Uranium Mill Tailings Remedial Action Program. Radiological Survey of Shiprock Vicinity Property SH08, Shiprock, New Mexico, October-November 1982

摘要

At the time of the survey, one residential structure was located on the property. The lands surrounding the structure were, for the most part, landscaped with lawn cover and other vegetation. The assessment activities included determination of indoor and outdoor surface radiation levels, for both fixed and removable contamination, through direct instrument and smear (indoor only) surveys; measurement of ambient external penetrating radiation levels at 1-meter heights; and analyses of air and soil samples. No evidence of radioactive contamination was found in the residential structure; background levels of radioactivity were indicated throughout. Radiation exposure rates were less than the 20 mu R/h above background limit. Short-term radon daughter measurements did not exceed the 0.02 WL limit for average annual concentration including background. The assessment did indicate elevated levels of radioactivity at a few areas in the outside environs. A general area of elevated radioactivity was found at the west edge of the property, paralleling the roadway and encompassing an area of about 70 ft exp 2 ; and another general area of contamination was found in the backyard, encompassing about 960 ft exp 2 , and extending into the alleyway, encompassing a general area of about 1100 ft exp 2 there. Radiochemical analyses of the soil sample collected from the general area in the backyard indicated a radium concentration of 6.7 +- 0.7 pCi/g, which cannot be confidently interpreted to be below the limit of 5 pCi/g above background, averaged over the first 15 cm of soil below the surface. However, analyses of surface soil samples collected at the alleyway from nearby vicinity property sites indicated radium concentrations in excess of those limits. Subsurface soil sampling was not conducted, and thus the vertical extent of the radiological contamination is not known. Remedial action for this vicinity site should be considered. (ERA citation 09:042998)