Stabilized gas laser oscillators Final report, 24 Jun. 1964 - 21 Jun. 1966

Phase-locking scheme for frequency-stabilized gas laser oscillator

A burnup survey of Pu-Th-BeO fuels and comments on selection of fuel for pebble bed reactors.

The results of a burnup survey for a BeO pebble bed reactor system studied by the Australian Atomic Energy Commission are reported. The survey was based on equilibrium model and carried out by means of the GYMEA complex of codes. A once-through fuel cycle was assumed with plutonium and thorium as the fissile and fertile materials. The selection of a fuel composition is discussed taking into consideration reactivity lifetime, initial power density, and temperature coefficients of reactivity. With a 200 MWe pebble bed reactor design, values of F.I.F.A. (fissions per initial fissile atom) of 1.2 to 1.4 appear to be achievable at an average bulk power density of 11W/cm3

Equilibrium model for calculation of burnup in a recirculating pebble bed reactor.

The general problem of burnup calculations for a pebble bed reactor is discussed An efficient calculational scheme is developed by treating operation at equilibrium with a random distribution of pebbles. Assuming a constant flux level and spectrum, analytical solutions are obtained for time averaged nuclide concentrations. With a specified feed composition average power density, and burnup consistent values of average nuclide concentrations and flux spectrum are derived in an iterative manner, It is shown by physical reasoning and numerical calculation that the assumptions are justified for the large pebble bed reactors based on PuO2 — ThO2 — BeO fuels selected for a reactor feasibility study. The spectrum weighted improved one—group treatment lends itself to efficient coupling of burnup and power plant optimization studies and it may also find application to other reactor systems