Surface contamination measuring instrument

When radioactive materials having a worry of being deposited on the surface of an object are sampled to detect the dose rate, volatile liquid is blown, in the form of spray, to contaminates on the surface of the object to be tested while moving the nozzle. This can wash out the contaminates together with the liquid. Liquid washed and flown down is collected to a tray placed beneath the object. The dose rate of the contaminates in the recovered liquid is measured by a radiation detector. With such procedures, the contaminates can be washed by the blowing not leaving unevennesses. Further, since the contaminates are removed satisfactorily, contamination does not remain on the surface to be tested, and contamination does not spread to other articles or circumstance. (T.M.)