ML19347B308
| ML19347B308 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 09/26/1980 |
| From: | Linder F DAIRYLAND POWER COOPERATIVE |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| LAC-7170, NUDOCS 8010140335 | |
| Download: ML19347B308 (4) | |
Text
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[k COOPERAT/VE eo two< si7 26is tasr As soin s. t4 crioser wisconsin s46oi afh3) 788 4000 September 26, 1980 In reply, please refer to LAC-7170 DOCKET NO. 50-409 Director of Nuclear Reactor Regulation ATTN:
Mr. Dennis M.
Crutchfield, Chief Operating Reactors Branch #5 Division of Operating Reactors U.
S.
Nuclear Regulatory Commission Washington, D.
C.
20555
SUBJECT:
DAIRYLAND POWER COOPERATIVE LA CROSSE BOILING WATER REACTOR (LACBWR)
PROVISIONAL OPERATING LICENSE NO. DPR-45 APPENDIX J, CONTAINMENT LEAKAGE TESTING l
Reference:
(1)
DPC Letter, Madgett to Reid, LAC-4408, dated December 21, 1976.
I Gentlemen:
Pages 3 and 4 of Reference (1) gave several reasons why we feel it is not prudent to revise the present testing program on the personnel airlock doors of the LACBWR Containment Building.
It is requested that an exemption, pursuant to the regulations of Title 10, Chapter 1, Code of Federal Pegulations, Part 50.12(a), to the requirements of paragraph III. O. 2 (b) (iii) of Appendix J, 10CFR Part 50 be granted.
The following information is provided as a basis for this request:
1)
Each of the two (2) personnel airlock doors in the LACBWR containment has been individually tested in accordance with Section 5.2.1.2 of the LACBWR Technical Specifications 38 times over the past 13 years and 9 additional times as part of the Type A Containment Leak Test.
There has never been a leak from the doors during any Class A test.
2)
Tha A,r seals have never failed a leak test due to wear or det cion.
3)
Two failures of the airlock leak test because of seal leakage, both through the inner door seal, have occurred.
Both of these were caused by failure to follow the bolting procedure necessary to conduct the airlock leakage test.
The inner door is designed to seal against pressure from inside containment, 8010140 3 3 5
Mr. Dennio M. Crutchfiold, Chiof LAC-7170 Operating Reactors Branch #5 September 26, 1980 therefore, because the leak test pressurized the volume between the doors, strongbacks are needed to hold the inner door in position against the seal during the 3eakage test.
Since both of these door seal failures were due to insufficient compression of the inner door seal and it became partially ex-truded during the pressurization, it is evident that these failures cannot be attributed to a defective door seal.
4)
During a recent outage, there were a total of 139 door openings for entrance to containment in a 10-hour period, with an equal number of door openings for exits.
During a day when plant is operating, there is an average of 40 entrances and 40 exits.
Even with this kind of usage, a gasket has never been replaced because of wear and deterioration.
5)
Reference (1) stated that continuous monitoring of the airlock door seals or frequent testing of the airlocks is not practical without a major modification to the door seal design.
We have obtained from the door fabricator a proposal to modify the LACBWR containment personnel airlock to accommodate testable-type door seals (see attached Sketch B on Contract 01741).
6)
We have analyzed this gasket design and have determined that it would be a significantly inferior seal because:
a.
The sealing surface contact area is reduced.
b.
The rubber tips are much more fragile and vulnerable to damage than the present rubber seal.
c.
The thin rubber tips are more subject to fatigue failure, d.
The thin rubber tips are more subject to abrasion and wear.
e.
The designer states that they believe that the gasket would not require replacement in less than a year, and some similar designs are functioning well at 3 years.
However, this does not compare with the present gasket lifetime, one of which is still good after 13 years and the other has never been replaced because of wear, fatigue or deterioration.
Of the 38 airlock leakage tests performed over the past 13 years, there have been 6 failures, all caused by components other than the door seals.
The present leakage test is done at design pressure and tests the overall airlock leakage.
This is a more comprehensive test than one which tests the door seals alone at some reduced pressure. i
Mr. Dennis M. Crutchfield, Chief LAC-7170 Operating Reactors Branch #5 September 26, 1980 The present 4-month test interval for a 52 PSIG test of the airlocks specified in Section 5.2.1.2 (d) of the LACBWR Technical Specifications exceeds the 6-month test interval required by Appendix "J".
It is proposed that the 4-month test interval continue to be used in lieu
..of the 6-month test interval when an exemption is granted.
If you have any questions, please call.
Very truly yours, DAIRYLAND POWER COOPERATIVE bdf W'lf/
J Frank Linder, General Manager FL: HAT:af cc:
J.
Keppler, Reg. Dir., NRC-DRO III NRC Resident Inspectors e
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