"The composition of the solder for the solder plug has been set as the tin-silver eutectic. Final tests on this solder show that life expectancies much longer than 6 months are probable with the current design. The design of the heater tube to contain the solder plug has been settled. This consists of a copper tube impregnated with U235O2. Arrangements have been made to have test specimens fabricated by powder metallurgy techniques. The equipment for the MTR in-pile test of trigger element response times has been largely completed and tested. The design of the complete inner capsule for the BF3 safety element has been developed as well as the cladding technique. Mock-up elements have been tested in the Hanford test reactor to determine the control that may be obtained with elements of this type, although the analysis of the results has not been made. Prototype elements are also ready for testing in the test pile, except for loading with B10F3. Experiments have been designed and submitted for approval for production pile tests of prototype."