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Since the development of relationships between rod changes and temperature shifts, the temperature distribution of the B Pile has been improved as much as possible by shifting the rods. Certain unbalances have been found which can only be removed by improvement of the poison pattern. At present the maximum imperfection in the B Pile is 5% diagonal quadrupole unbalance. An estimate of the poison pattern needed to correct these imperfections is given herein. This poison pattern has been calculated as an example of application of the principles and is not intended as a recommendation.

None

Shipping cans containing product from plant runs completed in the latter half of April and in May showed, in general, definitely higher levels of radiation than had been observed previously. Likewise, containers for the transfer of the F-10-P solution from the 224 Bldg. to 231 Bldg. (during May) exhibited higher radiation levels than could be attributed to higher power levels and increased batch sizes. These higher radiation levels were indicative that some radioactive element (or elements) was present in an amount greater than previously as would be expected from the shorter cooler periods, or that decontamination of elements previously present was less complete. It was considered essential to identify the source of these radiations and the cause for their presence has been investigated. The radioactive contaminant present in the final product has been identified rather definitely as Np{sup 239} which has 2.3d half-life a 0.25 MeV gamma ray and a weak beta ray. The amount of Np has increases as a result of the brand toward shorter cooling periods and the law decontamination factor for Np in the Separation Process.

This report presents a brief synopsis of an investigation of unusual incidents at the 100-B and 100-F areas at HAPO. (CBS)