lengths have increased, more has been demanded of the fuel assembly designs and materials. Materials testing shows that while Improved Zircaloy-4 provides significant corrosion improvement over standard Zircaloy-4, the added corrosion margin provided by ZIRLO will allow WCNOC to enhance fuel management even with the existing l limitation of 60,000 MWD /MTU on lead rod burnup. This additional corrosion I margin is necessary to take full advantage of advanced fuel design features (e.g. high burnup skeleton, IFBA, variable pitch plenum spring, and annular axial blankets) to achieve reduced fuel costs. ZIRLO has been designed to provide superior performance so that significant margin will exist at the current lead rod burnup limit. With Improved Zircaloy-4, it may not be possible to take full advantage all of the design features and still meet corrosion requirements.

Looking to the future, ZIRLO clad fuel is the first phase of a transition to higher burnup fuel. ZIRLO clad fuel is capable of achieving burnups in the 75 GWD/MTU range. Future core designs may feature longer cycles, higher capacity factors, and ultimately, higher discharge burnups. Using higher discharge burnups in the reactor core design reduces the number of fresh fuel assemblies required per reload. In order to support the required fuel enrichment and discharge burnups, ZIRLO cladding must be used to maintain corrosion margin and fuel integrity. Consequently, ZIRLO is the desired material for high burnup applications. A transition to higher discharge burnups cannot be made until all the assemblies in the core have ZIRLO cladding and proper NRC approval of the remaining changes, such as increased lead rod burnup limit, is obtained.

Ryaltation In Federal Register Volume 57, Number 169, dated August 31, 1992, Reference 1, the NRC published amended regulations to reduce the regulatory burden on nuclear licensees. The N'RC revised the acceptance criteria in 10 CFR 50.44,

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. 1 Attachm:nt I to ET 97-0020 Page 3 of 4 I

l Reference 2, and 10 CFR 50.46, Reference 3, relating to evaluations of ]

emergency core cooling systems and combustible gas control applicable to j Zircaloy clad fuel to include ZIRLO clad fuel. ZIRLO is a preferred cladding {

material since it provides significant improvement in corrosion margin and i fuel integrity. The NRC noted that the revision to include ZIRLO as an )

acceptable zirconium based cladding material will reduce the licensee burden l and will not reduce the protection of the public health or safety. )

l This change is consistent with 10 CFR 50.44 and 10 CFR 50.46. The change is also consistent with the NRC approved topical report, WCAP-13060, Reference 4, I which meets the intent of supplement 1 of Generic Letter 90-02, Reference 5. l In addition, the recommended revision is consistent with NUREG-1431, Revision l 1, Reference 6, which specifically includes ZIRLO as an acceptable cladding material option. l 1

An analysis of the safety implications is provided in an NRC letter to Westinghouse dated July 1, 1991, " Acceptance for Referencing of Topical Report WCAP-12610, ' Vantage + Fuel Assembly Reference Core Report' (TAC No. 77258)",

Reference 7. The report supports the following conclusions:

1) The mechanical design bases and limits for the ZIRLO clad fuel assembly ,

design are the same as those for the previously licensed Zircaloy-4 clad )

fuel assembly design, except that ZIRLO cladding improves corrosion performance.

2) The neutronic evaluations have shown that ZIRLO clad fuel nuclear design bases are satisfied and that key safety parameter limits are applicable.

The nuclear design models and methods accurately describe the behavior of ZIRLO clad fuel.

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3) The thermal and hydraulic design basis for ZIRLO clad fuel is unchanged.

4) The methods and computer codes used in the analysis of the non-loss of coolant accident (non-LOCA) licensing basis events are valid for ZIRLO clad fuel, and all licensing basis criteria will be met.

5) The large break loss of coolant accident (LOCA) evaluation model was modified to reflect the behavior of the ZIRLO clad raaterial during a LOCA.

It is concluded that the revised evaluation model satisfies the intent of 10 CFR 50.46 and Appendix K of 10 CFR 50. There is no significant impact on typical large break LOCA analysis results for che ZIRLO model revisions.

In addition, bounding large and small break LOCA rod heatup cases were evaluated for WCGS and all acceptance criteria were met, including those in 10 CFR 50.46. Adequate margin to the peak clad temperature limit of 2200 F is maintained. '

The effect of ZIRLO on the non-LOCA analyses has been evaluated, Reference 7.

Two eventa, Rod Ejection and Locked Rotor, were determined to be potentially affected. The results of the evaluation demonstrate that all acceptance criteria continue to be met and adequate margin to the peak clad temperature limit is maintained.

