A cold neutron source for the DHRUVA reactor: optimization calculations

Abstract

It is possible to obtain an increase in the flux of cold neutrons emerging from a nuclear reactor by remoderating the neutrons in a cold moderator. This paper evaluates the optimum height for a cylindrical liquid methane moderator (110 K) for the flux conditions in the DHRUVA reactor. Remoderated spectra emerging from cylindrical liquid methane moderator are calculated using a Monte Carlo technique for the height of the cylinder varying from 5 to 25 mm. The gain in flux quickly builds up with increase in height and nearly saturates beyond 20 mm. The effective temperature of the emerging spectrum is about 130 K. This calculation has been used to decide upon the height of the cylindrical cold source. It is possible to obtain an increase in the flux of cold neutrons emerging from a nuclear reactor by remoderating the neutrons in a cold moderator. This paper evaluates the optimum height for a cylindrical liquid methane moderator (110 K) for the flux conditions in the DHRUVA reactor. Remoderated spectra emerging from cylindrical liquid methane moderator are calculated using a Monte Carlo technique for the height of the cylinder varying from 5 to 25 mm. The gain in flux quickly builds up with increase in height and nearly saturates beyond 20 mm. The effective temperature of the emerging spectrum is about 130 K. This calculation has been used to decide upon the height of the cylindrical cold source.