The Materials Dosimetry Reference Facility

The Materials Dosimetry Reference Facility (MDRF) is a new reactor-driven reference neutron field for reactor dosimetry calibrations and methods validation. Basically, the facility design is a steel cylinder (15-cm o.d., 5-cm i.d.) mounted in the pool close to the core of the Ford Nuclear Reactor at the Phoenix Memorial Laboratory of the University of Michigan. Two spectrum options are available: one with a near-1/E distribution below 0.1 MeV, and the other with a ¹⁰B filtered spectrum that cuts off below 4 keV. Fast-neutron fluence rates (nominally 2.8×l0¹¹cm⁻²s⁻¹, E>1 MeV) are established by means of neutron fluence transfer from the ²⁵²Cf Fission Neutron Irradiation Facility at NIST. Neutron fluences for sample irradiations (conventional maximum 2×l0¹⁶n/cm², E>1 MeV) will be certified to uncertainties of ±(5−6)%, lσ. The neutron spectrum in the facility is established on the basis of neutron transport calculations and spectral index measurements, the latter with threshold, low-energy activation, and fission reactions. The results of calculations and measurements are reported in this paper.