Evaluation of the 17 June 1997 Criticality Accident at Arzamas-16

On June 17, 1997, a critically accident occurred at Arzamas-16, which resulted in the death (within three days) of A. N. Zakharov, a Russian scientist with 20 years' experience conducting multiassembly experiments. In this case, the multiplying assembly was a fast metal system consisting of a 235U (90% enriched) core and a copper reflector. According to the Russian press, ''Zakharov misjudged the degree of criticality of the breeding system and committed several gross violations of regulations.'' As we see it, there were three major causes of this accident. First, the experiment was flawed by Zakharov's misreading of the appropriate size of the assembly, which he took from a notebook that described the old experiment he was attempting to repeat. Second, he disregarded the appropriate procedures and safety regulations. Third, these two mistakes were compounded by an improperly set audible alarm system and Zakharov's unsafe use of the table. We also discuss our reconstruction of the accident based on information given by the Russians to US scientists and information culled from Russian newspaper and magazine articles. We also describe our thoughts on the behavior of the assembly following the accident and the radiation dose level Zakharov may have received. These levels match values we have lately obtained from translations of Russian news articles. This accident clearly points out the penalty for weak administrative control of work with multiplying systems. Criticality experimentation requires formality of operation. The experimenter, his peers, and a trained safety person need to document that they understand the experiment and how it will be conducted. Knowing that the experiment was successfully run several decades ago does not justify bypassing a safety evaluation