The neutron spectrum will be only partly moderated, perhaps to the point of being a fast neutron reactor.

A fast neutron spectrum has three main advantages:

For low enriched uranium fuel working on a thermal neutron spectrum, the difference between the average and effective delayed neutron fractions can reach 50 pcm.

This is because today's reactors use the mined uranium-plutonium cycle in a moderated neutron spectrum.

Also a harder neutron spectrum helps to achieve acceptable breeding without protactinium isolation.

With an startup fissile charge of only 1.5 tonnes, made possible through the soft neutron spectrum this makes $150 million.

Breeding in a thermal neutron spectrum is slow and requires extensive reprocessing.

Moreover he knew that Harwell were looking for the crucial neutron spectrum which, surely, would clinch everything.

Material science - fusion reactor material radiation damage study with a neutron spectrum similar to d-t fusion, of small components.

Bonner sphere spectrocopy (BSS) is one of the few methods that provide an accurate measure of the neutron spectrum.