More data before Fukushima water released

The full extent of the nuclear isotopes in the damaged plant’s tanks requires more study. There is insufficient information to assess the potential impact that releasing contaminated water from the Fukushima No. 1 nuclear plant into the ocean will have on the environment and human health.

Last month, the Nuclear Regulatory Authority announced its approval to discharge more than 1 million tons of contaminated water from the crippled Fukushima No. 1 nuclear power plant directly into the ocean.

Japan’s nuclear regulator has stated that this can be done safely, and the International Atomic Energy Agency has supported this position. We would argue that there is insufficient information to assess potential environmental and human health impacts. Issuing a permit at this time would be premature at best.

Tokyo Electric Power Company Holdings Inc., the plant’s operator, is taking this step as part of the decommissioning and cleanup process of the plant. Every day, more than 150 tons of water accumulates at the site. It is due to groundwater leakage into buildings and the systems used to cool the damaged reactors. The water is currently stored in more than 1,000 tanks at the site. What to do with their ever-increasing number has been a topic of concern for many years.

The justification for ocean discharge focuses largely on tritium’s assumed levels of radioactivity. Tritium is a radioactive form of hydrogen that cannot be easily removed by an advanced liquid processing system for treating contaminated water. Dilution of the tank water with seawater has been proposed o reduce tritium to 1/40th of the regulatory standards. However, tritium is only part of the story. A full assessment of all of the water contaminants stored in tanks on-site has yet to be made and verified by independent parties.

Concerns around releasing Fukushima water

Our specific concerns include the available data’s adequacy, accuracy and reliability. A key safety measure is a risk factor that combines the activities of more than 60 radioactive contaminants. This is known as the so-called sum of ratios approach. However, only a small subset of these radioactive contaminants — seven to 10 of them, including tritium — have been regularly measured. The assumption is that this subset alone will reflect the possible risks, and the other contaminants are at constant levels. We disagree with this approach. The data show wide variability in the contaminant concentrations between tanks and differences in their relative amounts.

For example, some tanks low in tritium are high in strontium-90 and vice versa. The assumption that concentrations of the other radionuclides are constant is not correct A full assessment of all 62 radioisotopes is needed to evaluate the true risk factors.

Moreover, only roughly a quarter of the more than 1,000 tanks at the site have been analysed. This means that final dilution rates for tritium and the cleanup necessary for all contaminants are not well known. There is also enormous variability among the tanks, creating additional problems. By Tepco’s estimates, almost 70% of the tanks will need additional cleanup. However, that estimate is uncertain until all the tanks are assessed.

Lack of tank contents knowledge a problem

Ultimately, it is impossible to engineer and assess the impact of any release plan without knowing what is in the tanks. The actual cost and duration of the project, as well as the amount of dilution needed, all depend upon the accuracy and thoroughness of the data. For example, the amount of seawater required and hence the time to release depend directly upon dilution factors.

Tepco stated in its radiological impact assessment that to meet its requirements, dilution will be needed by a factor “greater than 100.” The dilution rate we calculate is 250 on average and more than 1,000 times for many of the tanks where analyses are available. Scaling to those higher averages and extremes would increase capacity needs, costs and overall duration of the releases. Comparisons against other possible disposal options cannot be made without a better assessment of the current tank contents. Those alternatives include vapour release, using enhanced tritium removal technologies, and geological burial.

Focusing on tritium in Fukushima water

Its high levels are not adequately addressed even for tritium. It has been assumed to be present only in inorganic form as tritiated water. However, tritium (OBT) organically bound states undergo a higher degree of binding to organic material. OBT has been found in the environment at other nuclear sites. It is known to be more likely stored in marine sediments or bioaccumulated in aquatic biota. As such, predictions of the fate of tritium in the ocean need to include OBT. They also need to include the more predictable inorganic form in tritiated water. Tepco has yet to do this.

The focus on tritium also neglects that the non-tritium radionuclides are generally of a greater health concern. The increased health concern is evidenced by their much higher dose coefficient. That is a measure of the dose, or potential human health impacts associated with a given radioactive element, relative to its measured concentration, or radioactivity level. These more dangerous radioactive contaminants have higher affinities for local accumulation after release in seafloor sediments and marine biota. The old belief that the “solution to pollution is dilution” fails when identifying exposure pathways that include these other bioaccumulation pathways.

Although statements have been made that all radioactivity levels will meet regulatory requirements and be consistent with accepted practices, the responsible parties have not yet adequately demonstrated that they could bring levels below regulatory thresholds. Rebuilding trust would take cleaning up all the tanks and then independently verifying that non-tritium contaminants have been adequately removed, something the operator has not been able to do over the past 11 years. Post-discharge monitoring will not prevent problems but identify them when they occur.

Impact of Fukushima water release

Releasing contaminated material from the Fukushima No. 1 nuclear power plant would take at least 40 years. It could take decades longer if you include the anticipated accumulation of new water during the process. This would impact not only the interests and reputation of the Japanese fishing community, among others, but also the people and countries of the Pacific region. This needs to be considered as a transboundary and transgenerational issue.

Our oceans provide about half of the oxygen we breathe and store almost one-third of the carbon dioxide we emit. They provide food, jobs, energy, global connectivity, cultural connections, exquisite beauty and biodiversity. Thus, any plan to deliberately release potentially harmful materials must be carefully evaluated and weighed against these important ocean values. This is especially true when contaminated material is released that would be widely distributed and accumulated by marine organisms.

The Fukushima nuclear power plant disaster is not the first such incident, nor will it be the last. The current challenge is an opportunity to improve responses and chart a better way forward than to dump the problem into the sea. Moreover, even accepted practices and guidelines require much more thorough preoperational analysis and preparation than evidence.

Conclusion

We conclude that the current plan does not provide the assurance of safety needed for people’s health or sound stewardship of the ocean. We have reached this conclusion as members of an expert panel engaged by the Pacific Island Forum, a regional organisation comprising 18 countries. However, we have penned this commentary in our capacities. Our views may or may not be shared by the forum secretariat or its members.

The recent decision to support the release by the Nuclear Regulation Authority is surprising and concerning. In addition, the International Atomic Energy Agency should withhold its support for the release without these issues being resolved. Once the discharge commences, the opportunity to examine total costs and weigh discharge against alternatives will have been lost.

It has been stated that there is an urgency to release this contaminated water because the plant operator is running out of space on site. We also disagree on this point. Once the tanks are cleaned up as promised, storage in earthquake-safe tanks within and around the Fukushima facility is an attractive alternative. Tritium has a 12.3-year half-life for radioactive decay. That means that in 40 to 60 years, more than 90% of the tritium will have disappeared, and risks will be significantly reduced.

This is the moment for scientific rigour. An absence of harm is not evidence that harm will not occur. It simply demonstrates critical gaps in essential knowledge. Having studied the scientific and ecological aspects of the matter, we have concluded that the decision to release the contaminated water should be indefinitely postponed. Other options for the tank water revisited. We need more complete data to evaluate the economic, environmental and human health costs of ocean release.