ML20023E054

Deficiency Rept Re Narrow Range Resistance Temp Detectors Installed to Meet License Condition Failing to Operate.Cause Under Investigation.Detectors Replaced.Testing Modified Until Design Revised.Also Reportable Per Part 21

ML20023E054
Person / Time
Site:	North Anna
Issue date:	05/27/1983
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Clark R, Harold Denton Office of Nuclear Reactor Regulation
References
REF-PT21-83 10CFR-050.55E, 10CFR-50.55E, 257A, NUDOCS 8306070148
Download: ML20023E054 (2)

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VIROINIA ELECTRIC ann POWER COMPANY f V

Ricnxoxu,V HGINIA 20261 f W.L.STEWABIT k Vses Pmessoswr f Nect.mAm oramartown i

May 27, 1983  ;

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g, p Mr. Harold R. Denton, Director Serial No. 257A j y Office of Nuclear Reactor Regulation N0/SBE/JHL:acm l Attn: Mr. Robert A. Clark, Chief Docket No. 50-339 Operating Reactors Branch No. 3 License No. NPF-7 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D. C. 20555 4

Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT NO. 2 STATUS OF LICENSE CONDITION 2.C(4)(c)

In our letter dated May 6, 1983 (Serial No. 257), we reported the status of North Anna Unit 2 License Condition 2.C(4)(c) which requires the replacement of the wide and narrow range resistance temperature detectors (RTD's) in the reactor coolant system with qualified RTD's. In the letter, it was stated that qualified RTD's had been obtained and installed in 23 of 24 locations in the reactor coolant system. The last RTD (TE-2430) could not be replaced at the time due to an obstruction. These qualified RTD's are Weed Instrument Company narrow range (200 ohm platinum single element) Model No. N9000-2B-240

~ /9 and vide range (200 ohm platinum dual element) with sensor element SP612D-2B-C-6-F-13.5-0-0.

This letter is to inform yoa that the narrow range RTD's that were installed to meet this license condition have failed to operate properly. The failures were identified during bench testing or after installation while operating at a temperature between 195*F and 350*F. The failure mechanisms are still under investigation. The wide range RTD's are of a different design and experienced no such failures after installation.

Due to these failures, all of the narrow range RTD's (18 total) have been

, replaced. Vepco has located and installed 18 Rosemount RTD's (Model 176KF)

,) that have not been used. These units have been installed and tested by the J approved calibration and post installation testing procedures.

In addition, until the replaced RTD's can be repaired or redesigned to ensure the needed reliability is obtained or another qualified RTD can be obtained, j the installed Rosemount RTD's will be tested by the Arrhenius methodology and

/ also by the Loop Current Step Response method each calendar quarter. Vepco has assured that the cable connectors are adequately sealed. Therefore, the interim License Condition is being met.

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8306070148 830527 PDR ADOCK 05000339 E

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VIROINIA Etzernic Awp Powra Courm To Harold R. Denton Vepco has determined that these failures could create a Substantial Safety Hazard in a Basic Component and this is reportable pursuant to 10 CFR Part 21.

The initial verbal notification of this event was made to Mr. C. Julian (NRC Region II) at 1356 on May 24, 1983. A follow-up written report will follow within five days.

Very truly yours,

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,- k W. L. Stewart cc: Mr. James P. O'Reilly Regional Administrator Region II Mr. M. B. Shymlock NRC Resident Inspector North Anna Power Station