ML20084U014

Ao:On 700529,piping Restraints & Supports Damaged.Caused by Displaced HPCI Steam Line Beyond Outboard Isolation Valve. HPCI Outage Time Extension Requested

ML20084U014
Person / Time
Site:	Dresden
Issue date:	06/02/1970
From:	Hoyt H COMMONWEALTH EDISON CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084U000	List: ML20084T996 ML20084U014 ML20084U018
References
01870, 1870, NUDOCS 8306240425
Download: ML20084U014 (2)

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Dr7 Peter A. Morris , Director Div is 4An of Reactor Licensing U.S. Atomic Energy Commission cashington, u.C. 20545

Subject:

License DPR-19. Dres?cu Nuclear P_ower Station Unit 2, Section 6.t>A.T of the Technical Snec if ic a t ions .

Dear Mr. Morris:

This is to report an abnormal occurrence in which the HPCI steam line beyond the outboard isolation valve was displace.1 causing uamage to the piping restraints and supports and possible damage to the line itself. Problem and Initial Antion Tne situation was discovered at 12:50 a.r. ou Hay 2'>,1900 whea che:'cing the HPCI syste.n la preparatica for a test run, At _lais time the liPCI system oas immediately taken out of sersice for investigation end repair and surveillance startec on other ECCS componeats as requirca by >.,ec tion 4.5.C.2 of the Technical .Specifi-cations. Investination Investid ation of the cause of damage revealed the follouing cequence of events:

1. The HPOI turbine ha.. beca taken out of service at 9:30 a.m. on May 23 for steam strainer inspectioa. fnis uork was completed and the HPCI placed hacic in service at 4:28 p.m. on May 28, 1970.

2. Daring the outage a scran occurred following which water level rose to the level of the llPCI steam nozzle, which allowed water to enter the steam line up to the outboard isolation valve which was closed.

3. Unen the HPCI system was glaced in service at 4:28 p.m. the accumulated water, was forced down the steam line causing unusual hydraulic forces on the steam bh line, padticularly at the bends.

m v 7N74 During the HPCI outage' the inboard isolation valve, located close to the g reactor, was not closed. The' outboard isolation valve was closed along ahead of the turbine stop v e. l This was the established procedure. with valve o S 8306240425 700600 COPY dc.N I MtGION

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2 s Corrective AcLion A revised procedure has been placed in effect which requires t 'e inboard and outboard isolation valves to be closed when taking IIPCI out of service. This, along with a steam line draining proce.iore for restoring the system to service will insure eny collected water will be drained from the header before applying reactor pressure to the line. The repair program for the llPCI steam line consists of the following steps in addition to the restoration of the hangers and snubbers to their atiginal condition. (1) Renoval of insulation and dye-penetrant testing each weid joint from the Mmstream isolation valve to the iiPCI turbine stop valvc. (2) Inspection and testing of the turbine valve chect for possible camage. (3) Checking the bolts in the steam cheat for possible damage. (4) Retesting opecation of valving between the seconu isolation valve and the turbine. (5) Ilydrostatic testing of the steamline at 1560 psig. (6) IIcatup and pressurizing the steamline to 1000 psig and inspection for le'kage. (7) Replacing insulation as necessary. Measurements have oecn taken of tne steam line in its present condition and the pipe stresses present now are being compared by S & L with the previous computation run on stress analysis. Tne preceding program is enpected to be completed by Thursday night, June 4, l'370. 'lowev e r , tue amount of work involved in the above may not be completed in its entirety by that time, nor does the schedule reflect any consideration of possible labor difficulties. If stress analyses inuicate that its necessary to replace some of the piping, this would require extending the total' out-of-service time by an additional 7 days. In view of the above, it will be necessary to c.; tend the llPCI outage time beyond that allowed by Section 3.5.C.2. By this letter you are advised of the extended outage as required by Section 3.5.G. Sincerely yours, 1 l't 'f /. I '.l.,% ,

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II. K. Iloyt Superintendent M di"T, "' \, , Dresden Nucicar Power Station llKII:glw D

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For cor. cur. For action. 5ee me about tNo. MEMO ROUTE SLIP _ For signature. For information. Foran AEC-ft3 (Rev. hf my14.1943 Note and return. INITIALS REMARKS TO (Name and unit) J. P. O'Reilly

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p-INITIALS REMARKS TO (Name and unit) [ / FROM (Name and unit) DATs REMARKS (WL& H. D. Thornburg Attached is the original and three copies of a TWX reporting 4 CO:III the inoperable high pressure collant injection system at Dresden 2. 02338 PHONE N(h DATE 6-25-70 U. s. GovtRNut%T PRINTING orFICE 1%7- 0-422307 USE OTHER SIDE FOR ADDITIONAL REMARKS}}