The following document describes the usage of the LRL 9-ZOOM code, a neutron diffusion theory reactor code for the IBM 709. The code has been modified to solve configuration of a series of stacked cylindrical disks, designating a new geometry case.

This semiannual progress report and future reports will be published as two documents to permit a wider distribution of the unclassified material. The report numbers are assigned in sequence so that the two reports will fall together when filed by report number.

The Plutonium Recycle Test Reactor is heavy water moderated with a heavy or light water reflector contained by a complex aluminum vessel called a Calandria. ( See Figure 1). Construction of this vessel started in August, 1958, at a large West Coast vendor's plant and was completed at Hanford in December, 1959. The fabrication problems associated with a high integrity welded aluminum vessel were generally unrealized prior to this period. This report covers the fabrication of the Calandria and lists recommendations for improving the design and reducing the cost.

Applications of sheathed (metal) thermocouples may require in many instances, the insertion of the thermocouple thermal junction into an area that must be hermetically sealed to the outside. This same area usually contains highly reactive heat transfer medium such as an eutectic alloy of sodium and potassium of sodium alone. When fissionable materials are being irradiated, fission products that are driven off would also be present and must be contained under varying temperatures and pressures.