ML19347E526
| ML19347E526 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 04/23/1981 |
| From: | Withers B PORTLAND GENERAL ELECTRIC CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| IEB-81-01, IEB-81-1, NUDOCS 8105120362 | |
| Download: ML19347E526 (7) | |
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DMaCi' Trojan Nuclear Plant T g 'E Docket 50-344 g
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c Mr. R. H. Engelken, Director U. S. Nuclear Regulatory Commission, Region V 1990 N. California Blvd.
Walnut Creek Plaza, Suite 202 Walnut Creek, CA 94596
Dear Mr. Engelken:
By letter dated March 30, 1981, PCE proposed an alternative mechanical snubber testing program to that requested under IE Bulletin 81-01 for the Trojan Nuclear Plant. Recent conversations with members of the NRC sta'ff have indicated that additional inspections would be necessary.
Our response to Action Item 3 of Bulletin 81-01 has been revised in order to satisfy the NRC concerns and resolve this issue. The revised inspection program includes a vinal inspection of all the mechanical snubbers on safety-related systems plus a manual stroke test of 100 percent of the accessible and 20 percent of the inaccessible mechanical snubbers on safety-related systems.
During recent preparations for the mechanical snubber inspections, an anomaly was identified for a small mechanical snubber that is inacces-sible during normal operation. This snubber is located on a 3/4-inch Reactor Coolant Pump seal leakoff line inside Containment and was sup-plied by Bergen-Paterson. All of the safety-related Bergen-Paterson snubbers <50,000 lb had been thought to be hydraulic snubbers and were replaced by PSC mechanical snubbers.
It is apparent that this snubber was not changed to a PSC snubber since it already was a mechanical snubber. Since Bergen-Paterson was not known to be a manufacturer of mechanical snutabers, an investigation was launched to determine the identity of its manufacturer. The investigation revealed that it was manufactured by International Nuclear Safeguards Corporation (INC). This snubber will be replaced with a PSC snubber during the. next refueling outage, which is scheduled to begin next month. Review of the snubbers
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Portland Goocral ElectricConpany Mr. R. H. Engelken April 23, 1981 Page two on similar lines h a shown this to be an isolated case.
Since the true identity of the ma 4 facts 2rer was not known until after the PGE-to-NRC letter dated March 30, 1981 was submitted, the responses to Bulletin 81-01 Action Items 1 and 2 have also been revised.
PGE's responses to all the Bulletin 81-01 Action Items are presented in the attachment to this letter. The response to Action Item 4 did not change but was included for your convenience. We are proceeding with the proposed inspection program and have begun the inspection of the accessible mechanical snubbers. Please do not hesitate to contact us if you havr any questions on the above. Approximately 150 man-hours have been expended to date in the preparation of the responses to Bulletin 81-01.
Sincerely,
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Bart D. Withers Vice PresicTent Nuclear Subscribed and sworn to before me thiscf.I day of
'y 2 1981.
Y,wd, // Asa Notary Public of pregon
[rewe r,.7 'f /[M My Commission Expn es:
O' Attachment c: Mr Lynn Frank, Director State of Oregon Department of Energy Director NRC Office of Inspection
_ and Enforcement Washington, DC 20555 1
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.n Trojan Nuclear Plant Docke t 50-344 Page 1 of 5 License NPF-1 REVISED RESPONSES TO IE BULLETIN 81-01 FOR THE TROJAN NUCLEAR PLANT Item 1 Within 30 days of the issuance date of this bulletin, all normally accessible [al IhC mechanical snubbers installed on safety-related sys-tems or in storage shall be visually examined and tested as follows:
a.
Perform a visual examination for damage and, without causing the system to be inoperaole except as permitted by the facility technical specifications, verify that the snubbers have freedom of movement by performing a manual test over the range of the stroke in both compression and tension.
b.
Perform an operability test to confirm that (1) activa-tion (restraining action) occurs in both compression and tension and (2) the drag forces are within the specified range in both compression and tension. The tests shall be performed on all snubbers in storage and on a represen-tative sample (10 percent of the total of this type of snubber in use in the plant or 35,, whichever is less) of the normally accessible snubbers that are in service and can be individually removed without causing the system to be inoperable, except as permitted by the facility technical specifications. For each snubber that does not meet the test acceptance criteria, an additional repre-sentative sample (as defined above) of this type of snubber shall be tested. For each of these additional snubbers that do not meet the test acceptance criteria, another representative sample of this type of snubber shall be tested. This cycle shall be repeated until no more failures have been found or until all snubbers of this type have been tested. The samples should be made up of snubbers representing the various sizes.
c.
Snubbers which have been examined and tested in a manner comparable to Items la and Ib above within the last 6 months may be exempted.
d.
If any failures are identified in Items la or Ib above, take corrective action and evaluate the effect of the failure on the system operability pursuant to the. scility technical specifications for continued operation.
[a] "Normally accessible" refers to those areas of the plant that can be entered during reactor operation.
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Trojan Nuclear Plant Docket 50-344 Page 2 of 5 License NPF-1 REVISED RESPONSES TO IE BULLETIN 81-01 FOR THE TROJAN NUCLEAR PLANT e.
