Development of Low Neutron Response Dosimeters for Use in Research Reactors, e.g., EPR-based Teflon and Polyethylene Dosimeters

As we investigate the neutron response of the dosimeters we use in the mixed neutron/photon reactor environments that support our radiation testing, we are active in developing new dosimeters that minimize their neutron response. Rather than trying to compensate for the neutron contribution, we have looked at developing a dosimeter that is intrinsically more sensitive to photons than neutrons. Towards this end, we look to measurements that are sensitive to ionizing dose rather than displacement. Alanine and radiochromic film are not good candidates since, due to the hydrogen content, about half of the ionizing energy in a research reactor environment can come from the neutrons. We have been doing research on sensors that are sensitive to ionizing dose but are composed of higher atomic weight materials, such as Teflon, so as to minimize the neutron ionizing dose contribution. Silicon calorimeters are also an important sensor for use in reactor environments. Because of the delayed photon radiation component in a research reactor environment, in calorimeters we look for materials and designs that can provide a high thermal conductivity and where we can attempt to deconvolute the temporal response from prompt and delayed radiation components. One thrust has been to look at the use of calorimeters where the neutron-induced secondary gamma contribution is not significant, e.g. bismuth.

Contact: David Vehar