Nuclear Science Assuring Environmental Quality*

A former in situ leach (ISL) uranium mine facility in Texas ceased operations well before the new

millennium. However, decommissioning activities were not completed by the licensee.

Consequently, a legal proceeding was authorized between state and licensee representatives. In

the meantime, state funds were used to hire an independent contractor to perform radiological

surveys and assess the magnitude of residual radioactivity across the terrain of the site. The

purpose of this study was to apply advanced statistical methods to the survey data measured by

contractors at the old ISL site and precisely predict the locations of radioactive hotspots. To

accomplish this, methods beyond simple linear regression were employed to estimate areas of

excessive radiation levels. The descriptive statistics methods included geographical mapping of

targeted areas at the site coupled with summary statistical output. Inferentially, spatial analytical

techniques were employed to pinpoint the locations of elevated radiation levels above regulatory

limits. Our results suggests that some sections of the terrain will require additional remediation

activities along with continued surveying and monitoring efforts by state staff experts. This study

will impact the potential release of the former ISL uranium mine site for unrestricted use to

proprietors and scientifically validate the regulatory decision-making process.