ML20248L196
| ML20248L196 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 06/08/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20248L194 | List: |
| References | |
| NUDOCS 9806100489 | |
| Download: ML20248L196 (3) | |
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NUCLEAR REGUL.ATORY COMMISSION WASHINGTON, D.C. 30086 0001 Sg....
SAFETY EVALUATION BY THE C FICE OF NUCLEAR REACTOR REGULATION RFI ATED TO AMENDMENT NO. 232 TO FACILITY OPERATING LICENSE NO.
DPR-77 AND AMENDMENT NO. 22E TO FACILITY OPERATING LICENSE NO. DPR-79 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT. UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328
1.0 INTRODUCTION
The Tennessee Valley Authority (TVA, the licensee) requested amendments to Operating Licenses DPR-77 and DPR-79 for Sequoyah Nuclear Plant (SQN), Units 1 and 2, respectively, in a letter dated February 13,1998. The amendments would revise the SON Ur?s 1 and 2 Technical Specifications (TS) by adding a new Limiting Condition for Operation (LCO) 3.7.1.6 that addresses the requirements for the main feedwater isolation va!ve funct!ons required by the SON accident analysis. These functions include the main feedwater isolation valves (MFIVs),
main feedwater regulating valves (MFRVs), and MFRV bypase valves. The LCO would require the operability of these valves in Modes 1,2, and 3 and would require retuming an inoperable valve to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This time limit will not apply if actions to close or isolate the feedwater path have been completed. With two valves in the same main feedwater flow pa'h inoperable, the flow path is required to be isolated within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The proposed changes would require placing the plant in hot shutdown conditions if the actions or completion times are not satisfed.
2.0 BACKGROUND
. Section 182a of the Atomic Energy Act requires applicants for nuclear power plant operating licenses to state TS to be included as part of the license. The Commission's regulatory requirements related to the content of TS are set forth in 10 CFR 50.36. That regulation requires that the TS include items in five specific categories, including (1) safety limits, limitino safety system settings and limiting control settings; (2) limiting conditions for operation; (3) surveillance requirements; (4) design features; and (5) administrative controls.
The U. S. Nuclear Regulatory Commission'(NRC) issued Generic Letter (GL) 96-01, " Testing of Safety-Related Logic Circuits," on January 10,1996. TVA identified the need to add the feedwater isolation vslve function to the TS during the review for GL 96-01. The current SON TS do not have LCO requirements for the valves that support the feedwater isolation function The TVA smondment request states that the proposed LCO addition will satisfy the current requirements for 10 CFR 50.36.
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2 3.0 EVALUATION The main foodwater system valves isolate flow to the steam generators when required to mitigate the consequences of a steam line break, feedwater line break, excessive feedwater
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flow, and loss of normal feedwater (and station blackout) accident. Each foodwater line, consisting of an MFIV and an MFRV and associated oypass valve, has redundant isolation capability. When these valves are closed by a closed manualisolation valve, the safety function is fulfilled. A high-high steam generator level or safety injection actuation' condition will initiate this isolation function. The LCO would require the operability of these valves in Modos 1,2, and 3 and would require retuming inoperable valves to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
This time limit will not apply if actions to close or isolate the feedwater path have been completed. With two valves in the same flow path inoperable, the affected flow path is required I
to be isolated within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The proposed actions would also require placing the plant in hot shutdown conditions if the specifieKi action or completion time is not satisfied. An action is provided, for inoperable valves that satisfy the LCO actions by being closed or isolated, that verifies they are in this condition once every seven days. Each valve can enter these actions individually. Mode change is allowed with inoperable valves as an exception to TS 3.0.4.
Further, TVA proposed a surveillance requirement that will ensure that the valves will actuate on an actual or simulated automatic actuation signal.
i TVA proposes this change to ensure the availability of. safety systems for accident mitigation.
TVA adds a more conservative requirement in this request that will ensure the availability of accident mitigation functions. TVA test procedures verify the operability of these valves consistent with the proposed TS change and the design basis functions. TVA also complies with the expectations of 10 CFR 50.36 by adding this requirement to the SON TSs. This change meets the intent of the improved Standard TS (STS) for Westinghouse plants, NUREG-1431, Revision 1, " Standard Technical SpecMcations - Westinghouse Plants."
The proposed 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> completion time is acceptable because it takes into account the redundancy afforded by the remaining operable valves and the low probability of an event requiring feedwater isolation during this time period. With two valves in one flow path inoperable, the main feedwater automatic isolation function is lost. The 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> completion time for this condition is acceptable, based upon operating experience to complete the actions to isolate the flow path plus the low probability of an event requiring feedwater isolation during this i
time period. These completion times are also consistent with NUREG-1431.
1 Therefore, the addition of a limiting condition for operation to the SQN TS for the MFIVs and i
MFRVs and associated bypass valves will support the safety functions assumed in the accident analysis to minimize the consequences of an accident. The NRC staff, therefore, finds this change to be acceptable.
4.0 STATE CONSULTATION
i in accordance with the Commission's regulations, the Tennessee State official was notified of the proposed issuance of the amendments. The State official had no comments.
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5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes I
surveillance requirements. The NRC 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 be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (63 FR 19979, dated April 22,1998). Accordingly, 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 or environmental assessment need be prepared in connection with the issuance of the amendments.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (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 i
Commission's 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.
Principal Contributor: Ronald W. Heman Dated:
June 8, 1998 I-[
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