Design and Development of Radiation Detectors for Nuclear Reactors

Several B lined ionization chambers with and without gamma compensation have been developed with cylindrical and parallel plate electrode geometry. These detectors have been developed after extensive studies on the optimization ofthe neutron and gamma sensitivities, the voltage /current (V/I) characteristics and the response of the detectors as a function of neutron flux. The reliability and long term performance of these chambers is improved by use of some special techniques which include the use of composite stainless steel aluminum clad plate and use of easily machinable polyether ether ketone (PEEK) insulators. These materials have successfully withstood accelerated tests up to 1.26x 10nvt at Dhruva reactor. Gamma Compensated boron lined ionization Chambers (GCIC) employing the parallel plate electrode geometry with specially designed springs and ceramic spacers have been developed for the first time for LWRs. The use of the innovative design has resulted in mechanically rugged detectors for continuous operation up to 300°C with linearity of better than 10% over flux range of 10nv to 10nv. These detectors have been successfully integrated with hanger assemblies and qualified for shock, vibration and LOCA conditions. Inconel 600 SPND has been developed as an alternative to the Cobalt SPND for in-core neutron monitoring for reactor safety &control applications. Aquadag coated plastic ionization-chamber for gamma dose measurement has been developed for LWR and the chamber has withstand shock test. The paper delineates a summary of the innovations and special techniques used in the design of chambers, performance and the qualification tests conducted on the various chambers developed for the reactors. It also describes the setting up of calibration facility for the testing of the neutron chambers at KAMINI reactor.