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Information Notice No. 83-47: Failure of Hydraulic Snubbers as a Result of Contaminated Hydraulic Fluid
SSINS No.: 6835 IN 83-47 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C., 20555 July 12, 1983 Information Notice No. 83-47: FAILURE OF HYDRAULIC SNUBBERS AS A RESULT OF CONTAMINATED HYDRAULIC FLUID Addressees: All nuclear power reactor facilities holding an operating license (OL) or construction permit (CP). Purpose: This information notice is provided as a notification of a recently observed failure of hydraulic snubbers because hydraulic fluid was contaminated. No specific action is required in response to this information notice, but it is expected that recipients will review the information presented for applicability to their facilities. Description of Circumstances: On May 31, 1983, the Florida Power Corporation reported (LER 83-021) the failure of 107 out of 261 hydraulic snubbers to meet their functional test requirements at Crystal River Unit 3. Contaminated hydraulic fluid was the most frequently cited cause. During Crystal River's 1981 refueling outage, a similarly high failure rate was observed and reported (LER 81-063 and its revision). An evaluation of the event indicated that the most likely source of contamination was particulate matter left in the fluid reservoirs after fabrication. Consequently, the corrective action was limited to disassembling, cleaning, reassembling, and filling all the snubbers with new fluid. Following this latest failure, other sources of contamination were investigated with the result that the possible sources now are considered to be the fluid reservoir, the reservoir vent opening, and the new hydraulic fluid (GE type SF9650). In addition, the corrective actions have been expanded and now include the following. 1. The reservoir manufacturer has been required to flush each reservoir with clean solution before shipping it to the facility. 2. Independent pre-shipment inspections are performed to verify cleanliness before sending new reservoirs to the facility. 8306270404 . IN 83-47 July 12, 1983 Page 2 of 2 3. Reservoirs are flushed with cleaning solution before the snubber is assembled. 4. Reservoir vents that are open to the atmosphere have been replaced with filtered vents. 5. New hydraulic fluid is being filtered several times before use. First, the fluid is filtered as it is poured from the shipping container. The fluid is filtered again as it is pumped into the snubber. And, finally, following filling, the snubber is stroked several times and the displaced fluid passes through a filter and returns to the snubber with each stroke. No written response to this notice is required. If you have any questions regarding this matter, please contact the Regional Administrator of the appropriate NRC Regional Office, or this office. Edward L. Jordan Director Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement Technical Contact: R. J. Kiessel, IE (301) 492-8119 Attachments: List of Recently Issued IE Information Notices .
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