ML20212D960
| ML20212D960 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 12/22/1986 |
| From: | Koester G KANSAS GAS & ELECTRIC CO. |
| To: | Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 85-010, 85-10, KMLNRC-86-238, NUDOCS 8701050187 | |
| Download: ML20212D960 (4) | |
Text
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KANSAS GAS AND ELECTRIC COMPANY TD-ei ELECTAC COMPANY G L E N Pe L MOESTER
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December 22, 1986
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Mr. R. D. Martin, Regional Administratoe.
U.S. Nuclear Regulatory Commission L
I-M Region IV 611 Ryan Plaza Drive, Suite 1000 l
Arlingl.on, Texas 76011 KMLNRC 86-238 Re Docket No. 50-482 Subj:
Special Report 85-010, Supplement 1
Dear Mr. Martin:
The enclosed Special Report is submitted pursuant to Technical Specifications 4.8.1.1 3 and 6.9.2.
Youra very truly,
'g
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h Glenn L. Koester Vice President - Nuclear OLK oes 00: P0'Connor (2)
JCummins G7010501s7 861222 gDR ADOCK 03000402 PDR
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<e h* Y ll 201 N Market -Wictuta, Kansas - Mail Address: PO. Box 208 I W1chita, Kansas 67201 - Telephone: Area Code (316) 261645 t
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t SlWI'IAL REPORT 85-919, SUPPIDENT 1 i
i DIESEL GENERA'UR 'A' FAIIERES s
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.00 October 1 1985. tic failures (.,f diesel generator ' A' occurred. %is supplen.e'ntito Special Report 05-010 is being sutxnitted pursuant to Technical Specification's 4.8.1.h3 and 6.9.2, and contains information concerning a reclassification of'a'previously reported failure.
At approkimately 0335 C W D/G "A" was started to perform the required periodic testing in accordance with surveillance procedure STS KJ-005A, (Manual / Auto Start, Synchronization and Loading of Emergency Diesel Generator NE01".
W e acceptance criteria for a successful start were met, but, due to mild fluctuations in engine speed, the decision was made to secure the engine prior to a load attempt. As a precautionary measure, D/G
^
"A" was declared inoperable. At the time, it was postulated that the fluctuations were due to low oil level in the governor oil sump. The level was within the sight glass prior to engine start, but had decreased below the sight glass level when the engine was started.
%e operators added oil to the governor, and restarted the engine at approximately 0403 C W.
The engine started satisfactorily, and no unusual fluctuations were observed. It was concluded that the addition of oil had corrected the mild engine speed fluctuations experienced previously, and D/G "A" was, declared operable.
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N At approximately G407 CW, an attempt to parallel the engine to the bus was w
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unsuccessful due to the output breaker tripping on reverse power. D/G "A" was again.declaredsinoperable. Wo more attempts to close the output breaker, were also unsuccessful due to reverse power trips. The engine was secured at approximately 0441 C W.
During subsequent troubleshooting, a mispositioned governor needle valve was discovered in the D/G governor.
It was found in the closed position, whereas it should have been slightly open. %is valve is located in the g
mechanical portion of the governor.
(BACMGROU m h e mechanical hydraulic controller of the Woodward Governor only controls diesel speed during diesel engine starts or s
failure of the electro hydraulic controller of the Woodward s
i Governor.
s Upon a' diesel engine start the mechanical hydraulic speed
, sensing portion of the actuator controls speed. As engine speed increases and obtains 125 rpm, as sensed by the Syncro Start Electric Speed Switch (SSESS), internal contacts of the SSESS.close. %is control function closes -intermediate contacts of the tachometer relay (TR) which energizes the Low Speed Relay (LSR). %c LSR activates the static exciter field flashing circuit, for the generator voltage buildup.
We electro-hydraulic portion of the Woodward Governor is controlled by the EGA box. The electro-hydraulic transducer controla diesel engine speed via the EGA box when the exciter field is established. This is accomplished by the speed sensor in the EGA that is connected to Phase A of the diesel generator terminals. The frequency of the voltage sensed at these terminals is directly proportional to the engine speed.
