ML20085K060
| ML20085K060 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Peach Bottom, 05000000 |
| Issue date: | 12/20/1973 |
| From: | Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085K054 | List: |
| References | |
| NUDOCS 8310190357 | |
| Download: ML20085K060 (3) | |
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P$ADELPHIA ELECTRIC CC1PANY h
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December 20, 1973 Hr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing Washington, D.C.
20545
Dear Mr. Giambusso:
Reference:
Peach Bottom Atomic Power Station - Unit 2 Facility Operating License DPR-44 Docket No. 50-277
Subject:
Abnormal Occurrence The following two events were reported to Mr. Donald Cathton, A.E.C. Region I Regulatory Operations Office on December 13, 1973.
In accordance with Section 6.7.2.A of the Technical Specifi-cations, Appendix A of DPR-44 for Unit #2 Peach Bottom Atomic Power S ta ti on, this failure is being reported to the Directorate of Licensing as an Abnormal Occurrence.
HPCI Oil Pipino Failure Late on December 12, 1973, with the reactor at full temperature and pressure and at approximately 5% power, a mechanical failure of an oil line in the HPCI turbine control system rendered the HPCI turbine inoperable.
The failure occurred during startup testing of the HPCI at a turbine speed of about 3000 RPM. The HPCI systea had been operated successfully several times earlier in the day to support startup test-ing on this system.
The exact nature of the problem was immediately conynunicated from the test personnel at the turbine to the control room operator, who was al ready aware of an oil system problem due to the closure of the turbine stop valve and the auto-start of the auxiliary oil pump.
The closure of the turbine stop valve caused turbine speed reduction and when the turbine shaf t stopped, the auxiliary oil pump was stopped to terminate the oil spill to the skid.
Surveillance Testing required by Technical Specification paragraph 4.5.C.2 was performed to ensure operability of other core cooling systems.
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Investigation and Corrective Action Visual observation revealed a full circumferential sheer failure of the threaded portion of a lh x l'< inch pipe bushing, where the bushing enters a flange on the main turbine stop valve pilot piston.
This bushing is at the upper end of the vertical run of an "L" shaped section of piping.
The horizontal run of the "L" connects The "L" to adjacent oil piping through a flexible hose connector.
piping was not supported so that any vibration induced or piping weight movements of the horizontal run would be carried by the bushing.[.
This piping configuration was vendor supplied and skid mounted.
To preclude the possibility of a reoccurrence of this type of failure, the following steps were taken.
A piping specialist from the architect-engineers i
a.
visually checked the oil piping on the HPCI turbine [
skid for adequate support.
There were no other oil :
piping-support deficiencies.
f b.
The failed bushing was replaced and the horizontal run of piping was supported by a newly instatied bracket and U-bolt arrangement, as per the archi tect-engineers' reconnenda ti on.
c.
The turbine vendor representative at the site con-
[
curred in the recommendation.
The oil system was
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operated af ter the repai r was made to ensure opera-I bi li ty.
At the time of this writing, the reactor is depressurized for other reasons, so the HPCI turbine cannot be operationally tested until steam is available. An operability test shall be performed during the next startup.
Safety Imolications At the time of the failure, reactor power was approximately 5 percent. The core power history is such that there is no percep-tibic decay heat.
The redundant high pressure core cooling systems were tested satisfactorily, as were the low pressure core cooling systems.
No safety implications are associated with this failure.
dPIS-2-2-129A Setooint Shift During a routine functional test of dif ferential pressure switch dPIS-2-2-129A on Occcmber 12, 1973, i t was noted that the swi tch The was tripping and resetting below the permissibic operating range.
technical specification limit for switch actuation is 0.5 p 1.5 psig-This switch provides one of four inputs in a 1 of 2 twice logic on Jet Pump Riser Differential Pressure to the RHR Loop Selection Logic.
- ~ _.. _ _ _ _ _ _ _. _ _ _ __
Mr. A. Giamh so A
' Dec. 20, 1-
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Page 3 f
Investigation Investigation revealed that the set point shif t was caused by failure of the set point adjustment mechanism to lock the linkage in a permanent position.
The manufacturer of these switches has recently modi ficd these devices to provide a locking screw on the primary adjustment linkage arm.
Corrective Action The manufacturer of the instruments was contacted in an effort to obtain modi fication ki ts for these instruments.
These kits
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were not readily availabic.
Temporary measures have been taken to 1
provide a means to lock the set point primary linkage arm in a permanent position.
A survey was made on all similar devices in the reector protection system, primary con tainment isolation system and emergency core cooling system.
The temporary measures are being applied to those devices which lack the new manufacturer's modi fications. Modi fi ca ti on kits have beco ordered for all these devices.
These will be installed on a systematic basis when they become availabic.
The temporary method of locking the set point mechanism in place has been reviewed by the PORC and a representative of the Engineering and Research Department. The technicians performing this wor,k have been speci fically instructed as to how these changes are to O
be made.
The instruments will be recalibrated and functionally tested after the set point mechanism has been locked in place.
Safety Implications This switch is used in a one of two twice logic for LPCI loop selection and in its as found condition would have supplied one of the two signals needed to inject into the "A" recirculation loop.
Since the other three switches in this logic have been performing properly, there is no reason to believe that an erroneous loop selection would have occurred. Therefore, there is no safety implication associated
- i with this set point shi f t.
Very truly yours,
/
9 I h( Vf.il D. !
[M.,J.Cooney /
Asst. Geni. Supt.
Ge'neration Division WBW:1pm cc J. P. O'Reilly, Di rector, Region I Uo So Atomic Energy Commi. ion