Atomic Goal: 800 Years of Power From Waste

The quest is for a new kind of nuclear reactor that would be fueled by today’s nuclear waste

In a drab one-story building here, set between an indoor tennis club and a home appliance showroom, dozens of engineers, physicists and nuclear experts are chasing a radical dream of Bill Gates.

The quest is for a new kind of nuclear reactor that would be fueled by today’s nuclear waste, supply all the electricity in the United States for the next 800 years and, possibly, cut the risk of nuclear weapons proliferation around the world.

The people developing the reactor work for a start-up, TerraPower, led by Mr. Gates and a fellow Microsoft billionaire, Nathan Myhrvold. So far, it has raised tens of millions of dollars for the project, but building a prototype reactor could cost $5 billion — a reason Mr. Gates is looking for a home for the demonstration plant in rich and energy-hungry China.

(Mr. Gates, of course, has plenty of money of his own. This year Forbes listed him as the world’s second-richest person, with a net worth of $67 billion.)

“The hope is that we’ll find a country, with China being the most likely, that would be able to build the demo plant,” Mr. Gates said last year in a conversation with the energy expert Daniel Yergin. “If that happens, then the economics of this are quite a bit better than the plants we have today.”

Perhaps one of the most intriguing arguments supporters make about Mr. Gates’s reactor is that it could eliminate several routes to weapons proliferation. Iran, for example, says its nuclear program is for peaceful purposes, but it is enriching far more uranium than it needs for power generation. The United States has long said that Iran’s enrichment could lead to a nuclear bomb.

Today’s nuclear reactors run on concentrations of 3 to 5 percent uranium 235, an enriched fuel that leaves behind a pure, mostly natural waste, uranium 238. (A uranium bomb runs on more than 90 percent uranium 235.) In today’s reactors, some uranium 238 is converted to plutonium that is used as a small, supplemental fuel, but most of the plutonium is left behind as waste.

In contrast, the TerraPower reactor makes more plutonium from the uranium 238 for use as fuel, and so would run almost entirely on uranium 238. It would need only a small amount of uranium 235, which would function like lighter fluid getting a charcoal barbecue started.

The result, TerraPower’s supporters hope, is that countries would not need to enrich uranium in the quantities they do now, undercutting arguments that they have to have vast stores on hand for a civilian program. TerraPower’s concept would also blunt the logic behind a second route to a bomb: recovering plutonium from spent reactor fuel, which is how most nuclear weapons are built. Since so much uranium 238 is available, there would be no reason to use that plutonium, TerraPower says.

Countries that do not have nuclear weapons will still need lots of electricity, said John Gilleland, chief executive of TerraPower, and “we would like to see them build something that allows us to sleep at night.”

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