ML20084C734

AO 50-219/74-46:on 740826,one Torus to Drywell Vacuum Breaker Failed to Demonstrate Operability.Caused by Excessive Friction in Valve Hinge Pins.Burring Difficulty Discussed W/Atwood & Morrill Co,Valve Manufacturer

ML20084C734
Person / Time
Site:	Oyster Creek
Issue date:	09/03/1974
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084C738	List: ML20084C734 ML20084C751
References
AO-50-219-74-46, NUDOCS 8304080189
Download: ML20084C734 (3)

Text

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                   .ersey Central Power & Light Company D W

MADISON AVENUE AT PUNCH BOWL ROAD

• MORRISTOWN, N.J. 07960
• 201-539-6111 annasa w rus General Public Utilities Corporation ersran September 3, 1974 e h

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w .. cW. Mr. A. Giambusso y, ca t Deputy Director for Reactor Projects Directorate or Licensing

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yid:r}f k'i United States Atomic Energy Commission 9

                                                                                                                                   \f Washington, D. C. 20545                                                                       c.n

Subject:

Oyster Creek Station Docket No. 50-219 Abnormal Occurrence Report No. 50-219/74-46 The purpose of this letter is to forward to you the attached Abnormal Occurrence Report in compliance with paragraph 6.6.2.a of the Technical Specifications. Enclosed are forty copies of this submittal. truly yours, f G f Wl - Donald A. Ross Manager, Nuc1 car Generating Stations es Enclosures '

                                                                                                                      *     :9273 cc:    Mr. J. P. O'Reilly, Director                                                          '

Directorate of Regulatory Operations, Region 1 1 '. .o ( 0 ,a .g,j r 7j

                                                                                                     ,,             v 9304080189 740903 PDR ADOCK 05000219 s                   PDR COPY SENT REGION X                       ,

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k".h Jersey Central Power &f%@] Light Comp MADISON AVENUE AT PUNCH BOWL ROAD

• MORRISTOWN, N. J. 07960
• 201-539-6111 us uu n e na cenerat [,#'.;j*,', Pubhc Utahties Corporation

                                                         ,,m u OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74-46 Report Date September 3, 1974 Occurrence Date August 26, 1974 Identification of Occurrence Failure of one torus to drywell vacuum breaker to demonstrate operability. This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15D.

Conditions Prior to Occurrence The plant was at steady state power with major parameters as follows: Pouer: Core, 1906 MWt Electric, 636 MWe Flow: Recirculation, 15. 4 x 10'+ gpm Feedwater, 7.17 x 106 lb/hr Stack Cas: 13,175 pCi/sec Description of Occurrence On Monday, August 26, 1974, at approximately 1400, while performing surveillance testing on the fourteen torus to drywell vacuum breakers, it was found that one vacuum breaker (V-26-13) failed to demonstrate operability. Excessive force had to be applied to effect valve movement when V-26-13 was manually opened and closed. In addition, the valve would not rescat under the influence of gravity alone. Note that V-26-13 was found to be seated prior to testing, as indicated by the recently installed valve position indicating system. The valve was secured in the closed position soon after this problem was identified.

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? c (a,) O gj 1 Abnormal Occurrence Report No. 50-219/74-46 Page 2 Apparent Cause of Occurrence It is believed that this failure is caused by excessive friction in the valve hinge pins. Analysis of Occurrence The drywell-torus vacuum breaker system is required to prevent water oscillation in the downcomers due to low steam flow rates in the downcomers and to provide protection against negative pressure conditions in the containment vessel. The significance of this event is minimal since the bases of the Technical Specifi-cations state that one inoperat ve valve reduces the total vacuum relief area i by 7"o while only about 25'a of the available vacuum relief capacity is required to provide negative pressure protection. l The drywell-torus vacuum breaker valves are required to be closed during pipe

break accidents (particularly small breaks) to ensure proper steam condensation and prevent torus overpressuring. This valve would have performed this function, if required.

l Corrective Action l l An apparent " growing" characteristic has been experienced with the vacuum l breaker valve teflon bushings at several facilitics, including Oyster Creek. The bushing difficulty has been discussed with the valve manufacturer (Atwood 6 Morrill Company) and a proposal for a long-term solution is expected from the manufacturer. It is noted here that the bushings in each torus to drywell vacuum breaker valve were inspected and measured during the 1974 refueling outage. Prior to valve reassembly, bushings in eleven (11) of the fourteen (14) valves, including V-26-13, were machined to obtain acceptabic bushing I.D. - shaft 0.D. clearances. Failure Data l Basic valve data are as follows: 1 Manufacturer - Atwood 6 Morrill Company Type - Check Valve l Vent Area - 1.75 square feet per valve 1 Previous abnormal occurrence reports involving these vacuum breaker valves are: l

1. Abnormal Occurrence Report No. 50-219/73-2

2. Abnormal Occurrence Report No. 50-219/74-11

3. Abnormal Occurrence Report No. 50-219/74-14

4. Abnormal Occurrence Report No. 50-219/74-15

5. A normal Occurrence Report No. 50-219/74-16 l

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