ML20151Q344
| ML20151Q344 | |
| Person / Time | |
|---|---|
| Site: | Mcguire |
| Issue date: | 07/28/1988 |
| From: | Tucker H DUKE POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8808110125 | |
| Download: ML20151Q344 (10) | |
Text
--
DUKE POWER COMPANY P.O. HOX 33180 CHARLOTM!, N.o. 28242 IIAL B. TtJCKER TELEPHONE (704) 3MF4531 wwarmesern fif4tRAe PsOctNW July 28, 1988
-U. S. Nuclear Regulatory Commission Attention: Document Control' Desk' Washington, D. C. 20555
Subject:
McGuire Nuclear Station, Unit 2 Docket No. 50-370 Technical Specification 4.8.1.1.3 and 6.9.2 Gentlemen:
Pursuant to Technical Specification (T.S.) 6.9.2 ar. specified by T.S. 4.8.1.1.3, a special report concerning Diesel Generator (D/G) 2B was submitted on July 22, 1988. In the report the failure was identified as the seventh valid failure in
'the last 100 valid test starts on the Unit 2 D/G sets. Accordingly, find attached the_information required by Position C.3.b of the Regulatory Guide 1.108, Rev. 1, August 1977.
Should there be any questions concerning this matter, please contact S. E. LeRoy at (704)373-6233.
Very truly yours,
< ~ '
. IP gg Hal B. Tucker SEL/115/sbn Attachment xc:
Dr. J. Nelson Grace, Regional i.dministrator Mr. W. T. Orders U. S. Nuclear Regulatory Commission NRC Resident Inspector Region II McGuire Nuclear Station 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. Darl Hood INPO Records Center Office of Nuclear Reactor Regulation Suite 1500 U. S. Nuclear Regulatory Commission 1100 Circle 75 Parkway 0l f#
Washington, D. C.
20555 Atlanta, Georgia 30339 I,
8808110125 880728 PDR ADOCK 05000370 g
PNV g
l
.,.?
3 Duke Power Company McGuire Nuclear Station Unit 2 Diesel Generator Supplemental Report
==
Introduction:==
The following information is provided in response to the requirements of USNRC Regulatory Guide 1.108 revicion 1, section C.3.b.
This regulatory guide section requires that additional narrative material be supplied if the number of failures in the last 100 valid tests is seven or more. On June 2, 1988 a valid failure occurred on McGuire engine 2B and on June 24, 1988 a_ valid failure occurred on McGuire engine 2A.
This was the seventh and eighth valid failure in the last one hundred valid tests for the two McGuire Unit 2 emergency diesel generator sets.
Reliability Improvement Measures:
The following are descriptions and basis for corrective measures, taken or pl
.ned, to increase the reliability of the generator units.
On June 24, 1988 a low lube oil pressure switch tripped 2A diesel, a.
Procedure IP/0/A/3250/13D (Calibration Procedure for Custom Components Factory Set Pressure Switch) will be revised by IAE personnel to verify applicability of reference legs prior to calibration.
On June 2, 1988 a lube oil cooler sprayed large quantities of oil into the 2B diesel room, b.
Procedure MP/0/A/7400/13 (Diesel Engine Lube Oil Cooler Corrective Maintenance) will be upgraded to change the torque to increase the gasket crush on the tube to shell flange.
c Gaskets will be modified to cover the entire area of the flange so that the gasket does not slip out of position during assembly.
d.
Covers will be installed on all lube oil line flanges to prevent oil from being sprayed upwards over the room if a leak should occur.
On June 1, 1988 a lube oil leak on the governor of 2A diesel resulted in an l
overspeed trip Procedure MP/0/A/7400/14 (Diesel Engine Governor, Governor Oil e.
Cooler, and Booster Servo Motor Removal and Replacement) will be upgraded to check for adequate bolt length when installing lube oil y
cooler.
f.
Woodward Governor manufacturers drawing will be updated to show l
sufficient drawings for proper maintenance.
g.-
Failure analysis will be performed on governor removed to determine cause of failure which resulted in a frequency swing.
h.
A letter will be sent to Woodward Governor asking for any dimensional l
changes they have performed on the model EGB-350 governor.
i.
Maintenance personnel will be notified to inspect all threaded l
fasteners in the future for proper length.
On October 14, 1987 and October 13, 1987 a damaged oil mister drain valve, on the l
starting air system, resulted in a slow start on 2A and 2B diesel.
l j.
A station modification was issued to change the style of drain valve on the oil misters to prevent future failures.
l L
1
, k.
