ML20128N036
| ML20128N036 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 10/09/1996 |
| From: | Schwartz G COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 304-123-96-013S, 304-123-96-13S, NUDOCS 9610160270 | |
| Download: ML20128N036 (20) | |
Text
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, Commonwealth I dhon Company Zion tiencrating hution i 101.sitiloh Ikiulevard Zion, lL (h rJ9-2797 i Tel 8 67 7 Kw208 i October 9,1996 1
i U. S. Nuclear Regulatory Commission i Document Control Desk I Washington, DC 20555 l J
Subject:
Failure of 2B Emergency Diesel Generator (EDG) j i
Zion Nuclear Power Station Unit 2 i NRC Docket No. 50-304 The enclosed Special Report is being transmitted to you pursuant to Zion's Technical Specifications Section 4.15.B.5 to report the seventh valid failure of the 2B Emergency Diesel Generator (EDG) which occurred on September 9,1996.
S' cerely, , _
O. K. Schwartz Station Manager Zion Station Attachments: (1) Special Report for Failure of the 2B EDG (2) Zion Station EDG Reliability Program Data cc: A. B. Beach - Region III Administrator Zion Senior Resident Inspector Comed Distribution List i b>
9610160270 961009 PDR ADOCK 05000304 S PDR
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ZCORRRNspeciall3(1) l A Unicom Company
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! ATTACIIMENT I l
Zion Station Special Report No. 304-123-96-013SR This Special Report (Zion Station Special Report No. 304-123-96-013SR)is submitted in accordance with Zion Technical Specifications Surveillance 4.15.B.5.
This Special Report describes one failure which has'been determined to be valid per Regulatory Guide 1.108 section C.2.e.(2).
On September 09,1996 at 10:50 hours, while performing the 2B Emergency Diesel Generator (EDG) Loading Test (PT-11-2B), the 2B EDG was declared inoperable due to high lube oil system temperatures. The Zion Station EDGs are equipped with separate shell and tube heat exchangers for the lube oil, jacket water and intake air. These heat exchangers are cooled by the service water l system, which is supplied to the tube side of each heat exchanger. The service water side of the heat exchangers were subsequently inspected and found fouled with small pieces of broken zebra mussel !
shells, corrosion nodules, silt, fish parts and seaweed. This fouling resulted in insufficient heat transfer, limiting EDG loading to less than design.
Fouling was discovered in the 2B EDG lube oil (LO) heat exchanger (approximately 48.8%
equivalent tube blockage) jacket water (JW) heat exchanger (approximately 28.6% equivalent tube blockage), and intake air heat exchangers (approximately 17.5% and 12% equivalent tube blockage).
The current maximum tube plugging limits for these heat exchangers are 3% for the LO heat exchangers,6% for the JW heat exchangers, and 6% for the Intake air heat exchangers. After the previous failure of 2B on May 19,1996, all five D/G's have had their heat exchangers inspected, j cleaned and/or replaced at nine month intervals. The 2B EDG heat exchangers were last cleaned approximately 4 months ago in May 1996.
The 2B EDG lube oil and jacket water heat exchangers were opened, cleaned, inspected, and closed.
The intake air heat exchangers were replaced with clean ones. The 2B EDG was then tested by l I
successfully performing the 2B Emergency Diesel Generator Loading Test (PT-11-28) and at 17:16 hours on September 11,1996 the 2B EDG was returned to senice.
It is evident that the source of the zebra mussel shells and corrosion nodules came from the fire protection (FP) system. The zebra mussels shells that were discovered in the heat exchangers were all dead and many were killed as a result ofingesting water with elevated levels of chlorine evident by the whitish appearance of the shells. Many of the zebra mussel shells found in the 2B DG heat exchangers were too large to pass through the SW strainers and the fact that some of the shells had both halves connected indicates that they did not enter the SW system through the SW pumps or strainers, which would break the shells up. The fact that the SW pumps take their suction 15' above the floor of the pump bays limits the amount of zebra mussel shells drawn into the SW system.
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ZCORRRNspecial 13(1) l
On August 14,1996, the 10" FP header that supplies a backup water supply to each Unit 2 DG heat exchanger, was flushed out to the forebay. This flush is performed yearly on the FP piping. This flush causes exterminated zebra mussel shells, corrosion nodules, and other lake debris in the 10" FP l I
header to fall into the 4" FP headers that supplies the backup water to each individual DG. The debris in these 4" headers from the FP header is flushed into the SW header during quarterly valve stroking, and then into the DG heat exchangers (FP system is at a higher pressure than SW).
