ML20084B493
| ML20084B493 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 06/29/1972 |
| From: | Palmer F COMMONWEALTH EDISON CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084B496 | List: |
| References | |
| NUDOCS 8304060469 | |
| Download: ML20084B493 (3) | |
Text
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309 454 2241 O
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Commonwealth Edison Company Q U A D.ClilE S NUCLEAR PoWE R S T A TIO N Address teply so, POST offlCE Box 216
- ConDoVA, itLINot5 61242 FAP '(2 -124 s
l June 29, lg7(
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J.F.
O' Leary E, J.]
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]f Director, Directorate of Licensing F- :.]
,1 U.S.
Atomic Ener gy Comrcis s i on g:QQ E'
Washington, D.C.
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- o Dear Mr.
O' Leary:
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Ref:
Quad-Cities Nuclear Pover Station - Unit 2 DPR-30 Appendix A Section 1.A.h, Section 6.6.B.2 and Section 6.6.B.3 j
1 The purpose of this letter is to inform you of the j
details regarding the failure of electromatic relief valve 2 203-3D to open when given a manual signal.
This j
incident occurred at Quad-Citics Unit 2 on June 19, 1972
}
at h:50 a.m.
4 i
1 DESCR_IPTIO_U _0_F_ FAILURE i
j During Phase IV startup testing on Unit 2 at Quad-Cities Mucicar Pover Station with the reactor operating at 650 !Gt, Electromatic Relief Valve 2 203-3D failed to 1
open when given a manual initiation signal.
The turbine-l generator was not in operation at the time of the occur-rence.
Operation of the various relief valves van being carried out as a part of STI-98, Torus Movement Special l
Test.
Previous to this occurrence at 1: 41 a.m.
this same
]
day, the subject valve had operated successfully.
During j
the subsequent test to prove the operability of the HPCI i
system, it was discovered that there was an oil leak at the HPCI emergency oil pump.
It was decided to make the J
HPC1 s ys tem inopera.ble in order to repair the oil leak.
i In accordance with Specifications 3 5.C.3 and 3 5.D 4, shutdown of the reactor was initiated at 6:53 a.m.
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Mr.
J.F.
O' Leary 2-June 29, 1972 J
INVESTTGATION3 Investigations into the failure included =cacuring the resistance of the solenoid circuit for the electro-matic valve.
The f ou r operable valves were found to i
reasure 5 CHMS resistance; the inoperable "D"
valve was found to measure a pproxiestely 300 OEMS resistance.
Plans were ende to enter the dryvell and replace the solenoid on the "D"
valve.
Continued i nves ti ga ti ons into the problem revealed that of the two coils in the solenoid for each valve,
~ ~ ~ iisi s t a nie~ o f TO RMS ; the
~
the " Operating Coil" had a r second coil, called the " Holding Coil" had a resistance j
of 290 OHMS.
When the valve is closed, a shorting switch shorts out the holding c oil.
When the valve is opened, the shorting svi tch opens and allows the holding c oil to raintain the valve open.
It was reasoned that the shorting svitch had probably not closed the last time the valve closed.
This vould account for the censured resistance of 300 OHMS.
The subsequent inspection of the solenoid coils of the "D"
relief valve revealed that the shorting switch was " hung-up" on some of the wires within the control i
box for the valve.
It was observed that the wires had 4
_ not been properly " trained" when the box was vired.
- Thus, the vires _Ihterferred with the proper operation of the shorting switch.
REPAIRS The wires vere " trained" to their proper position to allow proper operation of the shorting switch.
At h:05 p.m.
that same day, the 2-203-3D electromatic reli ef valve was proven to be operable.
Scheduled start-up testing on the Unit resumed immediately.
1 The control boxes for the other Unit 2 electromatic relief valves were inspected and the viring was found to i
be satisfactory.
Inspection of the similar equipment on Unit 1 is planned at the next opportunity to enter the
- dryvell, f
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i e
4 Mr.
J.F.
O' Leary June 29, 1972 i
COMCLUSIO!!
I In conclusion, it in felt that a combination of i
I evento led to thic occurrence.
It is known that there I
10 norre vibrn ti on as s oci a ted wi th each relief valve operation.
An part of the scheduled testing that day, there vere a considernble number of relier valve operations.
Thene tvo items coupled with the unsatin-f ac tory virin6 within the control box led to the wires jiggling to n ponition that interferred with the nhorting l
svitch operation.
j f
very truly youro, COMMOINFALTH EDISON COMPANY Quad-Citien Nuclear, Power Station 4?-_ /
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j F.A. Palmer /
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