If failures are identified in Items la and Ib above, and if INC snubbers are known to be located in any inacces-sible areas, a plant shutdown shall be performed within 30 days after the discovery of the first inoperable snubber and inspections conducted in accordance with Item 2a and 2b below, unless justification for continued operation has been provided to the NRC.
Response
There are no normally accessible INC mechanical snubbers installed or in storage at Trojan.
Item 2 Visually examine and test all inaccessible INC mechanical snubbers installed on safety related systems at the next outage of greater than 5 days duration as follows:
a.
Visually examine and manually test all inaccessible snubbers as described in Item la above.
b.
Perform an operability test on a representative sample of inaccessible snubbers as described in Item lb above.
c.
Snubbers which have been examined and tested in a manner comparable to Items 2a and 2b above within the last 6 months may be exempted.
d.
If any failures are identified in Items 2a or 2b above, take corrective action to evaluate the effect of the failure on system operability pursuant to the facility technical specifications for resuming operation.
Response
Only one INC mechanical snubber is installed in an inaccessible location at Trojan. This snubber will be replaced with a PSC mechanical snubber during the next refueling outage, which will result in this item being not applicable for Trojan.
-,..,.., _. _. Item 3 Provide a schedule for an inspection program covering mechanical snubbers produced by other manufacturers. As a minimum, this inspection program shall:
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Trojan Nuclear Plant Docket 50-344 Page 3 of 5 License NPF-1 REVISED RESPONSES TO IE BULLETIN 81-01 FOR THE TROJAN NUCLEAR PLANT Include all snubbers installed on safety-related systems; a.
b.
Include the visual examination and manual test described in Item la above for all snubbers; c.
Snubbers which have been examined and tested in a manner comparable to Item 3b above within the last twelve months may be exempted; d.
Require tbc corrective action and evaluations described in Items ld and 2d above; and Be completed prior to the completion of the next refueling e.
outage. Plants t.hich are currently in a refueling outage should perform the visual examination and manual tests of inaccessible mechanical snubbers before resumption of
__ operations'unless some other basis for assurance of snubber operability is provided to the NRC.
Response
In lieu of the above, and for the reasons discussed in the PGE-to-NRC letter dated March 30, 1981, PGE is planning to perform the following inspection program:
a.
A visual examination of all the mechanical snubbers installed on safety-related systems will be performed to check for evidence of excessive loading or vibration.
b.
A representative sample of the mechanical snubbers will be manually struke tested per Item la of the Bulletin in order to verify that they have freedom of movement over the range of their stroke in both compression and tension. This representative sample will include 100 percent of the accessible mechanical snubbers and 20 percent of the inaccessible mechanical snubbers on safety-related systems. The sample population for inac-cessible snubbers will be carefully selected to include the follewing:
i) Snubbers that are subject to cyclic stresses.
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- 11) Snubbers that are installed on lines with a
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potential for impact loads and/or operational vibration of such amplitude as to routinely result in activation of the snubbers.
At least one snubber on each of these lines wil' be manually stroke tested.
Trojan Nuclear Plant Docket 50-344 Page 4 of 5 License NPF-1 REVISED RESPONSES TO IE BULLETIN 81-01 FOR THE TROJAN NUCLEAR PLANT Inaccessible snubbers are defined as those that are installed:
- 1) inside Containment; 2) in high-radiation exposure zones outside Containment; or 3) in locations outside Containment where accessibility it limited due to physical constraints such as the need for scaf folding.
Snubbers having a rated capacity of 35 kips or more will be excluded from manual stroke testing since manual movement is not practicable due to the high breakaway force involved.
c.
Snubbers which have been examined and tested in a manner comparable to Item 3b within the last 12 months may be included in the representative sample.
d.
If any mechanical snubbers are found to be inoperable due to vibretion or impact loads, all of the other mechanical snubbers on_the same line will be manually stroke tested.
An additional 10 percent of the inaccessible mechanical snubbers will be manually stroke tested for each inacces-sible mechanical snubber found to be inoperable due to causea other than vibration or impact loads.
This inspection program is scheduled to be completed by e.
the end of the next refueling outage.
Item 4 Submit a report of the results of the inspections, testing and evaluation requested in Item 1 to NRC within 45 days of the issuance date of this bulletin. Report the results of the inspections, testing and evaluation requested in Item 2 within 30 days af ter the inspection and testing have been completed. The response to Item 3 shall be submitted within 60 days of the issuance date of this Bulletin. The results of the inspections performed for Item 3 shall be submitted within 60 days af ter the comple-tion of the inspection.
The reports shall contain the following:
A description of the visual examinations and tests a.
perfo rmed.
b.
Nurf er of snubbers examined and tested. Grouping by manufacturer name, model number, and size is acceptable.
c.
Number of failures identified; manufacturer name, model number, size, mode of failure, cause of failure, correc-tive action, snubber location, effect of failure on plant
ei Trojan Nuclear Plant Docket 50-344 Page 5 of 5 License NPF-1 REVISED RESPONSES TO IE BULLETIN 81-01 FOR THE TROJAN NUCLEAR PLANT and system safety, and justification for continuing or resuming operation.
d.
The above information shall also be provided for the snubbers exempted by Items Ic, 2c and 3c above.
Response
PGE will submit the requested information within 60 day = af ter the completion of the inspection.
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