Dismantling of Contaminated Stacks at Nuclear Facilities

Nearly all nuclear installations utilize stacks to discharge ventilation air as well as gases and fumes from contaminated areas. Over a service lifetime that can span decades, stacks may become contaminated as the result of deposition of radioactive substances, such as aerosols on stack surfaces. In the longer term, this is a serious decommissioning issue. This contamination may be difficult to remove, depending on the operating conditions and the chemicalphysical environments over time. In addition, the physical logistics of stack dismantling may be complex, for example, the difficulty in severing concrete high above the ground. Relevant aspects include project planning and management, decontamination and dismantling, and the management and disposal of wastes. Although more than 40 previous IAEA reports have been published in the field of decommissioning, none focus on this subject. It can be assumed that generic decontamination and dismantling technologies would also apply to these bulky components, but such an approach disregards a number of specific physical and radiological characteristics that make stack decommissioning a unique project.