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Attachmtnt I to ET 97-0020 Page 4 of 4 WCAP-13060, Reference- 4, delineates the methodology used to evaluate applicable design criteria associated with reconstituted fuel assemblies that have solid filler rods replacing uranium filled fuel rods. Evaluations and analyses of fuel assembly reconstitution will be performed on a cycle specific basis whenever reconstituted fuel assemblies are used in the reactor core.

The WCAP. includes proposed technical specification changes based on the WCAP conclusions and the guidelines of Generic Letter 90-02, Reference 5.

Fuel configuration, size, enrichment, and cladding material shall be limited to those designs that have been analyzed with applicable NRC approved codes and methods and shown by test of cycle specific reload analyses to comply with all safety design bases. The use of ZIRLO fuel cladding'or filler rods will be justified by a cycle specific reload analysis in accordance with NRC i approved applications of fuel rod configuration. The justification of the core analysis methods must address the effect on core-wide analyses of permissible core configurations with the reconstituted fuel.

Based on the above discussions and the no significant hazards consideration determination presented in Attachment II, the proposed change does not increase the probability of occurrence or the consequences of an accident or  !

malfunction of equipment important to safety previously evaluated in the j safety analysis report; or create a possibility for an accident or malfunction i of a different type than any previously evaluated in the safety analysis )

report; or reduce the margin of safety as defined in the basis for any technical specification. Therefore, the proposed change does not adversely affect or endanger the health or safety of the general public or involve a significant safety hazard. ,

I References

1. Federal Register, Vol. 57, No. 169, Rules and Regulations, pg. 3935? and 39355, "Use of Fuel with Zirconium-Based (Other than Zircaloy) Cladding (10 CFR 50.44, 50.46, and Appendix K to Part 50)", August 31, 1992.

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2. 10 CFR 50.44, " Standards for Combustible Gas Control System in Light-Water-Cooled Power Reactors", U.S. Nuclear Regulatory Commission.

3. 10 CFR 50.46,' " Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Powcr Reactors", U.S. Nuclear Regulatory Commission.

4. Slagle, W. H. (Ed.), et al, " Westinghouse Fuel-Assembly Reconstitution ,

l Evaluation Methodology", WCAP-13060-P-A,(Proprietary), July 1993.

'5. Generic' Letter 90-02, Supplement 1, " Alternative Requirements for Fuel l Assemblies in the Design Features Section of Technical Specifications",

i U.S. Nuclear Regulator Commission, July 31, 1992. i

6. NUREG-1431, Revision 1, " Standard Technical Specifications for Westinghouse Plants", U.S. Nuclear Regulatory Commission, April 1995.

7. Davidson, S. L. and Nuhfer, D. L. (Eds.), " VANTAGE + Fuel Assembly Report",

WCAP-12610-P-A, April 1995, i

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.e Attachm:nt II to ET 97-0020 Pigs 1 of 4 ATTACHMENT II l NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION l l

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5 Attechment II to ET 97-0020 Prga 2 of 4 No Significant Hazarda Consideration Determination This license amendment request proposes revising Technical Specification Section 5.3.1, " Fuel Assemblies," to allow the use of an alternate zirconium based fuel cladding material, ZIRLO, for the Wolf Creek Generating Station (WCGS). The proposed change is consistent with the language in NUREG-1431, Revision 1, " Standard Technical Specifications for Westinghouse Plants," and with the guidance in Generic Letter 90-02, Supplement 1, " Alternative Requirements for Fuel Assemblies in the Design Features Section of Technical Specifications." Limited substitutions of zirconium-based alloy or stainless  ;

steel filler rods for fuel rods would also be permitted, if in accordnace with i NRC approved applications of fuel rod configurations. Wolf Creek Nuclear j Operating Corporation (WCNOC) is planning to insert Westinghouse fuel  !

assemblies containing ZIRLO fuel rod cladding during the ninth refueling outage, which is currently scheduled to begin in late September 1997.

1 The proposed change does not involve an unreviewed safety question because i operation of WCGS with this change would not:

1) Increase the probability of occurrence or the consecuences of an accident or malfunction of ecuinment imnortant to safety Dreviously evaluated in the Safety Analysis Report.

The methodologies used in the accident analysis remain unchanged. The proposed changes do not change or alter the design assumptions for the ,

systems or components used to mitigate the consequences of an accident.

Use of ZIRLO fuel cladding does not adversely affect fuel performance or impact nuclear design methodology. Therefore accident analyses are not impacted.

The operating limits will not be changed and the analysis methods to demonstrate operation within the limits will remain in accordance with NRC approved methodologies. Other than the changes to the fuel assemblies, there are no physical changes to the plant associated with this technical specification change. A safety analysis will continue to be performed for each cycle to demonstrate compliance with all fuel safety design bases.

