Composite analysis for low-level waste disposal in the 200 area plateau of the Hanford Site

Abstract

This report presents the f i r s t iteration of the Composite Analysis for Low-Level Wmte Disposal in the 200 Area Plateau of the Hmford Site (Composite Analysis) prepared in response to the U.S. Department of Energy Implementation Plan for the Defense Nuclear Facility Safety Board Recommendation 94-2. The Composite Analysis is a companion document to published analyses of four active or planned lowlevel waste disposal actions: the solid waste burial grounds in the 200 West Area, the solid waste burial grounds in the 200 East Area, the Environmental Restoration Disposal Facility, and the disposal facilities for immobilized lowractivity waste. A single Composite Analysis was prepared for the W o r d Site considering only sources on the 200 Area Plateau. The performance objectives prescribed in U.S. Department of Energy guidance for the Composite Analysis were 100 mrem in a year and examination of a lower dose (30 mrem in a year) to ensure the "as low as reasonably achievableyy concept is followed. The 100 mrem in a year limit was the maximum allowable all-pathways dose for 1000 years following Hanford Site closure, which is assumed to occur in 2050. These performance objectives apply to an accessible environment defined as the area between a buffer zone surrounding an exclusive waste management area on the 200 Area Plateau, and the Columbia River.Estimating doses to hypothetical future members of the public for the Composite Analysis was a multistep process involving the estimation or simulation of inventories; waste release to the environment; migration through the vadose zone, groundwater, and atmospheric pathways; and exposure and dose. Doses were estimated for scenarios based on agriculture, residential, industrial, and recreational land use.The radionuclides included in the vadose zone and groundwater pathway analyses of future releases were carbon-14, chlorine-36, selenium-79, technetium-99, iodine-129, and uranium isotopes. In addition, tritium and strontium-90 were included because they exist in groundwater plumes. Radionuclides considered in the atmospheric pathway included tritium and carbon-14.Most of the radionuclide inventory in past-practice liquid discharge and solid waste burial sites on the 200 Area Plateau was projected to be released in the f i r s t several hundred years following H d o r d Site closure and a significant fraction of the inventory was projected to be released prior to closure. The maximum predicted agricultural dose outside the buffer zone was less than 6 mrem in a year in 2050 and declined thereafter. The maximum doses estimated for the residential, industrial, and recreational scenarios, were 2.2,0.7, and 0.04 mrem in a year, respectively, and also declined after 2050. The radiological doses for all of the exposure scenarios outside the buffer zone were well below the performance . objectives.. Significant uncertainties exist in the f i r s t iteration Composite Analysis, with the largest uncertainty associated with the inventories of key mobile radionuclides. Other sources of...

Performance Assessment Monitoring Plan for the Hanford Site Low Level Waste Burial Grounds

“…An advance notice of one quarter is needed to initiate new sampling. This appendix documents computation of the relative hazard index for each mobile constituent identified in the performance assessment Wood 1996 and and the composite analysis (Kincaid et al 1998 …”

“…Site-specific performance assessments , Wood 1996) and the composite analysis (Kincaid et al 1998) were conducted for the 200 East Area and 200 West Area Low-Level Burial Grounds. Long-term monitoring of the performance ofthe disposal facility is a practical way to verify assumptions, reduce uncertainties, and build confidence in the results and conclusions of the performance assessment and composite analysis.…”

“…As identified in the performance assessment , Wood 1996) and composite analysis (Kincaid et al 1998), groundwater is considered to be the most significant long-term exposure pathway (Table 1. I ) and, therefore, is the primary focus of this supplemental plan.…”

Hanford Site National Environmental Policy Act (NEPA) Characterization Report, Revision 17

“…Several compilations of vadose zone contamination have been formulated through the past years. DOE (1997b), Kincaid et al (1998Kincaid et al ( , 2001, and Simpson et al (2001) contain the most recent inventories of contaminants disposed to past-practice liquid disposal facilities in the 200 Areas. Dorian and Richards (1978) list contaminant inventories disposed to most 100 Area past-practice facilities.…”

Single-shell tank retrieval program mission analysis report

“…Several SSTs contain waste types associated with unacceptably high temperatures, organic concentrations, and potentials for generating flammable gases. The tanks are equipped with real time monitoring for potentially hazardous conditions (Kincaid et al 1998).…”