On-line dry wood measurement in chips by nuclear means

A system which has been installed and operating for two years in a Norwegian paper mill is described. It consists of a radiometric conveyor belt weighing instrument, a radiometric moisture guage and a data processor. The weighing instrument uses a cesium 137 source located above the conveyor belt with the radiation detector under the belt. The moisture gauge employs an americium-beryllium neutron source and a slow neutron detector, both placed above the belt. The data is processed and the moisture content calculated is continuously displayed. 4 analogue outputs are also available for automatic on-line process control. The results over a period of 20 months are shown, compared with results from laboratory measurements of samples. The two curves follow each other fairly closely. (JIW)