Westinghouse Wins Safety Upgrade Contract at Palo Verde Nuclear Generation Station

Westinghouse Electric Company was contracted by Arizona Public Service to provide the first Mobius system, a continuous mobile boration system designed for use at the Palo Verde Nuclear Generation Station. Work already is underway on the project. Delivery of the Mobius system to Palo Verde is scheduled for late 2015.

 The Mobius system provides a continuous supply of highly borated water at high flow rates. Westinghouse developed this patented approach at the request of international customers in response to post-Fukushima safety requirements. Working with Palo Verde, the approach was customized to provide plant-specific operational benefits, including an automated control system with touch screen operator interface.

At Palo Verde, the Mobius system will be used at the start of outages to borate the plant to refueling boron concentrations much faster than current methods, resulting in reduced outage duration. The system then will be used as part of the defense-in-depth outage risk mitigation strategies.

“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 defense-in-depth by having an alternate method of borating the plant if needed."

Terry Rudek, Westinghouse vice president, Systems and Components Engineering, stated: “The fact that we could apply this system to also obtain operational benefits is an added advantage. The system provides additional defense-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 Westinghouse Mobius system requires four main inputs: water, a power source, boric acid powder and a pH control agent powder. Both discharge flow rate and concentration are controlled using an automated platform.