Westinghouse has been contracted by Arizona Public Service to provide a continuous mobile boration system for use at the Palo Verde nuclear generation station.
The Mobius system provides a continuous supply of highly borated water at high flow rates, and requires water, a power source, boric acid powder and a pH control agent. Discharge flow and rate concentration are controlled using an automated platform.
Mobius was developed at the request of customers in response to post-Fukushima safety requirements. It provides plants with additional defence-in-depth to respond to the Nuclear Regulatory Commission Mitigating Strategies Order for plants that have not implemented low-leakage seals or that do not have enough protected borated water sources to support shutdown modes.
The Mobius system also has operation benefits. At Palo Verde, it will be used at the start of outages to borate the plant to refuelling boron concentrations much faster than current methods.
"Other systems on the market were batch systems that were limited in flow rate and duration," said Palo Verde engineering director Panos Paramithas. "This was the only system on the market that could provide a continuous flow of highly borated water and meet our needs. By pre-deploying this system at the beginning of an outage, we will reduce our outage time and will increase our level of safety through defence-in-depth by having an alternate method of borating the plant ifneeded."
Work on the Mobius™ system is already is underway with delivery scheduled for late 2015, Westinghouse said.