THE AIRCRAFT NUCLEAR PROPULSION PROGRAM AND GENERAL REACTOR TECHNOLOGY QUARTERLY PROGRESS REPORT for Period Ending November 30, 1949 (ORNL-0528)
A. M. Weinberg, Program Director Report
Edited by C.B. Ellis
November 30, 1949
Reactor Design. Exploratory studies are underway on some possible new cycles not previously considered for aircraft reactors. New mathematical methods are also being investigated for analysis of reactor cores having intricate internal geometry.
Shielding. Possible designs are being studied for a new testing facility to measure attenuations up to lo*. This should probably be in some ‘form of a critical assembly which wi l l operate at power levels up to 10 kw.
On the lid tank, bulk shielding measurements of iron and water are now underway.* It is hoped to begin two-shift operation shortly.
Theoretical analysis is in progress on (a) thick shields composed of a mixture of pure scatterers; (b) neutron penetration of a water shield, using Monte Carlo techniques, and (c) neutron streaming in ducted geometries.**
A new instrument for measuring fast neutron flux is being developed. This consists of a thin Pd film fired on a ceramic core. The proton recoils from the neutrons bombard the Pdinsuch a way as to change the electrical resistance of the film.
The NEPA neutron spectrometer, based on counting proton recoils from a radiator, is now installed a t ORNL and is being calibrated.*
In the work on shielding materials, combinations of Pb, H2O, and B or B4C are being studied, and irradiation tests on Boral have been made. The tensile strength of the latter appears to increase under irradiation. Also, a new plastic has been developed which contains 50% boron by volume. It may be made into strong, flexible sheets, mechanically similar to leather, which can be easily glued onto metal surfaces for thermal neutron shielding. Work on improved concretes for shielding also continues.
Heat Transfer. The summary of atomic energy heat transfer work, ORNL 156, has been broughtupto date and abridged for declassification. A new empirical relation has been developed for heat transfer in annuli which will hold for all cases where the liquid wets the walls-including liquid metals. It has phenomenon of “polarized turbulence”‘ does not exist. The thermal conductivity and heat capacity of molten NaOH have been measured a t 900” F.
Equipment is being designed for work onhandling methods and heat transfer A properties for liquid metals at aircraft reactor temperatures.