ML13213A018

Application to Modify Technical Specification 4.3.1, Criticality, (WBN-TS-2012-03)

ML13213A018
Person / Time
Site:	Watts Bar
Issue date:	07/30/2013
From:	James Shea Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
WBN-TS-2012-03
Download: ML13213A018 (26)

Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 July 30, 2013 10 CFR 50.90 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant Unit 1 Facility Operating License No. NPF-90 NRC Docket No. 50-390

Subject:

Watts Bar Nuclear Plant (WBN) Unit I - Application to Modify Technical Specification 4.3.1, "Criticality" (WBN-TS-2012-03)

In accordance with the provisions of 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Tennessee Valley Authority (TVA) is submitting a request for an amendment to Facility Operating License No. NPF-90 for Watts Bar Nuclear Plant (WBN) Unit 1.

The proposed license amendment request (LAR) revises WBN Unit 1 Technical Specification (TS) 4.3.1.1, "Criticality," to clarify the requirements for storage of new and spent fuel assemblies in the spent fuel racks currently provided in TS 4.3.1.1 .d and TS 4.3.1.1.e.2. This change is necessary to update the current WBN Unit 1 TS 4.3.1.1 to ensure consistency with the proposed TS 4.3.1.1 for WBN Unit 2. In addition, editorial changes are being made to TS 4.3.1.1 .a and TS 4.3.1.1 .e.3. The proposed changes also modify the current licensing basis, as described in Section 4.3.2.7 of the Updated Final Safety Analysis Report (UFSAR).

The enclosure to this letter provides a description, technical evaluation, regulatory evaluation and environmental consideration of the proposed changes. Attachment 1 of the enclosure provides the existing WBN Unit 1 TS pages marked up to show the proposed changes. of the enclosure provides the existing WBN Unit 1 TS pages retyped to show the proposed changes. Attachment 3 of the enclosure provides the changes to the UFSAR that result from this proposed change. Attachment 4 of the enclosure provides changes to the Technical Specification Bases that result from this proposed change (for information only).

TVA requests that the NRC approve this amendment by April 30, 2014, with implementation within 60 days of issuance.

Printed on recycledpaper (D t#.W3.

U.S. Nuclear Regulatory Commission Page 2 July 30, 2013 TVA has determined that there are no significant hazards considerations associated with the proposed changes and that the changes qualify for a categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51.22(c)(9).

The WBN Plant Operations Review Committee and the WBN Nuclear Safety Review Board have reviewed the proposed changes and determined that operation of WBN in accordance with the proposed changes will not endanger the health and safety of the public.

Additionally, in accordance with 10 CFR 50.91(b)(1), TVA is sending a copy of this letter and the enclosure to the Tennessee Department of Environment and Conservation.

There are no regulatory commitments associated with this LAR. Please address any questions regarding this request to Ed Schrull at 423-751-3850.

I declare under penalty of perjury that the foregoing is true and correct. Executed on this 30th day of July 2013.

Respec Ily, J. .ea Vcresident, Nuclear Licensing

Enclosure:

Evaluation of Proposed Changes cc (Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant, Unit 1 NRC Senior Resident Inspector - Watts Bar Nuclear Plant, Unit 2 Director, Division of Radiological Health - Tennessee State Department of Environment and Conservation

ENCLOSURE EVALUATION OF PROPOSED CHANGES TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNIT 1

Subject:

Watts Bar Nuclear Plant (WBN) Unit I - Application to Modify Technical Specification 4.3.1, "Criticality" (WBN-TS-2012-03) 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION 2.1 Proposed Changes 2.2 Need for Proposed Changes

3.0 TECHNICAL EVALUATION

3.1 Current Licensing Basis for Fuel Storage in the Spent Fuel Storage Pool 3.2 Proposed Changes to the Current WBN Unit 1 Licensing Basis 3.3 Acceptance Criteria 3.4 Criticality Modeling 3.5 Effect of Proposed Changes

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements and Criteria 4.2 Precedent 4.3 Significant Hazards Consideration 4.4 Conclusions

5.0 ENVIRONMENTAL CONSIDERATION

ATTACHMENTS

1. Proposed WBN Unit 1 TS Changes (Markups)

2. Proposed WBN Unit 1 TS Changes (Final Typed)

3. Proposed WBN Unit 1 UFSAR Section 4.3.2.7 Changes (Markup)

4. Proposed WBN Unit 1 TS Bases Changes (Markup)

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ENCLOSURE EVALUATION OF PROPOSED CHANGES El-2

