Several incinerator facilities within federal laboratories or private sites have been designed for incinerating waste that might contain harmful chemicals. One particular incinerator in a federal facility has been designed for burning mixed waste, waste that contains low level radioactivity and RCRA (Resource Conservation and Recovery Act) metals. The particular elements that are of concern are Cl, Hg, Pb, Cr, Cd, As, and Be . For homogeneous waste, and for an incinerating rate well below the designed capability of the facility, sampling and subsequent laboratory analysis were found to be adequate for the control of RCRA metals and Cl emissions. As the amount of the incineration material increased and the facility started accepting inhomogeneous waste, sampling techniques were found to be inadequate.

In the quest for a method that would produce more reliable results, we studied the possibility of installing a Non-Destructive Assay (NDA) method that could determine the elements of interest with Minimum Detection Limits (MDL) in the range of a few tens of ppm. A technique that has been found to produce very promising results for the detection of the above elements is fast neutron activation. A waste container was irradiated for a time period that varied between a few minutes to 2 hours depending on the element. The container was then removed and the residual radioactivity was measured. For several of the above elements, MDL’s have been established comparable to the requested MDL’s.

• Figure 1. The shielded box for the measurement of residual radioactivity.

• Figure 2. The contents of a typical waste box, containing contaminated clothing articles.