Development of control and instrumentation for closed loop nitrogen gas system for DPEND radioactive hot cells

A high purity inert gas environment is required in the hot cells for carrying out post irradiation metallurgical examination of carbide fuels of fast breeder test reactor. A recirculatory type of ventilation system with high level of leak tightness is designed. The system consists of blowers, filters, cooling systems, purification columns and final control elements viz butterfly valves. The instrumentation and control system continuously monitors and controls various parameters viz pressure, temperature, oxygen and moisture levels in the hot cells to enable strict surveillance and control of parameters within the specific limits. The signal conditioning circuits, control logics with necessary interlocks for driving the final control elements, the status parameter display system and a PC based 256 channel data acquisition system with standard DAS as features have been developed. (author)