United States Nuclear Regulatory Commission - Protecting People and the Environment

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. 

Page Last Reviewed/Updated Tuesday, November 12, 2013