Details are given of a monitor for the continuous determination of deuterium in helium. Excess oxygen is added to the gas stream and the oxygen concentration determined before and after passage of the gas through a deuterium-oxygen recombination unit. Oxygen concentrations are measured with galvanic cells. The accuracy is better and +- 10 percent in the range 200 - 5000 v.p.m. deuterium. operating instructions for the Lucas Heights equipment are given.

This program was prepared as a pilot program for a larger computer and handles symmetrical reactors with core, side reflector and end reflectors, using 10 radial and 10 axial mesh regions. The output consists of the effective multiplication constant, the two flux distributions, and the fission source distribution. The extrapolated Liebmann process is used for the inner iterations.