Hanford's production of plutonium 239 could be divided into two basic steps:

-- Using a reactor to create plutonium from uranium.

-- Chemically extracting plutonium from the irradiated uranium.

The process began in Hanford's 300 Area, where uranium imported from the Belgian Congo (now Zaire) was used to build special fuel rods. The rods consisted of naturally occurring uranium (U-238), and 0.8 percent U-235, another uranium isotope.

When the fuel rods were arranged in a certain pattern in a reactor, fission occurred. The U-235 released neutrons, which collided with other U-235 neutrons, releasing more neutrons in a chain reaction.

Graphite in the reactor core slowed the neutrons so they could be absorbed by the U-238.

Then the U-238 became U-239, which decayed and transmuted into plutonium 239, scattered in tiny bits within the uranium. Each metric ton of uranium removed from the reactor contained about 250 grams of plutonium, plus other impurities.

At T Plant, the uranium was dissolved and chemicals were added to bind with the plutonium. A centrifuge separated the plutonium-carrying particles from the solution.

The process was repeated several times, using different chemicals to dissolve the plutonium compound and a centrifuge to separate the nonplutonium substances from the solution.

Finally, a pure plutonium solution was left that looked like partly set jello.