ML17252A539
| ML17252A539 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 06/12/1974 |
| From: | Stephenson B Commonwealth Edison Co |
| To: | O'Leary J US Atomic Energy Commission (AEC) |
| References | |
| BBS Ltr. #420-74 | |
| Download: ML17252A539 (2) | |
Text
Commonw.Ah Edison One First Na-tic.Plaza, Chicago, Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690
__ BBS_ Ltr.#420-74-- -
- -Dreioen-NuclearP-ower stat ion 1Regulatory Docket File Mr. J. F. O'Leary, Director / *~,-,,....,....... ~,
Directorate of Licensing u *. s. Atomic Energy Commission Washington, D. c.
20545 R. R. fll A.Morris, Illinois une 12, 1974
SUBJECT:
LICENSE DPR-25, DRESDEN NUCLEAR POWER STATION, UNIT #3, REP OF ABNORMAL OCCURRENCE PER SECTION 6.6.B.l.a OF 1'HB TECHNICAL SPECIFICATIONS.
MAIN STEAM LINE RADIATION MONITOR TEST FAD.URE.
References:
- 1) Notification of Region III of AEC Regulatory Operations Telephone: Mr. F. Maura, 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br /> on'3une 4, 1974 Telegram: Mr. J. Keppler, 1425 hours0.0165 days <br />0.396 hours <br />0.00236 weeks <br />5.422125e-4 months <br /> on June 4, 1974
- 2) Dwgs: P & ID M-12 S&L 12E2464
Dear Mr. 0 'Leary:
This letter is to.report a condition relating to the operation of the unit at about 0030 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> on June 4, 1974. At this time, during routine testing of the "D" main steam line (MSL) radiation monitor, an upscale-trip failure was reported.
This malfunction is contrary to Table 3.2.l of the Technical Specifications which requires that tWo radiation monitors per trip channel be operable.
PROBLEM At the time of the occurrence, Unit 3 was in the startup mode at 0 MWt power.
Routine weekly surveillance was in progress on the main steam line radiation monitor.
During the functional test on monitor "D",
the trip and alarm did not function.
Approximately 20 minutes later, a spurious alarm and trip was received from the "D" monitor.
The Instrument department was immediately notified, and invest-igation into the problem began at approximately 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on June 4, 1974.
The normal function of t~e radiation monitors is to initiate a reactor scram and isolation if background radiation exceeds 300'%. normal level.
5402
~..
A J. F. O'Leary
- June 12, 1974
'INVESTIGATION ______ --- -- ------ ----
The Instrument department ran several tests on the "D" radiation monitor at approximately 0900*hours on June 4, 1974.
No abnormalities were noted.
The monitor was again successfully tested ~everal times throughout the.day.
The monitor was then replaced with a spare so that further bench checks could be made.
CORRECTIVE ACTION
- The corrective action, c0mpleted.on Jµne 4, 1974, was to replace the "D" main steam line radiation monitor with a spare unit.
The monitor will be bench checked to determine the cause of the trip failure.
EVALUATION
'J..
The main steam* line radiatfori monitoring system consists of four monitors. connected in a' one..:out-of-two*twiCe l.Ogic configuration. *.*.The remaining three monitors functioned properly during the surv.eillance~ It is therefore conclu.dfi~,tha't t.he -safety oLthe 'general public or the plant*
personnel was not jeop~!rdized as,a result of. this occ~rre~c;e..
... ~* ~:**
~
The c~ulative experience to date: indicates that the*;*radiation
- monitors seld.om malfunct~on, and the few problems that have occurred were unrelated to this occurrence.
BBS:WEH:do Sincerely, B. B *. Stephenson Superintendent