On September 5,1996, the 2B AFW Pump Lube Oil Cooler was opened, inspected and replaced. )
Only 2 of the 56 tubes were plugged with small zebra mussel shell fragments, and on August 30, !
1996 the 1 A DG lube oil and jacket water coolers were opened, inspected, and cleaned. There was l I
~ 1% blockage in thejacket water cooler and 10.6% in the lube oil cooler with zebra mussel shell fragments, seaweed, algae and fish parts. All of these fouling levels are below design and much lower than observed in the 2B DG heat exchangers. The fouling levels are low, corrosion nodules were not found and the shells found were small fragments (no whole shell or large ones). Based on these recent heat exchanger inspection results, it is concluded that debris is from the FP system and not the SW system.
The 0 DG heat exchangers have been last cleaned on July 27,1996, the l A DG heat exchangers on August 30,1996, and the IB DG heat exchangers on July 31,1996. The 10" FP header that supplies a backup water supply to each Unit 0 and 1 DG heat exchanger, has not been flushed via PT-218D after these DG heat exchanger cleanings. The 0 DG was operated on July 29,1996 and August 13, 1996. The 1 A DG was operated on July 29,1996 ad August 31,1996. The IB DG was operated on August 1,1996 and August 29,1996. The operation of the 0, l A and 1B DG's did not indicate any heat exchanger problems. Therefore, it is believed that the 0, I A and IB DG heat exchangers are clean and are operable.
The 2A DG heat exchangers have been last cleaned on June 11,1996. However, the MOV from the FP system was stroked on July 1,1996 and the 10" FP ring header for the Unit 2 side was flushed on August 14,1996. To prove operability of the 2A DG, PT-11-2ADG, "2A Diesel Generator Loading Test" was performed at full load with lake temperatures ~ 76 degrees F. (design is 80 deg F). This PT was performed successfully with lower than design lube oil, jacket water and air temperatures.
This was the seventh valid failure of the 2B EDG in the last one hundred (100) valid demands. The required test frequency of the 2B EDG is every 7 days until 11 valid successful tests have been completed. During this event the 2B EDG was unavailable from 09 Sept.,1996 at 10:50 hours until 11 Sept.,1996 at 10:59 hours, a total of 48:09 hours.
The following additional information is provided as required by Regulatory Guide 1.108 section C.3.b.
Attachment (1) is a summary of all tests (valid and invalid) that occurred within the time period over which the last 100 valid demands were performed. This summary shows that surveillance testing performed over this period has been in conformance with the schedule of Regulatory Position C.2.d.
ZCORRRNspecial 13(1)
The following is a summary of the seven valid failures that occurred during the last 100 valid demands:
FAILURE 1 On 03/07/94 the 2B EDG was shutdown due to voltage fluctuations. A fuse on the potential transformer that supplies power to the voltage regulator was i determined to have an intemittent open and it was suspected of causing the problem.
The fuse damage was mechanicalin nature, possibly due to vibration and not due to electrical overload. There was no like-for-like replacement fuse in the supply system so it was replaced with an installed spre. Subsequent testing revealed that the voltage l fluctuations were no longer a problem and the EDG was returned to service.
l These fuses were scheduled for replacement as part of the control system modification which had been installed on the 0, I A and 2A EDGs and was pending installation on IB and 2B EDGs. These modifications have since been completed.
FAILURE 2 On 04/15/94 the 2B EDG was shutdown due to voltage fluctuations.
The fluctuations were similar to those observed on 03/07/94. Again, a fuse on the potential transformer that supplies power to the voltage regulator was found to have a I
intermittent open. This time the fuses were replaced with the upgraded, slow-blow, glass filled fuses like the control system modification had installed in the 0, l A and 2 A EDGs.
The fuses in the IB EDG potential transformer were also replaced with the new style at this time.
FAILURE 3 On 05/27/94 the 2B EDG was shutdown due to voltage fluctuations.
Troubleshooting identified the voltage regulator as the problem and the voltage regulator was replaced. The 2B EDG was subsequently tested satisfactorily and returned to service. The failed voltage regulator was sent to Failure Prevention International, Inc. (FPI) for root cause analysis. FPI was unable to duplicate the problem in the lab and requested to be sent the voltage regulator motor operated potentiometer (MOP) for testing. The MOP was removed and sent to FPI. FPI was able to duplicate the problems with the MOP connected to the voltage regulator.