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% e function of the mechanical needle valve is to equalize the compensating force at a rate proportional to the increase or decrease in the mechanical hydraulic speed signal as set speed is reached. We mechanical hydraulic speed control is removed at a diesel engine speed of 125 rpn (i.e., prior to set speed). Herefore, the mispositioning of the mechanical governor needle valve is inconsequential.
Per conversar. ion with Woodward Governor Company personnel on December 5,1986, even if diesel engine speed control was being maintained by the mechanical governor with the needle valve closed, it would not inhibit speed control. Also the mechanical necile valve is used to eliminate any trapped air from oil pass:.ges when starting the diesel engine for the first time via special instructions in the Woodward Governor Technical Mant.al.
It is believed that this needle valve has been in the closed position since the ampletion of preoperational testing. Ib adverse effect has been observed due to the mispositioning of this valve during testing since that time. Since the valve is internal to the governor, any repositioning since that time is highly improbable. Furthermore, the electrical portion of the governor controls engine speed during normal engine runs. Conversations with the governor manufacturer, Woodward Governor Company, concluded that the mispositioning of this valve should have negligible effect on governor operation, and should not have resulted in engine speed fluctuations to the extent that a reverse power trip of the output breaker would occur. Ib other abnormalities in the system were identified during this troubleshooting effort.
W e governor needle valve was positioned in accordance with the Woodward Governor Technical Manual, and D/G "A" was restarted at approximately 1009 C W in accordance with STS KJ-005A. The start was successful, and the engine was subsequently run loaded for sixty-two minutes, thus empleting a valid successful test and restoring the engine to operable status at 1200
+
CW.
D/G "A" was unavailable for service for approximately eight and one-half hours, from the time it was originally de:lared inoperable until the successful completion of STS KJ-005A.
W e 0335 start of D/G "A" is not considered to be a valid test or failure based on the criteria provided in Regulatory Guide 1.108, Revision 1.
This start attempt was terminated intentionally without loading, and is an invalid failure per Regulatory Position C.2.e. (4).
Operations personnel had been verifying that the oil sump level was within the sight glass on a daily basis in the course of their normal rounds.
Previous discussions with the manufacturer resulted in recommendations that the oil level should be verified to be above the level of the sight glass when the engine is shutdown. However, subsequent discussions on December 5, 1986, with the Woodward Governor representative revealed that the only way to entrap air in the governor would be to drain it entirely. With oil level within the sight glass prior to start, sufficient inventory should have been available for proper control. As a result of the initial conversation with the Woodward Governor representative, procedure SYS KJ-121, ' Diesel Generator IE01 and IE02 Lineup for Automatic Operation", has been revised to include a verification that the oil level is above the level of the sight glass prior to each engine start.
.'o We 9403 CUP engine start is not considered to be a valid test or failure per Regulatory Guide 1.108. This start was a successful start followed by unsuccessful loading which can definitely be attributed to operating error, and therefore is not a valid failure per Regulatory Position C.2.e(2). The reverse power condition causing the output breaker trips was the result of improper synchronization and loading techniques. In an emergency situation, the reverse power trip circuitry is bypassed. Hence, this operating error would not have prevented the engine from performing its intended function during an emergency situation.
Including the events described in this report, there have been thirteen (13) valid successful tests and nine (9) invalid failures of D/G 'A' since the l
completion of preoperational testing on D/G
'A'.
Were have been twelve (12) valid successful tests and four (4) invalid failures of D/G 'B' during this same time frame. tb valid failures have occurred on either diesel unit.
We invalid failures discussed in this report had no effect on the diesel l
generator testing frequency of once per thirty-one days. This is in conformance with the schedule presented in Regulatory Position C.2.d. (1) of Regulatory Guide 1.108 and with Technical Specification Table 4.8-1, which require the testing interval to be not more than thirty-one days if the number of valid failures in the last 100 valid tests is one or zero.
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