Hanford Watch

Computer model of present and future
Hanford groundwater radioactive exposure

Lynn Porter, July 2003

This is a PowerPoint presentation from the Dept. of Energy, a projection into the future of radiation exposure at Hanford due to drinking the groundwater. A copy was emailed to us by a technical expert who does not work for DOE.

The expert said this is a bad computer model and a "gross simplification of reality" -- e.g., movement of radioactive waste through the soil. The model does not analyze movement through the soil of radionuclides which DOE believes won't move, e.g., plutonium.

He said DOE averaged radically different results of several runs of the program, and then tweaked the model to get the radiation exposure results they wanted. Even so, by 2700 their model predicts that the risk from drinking the groundwater would exceed the legal limit by 16 times.

This model is part of the risk assessment for the Solid Waste Environmental Impact Statement, so it is significant for evaluating that EIS. Hanford's solid waste, much of it in barrels buried in trenches, is one source of groundwater contamination. If the model is invalid, then so is the Solid Waste EIS risk assessment. The Solid Waste EIS governs all Hanford solid radioactive waste which is not tank waste or spent reactor fuel.

DOE, the expert tells us, is arguing that it can use groundwater as a buffer to absorb radioactive pollution, and then just not let people use the groundwater. A hard rule to enforce far into the future.

He said that the whole idea of "acceptable risk," which the Solid Waste EIS is based on, is meaningless -- "don't go there." The main point of the EIS should be to specify how solid waste would be processed and what form it should be put in to keep it out of the environment. The EIS does not do this.

The EIS depends on the soil between the surface and the groundwater -- sometimes called the vadose zone -- to keep radioactive materials out of the groundwater.

Below are some more of his comments about the computer model:

Per your request - here is the PowerPoint slide presentation of the averaged results of the first 25 runs of the Systems Assessment Capability (SAC).

The project staff discovered an error in the data used for these runs, after the runs were completed. Apparently, they included a large amount of Technetium-99 as being disposed in the 200 West area - that isn't there. This created an error. It is my understanding from Bob Bryce that though this is a large error, it does not dominate the model results. Also, I should note that with DOE's new proposals to leave the Technetium in the low-activity high-level waste disposed at Hanford, that DOE is proposing to dispose of this material at Hanford. As a result, the Technetium would still release. It would however release from a location east of where the first 25 runs had it. And it might occur somewhat farther in the future.

It is interesting and informative to compare the predictions from these first 25 runs with the later predictions in the [Solid Waste] EIS. There was no new data developed to make significant changes between these runs. As a result, the differences show the large uncertainty inherent in the modeling. It also calls into question whether the EIS is a conservative prediction of the potential impacts. Or, conversely -- is it a hopeful prediction of the lack of impact.

The Web slide show, is here. If you have a slow Internet connection you will have to be patient. Each slide takes a while to download.

You might prefer to download and run the PowerPoint file -- 761KB. It will run in your Web browser.