ML20039B768

Part 21 Rept Re Resistance Temp Detectors (RTD) & Associated Signal Processing Equipment Scheduled for Installation During Refueling Outage in Early 1983.Steps Taken to Ensure Reliable RTD Operation in Interim Listed

ML20039B768
Person / Time
Site:	Millstone
Issue date:	12/08/1981
From:	Counsil W NORTHEAST NUCLEAR ENERGY CO.
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
REF-PT21-81-540-000 B10342, PT21-81-540-000, TAC-47355, TAC-47389, TAC-47473, NUDOCS 8112230538
Download: ML20039B768 (2)

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~l:::::;27::""~" ammeen k L J Cf!C;%UCU December 8, 1981 Docket No. 50-336 B10342

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Mr. Ronald C. Haynes, Director Region I Office of Inspection and Enforcement U. S. Nuclear Fegulatory Commission 631 Park Avenue King of Prussia, PA 19406

Reference:

(1) Letter, W. G. Counsil to V. Stello, Jr. , dated July 10, 1981. W cd

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(2) Letter,W.G.CounsiltoD.G.Eisenhu.Nhte4 9 August 26, 1981.

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Millstone Nuclear Power Station, Unit No. 2

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Resistance Temperature Detectors y

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_4'\ P In Reference (1), Northeast Nuclear Energy Company (NNECO) advlsed lthed' NRC Staff of the apparent degradation of certain resistance temperature detectors (RTDs) at Millstone Unit No. 2. Included in Reference (1) were NNECO's plans to replace all RTDs at Millstone Unit No. 2 with RTDs of a different manufacturer. This replacement was scheduled for the 1981 -

refueling outage.

NNECO has since revised the schedule for the RTD replacement to coin-cide with the next refueling outage planned for early 1983. The delay is the result of differences in the design of the current RTDs and the intended replacements. The replacement RTDs are a three-wire design.

The necessary signal processing equipment required to accommodate the change from the current four-wire designed RTDs will not be available to support the original plans to replace the RTDs during the upcoming refueling outage.

Since the replacement RTDs cannot be installed during the 1981 refueling outage, NNECO intends to take the following actions to ensure continued reliable operation of the existing RTDs:

1. All terminal blocks, crimps, and lugs in the RTD connection heads on all RTDs will be replaced. The replacement parts are those provided by the vendor in response to the corrosion problems identified in Refereuce (1).

2. Fully nuclear qualified conduit seal assemblies will be used on the connection head to cc=pletely seal the connection head internals from the surrounding environment. This is consistent with the conmtitments made in Reference (2) regarding equipment I]

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3. New 0-rings will be installed upon reassembly of the RTD con- J nection head.

4. Twelve RTDs will be replaced with spare RTDs of the current design.

The actions described herein are judged to be optimal with regard to interim corrective measures to prevent degradation of the RTDs by cor-rosion until the fully qualified replacements can be installed. The new RIDS and their associated signal processing equipment are scheduled for installation during the refueling outage in early 1983.

We trust you will find this information satisfactory.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY

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W'.'G. Counsil Senior Vice President ec: D. G. Eisenhut L; 4 J hE ~'

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