Examination revealed contaminantes (fibers) on the wiper and winding of the MOP and FPI concluded that the MOP was the cause of the problem.
A design change has been prepared that will replace the MOP with a more suitable range and sealed device to correct the problem. This design change also provides l circuitry which will remove the MOP from the circuit and put a fixed resistor into the l circuit for emergency starts. This design change is being installed on the Unit two EDGs during the Fall 1996 outage and on the 0 and Unit one EDGs during the Spring 1997 outage.
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[ As an interim measure, until the MOP design change is completed, tN MOPS are being replaced with new ones approximately every 6 months on each rDG. New voltage regulators have been installed on all EDGs except the 2A .m the 2A EDG voltage regulator replacement is scheduled for the Fall 1996 outage. Additionally, a 10-year Preventive Maintenance activity has been created for the voltage regulators which includes replacement of certain components suspected of aging.
FAILURE 4 On 06/16/94 the 2B EDG was shutdown due to turbocharger failure.
The turbocharger was replaced and the 2B EDG was tested and returned to service.
Root cause investigation determined that the radial bearings had failed and was the root cause of the problem but there was also foreign material found in the turbocharger debris which was later determined to be from an exhaust thermocouple sheath. Zion Station has had a history of turbocharger bearing failures. Unlike the ET-24 turbochargers used at Byron & Braidwood Stations, the ET-18 turbocharger used at Zion uses labyrinth seals to keep lube oil out of the engine's intake and exhaust.
These seals limit the ability to lubricate the bearings during standby periods. A 1991 study concluded that the best solution was to install a modification to the lube oil system that would provide for a small drip feed of oil to the bearirgs during standby conditions. The drip oil feed is designed to keep the bearings from dry-out which can leave a hard dry dirty residue on the bearing surfaces which could result in accelerated wear during subsequent start-up.
This modification was installed on the 0, I A and 2A EDGs during the outage which ended 3/94. The same modification was installed on the 2A & 2B EDGs during the Z2R13 outage which ended 3/95. There have not been any turbocharger bearing i failures since this modification was installed.
Zion Station later discovered that one of the exhaust thermocouples (installed in the exhaust from each cylinder) on the 2B EDG was missing its sheath (a metal tube which protects the wires). Discussion with the r. anufacturer revealed that some ;
thermocouples had been manufactured using a process that could result in faHure of the sheath. Failure in service could allow the sheath to become a foreign object in the exhaust system and possibly enter the turbocharger and cause damage. Cooper Bessemer issued a 10CFR21 notice based on this Zion Station event. Zion Station inspected the thermocouples in all engines, replaced all suspect thermocouples and performed searches of the exhaust system and turbochargers of the 2A and 2B engines due to finding missing sheaths on one or more of these engine's exhaust thermocouples.
FAILURE 5 On 02/13/96 the 2B EDG failed to start when a valid start signal was applied. The right bank air start distributor was determine to be the cause. The distributor rotor was found seized in the body and would not rotate. The rotor ZCORRRNspecial 13(1)
stopped rotating and caused the bronze drive coupling to shear, as designed. Possible contributors were identified previously in Zion Special Report No. 304-123 009SR dated June 18,1996.
FAILURM On 05/18/96 the 2B EDG was shutdown due to high temperature of thejacket water and lube oil.
On May 18,1996 at 23:12 hours, while performing the 2B Emergency Diesel Generator (EDG) Loading Test (PT-11-2B), the 2B EDG was declared inoperable due to high lube oil system temperatures. The Zion Station EDGs are equipped with separate shell and tube heat exchangers for the lube oil, jacket water and intake air.