1.0

SUMMARY

DESCRIPTION This evaluation supports a request to amend the Watts Bar Nuclear Plant (WBN) Unit 1 Facility Operating License No. NPF-90. This LAR seeks approval to make a change to WBN Unit 1 Technical Specification (TS) 4.3.1.1 that clarifies the requirements for storage of new and spent fuel assemblies in the spent fuel racks and corrects conflicting requirements in TS 4.3.1. 1.d and TS 4.3.1.1 .e.2. The TS 4.3.1.1 .d currently allows unrestricted storage of new and spent fuel assemblies in the spent fuel racks when initial enrichments are less than or equal to 3.80 weight percent Uranium-235 (U-235). However, TS 4.3.1.1.e.2 provides burnup restrictions on spent fuel assemblies from an initial enrichment of approximately 2.56 weight percent U-235 as specified in TS Figure 4.3-4 when those spent fuel assemblies are used in a checkerboard arrangement of two new and two spent fuel assemblies in the spent fuel racks. This TS LAR removes that conflict.

In addition, editorial changes are being proposed for TS 4.3.1.1.a to define an acronym and TS 4.3.1. 1.e.3 to correct a typographical error. to this enclosure provides the existing WBN Unit 1 TS pages marked up to show the proposed changes. Attachment 2 provides the proposed replacement WBN Unit 1 TS final typed pages. Attachment 3 provides proposed changes to the WBN Unit 1 UFSAR that result from this proposed technical specification change. Attachment 4 provides changes to the TS Bases that result from this proposed TS change.

2.0 DETAILED DESCRIPTION 2.1 Proposed Changes The proposed changes to TS 4.3.1 are listed below.

2.1.1 TS 4.3.1.1.a Currently TS 4.3.1.1 .a states:

Fuel assemblies having a maximum U-235 enrichment of 5. 0 weight percent; The editorial change to TS 4.3.1.1 .a consists of adding the acronym "(wt%)" as follows:

Fuel assemblies having a maximum U-235 enrichment of 5. 0 weight percent (wt%);

2.1.2 TS 4.3.1.1.d and TS 4.3.1.1.e Currently TS 4.3.1. 1.d states:

Fuel assemblies with enrichments less than or equal to 3.80 weight percent U-235 are allowed unrestrictedstorage.

Currently TS 4.3.1.1.e states:

Fuel assemblies with initial enrichments greaterthan 3.80 weight percent and less than a maximum of 5 percent enrichment (nominally 4.95 +/- 0.05 percent)may be stored in the spent fuel racks in one of four arrangementswith specific limits as specified below:

To clarify the allowance for unrestricted storage of new and spent fuel assemblies in TS 4.3.1 .1 .d and the restrictions for storing spent fuel assemblies in TS 4.3.1 .1 .e.2, a change is proposed to delete 4.3.1.1.d, and renumber and revise 4.3.1.1.e to state:

Fuel assemblies with initialenrichments less than a maximum of 5 wt% U-235 enrichment (nominally 4.95 +/- 0.05 wt% U-235) may be stored in the spent fuel racks in any one of four arrangementswith specific limits as identified below:

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2.1.3 TS 4.3.1.1.e.1 Currently TS 4.3.1.1 .e. 1 states:

Spent fuel assemblies may be stored in the racks without further restrictionsprovided the burnup of each assembly is in the acceptable domain identified in Figure 4.3-3, depending upon the specified initial enrichment.

To accommodate the deletion of TS 4.3.1.1.d, a change is proposed to renumber and revise TS 4.3.1.1.e.1 (renumbered 4.3.1.1.d.1) to state:

Fuel assemblies may be stored in the racks in an all cell arrangementprovided the burnup of each assembly is in the acceptable domain identified in Figure 4.3-3, depending upon the specified initial enrichment.

2.1.4 TS 4.3.1.1.e.3 Currently TS 4.3.1.1.e.3 states:

New fuel assemblies may be stored in 4-cell arrays with I of the 4 cells remaining empty of fuel (i.e. containing only water or water with up to 75 percent by volume of non-fuel bearing material.

The editorial change to TS 4.3.1.1.e.3 (renumbered 4.3.1.1.d.3) consists of adding a closing parenthesis as follows:

New fuel assemblies may be stored in 4-cell arrays with 1 of the 4 cells remaining empty of fuel (i.e., containing only water or water with up to 75 percent by volume of non-fuel bearing material).

2.1.5 TS Figures 4.3-3 and 4.3-4 Changes to the titles of TS Figures 4.3-3 and 4.3-4 are being proposed, as shown in the markup, for consistency with the revised specifications and to clarify their applicability to new and spent fuel configurations.

