Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
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.
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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.