These heat exchangers are cooled by the service water system, which is supplied to the tube side of each heat exchanger. The service water side of the heat exchangers were subsequently inspected and found fouled with lake debris, consisting of a combination of small pieces of broken zebra mussel shells, algae / seaweed, and a small amount of fish parts. This fouling resulted in insuflicient heat transfer, limiting EDG loading to less than design. l The fouling discovered in the 2B EDG lube oil heat exchanger (approximately 37% i equivalent tube blockage), jacket water heat exchanger (approximately 28%
equivalent tube blockage), and intake air heat exchangers (approximately 17.5% and 35% equivalent tube blockage) is indicative of the type of fouling that builds up slowly oser time. The current maximum tube plugging limits for these heat l exchangers are 3% for the LO heat exchangers,6% for the JW heat exchangers, and 6% for the Intake air heat exchangers per ZAP 410-03, " Generic Letter 89-13 )
Implementation Safety-Related Service Water Heat Exchangers." However, preliminary calculations 22S-B-009M-166,165, and 168 show revised maximum tube plugging limits to be 19.19% for the LO heat exchangers,11.18% for the JW heat exchangers, and 39.31% for the intake air heat exchangers. The EDG heat exchangers were initially cleaned every 18 months per the Preventive Maintenance program and the 2B EDG heat exchangers were last cleaned approximately 16 months ago in January 1995.
The 2B EDG lube oil and jacket water heat exchangers were opened, cleaned, inspected, and closed. The intake air heat exchangers were replaced with clean ones.
The 2B EDG was then tested by successfully performing the 2B Emergency Diesel Generator Loading Test (PT-11-2B) and at 16:40 hours on September 11,1996 the 2B EDG was returned to senice.
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ZCORRRNspecial 13(1)
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l s FAILURE 7 On 09/09/96 the 2B EDG was shutdown due to high temperature of the lube oil. Details of this event are provided at the top of this report The period over which the last 100 valid 2B EDG demands occurred dates to Feb.1993. Since Feb.,
1993 many improvements related to the EDGs have been implemented and previously reported to i you in Zion Special Report No. 304-123-96-009SR dated June 18,1996.
l Attachment (2) provides the Zion Station EDG Reliability Program data which includes all EDG
, tests as of September 15,1996. The data shows that all trigger valuas are currently being met.
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i ZCORRRAfspecial 13(1)
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ATTACHMENT 2 l
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- EDG3t's ?lA1 ilB !- !.2As-- -
?2B1 20i:
>TRIGGERd
'c. ,
i.;VALUEi
- of valid failures in last 25 demands 0 0 1 2 0 4 i UNIT 1 2 . VALUE-
- of valid failures in last 20 demands 0 1 3
- of valid failures in last 50 demands 0 2- 5
- of valid failures in l last 100 demands 3 6 8 1
1 J
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ZCORRRNspecial 13(1)
ZION EDG DEMANDS -
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. r OBS EDG EDG PROCEDURE REASON COMMENT REG FAILURE START START GUIDE -
DATE TIME ;
1 9/15/96 16:05 PT-11 Test prior to taking 2A OOS None VS '
to clean SW coolers i
2 9/11/96 10:59 PT-11 Test for RTS following None VS valid failure & subsequent cleaning of all SW supplied ,
coolers !
4;w 3;gg a s .
" < $2 - -
m ies' s ^ j!!g ^ gte , i;B ~ w i 3 9/9/96 9:29 PT-11 Routine test Engine was secured by operator because Lube oil VF 1 i temperature could not be maintained less than 180 degrees. Found cooler tubes plugged with lake debris including zebra mussel shells. LO cooler ,
was 46% plugged & JW was 30% replaced LO amount valve too. not considered a MPFF because coolers ;
just cleaned 4 months ago and cause of current l
fou'ing appears to be surveillance flush of FP hdr and not normal anticipated build up of lake debris.
l 4 8/13/96 4:45 PT-11 Test for 2A EDG inoperability VS 5 8/5/96 12:29 PT-11 Weekly Testing VS 6 7/29/96 13:00 PT-11 Weekly Testing Routine VS 7 7/26/96 12:43 PT-11 LCO for 0 EDG VS
, G 7/23/96 1:25 PT-11 Periodic weekly test The day tank level transmitter failed during the VS PT and a tygon tube had 20 be connected to the sensing leg to confia'n that there was >350 gallons as required by the PT before operations would secure the EDG even thought the procedure _
would permit it to be secured and the level con-ZCORRRA/special 13(1)
ZION EDG DEMANDS -
!OBS EDG EDG PROCEDURE REASON COMMENT REG FAILURE .
