non-fissile

Or to design nuclear weapons- from non-fissile material no less?

Fissionable, non-fissile isotopes can be used as fission energy source even without a chain reaction.

A claystone is lithified, and non-fissile mudrock.

Fissile U-235 and non-fissile but fissionable and fertile U-238 are both used in the fission process.

Because it is non-fissile, it can also be used with fissile material, such as uranium and plutonium, as a nuclear fuel.

Enrichment: The probability of a neutron reacting with a fissile nucleus is influenced by the relative numbers of fissile and non-fissile nuclei in a system.

Thus instead of rapidly decaying to the useful U, a significant fraction of Pa converts to non-fissile isotopes and consumes neutrons, degrading the reactor efficiency.

The mode of enrichment was the gaseous diffusion of uranium hexaflouride to separate the lighter fissile isotope, U-235, from the heavier non-fissile isotope, U-238.

Fusion neutrons are able to cause fission in ordinarily non-fissile materials, such as depleted uranium (uranium-238), and these materials have been used in the jackets of thermonuclear weapons.

As a consequence it is important that the chosen matrix allows the reactor to keep the ratio of fissile to non-fissile nuclei high, as this enables it to destroy the long lived actinides safely.

Some of the fast-spectrum neutrons produced by fission are absorbed by neutron capture in adjacent fertile fuel (i.e. the non-fissile depleted uranium), which is "bred" into plutonium by the nuclear reaction:

A fission chain reaction is self-sustaining when the number of neutrons released in a given time equals or exceeds the number of neutrons lost by absorption in non-fissile material or by escape from the system.

Because the proportion of the non-fissile even-mass isotopes of plutonium rises with each pass through the cycle, there are currently no plans to reuse plutonium from used MOX fuel for a third pass in a thermal reactor.

It was never tested, and initially, AWRE estimated its yield at 500 kt based on the Orange Herald test of 720kt, and non-nuclear tests of the HE implosion sphere fitted with non-fissile cores.

A letter from Bohr, commenting on the fact that the amount of energy released when he bombarded uranium atoms was far larger than had been predicted by calculations based on a non-fissile core, had sparked the above inspiration in December 1938.

As well as the establishment at Aldermaston, the UK nuclear weapons programme also has a factory at Burghfield nearby which assembled the weapons and is responsible for their maintenance, and had another in Cardiff which fabricated non-fissile components and a 2000 acre (8 km2) test range at Foulness.

Uranium enrichment is a difficult physical process, as U exists in natural uranium at a concentration of only 0.7%; URENCO used Zippe-type centrifuges for that purpose to separate the isotopes U from non-fissile U by spinning UF gas at up to 100,000 RPM.