the Power Reactor Development Company, or PRDC. During a series of meetings with the AEC's Safeguards Committee in March, PRDC presented its work to date, but much of it remained preliminary. As to the topic of the Doppler coefficient, Argonne National Laboratory, who ran EPR-I, presented on data from the accident including the issue with fuel rod drooping. Wayne Jens of PRDC presented three major accident scenarios he had been studying, including the possibility that the sodium coolant might boil off which could result in an explosion with the force of TNT equivalent. The other two were meltdown scenarios, but the numbers for these were too preliminary. Henry Gomberg, of the University of Michigan, presented his work on potential radiation leak events, but again the results were tentative. Although the work was ongoing, Cisler stated his confidence that they would all be completed by the time they applied for an operational license some years in the future. Another meeting and final review of the data was then arranged under the direction of Rogers McCullough of Monsanto on 2 June 1956 at the Chicago offices of Argonne. His review letter summarizing the meeting stated that "Even though there are no facts or calculations available to the Committee that clearly indicate the proposed reactor is not safe for this site, the Committee believes there is insufficient information available at this time to give assurance that the PRDC reactor can be operated at this site without a public hazard." Of particular concern was understanding exactly what happened in EPR and "a clear demonstration must be given that a coefficient of this magnitude cannot exist in the PRDC design." This could only be solved by further experimentation, and the group felt that the currently planned tests would simply not provide enough information in time for the proposed opening in 1959 or 1960. They suggested building a smaller reactor specifically to test the effects of temperature swings, and another to test whether the proposed containment building concepts could actually stop an explosion of the magnitude being presented by Jens. While additional information would be forthcoming from existing planned experiments, it would not be in time to influence the design before construction was completed, and existing experience on the smaller reactors "is not wholly reassuring." They recommended that the EBR-II program move ahead as rapidly as possible and be built as a true prototype of the