ML17252A903

Letter Reporting a Condition Relating to the Operation of Dresden Nuclear Power Station Unit 3 on 05/15/1974 - Violation of Main Steam Line Area Temperature Detectors

ML17252A903
Person / Time
Site:	Dresden
Issue date:	05/23/1974
From:	Stephenson B Commonwealth Edison Co
To:	O'Leary J US Atomic Energy Commission (AEC)
References
BBS Ltr. #368-74
Download: ML17252A903 (3)

Text

CommonweaA::dison One First Nations~.

Chicago, Illinois 60690 BBS Ltr.#368!!!,;"14:=..__

Olicago, Illinois Address Reply to: Post Office Box 767

• Dresden Nuclear Power Station R. R. #l - -

Morris, Illinois 60450 May 23, 1974 ---c-~

1.,,*::.) flf.({/f!Pi *~

Mr. J. F. O'Leary, Director f '~/ ~lfr-2-- Ytb Directorate of Licensing ~ ~'. \ !J.,~ .... ~19.llJ r .

~~s~in!~=~cD~~~gy i~~88ion 50 - 2 49 \\'-~-~~'*"'"':.~: ,

SUBJECT:

LICENSE DPR-25 DRESDEN NUCLEAR POWER STATION UNIT ii '-.. f!aEf l[f.'.;o!/

ABNORMAL OCCURRENCE PER* TABLE 3.2.l OF* THE TECHNICAL SPEC IONS *

.TECHNICAL.SPECIFICATION VIOLATION OF MAIN* STEAM LINE AREA TEMPERATURE DETECTORS. ** .

References.: 1) Letter from B. B. Stephenson to Mr. J-. F. O'Leary dated April ~, 1974.

2) *Notification of Region III of AEC Regulatory Operax.A.11--..9...--

Telephone: F. Maura, 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 P&ID M-12 S&L 12E2501

Dear Mr. O'Leary:

This letter is to report a condition relating to the operation of the unit on May 15, 1974. On this date, all o.f the 16 main steam line temperature sen!ors were found :to operate above the Technical Specification limit of _s_ 2000p, as specified in Table 3.2.l.

PROBLEM At the time of the occurrence, Unit 3 was being refueled, and scheduled refuel suryei~lance 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 kit had been used and was purchased to assure proper- calibra-

. tion of Fe~wal switches. (See 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 thermometer used for temperature .measurement has no air gap. The second problem was REGULATORY DOCKET FILE COPY 4709

- -,, ** 4. r.,;,.Mr. J. F. O'Leary

• May 23,. 1974 that the *Fenwa1--calibration kit proV.ided a setpoint valu.e-wbich was appr.ox-imately .15°F: higher than. the hot water method which was. previously used~.

The calibration results were as follows: . . " : .. . *. *. .* ,

First Repeatable As Switbh Trip Iri2. Left.

261-lSA 2600F 224<>r 181°F 261*15B 238°F 229°F 178°F 261-lSC 260oF 2440, 180°F 261*15D 2480, .212°F 182°1 261*16A 246oP 218°1 180°1 261*16B 216°F 212<>r 180°F 261*16C 225°F 221°F 180°F 261*16D. 212°F 212<>r 18l°F 261*17A 217°F 216°F *1790p.

261*17B 221°F 220°F 179°1.

261*17C 217"F 214°1. 1800, 261-11D* 214°F 211'T 180°F 26l*l8A 214°F 2ll°F 180°F 261*18B 204°F 2020, 18l°F

. 261*18C * * ;t- 219°1 . .* .,, 2190, <. *., 1800F

• 261*18D.' *' .* -:, '2J.'6°F. - '. 214oF . .' .*. ' c

• 18l°F

... , *~~'.*.\~:-: ~~*; L. ..... ~.

. The. proble~s. ~ncountered i~~* u~bg . the Cliiibration kit *were b11ought to the attention of Mr. James Winchenback of Fenwal Corp.,* Aaland, Mass. .

Mr *. Winchenback efaEed~.::aMt. the- Fenwal calibration kit . . would be of greater

• ., * ' * ,, ,It.. ..

• accuracy .than the previously used bot water method~ He al~o suggested that a Fenwal *temperature switch be. sent to the factory for certified calibration, ..

so .a comparison of calibration technique* could be made. The thermal switch, and a request for certification of the calibration kit are presently being .

• delivered to Fenwal Corp.: In addition, Mt. Harry Hogge of .Toutelut Inc~,

Riverforest, Ill. (a Fenwal distributor) visited Dresden Station and observed the problems in question* Mr. Mogge will work in conjunction with the factory to solve the various problems involved in'Fenwal calibration.

CORRECTIVE ACTION The immediate corrective action was to reset the switches to a setpoint of 180 :t S°F. 'Any additional corrective action will be depend~nt on the response of the vendor to the various problems thus far diacusieCl;-

As soon as practicable after these problems are resolved,. all Fenwal switches on both Units 2 and 3 will be checked for proper calibra.t.ion.

-~"-:;;. \:~4Mr. 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 nn" switch, would initiate isolation. AnaJysis of.the four groups of switches using the repeatable trip points* indicates operation at the*

following points. 261-lSA-D

• 224°F, 261-16A-B ... 218°F, 261-17A-B "" 214°F, 261-18A-B

• 2lloV. These valves represent a devi,ation of from.121 to 5.5'%.

of the L.. 200°F limit. In all cases, the switches did operate. The increased setpointwould have only delayed the detection of a steam 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 calibra~ion kit was, purchased. It 1is believ~d *that. after* the problems encountered in using the kit are resolved, reliable Fenwal temperature switch calibration will be maintained. "

-~,

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