2.2 Need for Proposed Changes During review of the WBN Unit 2 proposed TS 4.3.1, the NRC identified that clarification of the requirements in the proposed TS 4.3.1. 1.d, TS 4.3.1. 1.e, TS 4.3.1.1.e.2 and TS Figure 4.3-4, was required to correct a conflict in the requirements of TS 4.3.1 .1 .d and TS 4.3.1 .1 .e.2 for storage of new and spent fuel assemblies in the spent fuel racks. TVA initiated Problem Evaluation Report (PER) 465826 to review and address the discrepancy between the current Unit 1 and proposed Unit 2 TSs. A review by TVA identified the need for a correction to the WBN Unit 1 TS because the spent fuel pool is common to WBN Units 1 and 2.

The identified discrepancy involves TS 4.3.1.1 .d, which allows unrestricted storage of new and spent fuel assemblies with initial enrichments less than or equal to 3.80 weight percent U-235 in the spent fuel racks. However, TS 4.3.1.1.e.2 states that new and spent fuel assemblies may be stored in a checkerboard arrangement of two new and two spent fuel assemblies, provided that each spent fuel assembly has accumulated a minimum burnup in the acceptable domain identified in TS Figure 4.3-4. The TS Figure 4.3-4 specifies burnup requirements for spent fuel assemblies from an initial enrichment of approximately 2.56 weight percent U-235. Therefore, storage of spent fuel assemblies with initial enrichments between approximately 2.56 and 3.80 wt%

U-235 in a checkerboard arrangement of two new and two spent fuel assemblies is not "9unrestricted" as currently stated in TS 4.3.1. 1.d, even though the restrictive requirements of TS 4.3.1.1 .e.2 would override the no restrictions allowance provided by TS 4.3.1.1 .d for the spent E1-4

fuel assemblies. The proposed change to WBN Unit 1 TS 4.3.1 clarifies the fuel storage requirements and resolves the discrepancy identified in PER 465826.

The TVA process governing the processing and submittal of TSs changes and LARs requires that the appropriate organizations (e.g., Operations, Training, Engineering, Maintenance, Chemistry, Radiation Protection, and Work Control) identify the documents that are affected by each proposed change to the TSs and Operating Licenses. Among the terms that are considered are training, plant modifications, procedures, special implementation constraints, design documents, surveillance instructions associated with TSs Surveillance Requirements, Technical Requirements Manual, TSs Bases, and UFSAR. The process requires that procedures and design document changes necessary to support TSs Operability are approved prior to implementation of the license amendment. The process also provides assurance that the remaining changes, if any, are tracked for configuration control.

3.0 TECHNICAL EVALUATION

3.1 Current Licensing Basis for Fuel Storage in the Spent Fuel Storage Pool Section 4.3.2.7 of the WBN, Unit 1 UFSAR provides the current licensing basis for criticality of fuel assemblies stored in the spent fuel pool that conforms to the requirements of 10 CFR 50.68(b).

The high density spent fuel storage racks for WBN are designed to assure that the effective neutron multiplication factor (keff) is equal to or less than 0.95. Design calculations model the racks fully loaded with fuel of the highest anticipated reactivity, and with a margin for uncertainty in reactivity calculations including mechanical tolerances. Uncertainties are statistically combined, such that the final keff will be equal to or less than 0.95 with a 95% probability at a 95% confidence level.

The criticality analysis for the WBN racks was performed primarily with KENO5a, a three-dimensional Monte Carlo computer code, using the 238-group SCALE cross-section library and the Nordheim integral treatment for resonance shielding effects found in NITAWL. Depletion analyses were performed using CASMO4, a two-dimensional transport theory code. The models included explicit descriptions of the fission product nuclide concentrations, incorporating approximately 40 of the most important fission products.

The criticality analysis of the WBN spent fuel pool configurations assures that the maximum keff will be less than or equal to 0.95 with fuel up to a maximum of 5 weight percent U-235 (nominally 4.95

+/- .05 wt% U-235) enrichment provided specific storage restrictions are maintained. These restrictions are delineated in the WBN UFSAR and TS 4.3.1.1. No changes are being made to the current WBN criticality analysis associated with this submittal.

3.2 Proposed Changes to the Current WBN Unit 1 Licensing Basis TVA proposes to revise WBN Unit 1 UFSAR Section 4.3.2.7 to change the 3.80 weight - zero burnup storage limit to approximately 3.84 weight percent U-235 based on the burnup enrichment curve provided in UFSAR Figure 4.3-46 (Attachment 3). The Figure 4.3-46 burnup curve is reproduced as TS Figure 4.3-3. Changes are also being proposed to clarify that "any" of the four arrangements described is acceptable and that the fuel may be stored in an "all cell arrangement" provided the fuel assembly meets the burnup requirements of UFSAR Figure 4.3-46. These changes are necessary to support the proposed TS wording.

