ML20011A708

Interim Deficiency Rept Re Diode Failure Mechanism in Certain Pressure Transmitters,Initially Reported 810914. E-type Amplifier Cards Will Replace a or D-type Cards.All Mods to Be Completed by 820630

ML20011A708
Person / Time
Site:	Shoreham File:Long Island Lighting Company icon.png
Issue date:	10/13/1981
From:	Mccaffrey B LONG ISLAND LIGHTING CO.
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
10CFR-050.55E, 10CFR-50.55E, SNRC-637, NUDOCS 8110290315
Download: ML20011A708 (4)

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LONG ISLAND LIGHTING COMPANY j .aerawx*w e SHOREHAM NUCLEAR POWER STATION P.O. BOX 618. NORTH COUNTRY ROAD e WADING MlVER. N.Y.11792 l l

October 13, 1981 SNRC-627 Mr. Boyce Grier, Director Qh j Office of Inspection and Enforcement, Region I U. S. Nuclear Regulatory Commission 8 f Y,N

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LONG ISLAND LIGHTING COMPANY SHOREHAM NUCLEAR POWER STATION - Unit 1  % m\p l

. DOCKET NO. 50-322 l Dear Mr. Grier on September 14, 1981, in accordance with 10 CFR 50.55 (e), we reported verbally to Region I a deficiency in certain Rosemount, Inc. pressure transmitters used in safety-related applications at Shoreham. The transmitters involved are Rosemount Models

l. 1151 and 1152 pressure transmitters with "A" and "D" output codes. This letter serves as our 30-day report on this

! deficiency.

Description of the Deficiency

, We were advised by Rosemount's letter, dated February 9,-1981, that they had identified a diode failure mechanism in the subject transmitters which could result in abnormally high failure rates. The diodes are located on the amplifier board located directly under the electronics housing cover. Moisture trapped in some diodes during the manufacturing process could

, lead to instability and internal shorting. 1 This instability would present itself as noise on the normally.

stable output current signal. This noise would be normally less than 1% of the signal but could be as high as 4%; however, the instability was not found at signal current valves above 5 mA.

Failure of the diode would result in a fixed 12 to 14 mA transmitter output.

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Mr. Boyce Grier October 13, 1981 Page 2 Our initial assessment was that this problem would not constitute a significant deficiency, as there was no evidence that defective diodes were included in the Shoreham equipment and as the random failure of a single safety-related instrument would ordinarily not, due to redundancy, result in a significant safety hazard.

In the course of our own investigation, we further learned from Rosemount that this diode failure mechanism had a significant infant mortality characteristic, which was not indicated by their original letter. This prompted us to review our own transmitter failure history on transmitters which were going through startup testing. This review determined that nine defective amplifier boards had been found in Rosemount trans-mitters at Shoreham, and five of these had been traced to a defective diode matching the location and description provided by Rosemount. Subsequent investigations determined that the symptoms of the failure closely resembled those described by Rosemount.

Due to the apparently high rate of failure early in the life of the transmitter, which diminishes the random failure character-istic, as well as the fixed, mid-scale output failure mode, which might prevent a transmitter failure from being recognized promptly, we concluded that this situation could lead to a significant safety hazard and, accordingly, notified the NRC Region I inspector.

Fifty-one safety-related Rosemount transmitters are affected by this deficiency, of which thirty-nine are installed and twelve are spare. These transmitters are identified on the attachment to this letter.

Corrective Action The recommended modification which will correct the subject problem is the substitution of an "E"-type amplifier card, which provides the same function as the "A" or "D" type card, but which does not use the subject diode. Twenty-two of the affected transmitters have already been selected for "E" type card modification, as stated in our letter SNRC-514, dated November 5, 1980. We will, therefore, extend this modification program to encompass the additional 29 transmitters which are affected by the diode deficiency.

Corrective Action to Prevent Recurrence Upon completion of the "E" type card modification program, no "A" or "D" type cards will be in use in any safety-related J

r Mr. Boyce Grier

. October 13, 1981 Page 3 Shoreham application. Also, "A";or "D" type cards-will not be accepted 'for. any future safety-related Shoreham application.

Date of Full Compliance

, Our schedule -for performing these modifications will- be dependent upon material deliveries from RoseFount as well as the availability of'those transmitters which.'are already involved.in system startup testing. We estimate, however, that all modifications will be complete by June 30,~-1982.

Very truly yours,

/ 8d TN 9/

B. R.'McCaffr Manager - Projec Engineering Shoreham. Nuclear Power Station GKP/ law Attachment e

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-SAFETY-RELATED TRANSMITTERf ~

, . WITH "A" AND "D" OUTPUT CODEb MARK NO. SERVICE- 3

-C61I*LT 026 ~Supp; Pool

• PT'011 Service Water;He'a' der

• PT 106 SRV Air Header.

. Ell *FT 001'A, B' RHR Main ~ Flow -(GE)

• FT 006 A, B RHR Heat Exchanger-Service Water Inlet (GE)

E41 *PT 142. HPCI to Lube Oil Cooler

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. E51'*PT.142 RCIC to' Lube Oil' Cooler-Gil *FT 647 C Supp. Pool Pumpback M50 *FT 043 A,.B WC-3A/3B-Chilled Water

• FT 053 A, B WC-4A/4B Chilled Water

• PDT 019 A, 3 P41 *FT 054 A, B WC-3A/3B Cond. Water

• FT 059 A, B WC-4A/4B Cor d. Water

• FTE146 A, B _P42*E-Olla, B Serv. Water

, *FT 151 A, B Rad. Monittr Sample

' *PDT 150 A-D P41*S-001A-D.

P50 *PT 111 A, B ADS Accumulator

• PT ll6 A, B Service Air Header + >

4 T46 *PDT 003 A, B Filter lA, B

• PDT 043 A, B Reactor Building T48 *FT 005 HEPA Filter Inlet Z93 *LT.001 A, B 'Supp.. Pool Gil *FT 647 A, B To be Spared

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. Z91 *FT 001:A, B- Spare

• FT 639

• FT.'640

• FT 6 41

-*PDT 861'A, B, C

=*PDT 862 ~

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• PDT 863'.

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