Nuclear power plant outsources water treatment to SUEZ

One of the first advanced gas-cooled reactor (AGR) nuclear power plants built in the United Kingdom, was experiencing difficulty with its original demineralization (DI) water treatment plant. Previously, SUEZ was already providing MobileFlow* DI trailers for some time on a backup short-term service. This service was provided in the event any repairs to the water treatment plant could not be completed or as an emergency service when an alternative source of DI water was needed urgently.

With the deterioration of the water treatment plant and its critical role in the operation of the power station, the owners wanted a more secure and permanent source of DI water.

The owners faced three possible solutions:

• Purchase and build a new water treatment plant
• Fully refurbish the old water treatment plant
• Outsource the water treatment plant

A survey of the old plant showed it to be beyond economic refurbishment and in view of the remaining working life of the power station the owners were keen to curb any major capital expenditure on a new water treatment plant.

The owners selected outsourcing the water treatment to SUEZ as the most practical and economic answer. The solution provides a secure and reliable source of high purity water to meet the quality and quantity requirements. The owners also no longer needed to worry about the operation and maintenance of the water treatment.

With feedwater around 100 ppm Total Dissolved Solids (TDS), from municipal treated surface water, the plant operates by combining SUEZ standard fixed location and trailer mounted equipment such as the MultiFlow* and MobileFlow. This allows the customer to benefit from off-site regeneration of the ion exchange resin, avoiding local environmental issues.

The solution produces purification exceeding the customer set requirements yet on a much smaller footprint than the original water treatment plant.

The inbuilt flexibility of the system offers additional advantages including:

• Increasing DI production by bypassing the Reverse Osmosis (RO) straight to the MobileFlow DI trailer.
• Continued water production in the event of power loss to the system.
• No need for strong acids or caustics, relieving daily controls on chemical handlings and environmental penalties on discharge, as NaCl (salt) is used to regenerate the softener vessel which can then be discharged.
• Labor cost savings achieved by using automated systems with a SUEZ engineer only needing to visit the site weekly for routine maintenance.
• The RO provides a barrier against colloidal silica and most organics with Nominal Molecular Weight Limit (NMWL) >150 allowing increasing demineralized water production.

The site personnel noticed a significant change to the bottom ash removed from the boiler. It changed from very hard to a friable, granular composition.

No failure of the grate has occurred since the treatment was introduced.

Furnace cleanliness has improved with existing deposits being reduced by the addition of FuelSolv FS3954.

When viewing the furnace from an inspection port to a daily basis, the customer was surprised that no further build-up had occurred and in fact, the existing deposits were reduced.