START START GUIDE DATE TIME -
firmed later , prior to approving the PT. The IM found fluid on the reference leg side of the equalizing valve causirig the Rosemount transmitter to indicate failed r
9 7/15/96 13:23 PT-11 Routine weekly test & to During the course of performing the PT, the operator VS l perform engine analysis mistakenly increased load to 4600 KW for a !
moment. The operator was attempting to increase KVAR and he mistakenly went to increase on the govemor control switch versus increase on the voltage adjust switch. He realized his error and corrected it and informed othr3 The total transient lasted about 11 seconds ad wM R4600 for about 1.5 seconds. The v.cera'o(overcurrent relays were never challenged Cz:'un *he went.
t 10 7/9/96 8:32 PT-11 Weekly test None VS 11 7/2/96 10:05 PT-11 Weekly test None VS 1
12 6/24/96 17:16 PT-11 Weekly op test Test followed performance of the electrical controls VS !
system test TSS 3.8.1-17-8 which made the !
EDG inoperable. This was also the first run of the 2B PT-11 revised for TSIP.
I 13 6/17/96 9:05 PT-11 Weekly test None VS 14 6/10/96 19:52 PT-11 Test prior to taking 2A None VS OOS for SW HX cleaning 15 6/3/96 23:22 PT-11 Weekly test During this load run, when load reached 3350 kw VS i the right bank intake air temp reached the upper limit of 130 degrees and the SW throttle valve was in its max open SOi position. Load was belo at ZCORRRA/special 13(1)
ZION EDG DEMANDS -
OBS EDG EDG PROCEDURE REASON COMMENT REG FAILURE .
START START GUIDE DATE TIME -
3350 and temps were steady, including exhaust header temp which was 1050. The SW valve was opened fully for 10 minutes and the valve flushed.
Subsequently the EDG was full loaded and a
successfully completed the PT-11. This was evaluated and ,_
considered a valid PT-11 and no failure.
16 5/28/96 22:42 PT-11 Weekly test None VS 17 5/20/96 22:56 PT-11 PT for RTS following SW cooler Temperatures of JW, LO, Intake air all normal. VS cleaning & PROPER restoration JW pp discharge pressure normal at about 33# and of SW OOS. steady throughout the run. Cleaning of coolers fully successful.
18 5/18/96 23:12 PT-11 Monthly test The engine was shutdown by the operator due to VF 2 high temperatures on the jacket water and the tube oil systems. Found the heat exchangers fouled on the SW side causing the problem.
19 4/24/96 15:44 PT-11 ROUTINE TEST NONE VS 20 4/15/96 21:31 PT-11 PT prior to taking 2A OOS Operator thought he heard a strange noise as the VS for planned work engine coasted to a stop at the end of this test j 21 3/31/96 19:50 PT-11 PT-11 prior to taking "0" None VS EDG OOS for mair;tenance i 22 03/28/96 2:31 PT-11 PT-11 for RTS following RTS following installation of cam collars, fixing VS ;
l maintenance JW, LO, & FO leaks.
t !
23 03/20/96 15:51 PT-11 PT of engine because 2A was NONE VS inoperable due to failure l
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ZION EDG DEMANDS -
OBS EDG EDG PROCEDURE REASON COMMENT REG FAILURE START START GUIDE DATE TIME -
24 03/18/96 10:55 PT-11 PT prior to taking the 2A The plan was to take the 2A EDG OOS for fuel leaks VS EDG OOS for maintenance and cam lobes, but due to a problem on the 2C RCFC the 2A EDG could not be taken OOS. l 25 02/14/96 21:37 PT-11 Test for retum to service Successful test for retum to service VS ,
following valid failure [
and repair of air distributor ,
26 02/13/96 11:38 PT-10.3 Periodic safeguards test Engine failed to rotate on start signal. VF 3 found the right bank air start distributor rotor had seized in the body and caused the bronze drive coupling to shear.
