Neutrons are a pain to control as a beam because they have no charge, so methods employing electric or magnetic optics are not applicable. Typical pocket source

Neutrons are a pain to control as a beam because they have no charge, so methods employing electric or magnetic optics are not applicable. Typical pocket sources use the alpha(9Be,12C)n reaction to produce neutrons; if you have a reactor handy, you can moderate (slow) the neutrons produced and use them... this would be by far the most economical option. As a nuclear chemistry PhD, I am highly skeptical of the practicality of this as an energy source.