ML20052E545
| ML20052E545 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/05/1982 |
| From: | Lentine F COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20052E546 | List: |
| References | |
| NUDOCS 8205110220 | |
| Download: ML20052E545 (4) | |
Text
!
/^N Commonwealth Edison
) ona First Nitional Pttn, Chic;go Illinois 2
O '] Addr:ss R ply to: Post Offica Box 767 Cnicago, Illinois 60690 JP%
May 5, 1982
,f T
- g a,+ w, Mr. Harold R. Denton, Director C?
jm 1'0198F 3 Of fice of Nuclear Reactor Regulation d g gumzn3 NU U.S. Nuclear Regulatory Commission NC$f# g Washington, DC 20555 f
Subject:
Zion Station Units 1 and 2 N
Draf t Technical Specifications on Undervoltage Protection NRC Docket Nos. 50-295 and 50-304 Reference (a):
October 1,1980, letter from R. F.
Janece k to T.
M. Novak
Dear Mr. Denton:
In reference (a) Commonwealth Edison agreed to provide draf t Technical Specifications related to our proposed mooifications to provide a second level of Undervoltage Protection for the emergency power buses at our operating nuclear facilities.
Following discussions with members o f the NRC s taf f and consultants, we have developed the enclosed draf t Technical Specifications for Zion Station.
In February, 1982, the NRC posed a number o f questions following their review of an earlier draf t version of the proposed Technical Specifications.
Those questions were discussed in a conference call on February 24, 1982.
Attachment A to this letter provides Commonwealth Edison's responses to those questions.
Our current plans are to install the degraded voltage relays at Zion in each unit's first refueling outage following receipt of the necessary equipment.
At this time, we expect to begin installation in the Unit 2 refueling outage scheduled for Spring, 1983.
A formal request for a license amendment will be submitted prior to that time.
No te, however, that the amendment can not be made ef fective until the necessary equipment has been installed.
Commonwealth Edison will keep the NRC informed of our installation status.
Please address questions regarding this matter to this office.
O/I Very truly yours, Sjsend k
)
Frank G. Lentin e Nuclear Licensing Administrator Attachments 4055N 8205110220 820505 PDR ADOCK 05000295 j
P PDR
Attachment A Responses to Questions on Undervoltage Protection Technical Specifications 1.
Table 3.4-1 shows that the degraded voltage protection system consists o f-two-out-o f-two relay logic for each bus, that operation is allowable with one relay out of service (for any reason) and that no operator action is necessary with one relay out of service.
Per the NRC model technical specifications o f June 3, 1977, your technical specifications should require operator action, within one _ hour, to place an inoperable relay in the tripped position to keep the channel operational.
Response
Zion's existing Technical Specification 3.4.2.c (page 127) requires that failed channels or channels being tested be placed in the tripped mode.
2.
Table 3.4-1 shows that the degraded voltage relays will be set f
for 90% + 2% o f 4160V.
Your voltage analysis o f August 18, 1980 shows that this setpoint will not adequately protect the 480V motors from damage.
Per the NRC letter of June 3,1977, your setpoint, including tolerences, should be chosen as a result o f your analysis determined voltage requirements.
Response
Based on the results of our voltage analysis of August 18, 1980, the setpoint has been revised to 3846 volts 1 2%.
3.
The NRC understands that your degraded voltage channels are essentially identical to Dresden's and Quad Cities'; i.e., the degraded voltage relays have a minimum time delay before an aux-iliary timer is actuated.
The auxiliary timer is defeated, and the seperation of offsite power and the connection of onsite power is initiated with a safety injection signal.
This being t
l the case, your technical specifications should go beyond the model technical specifications o f June 3, 1977 and include the time delay and the tolerance of both the minimum time delay and
'the maximum time delay.
Responses The time delay has been specified as 5 1 5% minutes with 8 1 2 Seconds inherent time delay.
l
, 4.
The NRC letter o f June 3, 1977 requested that these relay channels ce given a functional test on a monthly basis, and a channel check on a shift basis.
Your propnsal does not con-form with this criteria.
Provide for adequate testing in your technical specifications to conform with this criteria.
Jus tif y in your basis any deviation from the testing requirements.
Response
The degradet voltage protection system will be tested on a monthly basis by actuation of each of the de-graded voltage relays, one at a time, by means of a test switch.
Since this test confirms relay actuation, it is somewhat more than a " channel check"; but it is not a complete functional test, since it does not include verification of timer operation.
The system will be given a complete functional test and calibration at each refueling outage.
The functional test will include verification of the operation of the 5-minute timer and the inherent 8-second delay.
Performance of these tests at the frequencies specified is judged to be sufficient to ensure proper system functioning.
This conclusion is based on the performance record of the existing first level undervoltage (blackout) protection system at Zion.
Over the past ten years, seventy - eight (78) successful functional tests have been performed, with no relay failures or significant setpoint drift.
The new relays for the second level undervoltage protection system are expected to perform as well or better than the older, first level relays.
Therefore, functional testing at a refueling frequency is judged to be sufficient for both the first and second level undervoltage protection systems.
5.
Your proposed diesel-generator testing (4.15.1.8.3.a) does not l
include verification that the load sequencer resets following a l
diesel generator circuit breaker trip.
This would be most easily accomplished by simulating the interruption and subsequent re-l connection of the diesel generator as discussed in the NRC letter o f June 3, 1977.
Provide this verification.
Response
The ability of the load sequencers to reset is checked as part of the existing station test procedures.
During this testing, the diesel generators are tested for simulated loss of of f-site power starting and safe shutdown (blackout) load sequencing, ano for starting on safety injection (SI) signal and SI load sequencing. Each sequencer is verified to reset following load sequencing.
con 't
, We understand that the NRC's desire for a test of load sequencer reset following diesel generator circuit breaker trip is associated with the following scenarios:
(1) SI signal with _ loss of o f fsite power, followed by diesel' generator trip, followed by restoration of offsite power; (2) SI signal with loss of offsite power, followed by diesel generator trip, followed by diesel generator restart and reconnection to the ESF bus.
Neither of these scenarios is appropriate for Zion Station.
In the first scenario, following restoration of o ffsite power, loads would not be sequenced automatically on to the ESF bus, but rather would be loaded manually as specified by station procedures.
With respect to the second scenario, all diesel generator trips are bypassed following a start from a safety injection signal, with the exception of overspeed and phase-dif ferential overcurrent.
These trips have a lock-out feature that precludes diesel generator restart until the trip condition has been cleared and manually reset.
Therefore, there is no possibility of a quick restart followed by automatic load sequencing, following a diesel generator circuit breaker trip.
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