Experience with neutronic channels and manufacture of second generation channels for FBTR

Neutronic instrumentation plays a vital role in monitoring, controlling and ensuring safety of the reactor in case of any operational occurrences. In FBTR, the neutron flux measurement at the sensor location varies over 11 decades from shutdown to full power of 40 MWt. The original instrumentation was indigenously designed and developed. The system has been operational for the last 11 years. In view of certain problems faced on these channels and to overcome component obsolescence, it is planned to replace these instrument channels, with second generation of instrumentation developed indigenously. This paper details the experience with the present channels and the special features adopted in the new instrumentation