The paper "A Conceptual Approach to Eliminate Bypass Release of
Fission Products by In-Containment Relief Valve under SGTR Accident" presents the conceptual design of the ICRV (In-Containment Relief Valve) as effective means to mitigate the release to the environment of
fission products from the SGTR (Steam Generator Tube Rupture) accident.
The beta decay of radioactive
fission products generates neutrinos in very large quantities.
In the Moltex design, the salt is held in vented tubes, which is possible because the
fission products form compounds a in the salt.
Depleted bundles contain small amounts of
fission products and fissile plutonium, which are dangerously radioactive.
"Over the years you have to pull the rods out higher and higher to expose more of the fuel because the fuel on the bottom of the core gets used up, or all these
fission products are keeping it from reacting efficiently," Clark said.
This radioactive nucleus, one of the
fission products resulting from the fissioning of uranium, is an effective absorber of thermal neutrons.
In the nuclear process, mildly radioactive uranium is taken from the ground and bombarded by neutrons--and that part of the uranium which can split (is "fissile") Uranium-235, is transformed into radioactive twins of safe and stable elements in nature: There are hundreds of these "
fission products." The human body doesn't know the difference between these lethal twins and safe and stable elements.
Antineutrinos are produced not only in the decay of uranium, thorium, and potassium isotopes but in a variety of others, including
fission products in nuclear power reactors.
About 3% of the mass of spent nuclear fuel consists of
fission products including strontium-90.' Because of its high decay energy and its long half-life of 30 years--it takes hundreds of years to decay naturally to harmless levels--strontium-90 is classified a high-level waste.