All fissionable and fissile isotopes undergo a small amount of spontaneous fission which releases a few free neutrons into any sample of nuclear fuel. Such neutrons would escape rapidly from the fuel and become a free neutron, with a mean lifetime of about 15 minutes before decaying to protons and beta particles.

At present, the nation’s nuclear facilities store spent fuel on-site in pools or dry casks. “Our agency is on record as being confident that fuel can be stored safely on-site at reactors in either pools or dry casks for at least 90 years,” says David McIntyre, an NRC spokesman.

Nuclear fuel is extremely dense. However, some advanced reactors designs being developed could operate on used fuel. The NICE Future Initiative is a global effort under the Clean Energy Ministerial that makes sure nuclear will be considered in developing the advanced clean energy systems of the future.

Reactors run smoothly and reliably for up to two years at a time, but they need maintenance and inspection. Some of this can only be done when the reactor isn’t running. So, the refueling periods—three weeks or so—are periods of intense activity.

A core damage incident can occur even after a reactor is shut down because the fuel continues to produce decay heat. A core damage accident is caused by the loss of sufficient cooling for the nuclear fuel within the reactor core.

Nuclear power plants run almost all the time, and refuel only once every two years or so. An outage usually takes only 40 days, so once every two years means the plant operates just under 100% of the time – 98% in the case of this nuclear plant.

You can do fission without uranium but the alternatives are generally either less effective or more difficult to find. For example Plutonium is typically found naturally only in trace amounts, and Thorium is generaly both less common and releases less energy (making it quite well suited for power generation).

In Canada we used an IIRC, an Americium source to generate alpha particles to then generate neutrons. In the US they used Plutonium as a source , but it was illegal to export it from the US so it must have been legal to own in the US at that time.

No, no one is allowed to own plutonium. However due to the recent market in people and collectors liking elements and an effort to collect almost any material in the periodic table the market for depleted uranium is quite active.

For chemistry students and teachers: The tabular chart on the right is arranged by the discovery year. The oldest chemical element is Phosphorus and the newest element is Hassium.

Scientists say the First, a gigantic space object that came from outside our solar system, can actually be extremely rare. According to them, it is a huge piece of hydrogen ice.

Technetium. The first element that was synthesised, rather than being discovered in nature, was technetium in 1937. This discovery filled a gap in the periodic table, and the fact that no stable isotopes of technetium exist explains its natural absence on Earth (and the gap).