Preventative Maintenance (PM) was established to check the condition of the oil mister drain valve every 18 months.
On August 4, 1987 a valid failure resulted due to oil in the governor being excessively high on 2B diesel.
1.
Diesel generator operating procedures PT/1/A/4350/02A, PT/1/A/4350/02B, PT/2/A/4350/02A, PT/2/A/4350/02B, OP/1/A/6350/02, and OP/2/A/6350/02 were changed to have operators inspect for proper governor oil level.
On June 21, 1987 a low lube oil pressure switch tripped 2B diesel.
Procedure MP/C/A/7400/71 (Diesel Engine tube Oil Removal and m.
Replacement) was changed to have IAE personnel vent lube oil sensing lines prior to starting the diesel engine after lube oil has been removed and replaced.
Engine Reliability Assessment Considering the 7 failures of the 100 valid tests covered by this report, engine 2A suffered 2 failures in 32 tests and engine 2B suffered 5 failures in 68 tests.
Two different approaches can be used to evaluate the reliability. One approach treats each diesel as having a separate failure rate. The failure rate for each engine is calculated and the two rates are then combined to give a reliability for the system. Using this approach engine 2A has a failure rate of 0.0625 with a 50% confidence level or 93.75% reliability.
Engine 2B has a failure rate of 0.0735 with a 50% confidence level or 92.65% reliability. The reliability of the system, or of at least having one of the two engines opcrate successfully is the product of the two failure rates subtracted from unity. This results in a reliability rate of 99.54% with a 50% confidence level.
The second method treats both engines as having an aver me failure rate of seven out of a hundred tests or each is 93% reliable. The reliability using this method is between 0.99063 and 0.99742 with a 50% confidence level and a mean of 0.99510 or 99.5% reliable.
Considering the 8 failures of the 100 valid tests covered by this report, engine 2A suffered 3 failures in 34 tests and engine 2B suffered 5 failures in 66 tests.
Using method one engine 2A has a failure rate of o.08824 with a 50% confidence level or 91.18% reliability. Engine 2B has a failure rate of 0.07575 with a 50%
confidence level or 92.42% reliability. The reliability of the system is 99.33%
with a 50% confidence level.
Using the second-method and an average failure rate of eight out of a hundred tests makes each engine 92% reliable. With a 50% confidence level the engine system is 99.367. reliable.
Both methods yield values that exceed the 0.99 reliability goal at a 50%
confidence level established by NUREG75/087 appendix 7-A.
Basis for Continued Operation McGuire Unit 2 will continue to be operated because the reliability of electric l
power to the engineered safety feature equipment exceeds the goal required by
r-t regulations and stringent programs are in place to improve engine reliability beyond this goal.
Summary of Tests The McGuire Technical Specifications currently require that the diesel engine operability test (PT/2/A/4350/02) be performed once every 31 days if four valid failures (VF) or less have occurred ~in the last 100 valid attempts and if one valid failure (VF) or less has occurred in the last 20 valid' attempts otherwise, testing will be performed weekly. Attached is a summary of the start attempts for engines 2A and 2B.
"Valid Attempt Number" is a counting of the most recent 100 valid successes (VS) or valid failures (VF) for the Unit 2 engines combined.
"Engine Start Number (s)" are assigned to each engine start and are recorded together with other information about each run, in the control room log books.
The numbers began when the engines were first declared operable at McGuire.
"Test Result" is one of four possible codes, VS, IT, IF or VF.
VS stands for valid success. For a test to be considered a valid success "VS",
all of the following conditions must be met:
a:
The diesel engine starts and accelerates to greater than or equal to 488 RPM (greater than or equal to 95% speed) within 11 seconds, b:
D/G voltage and frequency shall be at least 4160 plus or minus 420 volts and 60 plus or minus 1.2 Hz within 11 seconds after start signal, c:
The D/G is successfully loaded to greater than or equal to 2000 KW (50%
continuous rating) and operates at this load for at least one hour, d:
D/G shutdown was not due to an abnormal condition that would have ultimately resulted in D/G damage or failure.
IT stands for an "invalid test".
A test is considered an "invalid test" if any of the conditions described above for VS are not met due to an intentional shutdown prior to loading or operating for greater than one hour at 2000 KW or better that was not due to an abnormal condition that would have ultimately resulted in D/G damage or failure.
IF stands for an "invalid failure".
