The Trusted Radiation Attribute Demonstration System (TRADS) confirms attributes of nuclearweapons or components using only a high-purity germanium detector. For plutonium-bearingcomponents, the relevant attributes are a plutonium mass threshold and a ratio of 240Pu to 239Pu thatis consistent with weapons-grade material. The masses of all gamma-ray emitting isotopes andcharacteristics of intervening materials are estimated by fitting features in the spectrum associatedwith intensities of the gamma ray peaks and the low-angle scattering continuum. A trustedprocessor (TP), which is used for data acquisition and analysis, addresses the security requirementsof the host as well as the needs of the inspector. The TP employs simple processors (PC-104 cards)and a divided hardware and software design to isolate classified information from unclassifiedoutput. The processors are contained within a stainless-steel, tamper-indicating case, which can beuniquely identified and inspected for integrity using an eddy-current scanner. All of the software iscontained in read-only memory and a keyed hash algorithm is used to authenticate the software.
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