The change to TS 4.3.1.1 .d is being proposed to resolve the discrepancy between the allowance for unrestricted storage provided in TS 4.3.1.1.d and the restrictive arrangement described in TS 4.3.1.1 .e.2 which includes TS Figure 4.3-4 for storage of new and spent fuel assemblies in the spent fuel racks. Specifically, this LAR proposes to delete TS 4.3.1.1.d and revise and renumber E1-5

TS 4.3.1 .1 .e (new TS 4.3.1.1 .d) to clarify that meeting "any" one of the four described storage arrangements satisfies the technical specification requirement.

The change to TS 4.3.1. 1.e.2 (new TS 4.3.1. 1.d.2) is being proposed for consistency with the terminology provided in Unit 1 UFSAR Section 4.3.2.7. The proposed change clarifies that TS Figure 4.3-3 is applicable to all fuel assemblies not only "spent" fuel assemblies and is consistent with the proposed change to the title of TS Figure 4.3-3.

These proposed changes to WBN Unit 1 TS 4.3.1, "Criticality," clarify the requirements for storage of new and spent fuel assemblies and removes the identified discrepancy.

Editorial changes are being proposed for TS 4.3.1.1 .a to define an acronym and for TS 4.3.1.1 .e.3 to add a closing parenthesis that is missing in the current specification.

When this LAR is approved, TVA will revise WBN Unit 1 UFSAR Section 4.3.2.7 as shown in .

3.3 Acceptance Criteria The criticality analysis results must meet the following criticality accident requirements of 10 CFR 50.68(b)(4):

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. If credit is taken for soluble boron, 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 boratedwater, and the k-effective must remain below 1.0 (subcritical),at a 95 percent probability,95 percent confidence level, if flooded with unboratedwater.

3.4 Criticality Modeling The TSs include curves defining the limiting burnup for fuel of various initial enrichments for both unrestricted storage and checkerboard arrangements assuming the fresh fuel region is enriched to a maximum of 5 weight percent U-235 (nominally 4.95 +/- 0.05 wt% U-235). The calculated maximum reactivity is 0.948, which is within the regulatory limit of keff of 0.95 enrichment. This maximum reactivity includes calculational uncertainties and manufacturing tolerances (95%

probability at the 95% confidence level), an allowance for uncertainty in depletion calculations, and the evaluated effect of the axial distribution in burnup. Fresh fuel of less than a maximum of 5 weight percent U-235 (nominally 4.95 +/- 0.05 wt%) enrichment would result in lower reactivities.

Accounting for biases and uncertainties, the maximum keff values for the above spent fuel storage rack conditions are less than 0.95. The maximum keff was determined as follows:

keff = keff (KENO) + BIASES + UNCERTAINTIES Biases include the CASMO and KENO method biases and a bias for the extrapolation of enrichment from the critical benchmark comparisons. The uncertainties include the KENO statistical uncertainty, the KENO and CASMO method uncertainties, and the mechanical tolerance uncertainty.

The analyses conservatively do not take credit for the presence of borated water, the presence of discrete burnable absorbers, lower enrichment or higher burnup which would decrease reactivity.

Other conservative assumptions include:

• Ignoring radial neutron leakage from the spent fuel storage racks

• Ignoring the presence of control rods E1-6

• Ignoring the presence of spent burnable absorber assemblies in storage

• Ignoring the higher water temperature of the spent fuel pool

• Maximizing burnable poison history effects

• Maximizing water density history effects

• Minimizing the 1°B content in the Boral A water gap between two rack modules with Boral panels on both sides of the water gap (i.e., a flux trap), precludes any adverse interaction between the two modules.

The effect of various parameters on reactivity was determined to ensure the conservatism of the analysis. This was accomplished by performing sensitivity studies on these parameters with CASMO. Parameters evaluated were axial burnup distribution, water temperature/density, assembly placement, mechanical tolerances, poison loading, pellet density, cell dimensions/bow, borated water activity worth, Boral width tolerance, cell lattice spacing tolerance, stainless steel thickness tolerance, and fuel enrichment and density tolerance.

Although credit for soluble poison normally present in the spent fuel pool water is permitted under abnormal or accident conditions (double contingency principle), most abnormal or accident conditions would not result in exceeding the limiting reactivity (keff = 0.95) even in the absence of soluble poison. However, the inadvertent misplacement of a fresh fuel assembly in a location intended to be a water cell has the potential for exceeding the limiting reactivity and results in the worst-case accident scenario, should there be a concurrent loss of all soluble boron.

