During the March 1979 accident at the Three Mile Island Nuclear Power Station Unit 2 near Harrisburg, Pennsylvania, significant quantities of contaminated water were discharged to the Reactor Building and the Auxiliary and Fuel-Handling Building. This subjected the concrete floors and walls to various concentrations of contaminants.
Most of the floors and wall areas were protected by special epoxy coatings. On examination, contamination appeared to have migrated into the coatings and, to some extent, into the concrete substrate. In areas where the concrete was unpainted or the protective coatings failed, the penetration of contamination into the concrete was significant.
On-site remediation operations are challenging in a fully active facility. Decontamination activities have to be efficiently completed within the narrow time window allotted by temporary and infrequent outages. Remediation specialists must not only decon facilities without disturbing existing operations, or background cleanliness levels, but they must get out quickly as well, without interrupting resumed plant functioning.
At Kwajalein Atoll, in the Republic of the Marshall Islands in the South Pacific, the US Army decided to undertake a major effort to remove PCB contamination from the island. As part of that effort, PCB contaminated equipment was removed from service and placed in a warehouse until proper disposal could be arranged. But after only several months of storage, PCB fluid from the equipment had leaked and was detected on the concrete floor of the facility.
Advanced Sciences, Inc., the environmental service coordinator for the cleanup, determined that solvent cleaning would present both safety and logistics problems for the island and would be of questionable effectiveness. The job had to be completed right the first time.
When the Canadian government decided to sell government agency owned and operated nuclear facilities to private enterprises, the need arose for a major decontamination operation. Although the need was not urgent, the decision assumed a high profile as the use of these facilities would be entering a new phase for nonnuclear purposes.
Disaster struck ten years ago, when a two year old, 18-story office building in the northeastern United States experienced a fire. PCBs escaped from a transformer in the mechanical room and spread throughout the entire building.
The environmental service coordinator for the cleanup responded and decontamination began. Most of the building was decontaminated using conventional techniques. However, the mechanical room, the most contaminated area of the building, had been left alone since the accident and reserved as the last area to be cleaned.