ML19242A309
| ML19242A309 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 07/02/1979 |
| From: | Lainas G Office of Nuclear Reactor Regulation |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| TAC-10007, NUDOCS 7908010351 | |
| Download: ML19242A309 (4) | |
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UNITED STATES s.j d)., c '( h yy.
NUCLEAR REGULATORY COMMISSION p,C WASHINGTO;J, D. C. 20555
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JUL 2 M79 MEMORANDUM FOR:
A. Schwencer, Chief, Operating Reactors Branch #1, Division of Operating Reactors FROM:
G. Lainas, CYef, Plant Systems Branch, Division of Operating Reactors
SUBJECT:
BEAVER VALLEY UNIT 1, REQUESi FOR ADDITIONAL INFORPr !0N FOR DEGRADED GRID VOLTAGE (TAC 10007)
Plant Name:
Beaver Valley Unit 1 Docket No.
50-334 Responsible Branch:
ORB #1 Project Manager:
D. Wiggington Reviewing Branch:
Plant Systems Branch Status:
Awaiting Information In response to technical assistance request TAC 10007, the Plant Systems Branch has reviewed the licensee's gubmittal of March 7, 1979 and found that additior.al information is required in order to complete our re tiew.
The attached request for additional information should be forwarded to the licensee as soon as poscible with a reques t for response wi'! in 45 days.
G. Lainas, Chief Plant Systems Branch Division of Operating Reactors
Contact:
S. Rhow. X28077 C. Cleveland, EG&G
Enclosure:
A: stated cc w/ enclosure:
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cc w/ enclosure:
D. Eisenhut R. Vollmer B. Grimes W. Russell D. Silver G. Lainas D. Tondi M. Chiramal P. Shemanski S. Rhow C. Cleveland, EG&G r
REQUEST FOR ADDITIONAL INF0PJ4ATION BEAVER VALLEY POWER STATION DEGRADED GRID VOLTAGE (TAC 10007)
Upon review of your submittal of March 7,1979 concerning the staff positions on second level undervoltage protection several areas are in need of clarification.
Specifically:
- 1. Your proposal to add an additional undervoltage relay on each 4160V emergency bus does not satisfy the criterion of staff position 1 of the June 3,1977 letter or of IEEE 279-1971.
Please submit a proposal concurrent with this position.
- 2. The proposed setpoint of 90% voltage the 4160V bus may not be sufficient.
A review of your voltage analysis dated November 11, 1976, item 1.b., states tilat when the 4160V bus is at 3820V (91.8%)
the 480V bus is at 394V (82%).
Based on these figures it is interpretea that an approximate 10% voltage drop exists between the 4160V bus and the ?S0V bus when under load.
Therefore, please furnish a voltage drop analysis by calculation or masurement of the full load voltage at the 480V bus corresponding to the proposed sett oint on the 4160V bus.
- 3. The proposed time delay of 1 minute williprecl,.de spurious trips for short duration degradations and motor stat ting voltage drops.
However, it conbined with the approxicate 801 voltace at the 480V emergency busses may be too long.
Substantiate by 2nalysis that the safety related equipment can withstand this low voltage and time uelay without thermal damage.
( As stated in our January 16, 1979 letter, this setpoint reflected down to the 480" emergency busses is below the minimum allowed operating voltage pa MSI C84.1-1973 anc recognized industry practice.)
4 Position 2 of the staff's tter of June 3,1977 re',uires the bypass of load shed features once the onsite power sources are supplying power to the emergency busses.
It e'so requires the automatic reinstatement of load shedding upon a trip of the onsite supply breakers.
In as much as the starting of large induction rnotors on the emergency busses can cause large transients in voltage this bypass is necessary.
The undervoltage relay on the 4160V bus that initiates load shedding in 3 seconds could cause emergency loads to be shed when they are most needed.
Therefore, include the bypass and auto reinstatement features in your proposed design.
- 5. Yourproposed Technical Speci#ication changes do not meet our position 1.f.
Namely the limiting conditions for operation, surveillance requirements, trip setpoint with minimum ano maximum linits and allowable values for the second level undervoltage onitors have not been provided.
These changes would follow "odel Technical Specification (MTS) format as close as possible.
See enclosure 2 of the June 3, 1977 letter.
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. 6. Justify why :le loss-of-offsite power relays are not on the emergency buc and not designed as a Class lE system when their sole purpcse is an engineered safety feature.
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