ML17252A962
| ML17252A962 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 06/20/1973 |
| From: | Worden W Commonwealth Edison Co |
| To: | Anthony Giambusso US Atomic Energy Commission (AEC) |
| References | |
| WPW Ltr. #467-73 | |
| Download: ML17252A962 (2) | |
Text
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Commonw Edison 1 !;;7' 1 El One First Nati~aza, Chicago, Illinois
,;.Address Reply to: Post Office Box 767 Chicago, Illinois 60690 WPW Ltr.#467-73 Mr. A. Giambusso Deputy Director for Reactor Projects Directorate of Licensing U. s. Atomic Energy Commission Washington, D. C.
20545 l{egti1atory1
. ~..,
50-249 Dresden Nuclear Power Station R. R. #1 -
-::-:=.;:- - *-
- Morris, Illinois 60450 June 20, 1973
~
11£CEIVED 3
JUN26 1973a..
U.S. ATOMIC EHl!.RGY COMMISSIOK.
Regulatory llall SettloD
SUBJECT:
LICENSE DPR-25, DRESDEN NUCLEAR POWER STATION, UNIT /!3, SECTION 6.6.C.l OF THE TECHNICAL SPECIFICATIONS.
Dear Mr. Giambusso:
This is to rep.Ort a condition relating t;o the operation of the unit in which, during.a surveillance of the Automatic Pressure Relief System valve 203-3A failed to operate.
This condition was reported to Mr. Fred Maura of Region III Regulatory Operations via telephone on May 29, 1973.
PROBLEM AND INVESTIGATION (Reference P
- ID M-345)
On May 28, 1973 at 0630 hours0.00729 days <br />0.175 hours <br />0.00104 weeks <br />2.39715e-4 months <br />, t~e unit was heating up following a maintenance outage with the mode switch fin the "START" position, reactor.
pressure at 240 psig, and re~ctor water level at 30 inches.
As required by Technical :Specifications Section. 3* 5.D.l, the operability of* the Auto-matic Pressure Relief System was being checked.
When the automatic pressure relief valve 203-3A was tested, its pilot valve functioned as indicated by.
an "OPEN" light actuated in the control room but the main valve showed no indication of operating (i.e., no valve discharge temperature change and no surge in reactor water level.) Although the Technical Specifications Sectio~
3.5.D.2. allows.operation for thlrty days with one automatic relief valve
- inoperable (the High P*ressure Coolant Injection System operability had been demonstrated earlier in the heat-up), an orderly shutdown and cooldown was performed so that relief valve 203-3A could be repaired.
The reactor wa~
shutdown and below 90 psig at 0918 on May 28, 1973.
EVALUATIONS AND CORRECTIVE ACTIONS The Automatic Pressure Relief System is designed such that four of the five installed relief valves will provide adequate pressure relieving capability.
Therefore, loss of one valve do*~!:ilot materially affect the operating safety of the reactor plant. In addition, the inunediate cessation
M~ A *.._Giambusso
. {
June 20*~ 1973" of reactor startup in order to repair the valve prgyided~an:extra margin of safety even though it was not specifically required by the Technical Spec if ica t ions.
Following reactor cooldown, the discharge elbow 011. *relief valve 203-3A was removed so that the valve internais could be 'inspected.
A 3/16" thick full-face asbestos gasket was found installed on.~he discharge side of the valve.
The gasket had been used in conjunctio11 with a blind flange and another gasket to seal the discharge of the valve earlier in the maintenance outage.
Prior to start-,,tp, the blind* flaqge a[l~ one gasket had been removed but this gasket was inadvertant,ly *left in the valve dis-charge. Distortion of the gasket showed that valve 203'.93A had~ in actuality, operated~when tested but due to the thickness of th~ gaslCet.:'and the iow reactor pressure, the valye eJCJ>er~~nced no flow.
The full-face gasket was removed and the discharge elbow reassem-bled.
Valve 203-3A was subsequently retested and performed"~satisfactorily.
It should be noted that since the gasket was deformed at 200*psig, sufficient pressure would have existed under operating conditions to burst. the gasket and thereby allow the valve to relieve reactor pressure. Also, the other
- four relief valves in the system were demonstrated to be fully operational and were capable of providing lOOi of design pressure relieving capacity.
Since this is the first time this type of problem has arisen, no maintenance procedure changes have. been 1Jlssued.
However, the personnel involved have been cautioned to be more careful in the future and to ensure that maintenance on a system or component is indeed complete prior to releasing it for operation.
WPW:_d;o Sincerely,
'd-JULl _g. Vifl~.
A,,{\\__ W. P. Worden
~
- Superintendent