28 Mai 2015
May 27, 2015
By KEIZO FUKATSU/ Staff Writer
YOKKAICHI, Mie Prefecture--A manufacturer of traditional ceramics has created special blocks that can absorb water, a development that could enable radioactive water at the Fukushima No. 1 nuclear power plant to be stored safely.
“Contaminated water would not leak if it is stored inside the blocks,” said Taiji Mizutani, who heads Mizutani Shoten. “We will commercialize the product after verification experiments and hope evacuees from Fukushima will be able to return to their homes as early as possible.”
Mizutani came up with the idea of developing water-absorbing blocks with unglazed ceramics when he was working as a volunteer in the Tohoku region, which was devastated by the March 2011 Great East Japan Earthquake and tsunami.
The 37-year-old expressed concern about frequent reports of highly radioactive water leaking from storage tanks at the stricken plant.
Since the disaster, Mizutani has visited affected areas more than 10 times and interacted with people who were evacuated from their homes near the nuclear plant.
“I always wanted to help them return to their hometowns,” Mizutani said.
He first realized ceramics may be useful for storing radioactive water when he found biscuit ware absorbs glaze more easily. Then, Mizutani began testing the water-absorbing quality of ceramics.
He mixed chaffs of grain with soil mainly comprised of clay. Because rice hulls burn away when the soil is fired, hollows remain where the chaffs existed. Mizutani also kept the firing temperature at around 700 degrees to remove water from the clay and create tiny linear cracks.
According to Mizutani, the hollows and cracks help the ware absorb water. It took Mizutani almost a year to develop the highly absorbent material.
While ordinary unglazed ceramic ware absorbs 40 percent of its weight in water, Mizutani's “spongelike” block absorbed a volume equivalent to its own weight in just two minutes in one experiment, Mizutani said.
He has received patents for the special block as well as his original water-storage system, in which contaminated water is stored after being absorbed by the ceramic blocks laid on a huge pool made of high-density concrete.
He intends to reach out to Tokyo Electric Power Co., the operator of the Fukushima plant, so the product can be used in the decommissioning process at the crippled facility.