High Intensity X-Ray Sources to Eliminate High Activity Isotopes used for Sterilization

Three different modalities of radiation sterilization currently exist: gamma-ray sterilization, electron beam sterilization, and x-ray sterilization. One of the most common ways to sterilize goods is with gamma producing radioactive sources, most commonly Co-60 and Cs-137. Long-term possession of these sources is undesirable due to security concerns, Nuclear Regulatory Commission oversight, and rising replacement, storage, and disposal costs. In addition, gamma sterilization typically requires relatively long exposure times to achieve dosages necessary for effective sterilization. We propose to develop a radiation sterilization system which uses a superconducting linear accelerator (linac) to provide high radiation doses and thus eliminate disadvantages of utilizing Co-60 and Cs-137 sources. Electron linacs offer many advantages over radioactive sources. First, they can produce high energy bremsstrahlung x-rays by striking a metal converter on demand and can easily be turned on and off. Second, linacs can produce radiation of varying intensity, photon energy and power. Third, a bremsstrahlung photon cone is focused, compared with isotropic radiation of sources and thus is more efficient. Finally, linacs produce little radioactive waste, and they are a low security risk. These positive factors make linacs a compelling option when choosing among radiation sterilization methods. Niowave has been developing superconducting linacs for nearly a decade. Superconducting linacs produce a continuous wave electron beam and can operate nonstop at 100% duty cycle. The resulting electron beam has high average current, with a low peak current. Properly collimated, a superconducting linac can generate a high energy (well over the 10 MeV typical for sterilization), with a high flux (up to 1017 photons/cm2 per second) planar beam profile, eliminating the need for swept beam irradiation. Recent advances in superconducting accelerator technology have reduced the capital and operational costs to the point they are now competitive with conventional (normal conducting) linacs. These advances make high-dose, high-throughput bulk sterilization possible at a relatively low cost. Thus, the proposed sterilization machine can eliminate the need for high activity sources, which could be the source for a dirty bomb if these sources fell into the wrong hands.