ML20043A874
| ML20043A874 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 05/08/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20043A873 | List: |
| References | |
| NUDOCS 9005230225 | |
| Download: ML20043A874 (5) | |
Text
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1 E,NCLOSURE 2 f
SAFETY EVALUATION BY THE OFFICE 0F NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.138 TO FACILITY OPERATING LICENSE NO. DPR-77 I
TENNESSEE VALLEY-AUTHORITY
-SEQUOYAH' NUCLEAR PLANT, UNIT 1:
DOCKET NO. 50-327 a
~1.0' INTR'000CTION q
By letter dated January 12, 1990,- the Tennessee Valley Authority (TVA or' the,
. licensee) submitted a request for. changes to-the Sequoyah Nuclear Plant.
i Units 1 and 2 Technical Specifications-(Tss). which are needed for~ the use of -
VANTAGE 5' Hybrid (V5H) fuel assemblies for. the Sequoyah, Units 1 and 2' reload:
core and future cores.
The V5H fuel design evolved: from the V5H 0ptimized q
L Fuel Assembly-(OFA) andLStandard '(STD)ifuel assembly designs; TheLfeatures l-of the V5H fuel. assembly consist' of reconstitutable or removable: top nozzles,
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integral; fuel burnable adsorbers,L lower-pressure drop and snag-resistant.
l grids, debris filter bottom nozzles,(DFBNs), and the capability;of achieving extended burnups. These' features were previously reviewed and approved by.
J NRC in the Westinghouse' Electric Corporation topical report WCAP-10444-P-A,
" Reference Core Report-VANTAGE 5 Fuel Assembly," Addendum 2. (REF 1)'.'
In its letter, the licensee stated that'the evaluations performed for this new fuel accomodate the effects-from the following' modifications that are planned s
for the Cycle 4 refueling outage in'1990 for. each ' unit:
1.
Resistance temperature detector bypass elimination, 2.
Eagle 21 digital-protection system, 3.
Upper head injection removal, 4.
Boron injection tank deactivation.
5.
New steamline break protection, and 6.
Reactor trip on steam flow / feed flow mismatch.
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Unit 1 is currently in its Cycle-4 refueling outage and has put theLnew; fuel E
in the. core.
The new fuel will be used in the Unit 1 Operating Cycle'.5 once' it has restarted from the refueling outage. ~ Unit 2 will' shutdown for-its' Cycle 4 refueling outage in the fall of 1990. 'The new fuel will be put inLthe g
core at that' time.
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I Therefore, as a result of this fuel upgrade for Unit 1. TVA proposed to modify the Unit 1 TSs for the following changes:.(1) revise the TSs Bases for safety i
limits to refer to the WRB-1 correlation and to the associated safety analysis limit for departure from nucleate boiling ratio (DNBR); (2) revise TS 3.1.3.4 to l
incorporate a new rod drop time of less than or equal to 2.7 seconds;. (3) revise TS 3.2.3 to delete the rod bow penalty as a function of burnup in the FNH (Nuclear Enthalpy Hot Channel Factor) equation and delete Figures 3.2-3 and 3.2-4; (4) revise Table 3.2-1 and TS 3.2.5 to define the reactor coolant system l
(RCS) total flow rate limit, including uncertainties, to be 378,400 gallons.
perminute(gpm)forthedeparturefromnucleateboiling(DNB)parametersand add surveillance requirements for RCS total flow rate; and (5) revise the Bases for TSs 3.2.3, 3.2.5, and 3.4.1.
The titles in the index of the TSs for the following sections would also be revised: Section 3/4.2.3, Bases Section 3/4.2.2 and Bases Section 3/4.2.3.
The licensee provided additional information concerning the fuel' criteria used for the locked rotor analysis for the V5H fuel in its letter dated April 13, l
1990.
This information does not change the substance of-the. proposed action published in the Federal Register Notice (55 FR 4281) on February 7,1990 and does not affect the staff's initial determination of no significant hazards consideration in that notice.
2.0 EVALUATION During the staff's review of the VANTAGE 5 -fuel design in'WCAP-10444-P-A, the staff identified a few conditions to be resolved for licensees who proposed -
1 using the VANTAGE 5 fuel design.
