ML20010A725
| ML20010A725 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 07/20/1981 |
| From: | Withers B PORTLAND GENERAL ELECTRIC CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| IEB-81-01, IEB-81-1, NUDOCS 8108120111 | |
| Download: ML20010A725 (4) | |
Text
Docket No. 50-34a/81-01 18~-
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July 20, 1981 Trojan Nuclear Plant Docket 50-344 License NPF-1 4
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Mr. R. H. Engelken, Director f
U. S. Nuclear Regulatory Commission g
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Walnut Creek, CA'94596 y
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Dear Mr. Engelkeni
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An inspection of the mechanical snubbers instelled on safety-related systems at the Trojan Nuclear Plant was recently completed in response to IE Bulletin 81-01.
The results of this inspection are contained in the attached report. Please note that the International Nuclear Safeguards Corporation (INC) anubber identified in the PGE to NRC letter dated April 23, 1981 has been replaced with a Pacific Scientific Corporation (PSC) snubber.
Sincerely, I
^^ M Bart D. Withers Vice President Nuclear l
l Subscribed and sworn to before me this 20th day of July 1981.
l 4
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Notary Public of Og4gon l
My commission expires: August 9, 1983 i
i Attachment c:
Director l
NRC Office of Inspection and Enforcement Mr. Lynn Frank, Director IIj/
I State of Oregon Department of Energy C108120111 s!'072'O
{DRADOCK 05000344-PDR i SW Sunco Street Portand. Oregon 97203
Troj;n NuclGOr Plcnt Dock 2t 50-344 License NPF-1 i
Sheet 1 of 2 Attachment to PGE Letter Dated July 20, 1981 Report on IE Bulletin 81-01:
Inspection of Mechanical Snubbers All the mechanical snubbers installed in safety-related systems were visually inspected and manually stroke tested during the spring 1981 refueling outage and the month preceeding the outage at the Trojan Nuclear Plant. Visual inspections were performed to ascertain, as a minimum, the following conditions:
1.
Grout and anchor bolt integrity 2.
Weld integrity 3.
Nut and bolt tightness 4.
Pins and cotters 5.
Clamp location (eg, has any walking or rotation occurred) 6.
Any sign of structural distress (eg, bent or fretted steel) 7.
Any sign of lack of clearance for snubber movement 8.
Integrity of snubber ball bushings 9.
Snubber in end position In addition, snubber stroke testing was performed to verify f reedom of movement of the snubbers in both compression e.nd tension. This was accomplished by disconnecting one end of the snubber and manually stroking each snubber in both compression and tension to verify that lockup had not occurred.
A total of 370 snubbers were visually inspected and stroke tested, 67 of which are located outside of Containment. All were manufactured by Pacific Scientific Corporation (PSC). A break down into model number and q.santity is given below:
Model No.
Quantity PSA-1/4 42 PSA-1/2 76 PSA-1 35 PSA-3 111 PSA-10 101 PSA-35 5
TOTAL 370
=. -.
Troj:n Nucicar Plcnt Docket 50-344 License NPF-1 Sheet 2 of 2 i
f No snubber failures were indicated as a result of the visual exasination.
However, 22 snubbers were taken out of service on the basis of the manual stroke testing. _ Subsequent evaluation showed that only 12 out of i
the 22 anubbers had actually failed. Table 1 identifies the snubber model number, size, mode of failure, cause of failure, the location of the 22 snubbers and the system in which the snubber is installed.
Snubbers were decontaminated as required and shipped to PSC for test-ing, disassembly, evaluation, repair and re-testing (as required).
i Failure of nine of the snubbers was attributed to improper handling or I
installation. ~ Included in this classification are tha following:
1.
Four failures attributed to improper installation such as the rotation of the snubber ends in relation to each other (resulting in twisted rod and bearing assemblies and bent screw shaf ts).-
2.
Four failures attributed to improper handling such as personnel using small snubbers as hand or foot holds (resulting in bent screw shafts) or from other external j'
loads such as piping insulation. One snubber within this group failed to lockup during testing and was s
classified as " broken" in the attached table.
1 3.
