ML19345G124
| ML19345G124 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 12/05/1973 |
| From: | Searls F PACIFIC GAS & ELECTRIC CO. |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 8757, NUDOCS 8103020642 | |
| Download: ML19345G124 (3) | |
Text
.
Re~uk.tCq Fi's Cy.
PACIFIC GAS AND ELECTR,IC C O M PANY h b*f#3 l
77 BEALE S TREET e SAN F R A NCISCO, C ALIFOR NI A 94106 * (415) 781 4213 me. eem, 7mEDERicK T.sEAmLS g- ;.f".*yj,
,"*f3' December 5, 1973 a........... 6 c - m j _s
.,os = c. uoa a ssa e v g
,s,i gg----
y.....
,,N
<g y
. ~..
..m
. u......uo..
g-g (, 1 :s
- .*ff,".*,-';: ::..
..u..-.
,o-=.
1
-.. + ~. -
3 y
..tcou.
y 9Q Q;
- .;. =,":.;.*.;.y,~~
ca. 6
.v.-.=naw...
gg
- 6 e o 6
.... c.n u o.
i gl.
.......c..,...
p).
w% g'D Q=',;".{.:.5.
- ~ ~ ~ ' " ^ '
8 9,*3'E:E
Director 3
Directorate of Licensing
- 2" *a*O~~
- * ~ ~ ' ~ "
=g \\
Office of Regulation Dt
- 0. I U. S. Atomic Energy Commission f,
Washington, D. C. 20545
,;, M,
Re:
Docket No. 50-133 NC[
C Gb* h License No. DPR-7 e, %p/jg., &
Appendix A t-
.p;,.,
J //e Section IX.H.2.a(2)
Dear Sir:
3 Pursuant to Section IX.H.2.a(2) of Appendix A to the Hum-boldt Bay Power Plant Unit No. 3 Facility Operating License, we are hereby notifying you of a malfunction of the propane engine driven generator.
The malfunction was discovered during the performance of a routine monthly test on November 26, 1973.
The propane engine driven generator is given two types of routine tests.
One test consists of starting the engine remotely on a tri weekly basis and allowing it to run a minimum of one-half hour.
The other test is a routine monthly test which satisfies the Technical i
l Specification testing requirement (Section VI A.7.d.).
The performance of the routine monthly operational test for the propane engine generator simulates a low voltage condition on the normal section of Load Center No. 10, which automatically starts the engine generator preparing it to receive the load on the emergency l
section of Load Center No. 10.
Although an actual transfer of load is blocked the automatic transfer circuitry is verified when the engine generator is started.
On November 26, 1973, low voltage was simulated on the normal section of Ioad Center No.10, but the engine generator did not start (there was no indication that the engine tried to crank).
Three attempts were made to start the engine generator from the load center test station, all without success.
An attempt was made to start the engine generator from the engine generator local control panel, but this attempt also failed (engine did not crank).
At this point it was noticed that the cranking limiter was in the tripped position.
The cranking limiter was reset and a second attempt to start the engine generator was made from the local control panel; the engine f.
(..
Director, Directorate of Licensing December 5,1973 U. S. Atomic Energy Commission Page 2 generator started immediately.
After the engine generator had been operating for approximately 35 seconds, the cranking limiter again tripped.
This action did not cause the engine generator to trip, but would have prevented it from starting subsequent to its shutdown.
The engine generator was shut down, the cranking limiter was reset, a low voltage was simulated on Load Center No. 10, and the engine generator satisfactorily started.
The cranking limiter again tripped after 35 seconds of engine generator operation.
The engine generator was manually shut down, and an attempt was made to restart the engine generator for Load Center No. 10 with the cranking limiter still in the tripped condition; this attempt failed.
The cranking limiter was reset and the engine generator was started and allowed to remain run-ning until the electrical maintenance department could examine the cranking limiter.
The total elapsed time from the first attempt to start the engine generator until it was left in the operating condi-tion was less than one hour.
Examination of the cranking limiter revealed an open resistor in the circuit.
The resistor was replaced and the engine generator was returned to service.
The engine generator was then started locally and from Load Center No. 10 and performed properly.
The engine generator has started and performed satisfactorily during the three tests run subsequent to the repairs.
The malfunction is the first time a failure of this type has occurred.
At the time of the test, the propane engine generator was not required to satisfy the on-site power requirements as given in Section VI.B.7.a. of the Technical Specifications.
Emergency power was avail-able to the emergency section of Load Center No.10 by the normal backup source from Load Center No. 5 on Unit No. 1.
Off-site power sources were normal.
The malfunction was corrected and the engine generator returned to service within six hours.
Subsequent investigation re-vealed that the malfunction had probably occurred during the last routine tri-weekly test on November 23, 1973.
This means that the engine generator was unavailable for automatic starting since Novem-ber 23 and as such the plant was unknowingly operated in violation of Section VI.B.7.a. of the Technical Specifications.
During the period when the engine generator was unavailable, both 115 KV lines were in service, Unit No. 1 was operating, and all systems and components which are required for normal operation, the safe shutdown, and maintenance of safe shutdown even under accident conditions were in their normal operating or standby condition, with no trends existing which indi-cated imminent departure from normal conditions.
On November 26, 1973, a Region V Regulatory Operations Re-actor Inspector arrived on site to conduct a routine inspection.
He was informed of the malfunction and was told that the preliminary examination indicated that the resistor had failed on November 26, 1973.
Following our investigation he was notified that the failure had occurred on November 23, 1973.
O~
?
(,
Director, Directorate of Licensing.
December 5, 1973 U. S. Atomic Energy Commission Page 3 A review of the protective circuits ors the propane engine generator will be made to determine whether any change in the pro-tection circuitry is desirable.
Consideration will be given to eliminating unnecessary protective devices including the cranking limiter, oil pressure, and water temperature trips.
This review will include contacting the vendor for additional operating informa-tion.
Very truly yours, O,
CC:
Director Directorate of Regulatory Operations Region V U. S. Atomic Energy Commission P. O. Box 1515 Berkeley, California 94701 1
l l
i l
..