THE RADIOLOGICAL ASSESSMENT AND RECOVERY OF CONTAMINATED AREAS

The Civil Effects Test Operation Exercise CEX-57.1 following Operation Plumbbob was carried out to obtain information on decontamination procedures that could be used as radiological countermeasures. The test was conducted on D + 1 and D + 2 days after shot Coulomb C. Data were obtained on reclamation of land areas by scraping with a motorgrader, on fire-hosing and scrubbing a concrete- slab roof, and on fire-hosing a composition roof. In addition, some shielding data were obtained for a small building with 6-in.-thick concrete walls and roof. The conceptual nature of a radiological defense system and the role of decontamination or reclamation in such a system are discussed. Most of the report deals with methods for reducing the observed data to interpretive form because the data were taken within a large contaminated area. The decontamination effectiveness in terms of the fraction of contamination remaining was computed. It is concluded that low levels of contamination at the Nevada Test Site could be utilized to advantage to obtain data on gamma -radiation properties, such as the effects of materials and source geometries on the attenuation of fission-product gamma rays. However, higher levels of fall-out in terms of the fall-out particle mass, are required to obtain useful information and training on decontamination techniques; therefore the use of low levels of contamination to conduct studies in this area is not recommended. (auth