05000409/LER-1979-002, Forwards LER 79-002/01T-0
| ML19261A703 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 01/29/1979 |
| From: | Linder F DAIRYLAND POWER COOPERATIVE |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML19261A704 | List: |
| References | |
| LAC-6090, NUDOCS 7902060295 | |
| Download: ML19261A703 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| 4091979002R00 - NRC Website | |
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DAIItYIntND I'OWEIt COOI*EftATIVE Ba G one, O L onaa 54601 January 29, 1979 In reply, please refer to LAC-6090 DOCKET NO. 50-409 Mr. James G. Keppler Regional Director U.
S. Nuclear Regulatory Commission Directorate of Regulatory Operations Region III 799 Roosevelt Road Glen Ellyn,. Illinois 60137
SUBJECT:
DAIRYLAND POWER COOPERATIVE LA CROSSE BOILING WATER REACTOR (LACBWR)
PROVISIONAL OPERATING LICENSE NO. DPR-45 REPORTABLE OCCURRENCE NO. 79-02
Reference:
(1)
LACBWR Technical Specifications, Section 3.9.2.a.
(2)
DPC Letter, LAC-6072, Linder to Keppler, dated January 4, 1979.
(3)
LACBWR Technical Specifications, Section 5. 2.1. 2 (b).
Dear Mr. Keppler:
In accordance with Reference 1, this submittal constitutes the required follow-up report describing the occurrence which was initially reported in Reference 2.
The subject occurrence involved the discovery of abnormal degradation in the primary reactor con-tainment during periodic Type B surveillance leakage, rate testing.
As a result of conducting Type B leak tests on January 15, 1979, the indicated leakage flow rates from electrical penetration unit Nos. 3, 4 and 6 were found to exceed the permissible value pre-scribed in LACBWR Technical Specifications (Reference 3).
The leak-age ratas found were 0.412 SCFH on penetration unit No. 3, 8.27 3CFH on penetration unit No. 4 and 0.619 SCFH on penetration unit :To. 6.
The technical specification leakage rate acceptance criteria is 0.375* for each of these units.
- The permissible leakage rate shall not exceed 1% of leakage rate L where L is 37.5 SCFH.
po po The subject units employ the MI cable-type penetration.
This type has solid conductors, compacted magnesium oxide insulation and a round copper sheath.
The MI cable runs through an inner chamber 79020603 'lI Mr. James G. Keppler LAC-6090 Regional Director January 29, 1979 formed by the containment shell and an inner chamber wall; the chamber for each unit is 8 feet 8 inches high with a cross section 3 inches deep and 8 inches wide.
The penetration is made by passing the M: cable through brass glands which are screwed into 3/4-inch tapped holes in the containment shell and in the inner chamber wall.
The copper sheath is sealed at the gland.
The inner chamber is pressurized to leak-test the penetrations.
Each unit contains sixty-six (66) individual cable penetrations (see Figure 1).
The following individual cable penetrations were observed to be leaking on the outside of the containment shell:
PEN. UNIT NO. 3 PEN. UNIT NO. 4 PEN. UNIT NO. 6 2A 1B 8A 2A 9A 4B 19A 6A 10A 6B 32A 14A llA 8B 15B 23A 23A 21B 20B 24A 25A 23B 28A 27B 33A 29B 30B The specific points of leakage at the individual cable penetrations varied.
Leakage was frem the copper sheath / packing gland interface (i.e., where the MI cable penetrates the gland) on some of the penetrations and other penetrations were observed to be leaking at the point where the threaded gland screws into the containment shell.
Following the determination of unsatisfactory testing results for these penetrations, repairs were commenced.
The repairs consisted of cleaning and recoating the affected cable penetration glands and adjacent containment wall areas with Scoth Cast Resin #5 epoxy seal-ant compound (see Figure 2).
The subject electrical penetration units were post-mai tenance tested on January 18, 1979, with unit No. 3 leakage found to be 0.442 SCFH, again exceeding the permissible leakage rate.
Units Nos. 4 and 6 satisfactorily met the leakage acceptance criteria with indicated leakage rates of 0.295 SCFH and 0.0 SCFH respectively.
The following Unit No. 3 individual cable penetrations were observed to be leaking on the outside of the containment shell:
9A 16B 10A 26B 22A 28B 27A 30B 7B 33B 13B The above cable penezrations were repaired using the method previously c..
Nr. James G.
Keppler LAC-6090 Regional Director January 29, 1979 discussed.
Testing following maintenance was reperformed on January 20, 1979.
Test results indicated that Unit No. 3 was again leaking 0.442 SCFH.
Individual cable penetrations ob-served to be leaking included the following, six of which are located inside containment at the inner chamber wall:
PEN. UNIT NO. 3 Outside Containment Shell Inner Chamber Wall (Inside Containment) 23B 8B 9B 17B 25B 28A 32A Additionally, repairs were made to Unit No. 4 to reduce the leakage rate even though it was previously found acceptable.
The leakage of Unit No. 4 was found to be 0.147 SCFH.
Repairs on Unit No. 3 were again effected using the methods previously discussed (the repair methods for sealing the penetration glands at the containment shell are also used for sealing glands at the inner chamber wall within containment).
Post maintenanc.3 leakage testing was performed on January 21, 1979, which indicated that the penetration unit was leaking at a rate of 0.559 SCFH.
Final repairs were completed on penetration unit No. 3 on January 22, 1979, after the following individual cable penetrations were sealed at the inner chamber wall:
22A 15B 23A 16B 25A 17B 32A 19B 30B Post Maintenance leakage rate testing resulted in a ler.kage rate of 0.236 SCFH, thus meeting the applicable leakage rate acceptance criteria of 0.375 SCFH.
With the accomplishment of the sealing repairs and the attainment of successful Type B test results, no further corrective action was performed at that time.
The inability of some electrical penetra-tion seals to remain leak tight during test conditions has been kr. James G.
Keppler LAC-6090 Regional. Director January 29, 1979 attributed to hardening and embrittlement of the epoxy sealant compounds.
Due to the frequency with which numerous individual cable penetrations have leaked during tests, an in-vestigation of sealing materials has been undertaken for the Purpose of determining improvements to insure long range integrity.
A Licensee Event Report (Ref. Appendix A, Regulatory Guide 1.16, Revision 4) is enalosed.
Should you have any questions regarding this submittal, please contact us.
Very cruly yours, DAIRYLAND POWER COOPERATIVE Frank Linder, General Manager FL:LGP:af cc:
Director, Office of Inspection and Enforcement (40)
U.
S. Nuclear Regulatory Commission
~~
Washington, D. C.
20555 Director, Office of Management Information and (3)
Program Control U. S. Nuclear Regulatory Commission Washington, D. a.
20555 s.,.
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