Part 21 Report - 1998-301

ACCESSION #: 9807060138 NAMCO Namco Controls Corporation 5335 Avion Park Drive Highland Heights, Ohio 44143 Tel. (440) 460-1360 Fax: (440) 460-3800 May 1, 1998 Document Control Desk United States Nuclear Regulatory Commission Washington, DC 20555 FAX 301-492-8187 Phone 301-951-0550 SUBJECT: Notification of Product Anomaly Namco Controls EA180 Series Limit Switches Manufactured December 19, 1997 through March 27, 1998 Gentlemen: The purpose of this letter is to notify you of an anomaly with the subject product line that was brought to my attention by the Namco Controls' Evaluation Committee. During a review of our internal receipt inspection closed purchase order file on April 1, 1998, it was discovered that the supplier who impregnated the EA180 housings did not use the Namco Controls qualified impregnate. Our investigation has determined that 112 EA180 Limit Switches were shipped with this described condition. We are notifying the affected customers, see the attached list. At this time we are closing this issue and have generated a Technical Bulletin TB9801 summarizing the conclusions and recommendations to the affected customers by May 8, 1998. I have attached a copy of this Technical Bulletin for your reference. Thank you, Best Regards, Alex A. Joseph, President Attachments cc: Evaluation Committee file (D. Jackson III TB9801 NAMCO CONTROLS MAY 1998 TECHNICAL BULLETIN NOTIFICATION OF IMPREGNATION SEALANT ANOMALY PURPOSE: The purpose of this Notice is to-inform the Nuclear Power Plant Operators and others involved in the operation and maintenance of Namco Controls Limit Switches of an impregnation sealant anomaly. DESCRIPTION: During a review of the receipt inspection closed purchase order, it was discovered that the supplier who impregnated the EA180 housing did not use the qualified sealant. These limit switches were manufactured from December 18, 1997 through March 27, 1998. The list of affected customers is attached. NAMCO CONTROLS INVESTIGATION:. A comprehensive review program by Engineering, Quality, and Marketing was conducted. It was determined that 112 improperly impregnated housings were shipped to Nuclear customers, The Impregnation supplier used Imprex 95- 1000A which was not previously qualified by Namco Controls. NAMCO CONTROLS TECHNICAL REVIEW: Namco Controls uses Imprex 95-500 impregnate sealer to fill microscopic voids in the cost housing surface. The sealer is not required for the qualification of the Limit Switch, as long as the housing is look fight at time of manufacture. Based upon our experience, the majority of the cost housings would require no impregnant to be leak fight, although all housings are impregnated for ease of manufacturing. Imprex 95-500 is a mixture of Styrene and unsaturated polyester resin. The material and process was developed to meet the requirements of MIL-I-17563 and MIL-STD- 276. Due to environmental benefits, Imprex 95-500 is being discontinued and replaced with 9&1000A. Imprex 95-1000A is a mixture of Methacrylate and unsaturated polyester resin. The material and process was developed to meet the requirements of MIL-I-17.563 and MIL-STD-276, Imprex recommends 95-1000A as direct commercial and Military replacement for Imprex 95-500. The Namco Controls Engineering Report provides a comprehensive equivalency comparison of the physical properties of the two sealants. The comparison addresses the capabilities of Imprex 95-1000A sealant to withstand the Plant Service and Accident conditions. 1 of 3 TB9801 NAMCO CONTROLS MAY 1998 TECHNICAL BULLETIN NOTIFICATION OF IMPREGNATION SEALANT ANOMALY The Engineering evaluation addresses all areas of qualification including the critical areas of thermal aging/outgassing, gamma radiation, and LOCA. To address thermal aging and outgassing, an accelerated thermal aging test was performed. At the conclusion of the test the Imprex 95-1000A sealant passed the leak tightness requirement. Also, there was no noticeable discoloration of the housing. The possibility of outgassing evaluated by noting that the vapor pressure of 95-1000A is 1/5 of 95-500. The lower the vapor pressure the less outgassing would be present. This would indicate that 95-1000A would cause less contamination of the gaskets and contacts than 95-500. Also, there were no stains on the housings after thermal aging which indicates no out gassing of the impregnant. Gamma radiation was evaluated by noting that the effect of radiation on the plastic sealer would tend to swell the resin which would improve leak tightness. Namco Controls Engineering evaluation determined that the pressure during the LOCA test would not over stress either sealant. The estimated stress produced by the LOCA pressure was less than the tensile strength of the sealants. The published temperature capabilities of the sealants were found to be equivalent and in accordance with the Mil STD rating. All housings are required to pass a water pressure test after impregnation and after final assembly. The Imprex 95-1000A housings passed both of these leak tests before shipment. Namco Controls has conducted a thermal aging test to age the housing to an equivalent of 3.0 years of service. Based on this information, the EA180 Limit Switch with the Imprex 95-1000A Impregnant can be In service at 125 degrees F (51.7 degrees C) for 3.0 years with no effect on the integrity of the impregnant sealer. It is Namco Controls' Engineering opinion that Imprex 95-1000A is equivalent to 95-500 foe the conditions identified above. CONCLUSION and RECOMMENDATION: After a careful review and evaluation of the circumstances, it is our opinion that the described condition is not a safety-related event. In fact, it's our intent, upon full qualification, to replace the Imprex. 95-500 with 95-1000A as our qualified impregnant. Namco Controls is establishing a full qualification test for Limit Switches impregnated with Imprex 95-1000A. Testing is expected to be completed within the next 18 months. It is Namco Controls opinion, based on our Interim Engineering Report, that Limit Switches built with Imprex 95-1000A are equivalent to the originally qualified Limit Switches with 95-500. Namco Controls recommends the continued use of the Limit Switches, as stated above, while Namco, Controls completes the final Qualification Tests and Reports. Once the qualification testing is complete the affected customers will be notified of the results. The affected customers are being notified. The list of customers is attached. 2 of 3 TB9801 NAMCO CONTROLS MAY 1998 TECHNICAL BULLETIN NOTIFICATION OF IMPREGNATION SEALANT ANOMALY Customer List Alabama Power Arizona Public Service Automatic Valve Bettis Corp. BW/IP International Commonwealth Edison Consumers Power Duke Energy Company Duquesne Light Co. Florida Power and Light Northeast Nuclear Energy Northern States Power Ontario Hydro Vermont Yankee 3 of 3 *** END OF DOCUMENT ***

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