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Information Notice No. 80-42: Effect of Radiation on Hydraulic Snubber Fluid
SSINS No.: 6835 Accession No.: 8008220261 IN 80-42 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 November 24, 1980 Information Notice No. 80-42: EFFECT OF RADIATION ON HYDRAULIC SNUBBER FLUID Description of Circumstances: On August 7, 1980, Florida Power Corporation (FPC) filed a report in accordance with 10 CFR Part 21 that identified an upper service limit of 10 Mrad (megarad) of radiation on the General Electric Versilube F-50 fluid that was provided in Anker-Holth shock suppressors mounted on the reactor coolant pumps. This upper limit was obtained from the results of a study performed for FPC by Rensselaer Polytechnic Institute (RPI). These results contained two items of prime importance to the operation of the suppressors. The first result was a significant increase of the viscosity of the fluid to the extent that incipient gelation of the fluid occurred at exposures of approximately 50 Mrad. The viscosity increased linearly for exposures up to 20 Mrad and then increased exponentially for exposures greater than 20 Mrad. The second result showed that hydrochloric acid (HCI) was formed in significant quantities when the fluid was subjected to radiation. The following table lists the dose irradiation time and HCI formed. Dose Irradiation HCl Formed (Mrad) Time (Ppm) 0 2.78 1.2 1 minute 70.3 5.8 5 minutes 329. 5.8 10 hours 335. 18.5 11.2 minutes 555 50.3 15.2 minutes 1592 One of the recommendations by the RPI personnel was that the fluid be replaced before a limit of approximately 6 Mrads was reached. FPC reported that the fluid in service at Crystal River No. 3 plant had absorbed doses ranging from 2.3 to 3.6 Mrads, these values were determined by comparing the viscosity of the fluid in service to that of the test samples at RPI. The Technical Instruction Manual that is provided by the vendor for these suppressors contains a recommendation that 12.5 Mrads should be the maximum service life for Versilube F-50. This Information Notice No. is provided as an early notification of a possibly significant matter that is still under review by the NRC staff. Recipients should review the information for possible applicability to their facilities. No specific action or response is requested at this time. If NRC evaluations so indicate, further licensee actions may be requested or required. . IN 80-42 November 24, 1980 Page 2 of 2 No written response to this Information Notice No. is required. If you have any questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
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