Radiation-resistant lubricants for the decommissioning of the Fukushima plant

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Radiation-resistant lubricants
Workers decontaminating the Fukushima Daiichi nuclear power plant in Japan. © The Yomiuri Shimbun via AP Images

Radiation-resistant lubricants

Radiation-resistant lubricants – Japanese specialty lubricant manufacturer Moresco Corp. will supply radiation-resistant lubricants for the decommissioning of the Fukushima Daiichi nuclear power plant, which may take as long as 30 years to complete, a company spokesperson told Lube Report last Friday.

The radiation-resistant lubricant, Moresco-Hirad, is polyphenyl ether based. It is used as a vacuum oil and gear oil in a particle accelerator, which is subjected to large amounts of radiation, and also used as a bearing oil in 60Co gamma-ray radiation research facilities and remote-control equipment.

“We have been supplying the lubricant at the designing stage of the decommissioning equipment in 2019,” the spokesperson said. “The decommission work is expected to take about 30 years. Furthermore, equipment development for a full-scale decommissioning will take a long time to develop. So we expect the supply of Moresco-Hirad to continue until decommissioning work is completed.”

On March 11, 2011, an earthquake of magnitude 9.0 caused a 15-meter tsunami, which cut the power supply for cooling of three Fukushima Daiichi reactors. This caused three of the plant’s six reactors to suffer fuel rod meltdowns, leading to the decision to decommission the plant.
A major challenge in the decommissioning work of the Fukushima Daiichi nuclear power plant is the problem of deterioration of lubricants when exposed to high doses of radiation. For example, state-owned Tokyo Electric Power Company (Tepco), which owns and operates the  Fukushima Daiichi plant, has to use a remote-controlled robot with a 22-meter arm to remove fuel debris that is highly radioactive.
Fuel debris is made up of nuclear fuel rods that have melted and dropped onto the floor of the containment vessels, then cooled and re-solidified, emitting extremely high radioactivity.

Moresco-Hirad has the highest level of radiation resistance of any lubricant in the world, the company says. Medical radiation therapy applications are also being investigated.

The company’s sales of specialty lubricants grew 37% to ¥6.3 billion (U.S. $55.4 million) for the second quarter financial results ending August 31, 2021, due mainly to an increase in sales in specialty lubricants such as die-cast lubricants’ demand from an increase in automotive production, and others.

“Sales of cutting fluids were steady due to the expansion of new markets,” according to the company’s financial report released in October last year.

“Sales of high-temperature lubricants for grease-based oils increased against the backdrop of a recovery in domestic automobile production and a strong demand in China,” it added. “Demand for hard disk surface lubricants, hard disk drive for data centers, is expected to increase.”

Total sales in North America increased 5.9%, China jumped 41.6%, and South and Southeast Asia rose by 24.6%.