ML20085K070

Ao:On 740117,during Operability Test on Hpci,Sys Revealed to Be Inoperable.Caused by Burrs on Cylinder Wall & Piston of Turbine Stop Valve.Burrs Removed & All Parts Thoroughly Cleaned & Inspected

ML20085K070
Person / Time
Site:	Dresden, 05000000
Issue date:	01/25/1974
From:	Worden W COMMONWEALTH EDISON CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085K054	List: ML20085K060 ML20085K063 ML20085K067 ML20085K070
References
58-74, NUDOCS 8310200002
Download: ML20085K070 (3)

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Address R y to: Post Office Box 767 Chicago, latinois 60690 WPW Ltr.d58-74 Dresden Nuclear Power Station R. R. #1 6 i JM, r f Morris, Illinois 60450 o#

January 25, 1974

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Mr. J. F. O' Leary, Director

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SUBJECT:

LICENSE DPR-25, DRESDEN NUCLEAR POWER STATION, UNIT #3, REPORT OF ABNORMAL OCCURRENCE PER SECTION 6.6.B.1.a OF THE TECilNICAL SPECIFICATIONS.

HPCI SYSTEM INOPEPABLE.

References:

1) Notification of Region III of AEC Regulatory Operations Telephotw.: Mr. F. Maura,1415 hours0.0164 days <br />0.393 hours <br />0.00234 weeks <br />5.384075e-4 months <br /> on January 17, 1974 Telegraph: Mr. J. Keppler,1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br /> on January 17, 1974

2) Drawings: P&ID H-374 G.E. Co. 509E253AR

Dear Mr. O' Leary:

This letter is to report a condition relating to the operation of the unit at about 0300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> on January 17, 1974. At this time an operability check on HPCI, required because an electromatic relief valve had earlier been found inoperable, revealed HPCI to be inoperable.

This r21 function is contrary to section 3.5.C of the Technical Specifications which requires that all active components of the Automatic Pressure Relief Subsystem, Core Spray, LPCI and Isolation Condenser be operable when HPCI is inoperable.

IROBLEM With the reactor in "run" at 618 MWe, an operability test was conducted on HPCI. This was required because of an inoperable electro-matic relief valve.

It was discovered that the HPCI control valves would not open and HPCI was declared inoperable at 0330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br /> on the 17th. An orderly shutdown was icenediately cunmenced in accordance with Section 3.5.C.3 of the Technical Specifications.

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J nuary 25, 1974 s The HPCI steam turbine failed to start when the Motor Speed Changer was operated and the control valves failed to open. The problem was determined to be in the hydraulic control system.

No immediate action to effect repair to either HPCI or the electromatic relief was possible therefore shutdown of the reactor was commenced to bring plant status into compliance with the Technical Specifications. Reactor pressure was reduced below 90 psig by 1725 hours0.02 days <br />0.479 hours <br />0.00285 weeks <br />6.563625e-4 months <br /> on the 17th of January.

INVESTICATION Investigation of the hydraulic system failure revealed the sproblem to.be caused by a device called the " Interlocking Valve" which is a hydraulic cylinder with floating piston. This device prevents opening of the Turbine Stop Valve when the control valves are open and trips the control valves upon stop valve trip.

Internal inspection of this valve revealed the presence of " burrs" on the cylinder wall and piston. These "burra" were apparently present from initial installation and were aggra-vated with time and movement. They became sufficiently aggravated to cause interference with piston movement and thus prevented hydraulic fluid from entering the control valve actuating cylinder.

CORRECTIVE ACTION The " burrs" were removed and all parts were thoroughly cleaned and inspected. The valve was reassembled and checked for free movement which was satisfactory. Repeated testing of the entire hydraulic system verified proper operation of the repaired valve and the remainder of the system.

Repairs and testing were completed at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> on January 22, 1974.

No supplementary investigations or recommendations concerning Unit 3 are deemed necessary since the failure is concluded to be an isolated problem caused by an initici installation d;Iiciency.

To ensure that a similar situation does not occur on Unit #2 an inspection of the suspect valve will be made during the next extended maintenance outage.

EVALUATION The relief valves of the automatic pressure relief subsystem are a back-up to the HPCI system. Redundancy has been provided in the automatic pressure relief function in that only 4 of the 5 electromatic relief valves are required to operate.

Because of this single electromatic valve failure the system was, capable of providing its backup function.

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o Mr. J. F. O'Le ry January 25, 1974 i

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-The two systems used concurrently serve as an alternate method of cooling the core upon isolation from tha main condenser by using the relief valves and HPCI subsystem in a feed and bleed manner. Therefore, the high pressure relief function and the HPCI must be availabic together to cope with an anticipated transient so the LCO for HPCI and relief valves is set upon this function. However, because surveillance tests conducted on the isolation condenser proved it to be operable, the backup function was not required. Therefore, there were no safety implications to the i

plant or the general public.

Future failures of this type on HPCI are highly improbable in view of the type of failure. The problem was indigenous to this particular valve and cannot be considered generic in nature.

Since this is so,other similar equipment need not be suspect.

No cumulative experience regarding this type of failure exists nor is it expected to occur.

Sincerely, (d. bb W. P. Worden Superintendent WPW:do f

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ATOMIC CNEI?GY COMMISSION i

"y DIRECTORATC OF fit GULATOPY OPERATIONS Y

o _Ns~o' "j til'GIOf4 til 799 Hoosi:vcLT ROAD wuynouc GLCN CLLYtJ, ILLINO!G G0137 012) 854-2(C0 January 23, 1974 Co:mr.ouwcalth Wison Conpany Docheto No. 50-10 ATfN:

Mr. Byron Lec, Jr.

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Vice President 50-24 P. O. Box 767 Chicago, Illinois 60690 50d 50-295 50-304 70-1302 70-13/0 Centlemen:

Encioned, ca RO Eulletin 74-2, is infornation concerning a porcible truch ctrike that nay influence your shipment of special uues. car toterial.

Pleace note t. hat should the atrike occur and chould you have special nuclear caterial chipments routed thrcuch the strike crea, a report is requected of you.

Sincercly, James G. Reppler Regional Director Enclocure:

RO Dulletin 74-2 bec: _RO Files, DR Central Files PDR Local PDR OGC, Ecth, P-506A l

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Date: January 23, 1974 Directorate of Regulatory Operations Bulletin 74-2 TRUCK STRIKE POSSIBILITY lt has come to the attention of the Atomic Energy Commission that a truck strike may develop during the period of Jan"ary 24-31, 1974.

Preliminary information indicates that if.he strike occurs it will probably be localized in the northern Ohio and western Pennsylvania areas.

It is doubtful that the strike will be nationwide.

There in a possibility of isolated incidents.

In view of the foregoing and your obligation to safeguard special nuclear material subject to the requirements of 10 CFR Part 73, you are requested to consider the consequences of this possible strike in scheduling truck shipments of SNM in quantitics of 5 kilograms of contained uranium-235 or 2 kilograms of plutonium and/or uranium-233 for delivery during the duration of the strike.

Possible actions on your part to reduce the impact of cny such strike on safeguarding of SNM include:

(1) delay truck shipments until the strike period is over; (2) route shipments to avoid the strike arca; (3) use other modes of trans' ortation when available; (4) if shipment is already p

in transit and it cannot be routed to avoid the strike area, place ship-ment'in storage and keep under surveillance for the duration of the st

.ke.

If the strike does occur and you have truck shipments routed through the strike dreas, please advise us by telephone, confirmed in writing l

within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, of your shipping plans and any preventive actions you l

may take.

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