ML20248C175
| ML20248C175 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/31/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20248C083 | List: |
| References | |
| NUDOCS 8908090448 | |
| Download: ML20248C175 (4) | |
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NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D. C. 20655 6
ENCLOSURE 3 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 121 TO FACILITY OPERATING LICENSE NO. DPR-77 AND AMENDMENT NO. 110 TO FACILITY OPERATING LICENSE NO. DPR-79 I
TENNESSEE VALLEY AUTHORITY l
SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 l
DOCKET NOS. 50-327 AND 50-328
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1.0 INTRODUCTION
By letter dated March 27, 1989, the Tennessee Valley Authority (TVA) proposed changes to the Sequoyah Nuclear Plant, Units 1 and 2, Technical Specifications (TS). The proposed changes would increase the value of the base current for.;
the containment air return fans (CARF), in Surveillance Requirement (SR) 4.6.5.6, from 28 to 32 amperes. The band for ;n acceptable current, 7.5 amperes, is not being changed by this propm ed action.
2.0 EVALUATION.
The CARF system is described in Section 6.6 of the Sequoyah Final Safety Analysis Report.
There are two 100% capacity air return fans in the contain-ment.
Their primary purpose is to enhance the ice condenser and containment spray heat removal operation during an accident by circulating air from the upper compartment to the lower com'sartment, through the ice condenser, and then back to the upper compartment. The secondary purpose is to limit hydrogen concentrations in potentially stagnant regions of containment by ensuring a flow of air from these regions.
The surveillance test of the fan motors involves blocking the respective back-draft damper of the CARF and covering the damper with a tarpaulin. This is to prevent full-flow conditions and the inadvertent opening of the ice condenser doors. The existing plant configuration and design does not allow periodic full-flow testing of the fans to be performed because of the detri-mental effects that this type of testing would have on the ice contained within the ice condenser. A full-flow test of each fan was performed under (VA's preoperational testing program before initial plant startup.
The test confirmed the ability of each fan to move the proper amount of air. The base current value of 28 amperes in SR 4.6.5.6 is from the current measured for the motors for the preoperational surveillance test with the back-draft damper blocked and covered.
After the surveillance test is run with the back-draft damper blocked and covered, TVA stated that the fan is stopped, the damper is uncovered, unblocked, and verified to operate correctly by checking the torque value required to open the damper and the fan is placed in standby position.
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In its submittal, TVA explained that the CARF motors are rated 460-V ac and 58 amperes (fullload). The cables are rated for this current. A review of data from the surve111ance tests shows that the average ampere for the CARF motors is approximately 31.6 amperes (data average through 1985) and approximately 33.5 amperes (post-1985 data average). This data is in Attachment 1 of TVA's submittal. TVA stated that the amperage values obtained are only test values and do not affect calculations that are associated with the system's safety 1
analysis. These amperage values are lower than the design rating of the CARF motors because these tests were performed under normal environmental ccuditions l
and not accident conditions. The containment air during surveillance tests will be at different conditions than would exist under postulated accident conditions; and the CARF current values obtained would be expected to be lower under a non-accident-type environment of the surveillance tests.
TVA stated that the surveillance test data indicates that the base amperage value of 28 amperes is too low because the amperage values have consistently remained on the upper end of the amperage window and because the base amperage value of 28 amperes was determined prior to initial plant operation by perfor-mance of a single test for which the test conditions are not documented.
The' proposed base amperage value of 32 amperes was determined from surveillance data obtained from 1980 to 1988 during operating conditions. This increase does not affect the system's operation or function, but merely allows the establishment of a better base current value to verify CARF operability.
The staff has reviewed the TVA submittal dated March 27, 1989.
It concludes that the base fan motor current value in SR 4.6.5.6 should be increased to 32 amperes to agree with the average of the surveillance test data from 1980 to the present.
The current value of 28 amperes was only based on the perfortaance of a single test. All of the surveillance tests have resulted in measured ampere values greater than the current 28 amperes.
The band for an acceptable current (i.e.,
7.5 amperes) is not being changed by this proposal. The staff concludes that the proposed change is acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
These amendments involve a change to a requirement with respect to the instal-lation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements. The staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Comission has previously issued e proposed finding that these amendments involve. no significant hazards consideration and there has been no public comment en such finding.
Accord-ingly, the amendments meet 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 to be prepared in connection with the issuance of these amendments.
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4.0 ',0NCLUSI(W I
I The Comission made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Register (54 FR 15838) on April 19, 1989, and consulted with the State of Tennessee.
No public comments were received and the State of Tennessee did not have any
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J The staff has concluded, based on the considerations discussed above, that-(1) there is reasonable assurance that the health and safety of the public l
will not be endangered by operation in the proposed raanner, and (2) such activities will be conducted in compliance with the Commission's regulations, i
and the issuance of the amendments will not be inimical to the common defense and security nor to the health and safety of.the public.
Principal Contributor:
J. Donohew Dated:
July 31, 1989 L
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Document Name:
- SHOLLY 88-27 Requestor.'s - ID:
SANDERS j, 4-Author's;Name:
JDonohew'
-Document' Comment's:
Request for Publication S-A y
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