27 02/04/96 2:10 PT-11-2BDG Periodic test Routine test VS 28 01/13/96 23:27 PT-11-28 POST MAINTENANCE TEST TEST AFTER MAINTENANCE-NO PROBLEMS VS 29 12/21/95 13:27 PT-11-2BDG Routine Routine monthly test VS 30 11/30/95 8:55 PT-11-2BDG Periodic op test NONE VS 31 11/06/95 20:44 PT-11-DG2B Routine VS 32 10/06/95 13:12 PT-11-DG2B LCO for "0" EDG VS 33 09/26/95 0:46 PT-11-DG-2B LCO for SAT VS 34 09/16/95 2:14 PT-11-DG-28 LCO FOR UNIT 1 " SAT" VS 35 08/21/95 17:22 PT-11-DG2B ROUTINE VS f 36 07/20/95 8:26 PT-11-DG2B Routine VS ZCORRRNspecial 13(1)
ZION EDG DEMANDS -
OBS EDG EDG PROCEDURE REASON COMMENT REG FA1 LURE ,
START START GUIDE DATE TIME -
37 06/23/95 23:14 PT-11-DG2B Routine VS 38 05/24/95 16:35 PT-11-DG2B Routine VS 39 04/30/95 13:42 PT-11-DG2B Take 2a EDG OOS VS i
40 4/25/95 8:43 PT-11-DG2B Routine VS 41 3/31/95 11:42 TSS 43 SEC Refueling surveillance Ran at 4 MW while waiting for nop/not during unit start- VS 8.1 up 42 3/24/95 23:52 PT-11-DG2B- Refueling requirement for 24- 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run with 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at 4.4 MW VS R hour run 43 3/23/95 13:30 TSSP-023-94 Engine analysis, mod test VS with full load reject 44 12/30/94 17:48 PT-11 PT-11 for 2A failure PT-11 for 2A failure VS 45 12/13/94 8:30 PT-11-DG2B MONTHLY SURV. RUN VS 46 11/17/94 14:35 PT-11 PT-11 PT-11 VS 47 10/21/94 14:10 PT-11 PT-11 PT-11 VS 48 9/20/94 13:50 PT-11-DG2B WEEKLY TEST ROUTINE TEST VS 49 9/13/94 5:41 PT-11-DG2B Op test Retum to service following turbo replacement VS 50 9/5/94 20:45 PT-11-DG2B Op test Test prior to taking 2a OOS to replace turbo due VS to having found the 8L cylinder exh. t/c missing its sheat' .
51 9/1/94 8:25 PT-11-DG2B Normal test inspecting for thermocouple problems VS 52 8/28/94 1:20 PT-11-DG2B Test prior to taking 2A lLCFrun VS ZCORRRA/special 13(1)
ZION EDG DE%tANDS -
OBS EDG EDG PROCEDURE REASON COMMENT REG FAILURE I ' '
START START GUIDE DATE TIME -
EDG OOS forinspection of thermocouples for loose parts 53 8/26/94 3:05 PT-11-DG2B Test for retum to service Retum to service test following inspection for VS missing parts of the 3R and 8L cylinder exhaust thermocouples.
54 8/18/94 8:22 PT-11-DG2B Weekly surveillance run VS 55 8/10/94 20:09 PT-11-DG2B Weekly surveillance run VS 56 8/4/94 11:21 PT-11-DG2B Weekly surv. operability run due VS to O EDG OOS 57 7/29/94 14:04 PT-11-DG2B Weekly surveillance run Prior to the PT the engine was OOS to repair a VS minor oil leak on the turbocharger oil retum line that developed after the repair of a minor jacket waterleak on 7/21 SG 7/21/94 18:14 PT-11-DG2B Weekly surveillance run VS also retum to service following repair of a minor turbo water leak 59 7/14/94 14:27 PT-11-DG2B Weekly surveillance run VS 60 7/7/94 10:28 PT-11 PT-11 PT-11 VS 61 6/30/94 8:28 PT-11-DG2B Weekly surveillance run VS 62 6/23/94 8:25 PT-11-DG2B weekly surveillance run VS 63 6/17/94 14:48 PT-11-DG2B Retum to service run Performed turbo spin down per TSS 15.6.142 VS following turbocharger time 2:26 replacement ZCORRRA/special 13(!)
ZION EDG DEMANDS OBS EDG EDG PROCEDURE REASON COMMENT REG FAILURE START START GUIDE DATE TIME -
64 6/16/94 9:05 PT-11-DG2B Weekly surveillance run Engine shutdown by the NSO due to turbo failure. VF 4 Engine was operating at 4MW, observed load drop to 2.5 MW, smoke in room from turbo breather &
from exhaust stack and unusual noise from turbo.
Investigation found that the turbo radial brearings failed and probably caused the failure but a piece of foreign material suspected of being from an exhaust thennocouple sleeve was also found in the turbo debris. SMAD opinion is bearing failure was root cause.