If any of the conditions of a VS are not met and the test is not an IT as described and if any of the following conditions are met, the test in considered an IF.
a:
Operator error.
b:
Spurious operation of a trip that is bypassed in the emergency l
operating mode, i.
c:
Maltunction of equipment that is not operative in the emergency operating mode or is not part of the defined D/G unit design.
d:
The failure occurs during the process of trouble shooting.
1 L __
T 1
f:
The failure occurs during the process of a functional check out prior l
to returning the D/G to service following maintenance.
VF stands for "valid failure". A test is considered a valid' failure if any of the following conditions are true, a:
The test cannot be classified as a VS, IT, or IF as' described'above.
b:
The test is intentionally terminated because of an abnormal condition that would have ultimately resulted in D/G damage or failure.
c:
Performance of a cranking or venting procedure leads to the discovery of_a condition (such as excessive water or oil in a cylinder) that would result in engine failure during operation.
Engine 2A had 30 VSs, 2 VFs, 44 ITs, and 0 IPs and engine 2B had 63 VSs, 5 VFs, 37 ITs, and 6 ifs during the period that included 7 valid failures in the last 100 valid tests.
Engine 2A had 31 VSs, 3 VFs, 44ITs, and 0 ifs and Engine 2B had 61 VSs, 5 VFs, 39 ITs, and 6 ifs during the period that included 8 valid failures in the last 100 valid tests.
{
[..
,...s LUNIT DIESEL GENERATOR DATA:
~ VALID ENGINE 2A ENGINE 2B
. ATTEMPT TEST TEST-NUMBER START RESULT DATE START-RESULT DATE 628 IT 06-24-88~
100
- 654 VF
.06-24-88 627 IT 06-24-88
.626 IT 06-24-88
!ai
'99 653 "VS 06-21 98
-652
.VS 06-14-88
'97 651 VS 06-07-88
'96 *-
625 VF 06-02-88 95~
624 VS 06-02-88 650 IT 06-02-88 649 IT 06-02-88 94.
648 VS 06-02-88 647 IT 06-02-88 646 IT 06-02-88 645 IT 06-02-38
.93
- 644 VF 06-01-88 92 643 VS 01-88 e
642 IT.
06-01-88 641 IT 06-01-88 640 IT 06-01-88 639 IT 05-31-88 638 IT 05-31-88 637 IT 05-31-88 636 IT 05-31-88 635 IT 05-31-88 634 IT 05-31-88 633 IT 05-31-88 632 IT 05-31-88 631 IT 05-31-88 630 IT 05-31-88 h
629-IT 31-88 628 IT-05-31-88 627 IT 05-31-88 626 IT 05-31-88
-91 625 VS 05-31-88 90 623 VS 05-25-88 89-622 VS 05-31-88 88:
624.
VS 05-23-88 87-621 VS 05-19-88 86 620 VS 05-12-88 85 619 VS 05-05-88 84.
618 VS 04-28-88 83 623 VS 04-26-88 82 617 VS 04-21-88 81 616 VS 04-14-88 80 615 VS 04-07-88
-7 9 -
614 VS 03-31-88 78 622 VS 03-29-88 77-621 VS 03-24-88 76 613 VS 03-23-88
-75 620 VS 03-22-88 page 1 of 5
e
[ 'a -
- ' ' -VALID ENGINE 2A ENGINE 2B
/ ATTEMPT TEST TEST R
! NUMBER START RESULT DATE START RESULT DATE
,e 619-IT 03-22-88 74 612 VS 03-19-88 17 3 611 VS 03-10-88 72 610 VS 03-03-88 71
'609 VS 02-24-d8 70 618 VS 02-20-88 h
617 IT 02-19-88 69-608 VS 02-16-88 68 607 VS 02-09-88 67 606 VS 02-02-88 66 605
.VS 01-26-88 65 604 VS 01-20-88 64 616 VS 01-18-88 63 615 VS 01-13-88 62.
603 VS 01-12-88 61 602 VS 01-05-88 60 601 VS 12-29-87 59 600 VS 12-22-87 58 614 VS 12-17-87 57 599 VS 12-15-88 56 598 VS 12-08-87 55 597 VS.
12-01-87 54 596 VS 11-24-87 53 613 VS 11-19-87 52 595 VS 11-17-87 51 594 VS.
