ML17252A942
| ML17252A942 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 11/20/1973 |
| From: | Worden W Commonwealth Edison Co |
| To: | O'Leary J US Atomic Energy Commission (AEC) |
| References | |
| WPW Ltr. #865-73 | |
| Download: ML17252A942 (2) | |
Text
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Common,,.,,...th Edison One First Na_t_ Plaza. Chicago, Illinois Address Reply to: Post 0
- 767 Chicago, Illinois 606 7 lt\\t WPW Ltr.#865;..73 Mr. J. F. O'Leary, DirecL"Vii...-...,...-
Directorate of Licensing U. s. Atomic Energy C011DDission Washington, D. C.
20545 Dresdeo.*-Nuclear Power Station R. R. #1 60450
SUBJECT:
LICENSE DPR-25, DRESDEN NUCLEAR POWER STATION, UNIT /13, **
REPORT OF ABNORMAL OCCURRENCE PER SECTION 6.6.B.l OF.THE TECHNICAL SPECIFICATIONS.
HPCI SYSTEM HIGH STEAM FLOW ISOLATION SWITCHES OUT OF CALIBRATION.
References:
- 1) Notification*of Region Ill of AEC Regulatory Operations Telephone: H. Dance 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> on November 13, 1973.
Telegram: J. Keppler 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> on November 13, 1973
- 2) Dwgs: P & ID M-51.
Dear Mr. O'Leary:
The 'following is to report a condition relating to the operation of the 'linit in.which at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on November 12~ 1973, the steam flow switches for the High Pressure Coolant Injection System were found to be out of calibration.
This is a violation of Table 3.2~1. of the Technical Specifications which require a setting of £ 150" H 0 dp increasing.
2 PROBLEM
(......
~
The switches in question are dpis 3-2~52 and 3-23'53.
They are Barton model 288 differential sensors and were found with setpoints of 152" water and 160" water respectively.
INVESTIGATION The function of these switches is to isolate the High Pressure Coolant Injection System (HPCI) in the event of a break in the steam supply line. Barton model 288 switches have a history of setpoint drift in both the increasing and decreasing direction.
The swit~bes were last calibrated on October 9, 1973..
At that time, switch DPIS 3-21:52 was set at 144. 5" water and DPIS 3-Zi53 was set at 148.0" water.
These switches therefore drifted 7.5" and 12" respectively in a period of 32 days.
I e Mr. J. F. 0 Leary November 20, 1973 CORRECTIVE ACTION These switches were immediately reset to comply with the Technical Specification.
The problem with Barton switches is presently under investi-gation by the Dresden lnstniment Department, the local sales representative of ITT Barton Company, and ITT Barton Factory:f'"representatives.
The local sales representatives have made several field trips to Dresden Station and have analyzed several switches which have a drift history.
They have found several significant problems on several switches which includ~ mis-applications and loose or di~torted components.
The representative will return to complete an analysis on all problem switches and a plan to implement their recommendations will be formulated.
EVALUATION The switches did not trip at the desired setpoint but did trip, and would have functioned at a differential pressure of 152", which is only 2" above the Technical Specification limit. It is therefore concluded that the safety of the station personnel or the general public was not jeopardized as a,result of this instrument drift.
The corrective actions in progress are directed toward reducing setpoint drift problems.
In the meantime, r,edundancy in similar systems' instrumentation, shortened intervals between surveillance tests, and con-servative setpoint va~ues have reduced the ef~e~t. of these drifting set-points to where continued operation of the units is safe.
WPW:do Sincerely,
- W.
P'~ Worden Superintendent