ML20078G303
| ML20078G303 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/30/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20078G298 | List: |
| References | |
| NUDOCS 8310120048 | |
| Download: ML20078G303 (2) | |
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mv SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 31 TO FACILITY OPERATING LICENSE DPR-77 AND AMENDMENT NO. 22 TO FACILITY OPERATING LICENSE DPR-79 TENNESSEE VALLEY AUTHORITY i
INTRODUCTION In letters dated June 15, July 29 and September 21, 1983 Tennessee Valley Authority (TVA) requested a change to the diesel generator surveillance require-ments. The proposed surveillance requirements for the diesel generators would reflect the actual as-designed logic that exists for the Sequoyah Units 1 and 2.
The present design protects the diesel generator frem a sustained overcurrerit condition when in parallel with offsite power.
It does not have, however, the added feature of returning to a standby status if a safety injection signal occurs while in the test mode (parallel to offsite power).
l EVALUATION The technical specification requires verification at least once per 18 months during shutdown that, with offsite power available, the emergency diesel generator (EDG), while operating in a test mode and connected to its bus, shall return to standby operation with the initiation of a simulated safety injection signal (SIS).
This test is required with and without a concurrent SIS actuation signal. The Sequoyah Nuclear Plant design does not incorporate the return of the EDG to l
standby status under simulated SIS. However, with both SIS and loss of offsite power this function is accomplished via instantaneous overcurrent relays which l
trip tne diesel generator output breaker and return the EDG to standby operation.
l TVA states that while the EDG is under test, it is connected in parallel with the l
l offsite power source to the 6900 volt shutdown board. With either the normal or alternate offsite feeder breaker in closed position, the instantaneous overcurrent relays (one per phase) are placed into the EDG breaker trip circuit.
With the loss of offsite power to the shutdown board the respective normal or alternate breaker will open after a five-second delay. During this delay the EDG will see an overcurrent (approximately 457.) and its output breaker will open within 5 cycles.
The EDG will remain in the no-load running condition with all non-critical trips except for engine overspeed and generator differential bypassed. During this interval the loss of voltage relays on the emergency bus will clear all loads, and since the EDG is on ready standby will command the sequencing of loads on to the EDG. With offsite power available, if any SIS is initiated while the EDG is under test, the Class IE equipment will continue to run without interruption and the EDG will continue to operate in parallel with offsite power. The return of the diesel to standby operation is accomplished by manual action. TVA has proposed to verify the operation of the overcurrent relays while the EDG is in the test mode as a l
replacement to the surveillance requirement outlined in Section 4.8.1.1.2.d.11 of 8310120040 t330930 I
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Sequoyah's present technical specification. This revision deviates from the Stand-ard Technical Specifications.
This plant technical specification which requires testing of the test mode override feature was based on the Standard Technical Specifications which were in turn based on R.G. 1.108. This test requirement applies to designs where on SIS occurrence with offsite power available, the DG is automatically isolated from the bus and returned to standby mode..Since this function is manually performed in Sequoyah, the referred technical specification requirement is not applicable to Sequoyah and hence should be deleted.
ENVIR0! MENTAL C0!!SIDERATIO!{
We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power Svel and will not result in any signif-icant environmental impact. Having made t..
Stermination, we have further con-cluded that the amendment involves an action e.sch is insignificant from the stand-point of environmental impact and, pursuant to 10 CFR 51.5(d)(4),thatanenviron-mental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
C0fiCLUSION The Commission made a proposed determination that the amendments involve no signifi-cant hazards consideration (SHC) which was published in the Federal Register (48 FR 38382)onAugust 23, 1983, and consulted with the state of Tennessee. fio public comments were received and the state of Tennessee did not have any comments.
We have concluded, based on the considerations discussed above, that: (1)thereis reasonable assurance that the health and 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 Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated: September 30, 1983 Principal Contributor: Carl Stahle, Licensing Branch No. 4. DL John Emami, Power Systems Branch, DSI
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