Development of an Inconel self powered neutron detector

Full text: An Inconel 600 self-powered neutron detector has been developed and tested. The detector has an overall dia and length of 3.5 mm and 22 cm respectively. It is integrally coupled to a mineral insulated cable. With an effective neutron cross-section of 4b, the detector has a neutron sensitivity of 1.33 x 10-2A/nv, which is about 1/5th the neutron sensitivity of a cobalt detector. The gamma sensitivity was measured to be - 0.098 fA/R/h. The linearity of the detector response at power levels ranging from 50 kW to 200 kW was within ±5%. Tests at Apsara reactor showed that the prompt response of the detector was 0.94 as against the prompt response of 0.85 for the cobalt detector and gamma ion chamber respectively. Although the Inconel detector has the disadvantage of low response, the advantages of prompt response, low burnup and longer life make it ideally suited for reactor control applications and a better alternative to cobalt and platinum detector. Efforts are in progress to improve the neutron sensitivity of these detectors by coiling them. The expected neutron sensitivity of a coiled Inconel detector is 5.3 x 10-20 A/nv which is about 10 times the neutron sensitivity of 21 cm long straight cobalt detector