ML20084E856
| ML20084E856 | |
| Person / Time | |
|---|---|
| Site: | Ginna, 05000000 |
| Issue date: | 10/14/1970 |
| From: | Amish V ROCHESTER GAS & ELECTRIC CORP. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084E846 | List: |
| References | |
| NUDOCS 8304150583 | |
| Download: ML20084E856 (2) | |
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1 Cetober 14, 1970 y Gl Dr. Peter A. Morris Divicien of Reactor Licencina N
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Subject:
Malfunction of Care Deluge Valve No. 852B Ginna Etauan Unit No.1 s
Docket No.60-244
Dear Dr. Morric:
f Cn Munday, detober 4,1970 the Ginna unit was in a cold shutdown condition for cched ulmail t m. ace work.
Cne af the scheduled jaba en Sunday was to seal wold the diaphragm on the Accumulator Discharge Caeck Valve #867A.
Saturday evening a tect was ccnducted to have Recidual Heat Return go through Core Deluge Valvec !!Sb2A and ll852B instead of through Valve MC'V ir721. The reason for thic was to remove the Residual Heat Return flow from the pioe line ecntaining Check Valve #867A.
The PCRC met dunday morning, Cetober 4,1970, and approved the Yaintenance IYocedure for ceal welding the diaphragm on Check Valve 4807A. The approval waJ mada after reviewing the reculte of the Saturday night tect. This tect proved that the primary coolant temperature could be held below 1400 by returning the Recidual Heat Removal flow through the 1
Core Deluge Valvec.
When the welder announced that he was already to begin the real wald, the operator began changing the Residual ~ Heat Ivlow to the Core x'<
D21uge Valvec. Tha operator did not receive an open indication for Valve !!862B. Investigation revealed that the limitorque breaker overload had tripp?d the breaker open with the valve in the half-open position.
Valve #852E had operated naticfactorily during ita la.it surveillance tect (April 13,1970) and it wac operated, in tect, caticfactorily coveral timec cn Cetober 3,1970, an'! _ October 4,1970, before the failure. Operatora and '
maintenance personnel were,mable to get the valve more than half open.
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Another teat was run with thic Core Daluge Valve /!85214 in the j
half-open position and tne aata confirmed that even though this valve wa" only half-open, the primary coolant temperature matched the cLtta taken the night before with the vslve all the way open. The ceal welding on Valve l'807/t was started and completed satisfactorily.
O Disascembly of the valve operator in Valve No. 8b2B revealed the malfunction to be the seizure of the stem nut to the valve ctem. The cloue proximity of piping at the valve overhead required that the valve yok'e'l e cut to parmit removal of the valve operator for access to the clem nut. The stem nut wac removed and the reason for its seizure to the stem was found to be caused by a chip from the atem nut thread. The stem threads were undamaged and a new stem nut was installed.
The valve yoke was welded, the welds were radiographed and no flaws were found. The valve ocerator was reassembled, lubricated, test cycled reven timec, and proven to be an operable valve. With the plant in chutdown ecndition we also cycled the remaining cafeguard valven of this type in the containment in the presence of a pip 3 fitter, a mechanic, an electrician and an operator. All valves worked satisfactorily.
In many yearn af application of thic and similar type of valves, T
thic is the firrt time we have ever experienced a failure of this nature.
Tne supplier alco agrees that this was a unique and uncommcn type of valve failure.
Very truly youra,
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