Smarter radiation monitors for safeguards and security

Versatile microprocessor systems permit more efficient, and more useful methods for monitoring nuclear materials. One such method is simple stepwise monitoring, which has variable alarm levels to expedite monitoring where extended monitoring periods are required. Another method, sequential probability ratio logic, tests data as it accumulates against two hypothesis - background, or background plus a transient diversion signal - and terminates monitoring as soon as a decision can be made that meets false alarm and detection confidence requirements. A third method, quntitative monitoring for personnel, calculates count ratios of high to low energy gamma ray regions to predict whether the material detected is a small quantity of bare material or a larger quantity of shielded material. Microprocessor system subprograms can assist in detector calibration and trouble shooting. Examples of subprograms are a variance analysis technique to set hias levels in plastic scintillators and a state of health routine for detecting malfunctions in digital circuit components.