Several waste-generating processes were conducted at the Hanford Site, including the following:
- Bismuth phosphate production
- Uranium recovery process
- Reduction-oxidation (REDOX)
- Waste fractionation
- Plutonium-uranium extraction (PUREX)
- Processes conducted at the Plutonium Finishing Plant
The primary goal of these processes was to extract and/or process plutonium, or separate other selected radionuclides from the waste (strontium, cesium, cerium, neptunium, and americium, among others). Each of the waste-generating processes had a variety of waste streams.
After initial storage in the tanks, various other operations performed on the waste in the tanks, including removal/recovery of various materials (e.g., uranium, strontium, and cesium); evaporation; solidification; and settling, tank-to-tank waste transfers, and evaporator campaigns have mixed and spread many of these constituents through the single-shell tank (SST) and double-shell tank (DST) farms.
These organic compounds and their degradation products are the primary sources of gases and vapors.
Many additional organic chemicals were used in support work and discharged to the waste tanks. The chemicals undergo a series of thermal, chemical and radiolytic processes that can form volatile and semivolatile organic compounds as shown below.
Decades of experimental and analytical work has been conducted on Hanford tank chemistry at Pacific Northwest National Laboratory, Savannah River National Laboratory, Argonne National Laboratory, Los Alamos National Laboratory, Sandia National Laboratory, and by numerous other national laboratories and universities.
Based upon that process, the relevant chemicals were chosen as important to address as chemicals of potential concern.