Can you build a nuclear weapon WITHOUT high explosives?

[rowrrbazzle]

I remember reading the article described here:

@Zenster

Many years ago, Analog science fiction magazine detailed how to build a crude atomic bomb. The method involved depositing one subcritical mass at the bottom of a small diameter well shaft below your (not-so) safe house’s floor and then using an explosive charge to accelerate the other subcritical half into the former in order to precipitate the chain reaction.

As with any accurate article on this topic it was noted that obtaining the fissile material was by far the most difficult aspect of the task. The most ready source of the uranium would come from hijacking a truckload of unrefined reactor fuel. This immediately posed the extremely complex problem of refining said fuel into metallic form.