Maintenance experience of pumps in Cirus reactor

A total of 110 pumps are in service in different liquid handling systems of the CIRUS reactor which has completed more than 20 years of operation. Maintenance experience of these pumps is described. The related problem areas are categorised into: (1) noise and vibrations, (2) shaft seals, (3) installation and commissioning, and (4) design considerations. It is also described how they were tackled. Specific recommendations based on the maintenance experience are made which are given below. A vibration analyser should be used to identify the source of noise and vibrations in centrifugal pumps and each problem should be solved on an individual basis. An odd number of impeller vanes should be used to avoid sound harmonics. Coolant flow restriction should be done by an orifice plate instead of a valve. Two sumps of widely different (chemically) properties of fluid should not be located side by side, in the first place. If so located, both the sumps should be provided with pumps that can handle both types of fluids. Proper scheduling, surveillance and documentation enables to keep track of the conditions of pumps and to take decisions. (M.G.B.)