- The Washington Times - Wednesday, September 4, 2002

The objective of the World Summit on Sustainable Development just held in South Africa was to find ways "to meet the needs of the present without compromising the ability of future generations to meet their own needs." Alas, some conferees seemed more concerned about future generations than ours.

Take energy, for example. The conferees assume the world's supply of fossil fuels will soon be exhausted. So, they want us to shift to inexhaustible sources of energy. The greens even demand that 15 percent of the world's total energy production be produced by renewable energy sources by 2010.

Now, "renewable" is not synonymous with "inexhaustible." Cow dung may be in some sense "renewable," but hardly inexhaustible. In any case, cow dung, when burned, produces carbon dioxide, which, according to the greens, causes global warming. That would compromise future generations, so burning anything with carbon in it is out.

What about nuclear power? Once we have got "breeder" reactors on line, our supplies of uranium and thorium will be practically inexhaustible. Furthermore, nuclear power plants don't emit any cow dung gases.

So, why didn't the Sustainable Development conferees fall in love with one of the world's most promising nuclear power developments South Africa's Pebble Bed Modular Reactor (PBMR)?

The PBMR technology was developed and successfully prototyped in Europe and was licensed in 1996 to the South African utility Eskom. The PBMR consortium was formed to construct beginning this year a commercial 120 MW demonstration plant in South Africa. The consortium intends to manufacture PBMRs for export.

The South Africans estimate that manufacturing and exporting just 10 PBMRs a year would create 57,000 jobs and add nearly $700 million to South Africa's gross domestic product. South Africa alone will need about 200 of them just to meet domestic electricity needs in 2025.

Until April of this year, Exelon a U.S. utility that owns 17 nuclear power plants was a member of the PBMR consortium. Exelon had intended to submit a license application to the U.S. Nuclear Regulatory Commission this year for the sequential construction of ten PBMRs. Once approved by the NRC, Exelon hoped to have the first module constructed in only 20 months. It would take eight to 10 years to construct a conventional 1,200 MW nuclear power plant.

The PBMR gets its name from the fuel. Uranium, plutonium or thorium-sintered microspheres are coated with pyrolytic carbon and silicon carbide. Thousands of these microspheres are then incorporated into billiard-ball-sized pebbles, which are similarly coated. Gaseous or metallic fission products are prevented from escaping, even at 1,650 Celsius, far above the temperatures obtainable in the reactor core itself.

The PBMR reactor core is a cylinder filled with hundreds of thousands of these billiard balls. A small fraction of the billiard balls in this bed are continually withdrawn from the bottom of the cylinder and nondestructively tested for burn-up. If there remains unburned fissionable material in a pebble, it is then dumped back into the top.

The PBMR can run its entire 40-50 year life on one load of pebbles, and does not have to be periodically shut down for refueling.

The reactor uses helium gas which cannot become radioactive as a coolant to keep the operating temperature at about 950 degrees centigrade. Then the 950-degree helium which is also chemically inert is fed directly into a high-pressure gas turbine to generate electricity. The thermal efficiency for the high-temperature gas-cooled PBMR is very high, about 45 percent.

So why did Exelon pull out of such a promising venture? Well, earlier this year Rep. Henry Waxman ranking Democrat on the House Government Reform Committee found a favorable reference to the PBMR in the Bush-Cheney energy plan. Mr. Waxman charged it was there because Exelon had made contributions to the Bush-Cheney campaign. Within a matter of days, Exelon notified the PBMR consortium that it was withdrawing.

So, what is Exelon going to do, now? Shift to renewable sources of energy? No cow dung, of course, but lots of windmills?

And what will happen to the PBMR consortium? Well, the Russians, who have got a lot of weapons-useable plutonium to get rid of, have shown interest in the PBMR for that purpose. Furthermore, they already have a factory producing barge-mounted nuclear power plants. The Russian KLT-40 reactors, designed to power ice-breakers, use fairly highly enriched (60 percent U-235) uranium.

From the standpoint of meeting this generation's energy needs while preventing nukes from getting loose it would be a good thing if PBMRs could be mounted on those barges.


Gordon Prather has served as a nuclear physicist at Sandia National Laboratory, as a national security adviser to Sen. Henry Bellmon, and as a Reagan appointee in the Pentagon.


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