The Task of Easing Tritium Fears - Shenzhen Cesium Salts Group

Many people had probably never heard the word “tritium” until recent discussion of the release of treated wastewater from the Fukushima Daiichi Nuclear Power Station started going around.

My origin as a researcher was watching the TV anime Mobile Suit Gundam. The mecha suits in that anime were powered by tritium, and one of my research topics now is how to safely handle that fuel to achieve compact, highly efficient fusion reactors. One of my hobbies is also visiting natural springs all over the country to take samples and measure tritium concentrations. As a specialist heavily involved with tritium both in my personal and professional lives, I would like to share my understanding of the material in words as plain as possible.

The reason people are afraid of monsters is that they do not understand what they are. Tritium is the same, so if people can face it equipped with better understanding, they will have no reason for such extreme fear.

At Fukushima Daiichi Nuclear Power Station, water is being used to cool melted fuel debris, which results in water contaminated with high concentrations of radioactive materials. Ground water also flows into the reactor chambers and rainwater seeps in, creating about 100 tons of contaminated water a day. The water is run through adsorption equipment to remove most of the main radioactive elements of cesium and strontium. Then it goes through ALPS, or Advanced Liquid Processing Systems, to remove most other radioactive elements except for the tritium, after which it is stored in tanks. This final stage we call “treated water.”

ALPS can remove 62 types of radioactive material, except for tritium, from contaminated water, resulting in “treated water.” (© Nippon.com)

Tritium is an isotope of hydrogen with the same chemical properties but two more neutrons than a typical hydrogen atom. It exists in an unstable state and decays when it releases a beta particle, becoming a stable helium isotope with two protons and one neutron. The emitted beta particle is an energetic electron known as a beta ray. The energy of tritium beta rays, though, is extremely low relative to other radiation, and can be blocked by a sheet of paper. In other words, it cannot pass through skin or a container, so there is no risk of external exposure.

However, if water bearing tritium enters the human body, it can cause internal radiation exposure. It is most likely this point that is causing worries over releasing the ALPS-treated water into the sea. Of course, it would cause problems if the concentration of tritium in the human body grew too high, but the World Health Organization has released guidelines saying that it is safe to drink water with a tritium concentration of 10,000 becquerels per liter.

The plan at the Fukushima Daiichi Nuclear Power Station is to dilute ALPS-treated tritium water with seawater to a maximum concentration of 1,500 Bq/L, less than one sixth of the WHO guideline, before releasing it. In other words, if you removed the salt, the prerelease water itself would have no effects on the human body if drunk. Even if you drank this tritium-bearing treated water for a year, there would be no serious impacts from internal exposure. (And of course, seawater is itself undrinkable.)

Then that water will be discharged into the ocean. The dilution power of seawater is so great that it is extremely difficult to detect any discharge-related elevation in tritium in water collected or fish caught just a few kilometers from the discharge point.

Annual exposure doses are calculated from an assumed 2.25 liters of water consumed per day, in accordance with disaster preparedness guidelines.

Tritium is always produced in nuclear fission reactions, so that means that all the nuclear reactors and nuclear fuel reprocessing facilities in the world release tritium even during normal operation. The overall amount produced is far greater than the total in the ALPS-treated water from Fukushima Daiichi, and even so there has been no measurable rise in seawater tritium concentration.

Nuclear tests between 1945 and 1980 also released large amounts of tritium into the environment. The reason that seawater concentration has not increased despite the ongoing tritium discharge from the world’s nuclear facilities is that the release from nuclear tests was so large that the amount of that tritium in the oceans decaying even today is greater than that being newly discharged.

Additionally, during the 1960s when nuclear testing was at its peak, the concentration in rainwater hit a record of 110Bq/L in 1963. Since 90% of Japan’s drinking water comes from river sources, drinking water in those days had high concentrations. I myself was born in 1966, which means that I was drinking water with high tritium concentrations while growing up.

Decommissioning work at Fukushima Daiichi Nuclear Power Station is scheduled to ramp up in the future, and that will include removal of meltdown debris from the reactor chamber. This will require building sample analysis facilities, material and equipment storage facilities, and accident response facilities.

The grounds around the power plant are currently covered with water-storage tanks. To make progress on decommissioning, the ALPS-treated water must be discharged and the tanks removed, thereby making space to build the facilities needed to move on to the next stage.

Given that this incident was rated a seven on the International Nuclear and Radiological Event Scale, the most serious possible, and created anxiety throughout Japan, it is only natural that people feel mistrust of Tokyo Electric Power Company. It is likely inevitable that people will be emotionally unable to accept treated water discharge.

However, discharging the treated water is not for TEPCO’s benefit. Steady progress in decommissioning the reactor is necessary to achieve true recovery for Fukushima, and delaying the release of this water, which has little impact on the environment or human health, will only delay that recovery.

Construction of an underground tunnel to discharge treated water 1 kilometer offshore, taken in September 2022. (© Nippon.com)

There is likely nothing the government or TEPCO can say to satisfactorily explain the safety of this process. Once discharge of the ALPS-treated tritium water begins, there will be some who stop buying seafood until they see how things go. There is no avoiding some damaging rumors.

To reduce that as much as possible will require showing clear evidence, but testing for tritium to establish food safety takes a lot of time and work. Using the so-called official method to measure tritium can take more than a week to measure seawater concentrations and a month to measure the levels in water inside fish. But who will want to eat fish that has been sitting for a month after it was caught?

My students and I have run experiments to develop a “microwave heating method” out of the belief that rapid tritium concentration measurement is essential to confirm food safety. In simple terms, this method uses a microwave oven to efficiently recover water from fish. This method takes only about 30 minutes to measure tritium in seawater and less than one hour to measure it in the moisture inside fish. Fish can be analyzed and declared safe between being caught and reaching store shelves for sale.

I want this analysis method to be used by distributors so that supermarkets and restaurants will be able to supply, and consumers eat, Fukushima seafood with peace of mind. To that end, I have no plans to patent this technology and am continuing to support development by holding tritium measurement analysis workshops.

When I was born, my father worked in the Fukushima village of Kawauchi. Although I was too young to remember those days, I hope my birthplace of Fukushima Prefecture will achieve recovery as soon as possible. I want to use my science expertise to help that along by quashing harmful rumors as much as humanly possible.

(Originally published in Japanese. Banner photo: The treated water discharge facility at TEPCO’s Fukushima Daiichi Nuclear Power Plant at an event opening it to the press. Radioactive tritium-containing treated water is diluted with seawater before flowing through this pipe to the undersea tunnel. Taken on June 26 in Futaba, Fukushima Prefecture. © Jiji.)

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