Misplacement of a fuel assembly outside the periphery of a storage module, or a dropped assembly lying on top of the rack would have a smaller reactivity effect. Under this worst-case accident condition, calculations show that approximately 55 ppm of soluble boron would be sufficient to ensure that the limiting keff of 0.95 is not exceeded. Assuring the presence of soluble boron during fuel handing operations would preclude the possibility of the simultaneous occurrence of the two independent accident conditions. Administrative controls require that the spent fuel pool boron concentration be monitored (to ensure at least 2000 ppm) during operations requiring fuel moves in the pool until verification is made of assembly locations.

The VANTAGE 5H fuel design was modeled as the design basis fuel. The VANTAGE 5H design contains a smaller guide tube outer diameter and thus slightly increased neutron moderation compared with the Westinghouse Standard 17x17 fuel assembly. In addition, VANTAGE 5H fuel assemblies have zircaloy spacer grids as opposed to the more neutron-absorbing material Inconel found on the Standard 17x1 7 fuel assembly. As a result of these differences, VANTAGE 5H fuel has a higher reactivity for a given enrichment than Standard 17x17 fuel. Therefore, analysis of VANTAGE 5H fuel covers the storage of Standard 17x17 fuel.

The analysis of VANTAGE 5H also covers and is bounding for the Robust Fuel Assembly (RFA) design. An analysis showed the RFA fuel design is less reactive than the VANTAGE 5H fuel design at the same enrichment. The ZIRLOmaterial used in the midgrids, fuel cladding and guide tubes has a slight reactivity penalty relative to ZIRC-4.

3.5 Effect of Proposed Changes The proposed changes do not affect the design or use of the existing spent fuel racks. No changes to the criticality analysis were made in association with this change. It has not been revised since it was reviewed and approved for Unit 1 in the safety evaluations for Amendment 6 and Amendment 40 of the Unit 1 operating license. Therefore, there is no effect on the criticality analysis, or any other safety analysis, for the WBN spent fuel racks.

Referencing TS Figure 4.3-3 from TS section 4.3.1.1.e.1 (new 4.3.1.l1.d.1) allows new fuel with enrichments up to approximately 3.84 weight percent U-235 with no burnup to be stored in locations that would have been limited to enrichments of 3.80 weight percent U-235 or less with no E1-7

burnup by the current Unit 1 TS. New fuel with initial enrichment between 3.80 and approximately 3.84 weight percent is the only fuel affected by this change. The use of the Figure 4.3-3 intercept changes the technical requirements for storage of new fuel assemblies in the spent fuel racks to include these additional initial enrichments. This change is acceptable as it is supported by the existing criticality analysis.

The proposed changes to the UFSAR, TSs, and TSs bases have been prepared and are awaiting implementation upon approval of this amendment request to reflect this change.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements and Criteria 10 CFR 50, Appendix A, General Design Criteria (GDC) 62, "Prevention of Criticality in Fuel Storage and Handling," requires the prevention of criticality by physical systems or processes, preferably by use of geometrically safe configurations.

10 CFR 50.68 specifies requirements for the prevention of criticality accidents and mitigating the radiological consequences of a criticality accident.

In addition to regulatory requirements, acceptable guidance for meeting the requirements for GDC 62 is included in American National Standards Institute (ANSI)/American Nuclear Society (ANS) 57.1, ANSI/ANS 57.2, and ANSI/ANS 57.3, which relate to the prevention of criticality accidents in fuel storage and handling.

The requirements of the proposed TS 4.3.1 changes conform to the above regulatory requirements and guidance.

The requirements for storage of new and spent fuel assemblies in the spent fuel racks as described in this LAR, and as presented in the proposed revision of the WBN Unit 1 TS, contains sufficient information pertaining to the prevention of criticality by ensuring that a subcritical array is maintained. The requirements for storage of new and spent fuel assemblies in the spent fuel racks comply with the requirements of 10 CFR 50.68.

4.2 Precedent TVA did not identify any applicable regulatory precedent regarding the changes proposed in this LAR.

4.3 Significant Hazards Consideration The proposed changes modify WBN Unit 1 TS 4.3.1 to resolve an identified discrepancy in the requirements for storage of new and spent fuel assemblies in the spent fuel racks between TS 4.3.1.1.d and TS 4.3.1.1.e.2. TVA proposes to delete 4.3.1.1.d and revise and renumber 4.3.1.1.e to state:

Fuel assemblies with initialenrichments less than a maximum of 5 wt% U-235 enrichment (nominally 4.95 +/- 0.05 wt% U-235) may be stored in the spent fuel racks in any one of four arrangementswith specific limits as identified below:

1. Fuel assemblies may be stored in the racks in an all cell arrangementprovided the burnup of each assembly is in the acceptable domain identified in Figure 4.3-3, depending upon the specified initial enrichment.

