Evaluation of Proposed New LLW Disposal Activity Disposal of No Dose/Low Dose Scrap Metal in Slit Trenches

摘要

Activated metal is a special waste that requires evaluation for disposal. Contaminants in the activated metal will leach more slowly than will contaminants in generic waste. There is an inventory of activated scrap metal in the 105-L Disassembly Basin. Approximately 1,600 ft3 of the material is characterized as ''No Dose/Low Dose'' and consists mainly of activated aluminum and aluminum alloy pieces and parts and no stainless steel with a dose rate less than 200 mR per hr. Contaminants in the activated metal will leach more slowly than will contaminants in generic waste. The change in the leach rate will affect analyses for the groundwater pathway and intruder scenarios. For this evaluation, the slower leach rate from the activated metal waste will be neglected for the groundwater pathway, which is conservative because the higher leach rate used tends to produce higher groundwater concentrations and lower inventory limits. For this evaluation, the leach rate was set to zero for intruder scenarios, which is conservative for the inadvertent intruder because a slower leach rate will result in higher levels of radionuclides in the waste zone. The evaluation concludes that the existing limits are applicable to the disposal of No Dose/Low Dose activated scrap metal in slit trenches so that a Special Analysis is not needed to dispose of this waste stream.