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1Title:  Defueling the S2G reactor Add
 Summary:  This report describes the defueling of Seawolf's S2G reactor plant at Electric Boat in January 1959. This defueling was accomplished as part of the Seawolf's conversion from the sodium-cooled, intermediate range S2G reactor to a pressurized water reactor (PWR), owing to problems with the sodium-cooled design. These serious problems, which plagued the S1G (or Mark A) prototype and S2G shipboard plants, demonstrated the clear superiority of the PWR design in submarine propulsion. The report describes the importance of training (for Knolls Atomic Power Laboratory, Electric Boat, and Navy personnel who worked on the defueling) consisting of lectures and dry-runs that took place in the fall of 1958. The dry-runs enabled workers to check the condition of refueling equipment and time estimates for the completion of maintenance steps. (The summary on page 18 describes the importance of dry-runs and recommends some best practices for accomplishing them.) The dry-runs also contributed to the success in minimizing radiation exposure when the refueling was performed: "No individuals were exposed to more than the maximum permissible daily dose, 50 [millirem]" (3). The report provides an overview of the steps performed in defueling the sodium-cooled reactor. It also provides a summary of lessons learned, including: failure of a brazed joint in a cup designed to catch sodium drippage from fuel elements, which was identified during the dry run operation and fixed by using cups with welded joints; and, gas leakage from a transfer cask. Also, there was a report of difficulty in grappling an S2G fuel rod that was being removed, due to wear in the grappling equipment. After completion of the refueling, the S2G's fuel rods were shipped via train to the Idaho National Laboratory's Expended Core Facility. 
 Date:   1959 
 Subject(s):  S2G | Nuclear engineering | Naval Reactors 
 Type:  Text 
 Format:  PDF 
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