SAFARI-1 pool liner leaks

SAFARI-1 is a 20 MW tank-in-pool light water cooled, light water moderated, and beryllium reflected research reactor which first reached criticality on 18 March 1965. The aluminium pool liner has developed a leak in the 1980s. These leaks were repaired in 1989 during a lengthy shutdown which allowed for the pool to be drained and for adequate decay of the core structures to access the problem areas. Following the repair, the leak was acceptable until it required further repairs in 2003. The high utilisation of the reactor no longer allowed a lengthy shutdown, and methods were develop to pinpoint the location of the leaks and to repair it during normal shutdowns without draining the pool. By forcing reverse flow of a dye through the leak paths, the positions of the leaks were determined. The leaks were then repaired by painting an epoxy resin onto the leaking areas. A monitoring system was put into place to monitor and trend the leak rates. It became necessary to repair the leaks approximately every three years, following the same methodology. The pool liner leak issue at SAFARI-1 therefore appears to have been brought completely under control and, while a small leak reappears every three years or so, the method of eliminating it is very well established and successful. (author)