One failure attributed to a foreign glue-like substance I
stuck to ' the snubber shaf t, resulting. in only partial stroking of the snubber.
j I
The remaining three snubbers failed due to an apparent overloading condition.- Cause of the overloading is unknown at this time and is under l
investigation. An analysis of the potential for waterhammer in the
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supported system end a metallurgical evaluation of the failed parts are included as part of this investigation.
The remaining ten snubbers were removed from service due to difficult, j-erratic, or noisy operation. However, these snubbers were tested by PSC l
and found to be within acceptable limits and were therefore not classified l
as having failed.
Steess analyses were performed for the systems containing failed snubbers.
i l
A seismic reanalysis was performed for the system containing the broken l
snubber, and thermal stress analyses were performed for those systems containing the snubbers that had locked, partial stroke, and rough stroke-
-failure modes..These analyses indicated that the systems involved suffered no ill effects as a result of the failed snubbers and therefore the systems remained operable at all times. Nevertheless, all of the failed snubbers were replaced with spare snubbers prior to the end of the l
spring 1981 refueling outage.
LSP/4 jrlA24
e YABLE 1 e
TROJAN NUCLEAR PLANT SNUBBERS REMOVED FROM SERVICE DURING THE 1981 MECHANICAL SNUBBER INSPECTION PROGRAM Snubber Stre I t ein No.
_ Support Mark No.
Model No.
(Ibs)
Failed Mode of Failure Cause of Fallure Loc a t t or.
System 1
GCB-9-1-SS304 PSA-1/2 650 Yes locked leproper installation outside Containment CS 2
HBD-22-2-SS3001 PSA-3 3,000 No N/A N/A Outside Containment CCW 3
SI-150!R-1-1-SS300 PSA-1 1,500 No N/A N/A Outside Containment S1 4
GCB-7-1-SS300 PSA-1/2 650 No N/A N/A Outside Containment RHR 5
HBD-28-2-SS301 PSA-3 6,000 No N/A N/A Outside Containment CCW 6
MBD-27-3-S$302 PSA-3 6,000 No N/A N/A Outside Containment CCW 7
GCB-9-1-SS 301 PSA-3 6,000 No N/A N/A Outside Containment CS 8
SI-60lR-1-1-SS1218 PSA-10 10,000 Yes locked Overload Inside Containment 51 9
St-250lR-1-64-SS1101 PSA-1/2 500 Yes Rough stroke Improper handling Inside Containment
$1 10 SI-250lR-1-64-SS1102 PSA-1/2 500 Yes Broken leproper handling Inside Containment SI 11 SI-250lR-1-64-SS1108 PSA-1/4 250 Yes locked Improper Installation laside Coctainment 51 12 CS-250lR-4-61-SS1086 PSA-1/4 250 Yes Partial stroke Foreign substance on Inside Containment CVCS shaft 13 SI-2105R-2-4-SS1157 PSA-10 10,000 Yes Rough stroke Overload Inside Containment SI 14 SI-250lR-2-4-SS1158 PSA-10 10,000 Yes locked Overload leefde Containment SI 15 RC-2501R-4-1-SS1075 PSA-1/2 500 Yes locked leproper handling Inside Containment RCS 16 RC-601R-2-1-SS;9418 PSA-10 10,000 No N/A N/A Inside Containment RCS 17 RC-601R-2-1-SS1041*
PSA-10 10,000 No N/A N/A Inside Containment RCS 18 RC-601R-2-1-SS1259 PSA-10 10,000 No N/A N/A Inside Cantainment RCS 19 RC-250lR-4-1-SS1078 PSA-3 3,900 Yes Rough stroke leproper handlinR inside Containment RCS 20 SI-250lR-3-05-SS1035 PSA-1/4 2 *,0 Yes locked Improper installation Inside containment 51 21 CS-2 50lR-2941-SS1198 PSA-1/2 500 Yes locked Improper installation Inside Containment CVCS 22 RH-250lR-13-1-SS1210 PSA-10 10,000 No N/A N/A Inside Containment RHR N/ A - Not Appl ic able.
- - Tanden Support Assembly.