Dissolution of the large number of samples obtained from the natural uranium blanket of the Experimental Breeder Reactor after approximately 485,000 kw.-hr. of operation has been completed, and analysis of these samples for uranium consumed and plutonium formed is well along. An attempt is being made to distinguish quantitatively between uranium-238 and uranium-235 fission in the blanket area by determining the ratio of ruthenium-106 to cesium-137 in the fission products.

A method is described for preparing plaster of Paris replicas of irradiated fuel slugs. An impression mold is made by pouring the plaster about a fuel slug held in a specially designed holder. The slug is removed from the holder and the impression mold issued to cast a replica, also made of plaster of Paris. The replicas, including one end only, are accurate reproduction of the original slug for surface features down to about one-half mil and for dimensions within one or two mills. Two dental impression plasters were found to give satisfactory results. With the limits mentioned, the process will serve the purpose of preserving models of radioactive specimens for use as "museum pieces." However, the procedures are very exacting in achieving such results.

In this report it reviews a possible declassification of the content of report CP-2782 (February 15, 1945) that presents the data of the most careful measurements of the thermal neutron cross section of 9.2h Xe135 and re-evaluation of the particular methods of measuring neutron flux employed in this experiment had been made for other purposes.