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Effective Radioactive Waste Remediation

Paul M. Brown
Year: 1999
Keywords: radioactive waste, electrons, gamma rays, reaction, accelerator, fission, isotopes, burn-up process
A linear accelerator, preferably of the monochromatic type, accelerates electrons which are directed onto a high Z target such as tungsten to generate gamma rays about 9 MeV, which are directed onto the fuel material such as U-238 which results in the (y,f) reaction, thus releasing about 200 MeV. A reactor built according to this principle requiring an accelerator driven by 1 MW will develop about 20 MW of power. The reaction is not self-sustaining and stops when the beam is turned off. This accelerator driven reactor may be used to "burn-up" spent fuel from fission reactors, if simply operated at 10 MeV. The photo-fission results in typical spent fuel waste products such as Cs-137 and Sr-90 which undergo photodisintegration by the (y,n) reaction resulting in short lived or stable products. Chemical separations of the spent fuel isotopes is not necessary. Of course, more than one accelerator may be used to drive the reactor to higher power levels, and speed-up the burn-up process. The fact that the reaction is not self-sustaining is a safety feature allowing immediate shut-down in the event of a problem.