Field evaluation of ground disposal of reactor effluent: 1301-N crib

The minimum travel time of 79 days observed for /sup 3/H at the point of maximum flow along the riverbank spring-front gives a minimum decay time that can be also applied to other radioisotopes discharged to the crib. Actual travel times of isotopes discharged to the site are dependent on the interaction of the isotopes with the sediments (ion-exchange, chemical, adsorption, etc.). A travel time of 101 days observed for /sup 131/I is an indication of the dependence of actual migration rates on the isotope's interaction with the soil materials. The interaction of most isotopes with sediments is significantly greater than that of iodine. Therefore, most isotopes will have much ionger travel times. Significant quantities of the waste appear to be flowing northeast from the site into the Columbia River below 100-D Area. This would increase the length of flow path and travel times to the river by a factor of 10. Estimates of the distribution of long-lived isotopes at the site are based on laboratory measurements. Field evaluations of the actual distributions of long-lived isotopes are in progress. This study involves drilling and sampling of the sediments in and near the crib. Analyses of radiocontaminants in these samples will provide an even more accurate field-scale evaluation of disposal at the 1301- N crib than has heretofore been made. (auth