PNNL

Abstract

Background: The Chernobyl nuclear power plant (ChNPP) accident that occurred on April 26, 1986 destroyed Unit 4. After the accident situation was stabilized, it became apparent that sequestration of the damaged reactor was necessary to minimize long term radiological impact on personnel and the environment. A temporary confinement building, the Object Shelter (OS), was designed and constructed between May and November 1986. The primary purpose of the Object Shelter was to prevent further spreading of the radioactive dust and debris. It was built under extremely difficult and hazardous conditions and intended to last 15 years. Upon completion of construction, the building had more than 1,000 m2 of openings that allowed some dust to escape and water to enter the steel structure. Although some measures have been taken in the past 26 years to stabilize the structure and reduce corrosion, the risk of collapse of the Object Shelter continues to increase over time. Its confinement function needs to be performed by a new structure, and the Object Shelter needs to be dismantled in an orderly manner. The structural elements being dismantled will be large and heavy. Nuclear fuel material and other radioactive waste will be placed in heavy shielded containers. The dismantling activities and handling of heavy shielded waste disposal casks will require large and sophisticated cranes that are the subject of this paper.