In addition, TS 4.3.1.1.e.3 is editorially revised to add a closing parenthesis to state:

E1-8

New fuel assemblies may be stored in 4-cell arrays with I of the 4 cells remaining empty of fuel (i.e., containing only water or water with up to 75 percent by volume of non-fuel bearing material).

No physical changes to safety-related systems, structures, or components are required.

TVA has concluded that the proposed changes do not involve a significant hazards consideration.

TVA's conclusion is based on its evaluation in accordance with 10 CFR 50.91 (a)(1) of the three standards set forth in 10 CFR 50.92, "Issuance of Amendment," as discussed below:

1. Does the proposed amendment involve a significant increasein the probabilityor consequence of an accidentpreviously evaluated?

Response: No.

No change is being made to the parameters or methodology in evaluated accidents. As a result, there is no increase in the likelihood of existing event initiators.

The analyses that determine the subcriticality available in the spent fuel pool and the associated acceptable cell loading patterns have not been changed. Thus the acceptance criteria as stated in the UFSAR are met. Implementing the change involves no facility equipment, procedure, or process changes that could affect the radioactive material actually released during an event. As a result, no conditions have been created that could significantly increase the consequences of any of the events evaluated in the UFSAR.

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

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

Response: No.

The proposed changes do not require any new or different accidents to be postulated because no changes are being made to the plant that would introduce any new accident causal mechanism. This LAR does not affect any plant systems that are potential accident initiators. The change in TS wording is consistent with the current plant spent fuel pool criticality analysis. No change to the fuel, spent fuel racks, or spent fuel pool water chemistry are associated with this change.

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

3. Does the proposed amendment involve a significantreduction in a margin of safety?

Response: No.

The proposed changes do not alter the permanent plant design, including instrument set points. The change to make a minor change to the fuel storage enrichment limit does not affect the transient behavior of non-radiological parameters (e.g., Reactor Coolant System pressure, Containment pressure) that are pertinent to a margin of safety.

Therefore, the proposed changes do not involve a significant reduction in a margin of safety.

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 operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, E1-9

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.

5.0 ENVIRONMENTAL CONSIDERATION

A review 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.

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ATTACHMENT 1 Proposed WBN Unit 1 TS Changes (Markups)

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 (shown in Figure 4.3-1) are designed and shall be maintained with:

a. Fuel assemblies having a maximum U-235 enrichment of 5.0 weight percent (wt%);

b. kf,< 0.95 if fully flooded with unborated water, which, includes an allowance for uncertainties as described in Sections 4.3.2.7 and 9.1 of the FSAR;

c. Distances between fuel assemblies are a nominal 10.375 inch center-to-center spacing in the twenty-four flux trap rack modules.

d. Fuel assemblies width e-n~rihments less than or equal to 3.80 weight percent U235 aro9 allowed unrestirited Storage.

e. Fuel assemblies with initial enrichments great8r thaRn 3.80 weight pr-ce.t aPd-less than a maximum of 5 PeFwe~t-Wt% U-235 enrichment (nominally 4.95+/- 0.05 PeF~e*t wt% U-235) may be stored in the spent fuel racks in any one of four arrangements with specific limits as identified below:

1. Spet-fFuel assemblies may be stored in the racks witheut-furth9r reetrictionsin an all cell arrangement provided the burnup of each assembly is in the acceptable domain identified in Figure 4.3-3, depending upon the specified initial enrichment.

2. New and spent fuel assemblies may be stored in a checkerboard arrangement of 2 new and 2 spent assemblies, provided that each spent fuel assembly has accumulated a minimum burnup in the acceptable domain identified in Figure 4.3-4.

3. New fuel assemblies may be stored in 4-cell arrays with 1 of the 4 cells remaining empty of fuel (i.e., containing only water or water with up to 75 percent by volume of non-fuel bearing material).

(continued)

Watts Bar Unit 1 4.0-2 Amendment 6, 40 Al-1

Design Features 4.0 7.07 6.5 5,0.

5.5 5.0 4.5.

