Photoactivation of PBFA-II

PBFA-II will produce 30 MV peak output voltage. A substantial portion of the output energy will be lost as free electrons which produce hard X rays. Many X rays will have energies within the photoneutron giant resonance. A PBFA-II shot will produce about 5 X 10 E14 photoneutrons. These photoneutron reactions will induce radioactivity in and about PBFA-II. Activation of structural components in the center section will be limited by substituting aluminum for stainless steel in regions of high x ray intensity. Air will be activated above and below the center section after shots, however X ray shielding will limit initial concentrations to five times health guidelines. The short half-lives of air radioactivity will permit reentry following simple decay without ventilation. Some radioactive material will be eroded by arcing, but the resultant contamination should be small. Minuscule concentrations of radioactivity will be produced in the water surrounding the center section