Support for cofferdam

It allows to isolate temporarily the hydraulic structures of the cooling circuit in order to dry them up and meanwhile to execute the maintenance operations.

Temporary isolation of hydraulic structures of nuclear power plant’s cooling system is regularly required to dry them up and perform maintenance and inspection operations.

DIKO Subsea can provide technical services such as;

• Cleaning and inspection of hydraulic slide parts
• Sediments’ cleaning before installation of cofferdam
• Inspection of cofferdam’s base, walls and sealing
• Waterproofness of cofferdam

Water circuits & canals inspection

Water circuits and canals should be subject to a regular inspection and maintenance to guarantee the integrity of the facilities and the optimal water circulation required for the appropriate operation of the nuclear power plant´s cooling system including;

• Cleanup of raw water filtration circuit and removal of peddle sediments
• Cleanup of condenser cooling water system
• Cleanup with airlift pump of cofferdam openings
• Cleanup of electro-chlorination system
• Inspection and maintenance of fire protection system
• Bathymetry
• Control of water level regulator
• Measuring thickness of steel sheet pile

Sediments cleaning

To ensure the appropriate raw water supply and the safe and efficient operation of a nuclear power plant, water level shall be monitored. The water level will be impacted by the accumulation of sediments like mud or sand. DIKO Subsea may conduct prevention activities against accumulation of sediments including;

• Cleanup of spillways with pumps
• Cleanup of water circuits and canals
• Cleanup of gravel and other existing sediments by pumping

Maintenance, supervision & replacement spillway

Spillway grills play a significant role for the security of nuclear power plants but may also disturb the proper circulation of water through the cooling system due to the existence of accumulated sediments like wood or plastic particles or marine debris. Proper supervision, maintenance and replacement of spillway grills, when required, are critical for the safe and efficient operation of nuclear power plants and must be performed by professional and experienced divers.

Risk of frazil ice

Cold water could result in frazil ice formation and a potential interruption of cooling water supply, putting at risk the power production and security of nuclear power plants. In fact, one of the major risks associated with the operation of nuclear power plants is the obstruction of spillway grills used for the appropriate water influx into the cooling. Such grills are likely to be blocked by frazil ice resulting in a potential disruption of the whole cooling system.

DIKO Subsea is qualified to carry out inspection and maintenance operations of nuclear power plants’ cooling systems including the unblocking of spillway grills. Inspection and maintenance operations are executed by a team of 4 commercial divers qualified according to international hyperbaric standards, all of them being Class IIA certified and equipped with their personal protective equipment against frazil ice risk composed of;

• Diving equipment for non-polluted water
• Pneumatic scrapers