4.0 3.5 3.0 2.5-2.0 1.5 1;0 0.5-:

0.03.1 Initial Enrichment wt% U-235 FIGURE 4.3-3 MINIMUM REQUIRED BURNUP FOR UNRESTRICTED STORAGE OF SPENT-FUEL OF VARIOUS INITIAL ENRICHMENTS (continued)

Watts Bar Unit 1 4.0-9 Amendment 40 A1-2

Design Features 4.0 14 _ _ _ _ _ _

~121_ _

, 4, UNACCEPTABLE 6BURNUP DOMAIN 2-96... .3'b T77. . . T 1111 ,

2. 3. 4.00 4. ".00 Initial Enrichment wt% U-235 FIGURE 4.3-4 MINIMUM REQUIRED BURNUP FOR 2X3A CHECKERBOARD ARRANGEMENT OF 2 SPENT FUEL ASSE-MBLIES W!THAND 2 NEW FUEL ASSEMBLIES OF 5 wt% U-235 ENRICHMENT (MAXIMUM)

Watts Bar Unit 1 4.0-10 Amendment 40 A1-3

ATTACHMENT 2 Proposed WBN Unit I TS Changes (Final Typed)

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 (shown in Figure 4.3-1) are designed and shall be maintained with:

a. Fuel assemblies having a maximum U-235 enrichment of 5.0 weight percent (wt%); I.

b. keff < 0.95 if fully flooded with unborated water, which, includes an allowance for uncertainties as described in Sections 4.3.2.7 and 9.1 of the FSAR;

c. Distances between fuel assemblies are a nominal 10.375 inch center-to-center spacing in the twenty-four flux trap rack modules.

d. Fuel assemblies with initial enrichments less than a maximum of 5 wt%

U-235 enrichment (nominally 4.95+/- 0.05 wt% U-235) may be stored in the spent fuel racks in any one of four arrangements with specific limits as identified below:

1. Fuel assemblies may be stored in the racks in an all cell arrangement provided the burnup of each assembly is in the acceptable domain identified in Figure 4.3-3, depending upon the specified initial enrichment.

2. New and spent fuel assemblies may be stored in a checkerboard arrangement of 2 new and 2 spent assemblies, provided that each spent fuel assembly has accumulated a minimum burnup in the acceptable domain identified in Figure 4.3-4.

3. New fuel assemblies may be stored in 4-cell arrays with 1 of the 4 cells remaining empty of fuel (i.e., containing only water or water with up to 75 percent by volume of non-fuel bearing material).

(continued)

Watts Bar Unit 1 4.0-2 Amendment 6, 40 A2-1

Design Features 4.0 7.0 .

6.5 6i 5

6.0 -

5.5 - ' -

ACCEPTABLE 5.0 BURNUP DOMAIN "

405l w

4.0- -- , -

3.5.-

3.0- --

2.5--

2.0 I I UNACCEPTABLE BURNUP DOMAIN 1.0 0.5 -- - -T- - - -

0.0 - , r -" r- I - ,r r ,- ,~ - Ir -I-3.0 4.00 4.0 Initial Enrichment wt% U-235 FIGURE 4.3-3 MINIMUM REQUIRED BURNUP FOR UNRESTRICTED STORAGE OF FUEL OF VARIOUS INITIAL ENRICHMENTS (continued)

Watts Bar Unit 1 Amendment 40 A2-2

Design Features 4.0 20 I

1 I

1 I

=

5-i Initial Enrichment wt% U-235 FIGURE 4.3-4 MINIMUM REQUIRED BURNUP FOR A CHECKERBOARD ARRANGEMENT OF 2 SPENT AND 2 NEW FUEL ASSEMBLIES OF 5 wt% U-235 ENRICHMENT (MAXIMUM)

Watts Bar Unit 1 Amendment 40 A2-3

ATTACHMENT 3 Proposed WBN Unit I UFSAR Section 4.3.2.7 Changes (Markup)

WBNP- 10 The VANTAGE 5H fuel design[50 ] was modeled as the design basis fuel. The VANTAGE 5H design contains a smaller guide tube outer diameter and thus slightly increased neutron moderation compared with the Westinghouse Standard 17x 17 fuel assembly. In addition, VANTAGE 5H fuel assemblies have zircaloy spacer grids as opposed to the more neutron-absorbing material Inconel found on the Standard 17x 17 fuel assembly. As a result of these differences, VANTAGE 5H fuel has a higher reactivity for a given enrichment than Standard fuel. Therefore, analysis of VANTAGE 5H fuel also covers storage of Standard 17x 17 fuel.

VANTAGE 5H fuel assembly data is provided in Table 4.3-12. The analysis model bounds the design basis fuel assembly using the data provided in Table 4.3-12 or a more conservative value depending on the specific calculation.

