Diakont, a provider of refueling outage tooling and services to the nuclear industry, has announced that it has successfully provided underwater robotic decontamination services on a nuclear power plant’s refueling cavity and dryer-separator pool using a new ROV (remotely operated vehicle) tool system. Historically, nuclear plant operators have conducted cleaning and decontamination of these surfaces manually, after draining water from the space. However, manual decon is slow, and can result in excessive personnel dose exposure. Robotic methods present a vast improvement over manual decon because it reduces personnel dose exposure, reduces radwaste, doesn’t impact plant chemistry, and doesn’t risk inadvertently spreading contamination. By performing the decon robotically while the cavities are flooded, in many cases the critical path outage schedule can be shortened.
Able to decontaminate horizontal, vertical, and curved surfaces, Diakont’s tools easily navigate to areas within flooded cavities that are inaccessible to previous solutions, performing decon in parallel to other activities including fuel movement. The Diakont tools do not require continuous use of an overhead crane or other method of suspension while performing the decon activities.
The ROV-type decontamination tool attaches and drives along the cavity and component surfaces using a high-force, no-flow vortex generator, even in the presence of Residual Heat Removal (RHR) or shutdown cooling flow. Efficient, effective cleaning is performed using a rugged brushing action to detach the crud, while vacuuming it away at high flow rates to a submerged filter.
At the refueling outage, Diakont’s decontamination services were effective enough that no additional manual cavity decon was required after drain-down. Using the tool’s ability to swim, attach, and crawl, Diakont decontaminated the majority of the surfaces designated by the plant operator. Preliminary surveys indicated that all contamination levels were reduced to
Diakont’s cleaning and decontamination services can be used to service various underwater areas within nuclear power plants, including refueling cavities, spent fuel pools, fuel transfer canals, and drywell heads and other curved surfaces.
“Diakont’s remote decontamination service helped the plant operator meet the INPO/Industry collective radiation exposure goals,” says Jacco Goemans, Director of Nuclear Solutions for Diakont. “Diakont’s new robotic tooling paves the way for plant operators to perform a safer, more efficient, and more effective method of reactor plant decontamination.”