ML17252A949
| ML17252A949 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 10/24/1973 |
| From: | Worden W Commonwealth Edison Co |
| To: | Anthony Giambusso US Atomic Energy Commission (AEC) |
| References | |
| WPW Ltr. #797-73 | |
| Download: ML17252A949 (2) | |
Text
Co~mon.lth Edison Ffogulatory One First Nati I Plaza, Chicago, Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690 50-249 WPW Ltr-.11797* 73
-nre~den Nuclear Power Station R. R. #1 Morris, Illinois 60450 October 24, 1973 Mr. A. Giambusso
- Deputy Director for Reactor Projects Directorate of Licensing U. s. Atomic Energy C0111Dission-Washington, D. C.
20545
- 9.
SUBJECT:
LICENSE DPR-25, DRESDEN NUCLEAR POWER-.--...oorn*N, UNIT #3, SECTION 6.6.C.l OF THE TECJINICAL SPECIFICATIONS.
BPCI STEAM LIRE HIGH FLOW SWITCH OUT OF,CALIBRATION.
References:
- 1) Dwgs: P&ID-M-51. S&L 12E2527
Dear Mr. Giambusso:
This* letter is** to report a condition relating to the operation of the unit at about 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on Septemb~r 25, 1973.* At this time.high pressure coolant. injection *(HPCI) flow switch DPIS 3-2353 was found to have a trip setpoint of 152.0" H2o.
This setpoin_t is contrary to Table 3.2.1 of the Technical.Specifications_ which requiJ:e a setpoint of-~- 150" H20*
- PROBLEM At the time of' the occurrence, Unit 3 was operating in a steady
- state condition with a thermal 10ad of 2295 MWe.
Routine surveillance was.*
being performed by the Instrument Department whenHPCI flow;switch DPIS3-2353 was. found to have a.setpoint of 152" H20*
The switch was immediately..
reset to 148" H20*. The function -of DP-IS-3-2353 is to isolate the HPCI steam su~ply line in the event of a break in the steam piping.
INVESTIGATION The subject flow switc~ is _a __ Barton ~el
-~~8-~_:l,_ff~rential pressure _
sensor.
This switch has had a tendency to drift in both the increasing and decreasing direction. *A locking device was installed on the switch in February of 1973 in an at_tempt to eliminate the drift t!endency..
At the present time, the data from previous surveillances reveals that the locking device has not solved. the drift problem.
The overall problem of instrument setpoint drift is presently under investigation.
The problem has plagued the station since its beginning, and no adequate corrective action has been determined at this tiine.
7915
).;
~(,,*--
e Mr. A. G iambus so October 24, 1973 The--most-recent approach to the problem h8s been to solicit aid from the manufacturers of the various drifting sensors.
In the case of the Barton model 288, the factory representative has recommended that a field service engineer visit the station and analyse Barton switches with regard to application, factory adjustments, and calibration technique.
The Barton representative.has "lh\\sited the Station and we are now awaiting his recommenda-tions.
CORRECTIVE ACTION The immedia~e corrective act.ion was to change the setpoint of DPIS-3-2353 to bring it within the Technical Specifications.
The calibra-
. tion frequency for this switch will be increased to o~ce per month until such time as this switch has demonstrated its reliability. Additional corrective action will be based on recommendations made by the Barton field service engineer.
EVALUATION Flow switch DPIS-3-2353 is one of two flaw switches that isolate the BPCI steam line i~ the event of a break in the steam piping.
The second switch is DPIS-3-2352., and its setpoint at the "time of the occurrence was 146" H20. _Therefore, it i,s concluded t:hat.in the eve~t* of a break in the HPCI steam line piping, isolation would. have occurred well within the Technical Specifications, and thus the safety of the station personnel and the general public was in no way compromised.
The continued.. operation of the unit was considere~* safe.
'\\.
.WPW:do Sincerely,
\\DJ_~
W. P. Worden Superintendent