VANTAGE SH with IFMs fuel assemblies with ZIRLO clad fuel rods meet the same fuel assembly and fuel rod design bases as other VANTAGE 5H with IFMs fuel assemblies. In addition, the 10 CFR 50.46 criteria are applied to the ZIRLO clad rods. The use of these fuel assemblies will not result in a l change to the reload design and safety analysis limits. The clad material l is similar in chemical composition and has similar physical and mechanical l

properties as Zircaloy-4. Thus, the cladding integrity is maintained and the structural integrity of the fuel assembly is not affected. ZIRLO cladding improves corrosion performance and dimensional stability. No concerns have been identified with respect to the use of an assembly containing a combination of Zircaloy-4 and ZIRLO clad fuel rods. Since the dose predictions in the safety analyses are not sensitive to fuel rod cladding material, the radiological consequences of accidents previously evaluated in the safety analysis remain valid.

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i Attachment II to ET 97-0020

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Therefore, the proposed changes do not involve a significant increase in '

the probability or consequences.of an accident or malfunction of equipment important to safety previously evaluated.

2) create the possibility for an accident or malfunction of equipment of a ,

different tvne than any oreviously evaluated in the Safety Analysis Report.  !

VANTAGE SH with IFMs fuel assemblies with ZIRLO clad fuel rods satisfy the same design bases as those ' used for other VANTAGE SH with IFMs fuel  !

assemblies. All design and performance criteria continue to be met and no new failure mechanisms have been identified. Since the original design criteria are met, the ZIRLO clad fuel rods will not be an initiator for any new accident or malfunction of equipment important to safety. The ZIRLO cladding material offers improved ~ corrosion resistance and structural integrity.

The proposed changes do not affect the design or operation of any system or component in the plant. The safety functions of the related structures, systems or components are not changed in any manner, nor is the reliability of any structure, system or component reduced. The changes do not affect the manner by'which the facility is operated and do not change any facility design feature, structure or system. No new or different type of equipment will be installed. Since there is no change to the facility or operating procedures, and the safety functions and reliability of structures, systems, and components are not affected, the proposed changes do not create the possibility of- a new or different kind of accident or malfunction of equipment important to safety from any accident or malfunction of equipment important to safety previously evaluated.

3) Reduce the narcin of safety as defined in the basis for any technical specification.

1 Use of ZIRLO cladding material does not change the VANTAGE SH with IFMs  !

reload design and safety limits. The use of these fuel assemblies will take into consideration the normal core operating conditions allowed in the i Technical Specifications. For each cycle reload core, the fuel assemblies will be evaluated using NRC approved reload design . methods, including consideration of the core physics analysis peaking factors and core average linear heat rate effects.

The use of Zircaloy-4, ZIRLO or stainless steel filler rods in fuel assemblies will not involve a significant reduction in the margin of safety because analyses using NRC approved methodologies will be performed for each configuration to demonstrate continued operation within the limits that assure acceptable plant response to accidents and transients. These analyses will be. performed using NRC approved methods that have been approved for application to the fuel configuration.

Based on the above discussions, - it has been determined that the requested technical specification revision does not involve a significant increase in

! the probability or consequences of an accident or other adverse condition over previous evaluations; or create the possibility of a new or different kind of

accident or condition over previous evaluations; or involve a significant i

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Attachment II to ET 97-0020 PIga 4 of 4

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reduction in a margin of safety. Thus, the requested license amendment does not involve a significant hazards consideration.

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Attachm nt III to ET 97-0020 Page 1 of 2 1

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ATTACHMENT III ENVIRONMENTAL IMPACT DETERMINATION l

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. I Attechm:nt III to ET 97-0020 Paga 2 of 2 Environmental Impact Determination 10 CFR 51.22(b) specifies the criteria for categorical exclusions from the requirement for a specific environmental assessment per 10 CFR 51.21. This amendment request meets the criteria specified in 10 CFR 51. 22 (c) (9) as 1 specified below:

(i) the amendment involves no significant hazards consideration As demonstrated in Attachment II, the proposed change does not involve any significant hazards consideration.

J (ii) there is no significant change in the types or significant increase in the amounts of any effluents that may be released offsite The proposed change does not involve a change to the facility or operating procedures that would cause an increase in the amounts of effluents or create i new types of effluents.

(iii) there is no significant increase in individual or cumulative occupational radiation exposure The proposed change does not create additional exposure to personnel nor l

affect levels of radiation present. Also, the proposed change does not result 1 in any increase in individual or cumulative occupational radiation exposure.

Based on the above, it is concluded that there will be no impact on the

. environment resulting from this change and the change meets the criteria specified in 10 CFR 51.22 for a categorical exclusion from the requirements of 10 CFR 51.21 relative to requiring a specific environmental assessment by the Commission.