40K emission in energy production from straw

Straw has the highest concentration of the natural radioisotope⁴⁰K in comparison with other biofuels and as peat, wood, wood chips, and energy forest, Concentration of⁴⁰K have been measured in the ash remaining after wheast straw was burnt in a water heating plant. Samples wre also taken of the wheat ears, straw, and surrounding earth. The highest concentration of⁴⁰K found in the bottom ash was 6000 Bq/kg which is about twenty times higher than the activity concentration of⁴⁰K in the straw and about ten times higher than the natural⁴⁰K activity in the ground. Calculations of the maximum ground levels air concentration of⁴⁰K using the Gaussian plume model give a value of a few hundred Bq/m³. This value is found at a distance of only 100 m from the plant because of the short stack height.