Since the V5H fuel design adopts some features from the VANTAGE 5 fuel design, the staff's evaluation will address those conditions listed in the Safety Evaluation (SER) for WCAP-10444-P-A which could affect Sequoyah's V5H fuel. These conditions are the following:
(1)
Statistical Convolution Method In the SER on WCAP-10444, the staff stated that' the statistical convolution method should not be used in the VANTAGE 5 fuel.for evaluating the fuel rod shoulder gap. The licensee stated that the statistical convolution method was i
not used for the V5H fuel design for Sequoyah and the currently NRC approved method was used for evaluating the fuel rod shoulder gap. 'Therefore, the staff concludes that this is acceptable and the licensee has met this condition.
(2)
Irradiation Demonstration. Program In the SER on WCAP-10444, the staff required that an irradiation program be performed to confirm the VANTAGE 5 fuel performance.
The licensee stated that there were numerous demonstration programs involving 0FA fuel assemblies containing Zircaloy grids-irradiated in 14x14,15x15, and 17x17 fuel assembly array cores.
Sequoyah has a 17x17 core. The satisfactory performance of those demonstration assemblies resulted in 0FA with Zircaloy grids reload applications in many Westinghouse reactors.
The 0FA fuel assemblies with Zircaloy grids cover the-V5H fuel design features for Sequoyah; therefore, the staff concludes that the V5H fuel assemblies should perfonn satisfactc.*ily in Sequoyah and the licensees has met this condition.
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' (3)
Improved Thermal Design Procedure'(ITDTs In the SER on WCAP-10444, the staff stated that those restrictions in approving the use of Westinghouse improved thermal design procedure-(ITOP) should be j
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- applied to the VANTAGE 5 fuel design.
The licensee stated that they conform to these restrictions of ITOP for Sequoyah.
The staff, therefore, concludes that this is acceptable and the licensee has met this condition.
.(4) DNBR Limit In the SER on WCAP-10444. -the staff stated'that a plant-specific analysis should be performed to show that:the DNBR limit is not violated with the higher
- l value of FNH. The licensee. stated that'the V5H fuel for Sequoyah does not.
employ. higher v'alues of FNH, thus no reanalysis of-DNBR transients is needed..
s The staff, therefore, concludes' that: this condition is ' satisfied for V5H fuel at Sequoyah and the licensee has met this condition.
L (5) PositiveModeratorTemperatureCoefficient(MTC)
In the SER on WCAP-10444, the staff stated that if a positive moderator tempera-ture coefficient (MTC) is intended, the same positive MTC should be used in the plant-specific analysis. ~ The licensee stated that nol positive MTC was con-
.sidered for Sequoyah. The staff, therefore, concludes thatlthis condition is.
L satisfied for V5H fuel at Sequoyah.
(6) Reactor Coolant Pump Shaft' Seizure In the SER on WCAP-1044, the staff stated that the mi.chanistic approach.(2700*F peak clad temperature) in determining the. fraction of fuel failures during the l
reactor coolant pump seizure' accident was ' unacceptable and the, fuel failure -
criterion should be the 95/95 DNBR limit.
The licensee reanalyzed the reactor coolant pump shaft (locked rotor) accident based on a failure criterion ~of 95/95 DNBR limit:for V5H fuel. The licensee concluded that the fuel rod failure rate is less than 10% of the total ~ rods in'the core, which is bounded-in the FSAR analysis. The staff, therefore, concludes.that the reactor coolant pump shaft seizure accident is adequately. addressed. for 'V5H fuel!at Sequoyah.
2.2 Technical,Sec0ification Changes ThE proposed TS changes are related to the use of the V5H fuel at Sequoyah,=a new DNBR correlation, and'a new rod bow penalty methodology. 'The proposed changes are. evaluated below:
(1) TS Bases Section 2.1.1, Pages B2-1, B2-3, and B2-5' for Units 1 and 2 L
L The old W-3 DNBR correlation is changed to the WRB-1 correlation for standard and V5H fuel designs =.
This DNBR correlation has been approved by the staff for use in licensing applications. The staff concludes that these' changes are acceptable.
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(2) TS Bases Section 3/4.2.5 The phrase "a minimum DNBR of 1.30" is changed to "a minimum DNBR greater than or equal: to the safety analysis DNBR limit" because there is only one DNBR correlation intended for two different fuel designs.
The staff-concludes that this change is acceptable.
e (3) TS Section 3.1.3.4 The rod drop time is revised to be less than or equal to 2.7 seconds due to the use of the V5H fuel.
