Publications
Mathematical Aspects of Unique Signal Assessment
This report is a supplement to ''The Unique Signal Concept for Detonation Safety in Nuclear Weapons,'' SAND91-1269, which provides a prerequisite fundamental background on the unique signal (UQS) concept. The UQS is one of the key constituents of Enhanced Nuclear Detonation Safety (ENDS), as outlined in Section 1 of that report. There have been many documents written over the past quarter of a century describing various aspects of the UQS, but none of these emphasized the mathematical approaches that help explain why the UQS is effective in resisting inadvertent pre-arming, even in abnormal environments and how UQS implementations can be quantitatively assessed. The intent of this report is to describe various pertinent mathematical methodologies (many of which have not been previously reported) without duplicating, any more than necessary, background information available in other reports. Mathematical UQS analysis is needed because of quantitative requirements associated with ENDS, and because limited comparisons of various implementation approaches can be quantified under mathematical modeling assumptions. Some of the mathematics-based results shown in this report are presented to explain: (1) The reasons that the UQS methodology can provide greater protection against accident environments than could combinational techniques (Sections 2.1 through 2.4); (2) The reason that the probability of inadvertently duplicating a UQS comprising n bivalued events cannot be estimated as low as (1/2) inches (Section 2.4); (3) The value of, and the Sandia National Laboratories policy on independent sequential communication of UQS events (Section 3.4); and (4) The care that must be exercised if any signal processing is necessary (Section 4). There are also numerous examples (e.g., in Appendices A and B) of ill-advised deviations from UQS methodology that can seriously degrade safety. These examples help demonstrate that the UQS methodology should not be compromised.