PNNL

Abstract

For nearly five decades 252Cf sources have been used for testing and calibration over a wide range of neutron detection devices used for nuclear safety and radiation protection. However, the vastly increased cost of 252Cf sources, its short half-life, and concerns about future shortage have prompted nuclear facilities and radiological calibration laboratories that rely on high-intensity neutron sources to seek alternatives. There appear to be no other radionuclide neutron sources that would match “like-to-like” 252Cf performance characteristics. Alternatives of producing a fission-like neutron spectrum based on commercially available deuterium-tritium (D-T) generators, and without any fissionable materials or beryllium, have been explored. This paper describes efforts of designing the spectrum shaping assembly, its construction and installation. The produced neutron field was evaluated both from the perspective of the neutron fluence spectrum and the resulting dosimetric outcome. Finally, it was tested for practical application by examining response of various health physics instruments and personal monitoring devices in comparison to the response of those devices when exposed to 252Cf. The response of survey-type instruments tested within the prototype, surrogate fission, reference field are acceptably close to their response in the targeted 252Cf field.