Improvements in or relating to coal ash monitors

An improved monitoring system is described for determining the ash content of coal in wagons. Each wagon passes a neutron source and subsequently the intensities of the γ-rays, emitted by the isotopes produced by neutron reactions on the ash-forming elements in the coal, are detected and measured. Interlocks are used to ensure that the neutron source is only operated when a loaded wagon is in the appropriate position. (U.K.)