PB Power is developing, and has patented, what it calls “a new method of electricity generation” that combines the advantages of nuclear power generation with combined cycle technology. The hybrid system could be retrofitted to existing nuclear stations or used in new-build installations.

The process, called NuGas, links the steam cycles of the nuclear and gas-fired power plants to achieve improved efficiency and greater flexibility. According to PB Power “The system combines the advantages of both nuclear power generation and gas power generation, creating a highly reliable, highly efficient hybrid system.”

Paul Willson, inventor of the system and NuGas Project Director at PB, noted that the gas turbines used in today’s CCGT power stations are the result of billions of dollars of research funding. “Manufacturers are now finding that even the smallest incremental improvements needed to achieve a combined cycle efficiency of 60% have become prohibitively expensive and complex to achieve without sacrificing reliability,” he said. “The greater interest in nuclear power as a reliable and carbon-free source of energy prompted PB to consider whether synergies could be derived from combining nuclear and CCGT technologies,” Willson explained.

Linking the steam systems of the two plants increases the combined generated output and delivers an unprecedented level of efficiency, over 63% compared with 57% for a comparable conventional CCGT plant.

The thermal efficiency gains achieved by integrating a 1200 MWe nuclear plant with a conventional 400 MW CCGT block would provide an additional 42 MW of power without burning any more gas, says PB, while the combined plant is a “lower risk option for plant upgrading, as it uses existing technology operating under conventional conditions.”

“A key advantage of the NuGas technology is that, unlike previous concepts integrating nuclear and other cycles, independence of the cycles is retained,” Paul Willson points out. “This means that gas turbine shutdown does not upset nuclear plant operation, and that nuclear plant shutdown does not result in gas turbine shutdown or an increased disturbance to the electrical network.”

While the new-build application would allow maximum optimisation, the retrofit option will give “exceptional returns on investment with minimal impact on the normal day-to-day operation of the nuclear plant while the CCGT unit is being constructed”, says PB Power.

The company estimates there are between 30 and 40 existing nuclear power plants around the world suited to retrofitting with NuGas.