Representation of a Low-Yield Nuclear Weapon Neutron Spectrum Using an (α, n) Neutron Source

Abstract

Recent nuclear weapons testing in the limit of low-yield detonations has underscored the need to ensure that radiation detection and monitoring equipment can adequately respond to these events. Testing and validating equipment in appropriate reference fields have become difficult since the closing of the NATO primary fission spectra reference at the Aberdeen Proving Ground Fast Burst Reactor facility post-9/11. A simple and low-cost device was designed to perform testing of commercial off-the-shelf neutron detection equipment to the expected spectral shape from a low-yield nuclear weapon. By enclosing an ²⁴¹AmBe (α,n) neutron source within a heavy water-moderated sphere, the general shape of a 1-kiloton standard fission weapon was generated at 1 m, valid between 100 and 2000 keV. The 1-m dose rate expected from this configuration is ˜2.16 × 10^–10 μSv·h^–1·Bq^–1, which is less than one-half of the unshielded dose rate.