11-10-87 593 VS 11-03-87
-49' 592 VS 10-27-87 48 612-VS 10-26-87 47 591 VS 10-21-87 46 590 VS 10-14-87 u45 611 VS 10-14-87 44
'10-13-87 42
- 584
'VF 10-13-87 41 583 VS 10-09-87 40 582 VS 10-06-87 39 581 VS 09-29-87 38 609 VS 09-25-87 37 580 VS 09-22-87 36 579 VS 09-15-87 578 IT 09-15-87 l
35 577 VS 09-08-87 l-34 576 VS 09-02-87 j
33 608 VS 09-02-87 607 IT 09-01-87 l
32-575 VS 09-01-87
- page 2 of 5
a VALID ENGINE 2A ENGINE 2B ATTEMPT TEST TEST NUMBER START RESULT DATE START RESULT DATE 574 IT 09-01-87 31 606 VS 08-26-87 30 573 VS 08-24-87 29 572 VS 08-18-87 28 571 VS 08-11-87 27 605 VS 08-05-87 26 570 VS 98-04-87 569 IT 08-04-87 568 IT 08-04-87 567 IF 08-04-87 566 IT 08-04-87 565 IF 08-04-87 25
- 564 VF 08-04-87 24 604 VS 07-30-87 23 563 VS 07-28-87 22 562 VS 07-21-87 21 561 VS 07-14-87 20 603 VS 07-09-87 19 560 VS 07-07-87 18 602 VS 06-30-87 17 559 VS 06-29-87 16 558 VS 06-22-87 557 IT 06-22-87 556 IT 06-22-87 601 IT 06-21-87 555 IT 06-21-87 554 IT 06-21-87 15
- 553 VF 06-21-87 600 IT 06-17-87 599 IT 06-17-87 598 IT 06-17-87 597 IT 06-17-87 596 IT 06-17-87 552 IT 06-16-87 551 IT 06-16-87 550 IT 06-16-87 549 IT 06-16-87 548 IT 06-16-87 14 547 VS 06-16-87 546 IF 06-16-87 545 IT 06-15-87 544 IT 06-14-87 543 IT 06-14-87 542 IT 06-14-87 541 IT 06-14-87 540 IT 06-14-87 539 IT 06-14-87 538 IT 06-14-87 537 IT 06-14-87 536 IT 06-14-87 535 IT 06-14-87
- page 3 of 5
E Y
' VALID ENGINE 2A ENGINE 2B TATTEMPT' TEST TEST i-
' NUMBER START
-RESULT DATE START RESULT DATE 534 IT 06-14-87 533 IT 06-14-87 532 IT 06-14-87 595 IT 06-03-87 13 5941 VS.
05-31-87 12 593 "VS.
05-29-87
-592 IT.
05-28-87 591 IT 05-28-87 590 IT 05-28 589
.IT 05-28 588 IT 05-28-87 587 IT 05-28-87 586 IT 05-28-87 585 IT 05-28-87 584 IT 05-27-87 531 IT 05-21-87 11 530 VS 05-07-87 529 IT 05-07-87 528 IT 05-06-87 527 IT 05-06 87 526 IT 05-06-87 10 525 VS 05-06-87 524 IT 05-06-87 523 IT 05-06-87 9
- 522 VF 05-06-87 8
521 VS 05-05-87 583 IT 05-05-87 582 IT 05-05-87 520 IF 05-04-87 581 IT 05-04-87.
7 580 VS 05-04-87 6
519 VS 05-02-87 5
579 VS 05-01-87
'4
'518 VS 04-29-87 3
578=
VS 04-28-87 2
517 VS 04-26-87
-1 577 VS 04-25-87 0
516 VS 04-23-87
.(1) 576 VS 04-22-87 (2) 515 VS 04-20-87 (3) 575 VS 04-19-87
-(4) 514 VS 04-17-87
.(5) 574 VS 04-16-87 513 IT 04-16-87 512 IT 04-16-87
( 6)'
511 VS 04-15-87 573 IT 04-14-87 572 IT 04-14-87 l
'571 IT 04-14-87 l
(7) 570 VS 04-13-87 l
(8) 510 VS 04-11-87 i
page 4 of 5 j
4 /g [. ;. 2 L
- ~ ' ~ VALID ENGINE 2A ENGINE 2B-ATTEMPT TEST TEST NUMBER.
START RESULT DATE-START.
-RESULT DATE (9)
-569-VS
.04-10-87 568 IT 04-08-87
,~
.509' IT 04-08-87 508 IT 04-08-87 (10).
507 VS 04-08-87
- (11) 567 VS 04-07-87 (12)-
506' VS 04-05-87
- (13)
~ 66 VS 04-04-87 5
(14) 505 VS 04-02-87
. (15) 565 04-01-87 VSc P
- page 5 of 5
,