ML20002C686
| ML20002C686 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 06/28/1973 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8101100720 | |
| Download: ML20002C686 (3) | |
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June 28, 1973 Mr. John F. O' Leary, Director Re: Docket No 50-155 Directorate of Licensing License No DPR-6 United States Atomic Energy Commission Washington, DC 205h5
Dear Mr. O' Leary:
Mr. Donald J. Skovbolt's letter of August 3,1972 requested that we review our Big Rock Point facility to determine whether failure of any equipment, particularly the circulating water system, could cause flooding of critical equipment such as that which occurred recently at Quad Cities Unit 1.
Our response to the Flooding of Critical Equipment letter (Sewell to O' Leary dated October 2,1972) did not consider the equipment in the screenhouse. This inadvertent omission was observed by representatives of the Directorate of Regulatory Operations, Region III during an inspection conducted the week of May 14, 1973. This letter vill address the oversight.
A review of the equipment shows that the shock vave caused by the valve closure failure mechanism that occurred at Quad Cities still does not exist at Big Rock Point and such a massive failure of the expansion joint is not considered credible.
Two motor-operated discharge butterfly valves are located downstream of the expansion joints and condenser circulating water pump (one each per loop). The starting sequence of the pump is such that when the discharge valve is opened approximately 33% of full open the pump starts. When the pu=p is tripped, the valve then closes re-quiring approximately 20 seconds to close. The valve can also be closed during pump operation by depressing the "close" push button at the Limitorque operator of the valve. However, a continuous depress-ing of the "close" push button is required to close the valve; but even then, when the valve is closed to less than 33% open, the pump trips automatically. Any effort to close the discharge valve during its pump operation with the handwheel is prevented by the Limitorque drive. Therefore, the pump cannot be operated with the discharge valve in the el sed position.
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Mr. ' John F. O' Leary, Director-2
_Jun2 28, 1973 Even assuming that in some way the valve could be completely closed with the pump in operation, it is not considered credible that the expansion joint would fail since the design of the expansion joint (35 psig) is based on the shutoff head of the condenser circulating water pump (80 feet).
It should be noted also that in the Quad Cities case, the valves were hydraulic operated and the valve slammed shut during modifi-ce.tions to the system. At Big Rock Point, the valves are motor operated and move rather slowly.
(Approximately 20 seconds to close.)
There is also an expanrion joint in the 2h" crosstie line but there are no valves downstream and, hence, a massive failure again is not considered credible.
To assure that a small leak does not develop (which could be assined to propagate into a large breat) an inspection program has been developed. The arrangement of condenser circulating water pump piping is such that the expansion joint cannot be removed and visually in-spected without first removing the circulating water pump. Both of the discharge pump expansion joints were inspected and documented within the past year when the circulating water pumps were inspected. As a part of the preventive maintenance program, these expansion joints vill be removed and inspected for possible replacement every five years.
This coincides with the circulating va',er pump inspection interval. In addition, a visual inspection on the exterior side of expansion joints is being made with the routine inspectics of pumpe and packings that is presently being conducted at intervals of three times per week.
Yours very truly, f
cati RBS/ds Ralph B. Sewell Nuclear Licensing Administrator CC: BHGrier, LEAEC
AEC DIS' ' BUTION FOR PART 50 DOCKET MATF ' AL~
CONTROL NO: 5149 (TEMPORARY FORM)
FILE:
FROM:
DATE OF DOC DATE REC'D LTR MEMO RPT OTHER C:nsumers Power Company J2ckson, Michigan 49201 Ralph B. Sewell 6-28-73 7-2-73 x
TO ORIG CC OTHER SENT AEC PDR x
John F. O' Leary SENT LOCAL PDR 1 signed 39 CLASH (UNCLASS PROP INFO INPUT NO CYS REC'D DOCKET NO:
x 40 50-155 DESCRIPTION:
ENCLOSURES:
Ltr te our 8-3-72 Itr & their 10-2-72 Itr...
furnishing info inadvertently omitted fm
'ACKNOWLED r their 1tr 10-2-73 re the failure of any cquipment, particularly the circulating water system.....
PLANT NAME: Big Rock Point FOR ACTION /INFORMATION 7 73 LB BUTLER (L)
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