Nestled atop the Simi Hills, thirty miles from downtown Los Angeles, an experimental nuclear reactor experienced a major accident in July 1959. Thirty percent of the reactor core was damaged. Between five and ten thousand curies of radioactive fission products escaped the fuel elements in the core.¹ But the trajectory of those radioactive products remains a matter of controversy. Did these products decay safely inside the reactor, or did a significant amount of that radiation reach the surrounding environment? Aside from the small number of people involved with the Sodium Reactor Experiment (SRE) at the Santa Susana Field Laboratory (SSFL),