"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.
(The French have recently cited this "plutonium mine" scenario as one of their primary motivations for continuing to reprocess.) The technical feasibility of plutonium recovery will indeed increase with time as the fission product
radiation barrier decays away.
Some proposals have been made to mitigate this issue, such as producing SiC fibres rather than monolithic SiC and embedding the fibres to form a composite, though this has the disadvantage of being permeable to fission products
; thus a combination of monolithic and composite SiC would be needed for fission product
The fission products
dissolve in the salt and are removed continuously in an online reprocessing plant and replaced with new fuel or fertile material.
In conventional reprocessing, uranium and plutonium are separated from the fission products
and other actinides in the spent fuel.
The PWRs encompass more than two-thirds of operating light-water reactors worldwide and have one to two orders of magnitude of coolant and steam generation fission product
inventory compared to other reactors.
Even if it were, the anti-nuclear activist, Sheldon Novick wrote of fission products
in his book, The Electric War, "it is difficult to see in what way they are any more or less hazardous than other poisons produced by industry."
MELCOR can simulate various SA phenomena such as thermal-hydraulic response of the primary RCS, core uncovering, fuel heat-up, cladding oxidation, heat-up of the reactor pressure vessel (RPV) lower head by the molten core, lower plenum penetration, hydrogen production, and fission product
Jianzhu, "Fission product
release and its environment impact for normal reactor operations and for relevant accidents," Nuclear Engineering and Design, vol.
One of the important safety features of the HTGR is the robust fission product
retention capabilities of the fuel elements .
The fission product
emitted to the gas creates about L[E.sup.5] to 1[E.sup.6] electron-ion pairs along its path .