65 6/8/94 11:33 PT-11-DG2B Weekly surveillance run Collected fuel consumption data during run VS 66 6/2/94 16:15 PT-11 PT-11 PT-11 VS 67 5/28/94 12:34 PT-11-DG2B Retum to service run Engine was run at full load for 1 hr 20 min VS following voltage instead of the 2 hrs required by the PT due to regulator replacement low level in the storage tank.
The level remained above the Tech Spec limit, but fc;i Delow the alarm setpoint.
68 5/27/94 15:00 PT-10-3 Safeguards testing Engine was shutdown by local operator due to VF 5 large fluctuations in output voltage and frequency.
Testing identified the problem as the voltage regulator. The regulator was replaced and the DG was retumed to service. The old regulator was sent to FPI for root cause analysis. They could find no problem with the regulator and we were requested to send them the MOP. They concluded that the MOP was tne problem - contaminants were found on the wiper & winding.
69 ) 5/26/94 1:25 PT-11-DG2B Weekly surveillance run VS ZCORRRNspecial 13(1)
ZIOM EDG DEMANDS .
OBS EDG EDG PROCEDURE REASON COMMENT '
REG FAILURE START START GUIDE DATE TIME -
70 5/19/94 8:51 PT-11-DG2B Weekly surveillance run VS 71 5/12/94 8:01 PT-11-DG2B Weekly surveillance run 8L and 1R exhaust thermocouples are not working VS work requests written.
72 5/6/94 2:09 PT-11 PT-11 for RTS following tube oil PT-11 for retum to service following tube oil pump VS oil pump discharge hose discharge flex hose replacement. The old hose replacensent. failed due to a rub hole.
73 5/5/94 9:38 PT-11 PT-11 The main lobe oil pump discharge flex hoses was VS noted to have a small leak. ir vestigation revea!ed hole in the bellows convolutions where the covering braid had wom thru the convolution due to vibration over time. Decided we should change the hose.
74 4/28/94 14:49 PT-11-DG2B Weekly surveillance run Lube oil pressure adjusted during run. Was low VS during previous PT.
Vent fan control switch replaced prior to run because of problem noted during 4/15 PT.
75 4/22/94 9:39 PT-11-DG2B Weekly surveillance run 8L exhaust temperature readout not working - wrw VS 76 4/15/94 21:10 PT-11-DG2B Retum to service run VS following fuse repairs 77 4/15/94 1:46 TSS-15.6.35-2 Manual SI simultaneously Engine was shutdown by the local operator at the VF 6 started all 3 U2 EDGs direction of the control room due to full scale swings in frequency. Subsequent investigation found a broken fuse in the PT that supplies power to the voltage regulator. The fuse was mechanically damaged not electrically blown.
Fuse was replaced with new type (glass-sand filled) which is the same as the EDGs with the control ZCORRRAi necial 13(1)
ZION EDG DEMANDS -
~
OBS EDG EDG PROCEDURE REASON COMMENT REG FAILURE '
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j START START GUIDE DATE TIME mod have. These fuese are in the maint. program for periodic replacement. l 78 4/9/94 9:55 PT-11-DG2B Monthly surveillance run 8.35 second start time VS 79 3/31/94 22:40 TSS-15.6.35-2 Simulated SI/UV Diesel started from train a safeguards initially VS then at 2346 it received a train b start signal load shed and resequenced all loads.
80 3/9/94 6:04 PT-11-DG2B Retum to service run Start time 9.16 seconds VS ,
after cleaning zebras out of all the coolers G1 3/7/94 6:16 TSS 15.6.43-2 Surveillance testing Engine was shutdown by local operator due to VF 7 simulated Si start and voltage fluctuations. breakertripped because load run output voltage fell below allowable level. Found a fuse on the potential transformer to have an inter-mittent open due to mechanical damage. Replaced fuse with other one from Generator lead as none ,
in stores. Also cleaned SW HXs while OOS and found lots of shells - suspected of coming from the fire header emergency cooling water supply.
82 3/7/94 1:08 PT-11-DG2B Heat up engine prior to VS TSS 43 hot restart test 83 2/17/94 5:35 TSS 15.6.43-2 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> endurance run and Operated at 4.4 mw 1055 to 1303. VS ,
fullload reject 84 2/10/94 11:55 PT-11 PT-11 VS i
65 1/3/94 16:53 PT-11-DG2B Surveillance run after iStart time 8.06 seconds VS i replacement of output breaker frequency
- ZCORRRA/special 13(1) l
ZION EDG DEMANDS .
