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July 25, 2008

Very high temperature gas-cooled reactor could burn 65% of uranium

The US Department of Energy (DoE) is planning to build a very high temperature gas-cooled reactor (VHTR) at Idaho National Laboratory, with the prime objective of supplying heat at about 900°C. This heat could be used to generate electricity, or for other industrial processes such as hydrogen production or water desalination at a neighbouring facility.

The current timeline to have the first VHTR completed is 2021 assuming it the NGNP was fully funded from now until 2021.

Dan Yurman indicates that the NGNP had been getting $30 million per year sincc 2005 which is 1/3 the needed level and then in Dec 2007 had gotten $100 million which will help to get some more work done but still have the project slightly behind the 2021 schedule.

The vision for Idaho National Labs for the VHTR is similar to the vision of the Uranium Hydride reactor by Hyperion Power Generation and the Chinese 200 MW HTR-PB.

If NextGen is successful, between 15 and 20 years from now North Americans will build dozens - maybe hundreds - of comparatively small, high-temperature gas-cooled reactors to breathe heat into refineries and chemical plants, especially plants to make hydrogen. Right now on-site industrial heating plants are fueled with gas, coal or oil and most nuclear power today is generated from big light-water reactors to meet base-load electrical demand.

Light-water reactors that operate today drive turbines by attaining temperatures of 300 degrees C or so but high-temperature, gas-cooled reactors can reach 900 degrees C or higher. That means such reactors can provide more than enough heat to refine crude oil or to separate bitumen from shale or sand in the Western United States and Canada - all of which helps extend domestic energy supplies.

Even more hope is needed when you consider the project's main industrial goal, hydrogen production, which requires temperatures of 800 degrees C.

If all this is to happen in a by 2021, engineers and scientists must perfect heat-resistant materials and other aspects of the design while private companies must risk billions beyond the federal tax dollars on the $3 billion to $4 billion project.


Research commissioned this week by the DoE would see two teams of scientists examine the potential of a VHTR such as NGNP for 'deep-burn' of nuclear fuel. 'Deep-burn' refers to the VHTRs ability to burn up to 65% of its inital fuel, compared to burn-up levels of around 5% in conventional light-water reactors. Instead of 95% of the uranium going into what would be nuclear waste. This reactor would only have 35% become nuclear waste.


This deep burn capability would not be as good as a molten salt nuclear reactor. A Molten salt reactor can burn 99% of initial fuel. Clearly the 65% deep burn would be an improvement of 13 times over existing reactors. The higher temperature of the reactor would all 60% of the heat to be converted to electricity instead of 33% for current reactors.

The concept of deep burn relates to the US-led Global Nuclear Energy Partnership, in which advanced reactors would destroy similar wastes produced by mainstream light-water reactors of the kinds widely used today. It is projected that volumes of high-level waste could be reduced by a factor of 50, while extra electricity is generated. The reactor envisaged for GNEP, however, would be a sodium-cooled model.

The VHTR would have about one third the volume of high level waste.

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