Starting in Cycle 2 with Reload 1, Watts Bar will use the Westinghouse fuel assembly designated a Vantage+/Performance+ (V+/P+). The V+/P+fuel design is less reactive than the VANTAGE 5H fuel design at the same enrichment. The ZIRLO material used in the midgrids, fuel cladding and guide tubes has a slight reactivity penalty relative to ZIRC-4.[sr] Therefore, the analysis of Vantage 5H also covers and is bounding for the V+/P+ fuel design. In addition, the analysis evaluated the Robust Fuel Assembly (RFA) design and determined that the Vantage 5H design is bounding for the bumups of interest.

Analytical Technique and Results The criticality analysis for the WBN racks were performed primarily with KENO5a, a three-dimensional Monte Carlo computer code, using the 238-group SCALE cross-section library and the Nordheim integral treatment for resonance shielding effects found in NITAWL. Depletion analyses were performed using CASMO4, a two-dimensional transport theory code. The models included explicit descriptions of the fission product nuclide concentrations, incorporating approximately 40 of the most important fission products.

Analysis of the spent fuel racks confirmed the racks can safely and conservatively accommodate storage of fuel up to 5 wt%/o U-235 enrichment with the following storage conditions:

1. Fuel assemblies with 3.8 v4 or-less U 235 enrichmeit may be stored withlut

-21. Fuel assemblies with initial enrichment greater than 3.8 ,0% U 235 and less than a maximum of 5.0 wt% U-235 (4.95+/-0.05 wt% U-235) may be stored in anyone of four arrangements with the limits specified below:

A. Fuel assemblies may be stored in the racks without faf'h-"rest.. tionsin an all cell arrangement provided the bumup of each assembly is in the acceptable domain identified in Figure 4.3-46, depending on the specified initial enrichment.

4.3-33 A3-1

7.0 R

C C

"a z

go I

Initial Enrichment wt% U-235 AMENDMENT 4 WATTS BAR NUCLEAR PLANT FINAL SAFETY ANALYSIS REPORT MINIMUM REQUIRED BURNUP FOR UNRESTRICTED STORAGE OF SPENT FUEL OF VARIOUS INITIAL ENRICHMENTS FIGURE 4.3-46 A3-2

10.

=i UNACCEPTABLE BURNUP DOMA/

2, -/___

2.D 6.4. 4. WO Initial Enrichment wt% U-235 AMENDMENT 4 WATTS BAR NUCLE R PLANT A FINAL SAF Y ANALYSIS RE ORT -3 MI UM REQUIR RNUP FOV 2-.4 CHECK R#DARD ARRANGEMENTOF ENT -,EN ASSEMBLIES W! NEW FUEL

,ASSEMBLIES OF 5Z NRICHMENT S-, - F IGURE.4..3-47

ATTACHMENT 4 Proposed WBN Unit I TS Bases Changes (Markup)

(For Information Only)

Spent Fuel Assembly Storage B 3.7.15 B 3.7 PLANT SYSTEMS B 3.7.15 Spent Fuel Assembly Storage BASES BACKGROUND The spent fuel pool contains flux trap rack modules with 1386 storage positions and-that are designed to accommodate new fuel with a maximum enrichment of 4.95:1 0.05 weight percent U-235 enrichment and fuel of various initial gnrirthmnta whn h ctnrarl in nt-nerr'rlnroa with nrcrnnh niab-.m 3.8 Weight percent U 235 without rostrictionS. Storage of fuel

assombios~r with ArnrihmAnt hbeteen 3.8 -and50- ~ h porcont requiros oithler fuel burnup in .cordanco with paragraph 4.3.1.1 or placement in storage locatone~s whc have face adjacent storage coils containing oithor water or 4

.nfit-

- - a 1% VtI 'n*a tAApnk~n..pqk A I an AtA r kiJ arm,. - nt ^- .. , --n.r. - ")A- A MVVW t KgU in accordanc9 with Specific.atin 4.3.1.1 in Section 4.3. Fuel Storage.

The water in the spent fuel storage pool normally contains soluble boron, which results in large subcriticality margins under actual operating conditions. However, the NRC guidelines, based upon the accident condition in which all soluble poison is assumed to have been lost, specify that the limiting keff of 0.95 be evaluated in the absence of soluble boron. Hence, the design is based on the use of unborated water, which maintains the storage racks in a subcritical condition during normal operation with the racks fully loaded. The double contingency principle discussed in ANSI N-16.1-1975, and the April 1978 NRC letter (Reference 1) allows credit for soluble boron under other abnormal or accident conditions, since only a single accident need be considered at one time. For example, an (continued)

Watts Bar-Unit 1 B 3.7-75 Revision 11, 61 Amendment 6, 40 A4-1