OBS EDG .5DG PROCEDURE REASON COMMENT REG FAILURE ,
START UTART GUIDE DATE TIME -
permissive relay 86 1/3/94 1:30 PT-11-DG2B Monthly surveillance run Output breaker frequency permissive relay was VS replaced prior to this run.
87 12/1/93 9:59 PT-11-DG2B Monthly surveillance run 8.69 seconds to start VS 88 10/31/93 17:42 PT-11-DG2B Retum to service run VS following connection of temporary service water for DUO 89 10/15/93 22:41 PT-11-DG2B RETURN TO SERVICE AFTER During maintenance work the pre-lube pump was VS MAINTENANCE replaced, air cleaner cleaned and patched, fuel
- cam lobes inspected, generator outboard bearing i
disassembled and inspected.
90 9/21/93 22:35 PT-11-DG2B Verify operability due to O failure VS 91 8/26/93 8:27 PT-11-DG2B Monthly surveillance run VS 92 7/28/93 21:37 PT-11-DG2B Monthly surveillance run VS 93 6/28/93 0:17 PT-11 PT-11 VS 94 6/15/93 2:35 PT-11-DG2B Retum to service after The 1R and 7R injectors and the 1R injector pump VS maintenance were replaced. In addition several minor oil leaks were repaired. Engine analysis was performed during the retum to service run.
95 5/12/93 8:20 PT-11 PT-11 Fuel pressure was adjusted during this run. VS 4
96 4/11/93 20:08 PT-11 PT-11 for 2A OOS VS 97 3/29/93 21:40 PT-11 RTS FOLLOWING FUEL LEAK PT-11 FOLLOWING REPAIRS TO FUEL PRESSURE VS i REllEF ZCORRRNspecial 13(1)
i ZION EDG DEMANDS .
l OBS EDG EDG PROCEDURE REASON COMMENT REG FAILURE ,
START START GUIDE DATE TIME REPAIR AND OUTBOARD BRG VALVE AND OUTSOARD BEARING TEMP INDICATOR.
TEMP INDICATOR REPAIR 98 3/22/93 9:48 PT-11 PT-11 PT-11 following relay changeout to obtain samples VS for HELB analysis ,
99 3/15/93 9:34 PT-11 Weekly surveillance run Start time 8.76 seconds VS and engine analysis Engine analysis showed 1R still lowest and ,
firing angle of 20 degrees. Unable to do compression readings because no procedure.
100 3/8/93 16:08 PT-11 Weekly surveillance run, VS ,
LCO run due to 2A OOS for SA check valve repairs.
101 3/2/93 9:13 PT-11 Weekly surveillance run 8.83 second start time VS 102 2/23/93 11:11 PT-11 Weekly surveillance run VS 103 2/17/93 1:34 PT-11 Retum to service and End of run was 4MW load reject instead of normal VS pre conditioning for load ramp down. This was down as part of TSS 15.6.43 TSS 15.6.43. Length of full load run was extended to provide a hot engine as required by TSS.
This run was also used to verify operability of the engine after the three trips experienced during testing.
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104 2/16/93 5:28 TSS 15.6.43-2 Section 8.2 With the EDG carrying the bus, the bus voltage VF Simulated Si and UV start dropped below 2870 V and all of the loads shed ;
and then resequenced back on. The EDG remained running during this event. Ine EDG was paralleled to the grid and loaded to 4 MW. After approxi-mately 1 1/2 hours at full the EDG tripped. Cause ZCORRRNspecial 13(1)
ZION EDG DEMANDS .
OBS EDG EDG PROCEDURE REASON COMMENT REG FAILURE ~ '
START START GUIDE
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DATE TIME of the trip was not clear. Troubleshooting found problem to be a combination of improperly ad-justed overspeed trip, oil leak on O/S govemor and small 30 PSI air leak.
105 2/15/93 3:36 TSS 15.6.43-2 24 hourload run Engine operated at 4400 kw 0935 to 1135 on 2/15 VS then retumed to 4000 until breaker opened.
The end of this run is a fullload reject to !
verify the diesel will remain running.
106 2/5/93 0:15 PT-11 Retum to service after ' art time 9.56 seconds. New starting air VS 5 yr overhaul lsistem installed during overhsul. ,
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i ZCORRRA/special 13(1)
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