ML20084R093
| ML20084R093 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities, 05000000 |
| Issue date: | 01/11/1974 |
| From: | Stephenson B COMMONWEALTH EDISON CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084R054 | List: |
| References | |
| NUDOCS 8306140795 | |
| Download: ML20084R093 (2) | |
Text
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Cm ulth Edis:n J,,
l p' C ' 4 Ouad Cities Generating Station d
Post Ofhce Box 216 V
Cordova. Illinois 61242 s
Telephone 309/054-2241
'/s January 11, 1974 O
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John F. O' Leary, Director t, { ;.5" O
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Directorate of Licensing Regula tion
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S. ATOMIC ENERGY COMMISSION washington, D. C.
20545
SUBJECT:
Quad-Cities Nuclear Power Station, Units 1&2 Docket Nos. 50-254 and 50-265, Hydraulic Shock Suppressor (Snubber) Inspections
REFERENCE:
D.J. Skovholt letter dated October 1, 1973 to J. S. Abe l
Dear Mr. O' Leary:
The purpose of this letter is to inform you of the results of a routine inspection performed on the hydraulic shock suppressors during a double outage of Quad-Cities Unit 1 and Unit 2.
UNIT 1 On December 31, 1973, the unit was started down due to a suspected condenser tube leak.
Drywell de-inerting was begun at 2029 and the reactor was in the cold shutdown condition at 1010 the follow-ing morning.
On January 1, 1974, the thirty-three hydraulic shock suppressors in the drywell were inspected.
On January 2,
- 1974, the remaining fourteen were inspected throughout the plant.
The only discrepancy noted in the inspection was one of the enubbers in the drywell contained no oil.
The snubber was a Bergen-Patterson model, serial number G22690-I-20RA, located on the A recirculation pump discharge valve, MO-1-0202-5A.
On January 2, 1974, the snubber was removed for in-spection and replaced with another Bergen-Patterson snubber, ser-ial number F62955-2.
The defective snubber had been rebuilt on September 26, 1973 using ethylene propylene o-rings and polyurethane cup seals and wipers.
The cause of failure was determined to be a.
slight misalignment of the rear mounting bar and the rear accumu-lator cap.
This misalignment caused an insufficient compression of the o-ring between the rear accumulator cap and +-he valve block, thus allowing fluid leakage.
The effected o-ring was inspected and showed no signs of any deterioration.
To preclude further occurences.of this nature, the importance of proper alignment will be stressed to maintenance personnel'and the repair procedure will be revised accordingly.
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F. O' Leary, Director Page 2 Unit 1 was again made critical on January 6, 1974, and the genera-tor was synchronized at 0042 on January 7.
UNTT 2 On January 4, 1974, Unit 2 started dropping load to investigate a suspected failure of a main steam tunnel high temperature switch.
The generator was tripped at 0306 on January 5, and all rods were in at 0535.
At 1010 the reactor head vents were opened, at 1020 de-inerting was begun, and the mode switch was placed in shutdown at 1025.
The cause of the main steam tunnel high temperature signal was determined to be a short to ground in the wiring from the switch.
This short caused the fuse to blow and gave a channel B group I isolation.
The problem had no effect on the safe operation of the unit since the system failed in the safe direction.
Although it was corrected in a short period of time, the decision was made to utilize the down-time of the unit to make a limited inspection of the snubbers.
At 1630 on January 5, a drywell entry was made.
As complete an inspection as time allowed indicated that the snubbers looked at in the drywell were all intact and showed no signs of excessive oil leakage.
A complete inspection will be conducted prior to February 19, 1974 in accordance with D. J. Skovholt's letter of October 1, 1973.
Unit 2 was made critical again at 0605 on January 6, 1974, and the generator was synchronized at 1420 the same day.
We will continue to keep you advised of all further snubber in-spections.
Very trul
- yours,
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B. B. Steppenson Station Sdperintendent BBS-74-7 BBS/dkp cc:
Regional Director Directorate of Regulatory Operations - Region III 1
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