Even the reactor's spent fuel, which was stored in a cooling pond, posed a danger, because such material can be refined into bomb ingredients.

One would require manufacturers to mark bomb ingredients so they could be traced in detonated explosives.

A month later he made two purchases of diesel fuel, another bomb ingredient, Federal officials say.

The main bomb ingredient to be produced at the new reactor is tritium, a radioactive gas that increases the explosive power of nuclear bombs.

The imminence of the papal visit explains why the Philippine police were so concerned about finding bomb ingredients in the apartment.

In February, he rightly called for tighter controls over nuclear fuel processing, used by several countries to produce bomb ingredients.

But it, too, has the money to buy bomb ingredients or scientific expertise.

In Britain, nine other people were arrested and 1,320 pounds of ammonium nitrate fertilizer, a potential bomb ingredient, was seized.

A byproduct is spent fuel with plutonium and other highly radioactive products, which can be processed to make bomb ingredients.

That approach began in the early 1990's when Pyongyang appeared ready to reprocess nuclear reactor fuel into bomb ingredients.