ML20085J903
| ML20085J903 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 05/23/1974 |
| From: | Stephenson B COMMONWEALTH EDISON CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085J908 | List: |
| References | |
| 368-74, NUDOCS 8310190189 | |
| Download: ML20085J903 (3) | |
Text
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(('r:' e]}rCommonalth Edison s
C One First fs lai Plaza. Ch cago. Ilknois b C ~ 7 Address fd6Iy ioTPojt Off20 06i7G7 *
'g Chicago, Ithnois 60690 BBS Ltr.0368-74 Dresden Nuclear Power Station
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i R. R. #1 Morris, Illinois 60450 May 23, 1974 fi?Qb fn \\)>b",s([;,
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- Mr. J. F. O' Leary, Director Directorate of Licensing
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SUBJECT:
_LICF.NSE__DpR-25, DRESDEN !!UCLEAR POWER STATION, UNIT #33 nEPORT OF-AP,UO3 MAL _ OCCU3RENCE PER TAUL3 3.2.1 OF Tile TECi!NICAL SPECIFICATI0US.
TEC!iNIC\\L SPECIFICATION VIOLATION OF l'AIN STEAM LINZ AREA. TE ?ERATURE DETECTORS.
References:
- 1) Letter frcm B. B. Stephenson to Mr. J. F. O' Leary dated April 3, 1974.
- 2) Notification of Region III of AEC Regulatory Operations Telephone: F. Ibura,1045 hours0.0121 days <br />0.29 hours <br />0.00173 weeks <br />3.976225e-4 months <br />, May 15, 1974 Telegram: J. Keppler, 1135 hours0.0131 days <br />0.315 hours <br />0.00188 weeks <br />4.318675e-4 months <br />, May 15, 1974
- 3) Drawings P61D M-12
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Dear Mr. O' Leary:
This letter is to report a condition relating to the operation of the unit on Iby 15, 1974. On this date, all of the 16 main steam line
-temperature sensors were found to operate above the Technical Specification limit of,1, 2000F, as specified in Table 3.2.1.
PROBLEM At the time of the occurrence, Unit 3 was being refueled, and scheduled refuel surveillance was in progress.
To implement the surveillance on the main steam line high temper-ature switches, a Fenwal calibration kit was being used. This was the first time the Fenwal hit had been used and was purchased to assure proper calibra -
tion of Fenwal suitches. (Sco above referenced letter). Two problems.
developed from the use of the calibration kit. First, the first operation of the switches could not be considered the switch setpoint.
It is believed that this is due to the air gap around the Fenwal switch. The therme=eter used for temperature measurement has no air gap. The second problem was
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May 23, 1974 that the Fenwal calibration kit provided a setpoint value which was approx-0 fanately 15 F higher than the hot water method which was previously used.
The calibration results were as follows:
First Repeatable As Suitch Trip Trfp Left 0
261-15A 260 F 2240F 1810F 261-153 2380F 2294 178T 261-150 2600F 2440F 180T 261-15D 2480F 2124 1820F 261-16A 2460F 218T 1800F 261-16B 2164 212T 1804 261-16C 225 F 221 F 1800F 0
261-16D 2124 2120F 1814 261-17A 2170F 216T 179 F 0
261-17B 2210F 2204 1790F 261-17C 2170F 2144 1800F 4
261-17D 214 F 211 F 180 F 0
0 0
261-18A 214 F 211 F 180"F 261-18B 2040F 202 F 1814 261-18C 2190F 2190F 1800F 261-18D 2164 2144 1810F The problems encountered in using the calibration kit were brought to the attention of Mr. James Winchenback of Fenwal Corp., Asland, Mass.
Hr. Winchenback stated that the Fenval calibration kit would be of greater accuracy than the previously used hot water method. He also suggested that a Fenwal temperature switch be sont to the factory for certified calibration, so a comparison of calibration technique could be cado. The thermal swit'ch, and a request for certification of the calibration kit are presently being delivered to Fenwal Corp.
In addition, Mr. Harry Hogge of.Toutelut Inc.,
Riverforest, Ill. (a Fenual distributor) visited Dresden Station and observed the problems in question. Mr.-Hogge will work in conjunction with the factory to solve _ the various problems involved in Fenwal calibration.
CORRCCTIVE ACTION The immediate corrective action was to reset the switches to a setpoint of ISO i SOF. Any additional corrective action will be dependent on the response of the vendor to the various problems thus far discussed.
As soon as practicable af ter those prob 1 cms are resolved, all Fenwal switches on both Units 2 and 3 will be checked for proper calibration.
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Hr. J. F. O' Leary ( May 23, 1974 EVALUATION The main steam line area temperature sensors are arranged in a "one out of two twice" logic array, in that any "A" or "C" switch plus any "B" or "D" switch, would initiate isolation. Analysis of the four groups of switches using the repeatabic trip points indicates operation at the following points.
261-15A-D = 2240F, 261-16A-B = 2180F, 261-17A-B = 2140F, 261-18A-B = 2110F. These valves represent a deviation of frem 127. to 5.5%
of the 29,200 F limit.
In all cases, the switches did operate. The increased cetpoint would have only delayed the detection of a stcem leak by a short period of time.
It is therefore concluded that the safety of the plant personnel or the general public was not seriously jeopardized as a result of this occurrence.
The cumulative experience to date indicated that the hot water method of calibration was not satisfactory, and therefore the calibration kit was purchased.
It is believed that af ter the problems encountered in using the kit are resolved, reliable Fenwal temperature switch calibration will be taintained.
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Sincerely, f'
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'B.~B. Stephensen Superintendent BBS:UE!!: do
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