Advanced Remote Decontamination Techniques Reduce Costs and Radiation Doses

Abstract

A highly contaminated cell in the Pacific Northwest Laboratory’s (PNL) 324 Building Radiochemical Engineering Facilities was recently decontaminated using a series of remote and contact techniques. The approach used in decontaminating the cell was very successful: It resulted in an 87% lower radiation dose to workers and a cost saving of 39% compared with a hands-on procedure used in another cell 2 yr earlier.Eight cycles of remote decontamination, combining use of an alkaline cleaner foam spray and pressurized water rinse, preceded manned entry. Initial radiation readings in cell C, averaging 50 rad/h, were first reduced to <200 mrad/h using remote techniques. Contact decontamination was then permissible using ultrahigh-pressure water at 270 MPa, further reducing the average radiation level in the cell to <86 mrem/h. The radiation dose and the costs to achieve a 244-fold reduction in radiation contamination were 17.8 mrem/m2 and $1033/m2 of cell surface area.This work is part of a larger effort sponsored by the U.S. Department of Energy’s Surplus Facilities Management Program to clean out six radioactive cells and to dismantle PNL’s pilot-scale radioactive liquidfed ceramic melter. In this program, numerous other advanced techniques are being developed and are proving valuable, particularly in lowering radiation doses.