Study reveals chromium’s role in molten salt reactor corrosion

Excessive temperatures and ionizing radiation create extraordinarily corrosive environments inside a nuclear reactor. To design long-lasting reactors, scientists should perceive how radiation-induced chemical reactions influence structural supplies.

Chemists on the U.S. Division of Vitality’s (DOE) Brookhaven Nationwide Laboratory and Idaho Nationwide Laboratory just lately carried out experiments exhibiting that radiation-induced reactions could assist mitigate the corrosion of reactor metals in a brand new kind of reactor cooled by molten salts.

Their findings are published within the journal Bodily Chemistry Chemical Physics.

“Molten salt reactors are an emerging technology for safer, scalable nuclear energy production. These advanced reactors can operate at higher, more efficient temperatures than traditional water-cooled reactor technologies while maintaining relatively ambient pressure,” defined James Wishart, a distinguished chemist at Brookhaven Lab and chief of the analysis.

Not like water-cooled reactors, molten salt reactors use a coolant made solely of positively and negatively charged ions, which stay in a liquid state solely at high temperatures. It is just like melting desk salt crystals till they movement with out including every other liquid.

“To assure the long-term reliability of these new reactors, we have to understand how molten salts interact with other elements in a radiation environment,” Wishart stated.

The scientists had been significantly involved with monitoring chromiuma frequent constituent of the steel alloys proposed for molten salt nuclear reactors.

“Chromium tends to be the easiest element to corrode from most alloys and will ultimately accumulate in the coolant of molten salt reactors,” Wishart stated.

As chromium dissolves into the molten salt, a few of its chemical types can speed up corrosion processes, compromising the structural integrity and efficiency of the reactor. The distribution of chromium ion oxidation states—what number of electron vacancies these ions have out there for chemical reactions—will be the issue that determines whether or not corrosion happens.

“The presence of dissolved trivalent chromium (Cr³⁺with three electron vacancies) can accelerate corrosion in some cases, whereas divalent chromium (Cr²⁺with just two vacancies) does not,” Wishart stated.

Since chromium is secure as each Cr³⁺ and Cr²⁺ in most molten salts, “it is essential to understand how Cr³⁺ and Cr²⁺ react chemically with species produced in the radiation field of a reactor, and what products they make,” defined Wishart.

Brookhaven Lab is the right place to research these processes as a result of it homes amenities that may set off radiation-induced reactions and monitor them in actual time, from trillionths of a second to minutes. These amenities are the Laser Electron Accelerator Facility and the two-million-electron-volt Van de Graaff accelerator, each within the Lab’s Chemistry Division.

Wishart and his collaborators used these amenities to measure the charges and temperature dependencies of reactions of the 2 varieties of chromium ions with reactive species generated by radiation in molten salt.

“Our analysis indicated that the net effect of radiation in the molten salt environment is to favor the conversion of corrosive Cr³⁺ to less-corrosive Cr²⁺,” Wishart stated.

This analysis was a product of the Molten Salts in Extreme Environments Vitality Frontier Analysis Middle established at Brookhaven Nationwide Laboratory by the DOE Workplace of Science in 2018 to discover the fundamental properties and potential functions of molten salts in nuclear environments.