The increased rod drop time is due to the reduced-guide tube diameter for the V5H fuel grids and the resulting increased dash pot effect. The licensee has taken into account the effect of,the-increased-a rod drop time in the safety analyses.- The staff concludes that this change is 1
acceptable, y
.(4) TS Section 3/4.2.3, and TS Bases Sections 3/4.2.2 and 3/4.2.3 i
The rod bow penalty is revised to incorporate a new methodology.which reduces the rod bow penalty. The Figures 3.2-3 and 3.2-4 are being deleted.
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statisticalwethods have been developed by Westinghouse that verify that the past treatment of rod bow penalty provided an. overestimation of the affects on DNB. Application of the new methods to-Sequoyah for the standard and the V5H fuel has verified the reduction in rod bow penalty..The reduction allows.
for accomodation of the entire penalty in the establishment-of the DNBR safety limit. The licensee has demonstrated that the use of new DNBR correlations has enough margin to offset.the rod bow penalty ~at burnups greater than 24,000.-
mwd /MTU. The staff concludes that the proposed reduced rod. bow penalty is ~
acceptable for Unit 1.
(6) TS Section 3/4.2.5 These proposed changes are to include the reactor coolant system (RCS) total-flow rate in the list of DNB parameters. The RCS flow limit and its associated surveillance requirements have been moved from'TS 3/4.2.3 to TS 3/4.2.5, DNB parameters, which now establishes a' minimum allowable RCS flow to prevent violation of the DNB safety: limit during normal operation and accident conditions. The maximum limit of 378,400 gpm was established for this flow.
The staff concludes that these change are acceptable for Units 1 and 2.
2.3 Conclusion The staff has evaluated the licensee's submittal on the V5H fuel design and the proposed TS changes for Sequoyah Units 1 and 2 transition cores.and all future V5H cores.
Based on the NRC approved generic-topical. report WCAP-10444-P-A and the plant-specific Sequoyah analyses discussed above, the staff concludes that the use of V5H fuel at Sequoyah and-the proposed TS-changes for Sequoyah Units 1 and 2 are acceptable.
4 The transition cores are the cores starting from the reload core for the Operating Cycle 5 until all the fuel in the core are the V5H fuel.
Unit 1 is in its Cycle 4 refueling outage preparing to restart from the outage and begin its Operating Cycle 5.
Therefore, the Unit 1 TSs will be changed at this time. The Unit 2 TSs will be changed during its Cycle 4 refueling outage which is scheduled to begin in the fall of 1990.
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3.0 ENVIRONMENTAL CONSIDERATION
This amendment involves' a change to 4 requirement with respect to the installa-tion or use of a facility component located within the restricted area as j
defined in 10 CFR Part 20 and changes to the surveillance requirements. The-1 staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may 3
be released offsite, ano that-there is no significant increase in individual or cumulative -occupational radiation exposure. The Comission has previously issued a proposed finding that this amendment involves no significant hazards consideration and_ there.has been no public comment on such finding. Accord-ingly, the amendment meets the eligibility criteria for categorical. exclusion set forth in 10 CFR 51.22(c)(9). Pursuant:to 10 CFR 51.22(b), no environmental.
impact statement nor environmental. assessment need be prepared in connection with the issuance of.this amendment.
4.0 CONCLUSION
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The Comission maae a proposed cetermination that the amendment involves no significant hazards consideration which was published in the' Federal Register (55 FR 4281) on February 7,1990, and consultua.with the State of Tennessee.
No public comments were receivea and the State of Tennessee did not have any comments.
The staff has concluded, based on the considerations discussed =above, that:
(1)-there is reasonable assurance that.the' health.anc safety of the public will _ not be endangered by operation in the proposed manner, and '(2). such activities will be conducted in compliance with the Ccmission's regulations, and the issuance of the amendments will not be inimical to the comon defense dnd security nor to the health and safety of the public.
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5.0 REFERENCE l
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1.0 Letter from C. Thomas (NRC) to E.P.' Rahe (Westinghouse Electric Corporation),
Subjecti
" Acceptance For Referencing of Licensing Topical Report WCAP-10444,
' VANTAGE 5 Fuel Assembly;" dated July 18, 1985.-
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Principal Contributor:
S. Wu Da ted: 'May 8, 1990 1
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