ML20070E577
| ML20070E577 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/11/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20070E576 | List: |
| References | |
| NUDOCS 9407150198 | |
| Download: ML20070E577 (2) | |
Text
f.
p @*vt s
4 UNITED STATES p*
j j
NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20566 4001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.184 TO FACILITY OPERATING LICENSE N0. DPR-77 AND AMENDMENT NO.176 TO FACILITY OPERATING LICENSE NO. DPR-79 TENNESSEE VALLEY AUTHORITY SE000YAH NUCLEAR PLANT. UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328
1.0 INTRODUCTION
By application dated May 16, 1994, the Tennessee Valley Authority (the licensee) proposed amendments to the Technical Specifications (TS) for Sequoyah Nuclear Plant (SQN) Units 1 and 2.
The requested changes would change the wording of the Electrical Power Systems Surveillance Requirement (SR) 4.8.1.1.1.b to reflect the use of the new common station service transformers with auto load tap changers as the normal power supply for the 6.9 kilovolt (kV) unit boards.
2.0 EVALUATION The 161 kV switchyard is the preferred power supply for station loads during normal and accident conditions.
The common station service transformers (CSSTs) are powered from the 161 kV switchyard and, at present, are the alternate power supply for the 6.9 kv unit boards.
Each of the two unit station service transformers (USSTs) are powered from its main generator and is, at present, the preferred power supply for the 6.9 kV unit boards when the generator is operating.
Power can be transferred either manually or automatically from the USSTs to the CSSTs and SR 4.8.1.1.1.b requires that this feature (manual and automatic transfer from the normal power supply to the alternate power supply) be tested at least once every 18 months.
1 TVA has replaced the existing CSSTs with new CSSTs that have auto tap changers to accommodate voltage variations in the 161 kV system. The existing CSSTs use manual, off-line, tap changers; whereas the new transformers will be able to adjust secondary voltage to plus or minus 10 percent by using 16 taps that i
provide 1.25 percent adjustment per tap. The changer is capable of changing j
taps at the rate of approximately one tap each second after a two-second delay. The delay prevents unnecessary operation of the tap changer for momentary voltage changes on the 161 kV bus.
With installation of the new CSSTs, the normal lineup for powering the 6.9 kV j
unit boards will be changed so that normal bus power will be supplied from the CSSTs and alternate power supplied from the USSTs.
Thus, it will no longer be i
necessary to transfer power during unit startups and shutdowns, or to rely on 9407150198 940711 PDR ADOCK 05000327 P
1
<e automatic power transfer in the event of a fault or plant trip in order to maintain power to the 6.9 kV unit boards. However, since this feature will continue to be available should it be necessary for maintenance, the SR is being retained but the circuit designations reversed. Therefore, in order to provide a more accurate indication of the transfer requirements when normal l
alignment is changed to the CSSTs, the licensee proposed changing the word i
" normal" to " unit generator supported" and " alternate" to " preferred power (GDC 17)" in SR 4.8.1.1.1.b.
Since the wording change to SR 4.8.1.1.1.b does not change the testing frequency nor the test method (i.e., the test continues to show that power can be transferred from the USSTs to the CSSTs manually and automatically), the staff finds the proposed change acceptable.
3.0 STATE CONSULTATION
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.
i
4.0 ENVIRONMENTAL CONSIDERATION
i The amendments change a requirement with respect to installation or use of a i
facility component located within the restricted area as defined in 10 CFR i
Part 20. The NRC' 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 r
exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (59 FR 29637). 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.
5.0 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 Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: David E. LaBarge Dated: July 11, 1994
-+
c,
'j AMENDMENT N0. 184 FOR SEQUOYAH UNIT NO. 1 - DOCKET NO. 50-327 and AMENDMENT NO. 176 FOR SEQUOYAH UNIT NO. 2 - DOCKET NO. 50-328 DATED: July 11, 1994 DISTRIBUTION:
Docket Files NRC & Local PDRs SQN Reading File S. Varga 014-E4 F. Hebdon B. Clayton D. LaBarge E. Merschoff RII M. Lesser C. Berlinger 07-El l
OGC 015-B18 G. Hill T5-C-3 (2 per docket)
C. Grimes 011-E22 ACRS(10)
OPA 02-G5 OC/LFDCB T9-E10 cc:
Plant Service List m