Sensors could monitor nuclear plants during natural disasters

New energy-harnessing sensors could help monitor a nuclear power plant even in the event of a Fukushima-style disaster, according to researchers.

Engineers from Penn State University in the US have developed the sensors, which are driven by the heat of a nuclear reactor, in order to keep transmitting data even if the plant’s electronic networks fail.

The thermoacoustic sensors were designed to avoid the situation that occurred at the Fukushima Daiichi power station in Japan in 2011 when operators were unable to monitor the fuel rods in the reactor and spent fuel in the storage ponds because the earthquake and tsunami had knocked out the station’s power system.

‘Thermoacoustic sensors can operate without moving parts and don’t require external power if a heat source, such as fuel in a nuclear reactor, is available,’ said researcher Randall A Ali in a statement.

The sensors use a thermoacoustic engine to produce different sound waves depending on the fuel rod’s temperature that can then be transmitted through the water that surrounds the reactor or storage pond.

The thermoacoustic engines are comprised of a heat source — in this case a fuel rod — and a stack of ceramic sheets, according to Ali. ‘These stacks facilitate the transfer of heat to the gas in a resonator, and heat is converted to sound when there’s a temperature difference along the stack.’

The device will also enhance heat transfer from the fuel to the surrounding heat-transfer fluid via the gas that circulates inside driven by the acoustic waves.

Penn State is now working with Idaho National Laboratory to investigate using thermoacoustic sound to monitor microstructural changes in nuclear fuel, to measure gas mixture composition and to act as a fail-safe device in emergency situations.

Scientists at the National Physical Laboratory in the UK are also developing acoustic sensors for use in nuclear power stations in order to create thermometers that don’t lose accuracy in the harsh environment inside the reactor.