Waterworld: How Worried Should We Be About Fukushima?

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Waterworld: How Worried Should We Be About Fukushima?

Not as much as many headlines suggest, but the cleanup still needs to deal with a complex water issue.

Waterworld: How Worried Should We Be About Fukushima?
Credit: REUTERS/Kimimasa Mayama/Pool

Almost 20 years ago, when Kevin Costner’s Waterworld rolled out into theaters, it was already epic – not necessarily for its post-apocalyptic science-fiction, but because filming on sets built on water made it the most expensive movie in history. Expectations of a box office hit were high. As it happened, critics neither loved nor hated it, and attendance was mediocre. After such pre-release fanfare, news reports predictably derided the film as an epic failure. Today, we are suffering a different type of Waterworldproblem at the stricken Fukushima Daiichi Nuclear Power Plant, where the taming of water – in this case, radioactive water containment – is being met with a flood of negative news reports of leaks and being answered with ballooning budgets.

Of course, the situation at Fukushima is not a Hollywood film, and the stakes are enormous. Still now, two-and-a-half years on from the initial disaster, the water at the nuclear plant has yet to be tamed. The site is awash with continuous underground flows and rainwater, becoming tainted by radioactive matter on their passage through the area. This poses a massive problem for the containment effort.

The response has been to furiously build more water storage tanks, but more tanks also inevitably mean more leaks, which in turn lead to greater public outcry. The government clearly recognizes this is an unsustainable path and continues to take action (and spend money) to slow the increase of contaminated water. Eventually the water must be discharged, and decisions are looming as to how much and when. These decisions demand public engagement, and for that, understanding the different water issues is crucial.

The recent rash of headlines – about radioactive leaks, exposed workers and contaminated fish – paints a bleak picture, but to be fair all is not bad. The situation is less dire than many headlines suggest, and Prime Minister Shinzo Abe’s declaration in September to the International Olympic Committee that things are “under control” is a legitimate claim.

The tremendous recovery efforts have garnered little attention because much of it is going well. Stabilization of the nuclear fuel has so far been successful. This is the highest priority of containment efforts since overheating could result in another huge environmental release. The fuel in the reactors, as well as those in the spent-fuel pools – most notably spent fuel pool #4 – has been stable since the fall of 2011, primarily because of the effectiveness of the makeshift cooling system. (Additionally, a major effort is underway to transfer the rods from spent-fuel pool #4 to more suitable, worker-accessible facilities). Moreover, the natural radioactive decay means that the fuel’s potential for overheating has and will continue to diminish over time.

Other substantial efforts to contain contamination have also met with some success: filtration systems and building coverings close off airborne pathways; and the re-suspension of radioactive dust particles into the air have been minimized by fixatives. Even efforts to contain the huge volumes of contaminated water in difficult conditions have been somewhat effective; the majority of the water is now held in the basements of the buildings, various trenches, and hundreds of purpose-built tanks and cisterns.

But this patchwork effort of containment is struggling as it is being constantly challenged by the relentless natural forces of groundwater and rain. As the volume of contaminated water continues to grow, and as stories of spills and leaks pile up, one wonders for how long it will remain possible or sensible to try to contain (and retain) all that water.

This brings us to the problem of the day: the escape of tainted water. While frequently lumped together as the same problem, there is a considerable difference between the contamination being carried away by groundwater on the one hand, and the leaks and spills which occur from tanks on the other. Naturally produced water effects – such as those from the ground, rain or tides – usually present relatively low concentrations of radioactivity if contaminated, but come in very large volumes. Leaks from facilities such as tanks or processing systems typically involve lower volumes but higher concentrations of radioactivity. As we will see, both present different challenges and require different solutions.

The stricken reactor buildings are interconnected by underground conduits, tunnels and trenches, providing numerous pathways for the water to move. Robotic videos have shown clean groundwater leaking into the buildings’ contaminated basements from at least one of those pathways, increasing the volume of water that becomes tainted and must be retained. The amount of water in the system grows by some 400 tons per day, equal to the carrying capacity of about 13 large gasoline trucks. However, this volume is only the net inflow. Recent radioactivity trends in groundwater samples suggest leakage is occurring out of the basements and trenches and into the ground below. As groundwater migrates towards the sea, and as tides rise and fall, some of this leaked contaminated water is carried away. In August, Tepco concluded that this leakage appears to have been going on since the initial accident, constituting the single largest source of continuing contamination entering the environment and migrating to the harbor.

Rainwater is also a complicating factor. Because dripping pipes and puddles are the key indicators of tank leaks and require investigation, wet weather creates a great deal more work. Moreover, the additional water must also be monitored and controlled. Twice this autumn, heavy typhoon rain filled dikes around the tank farms to the brim, and if shown to be contaminated, albeit dilute, had to be retained.

The tanks are another issue. Nearly 1000 storage tanks and a massive web of connected piping already groan with enough water to fill 120 Olympic-size swimming pools, with more being built to accommodate the continuous inflow. Building and managing such a vast array of storage tanks involve a colossal effort and, not surprisingly, leaks have begun to appear.

Numerous tank leaks of varying severity have been reported this year. Though they frequently make headlines, tank and pipe leaks are typically quite limited in both volume and impact. The majority of the water in these tanks has undergone cesium filtration which significantly reduces, though does not eliminate, the contamination levels. Further, since the tanks are located several hundred meters from the harbor, the risk of a tank spill contaminating the sea is low. One noteworthy outlier – a recent large leak of about 300 tons – was alarming enough to prompt Japan’s Nuclear Regulation Authority to declare it a “serious incident” on the International Nuclear Events Scale (INES). As it turned out, the amount of radioactivity which escaped to the environment did not result in any elevated readings at the shoreline. Other tank leaks have been less significant.

This is not to say that tank leaks are of no concern. They place a tremendous burden on an already over-taxed workforce in their monitoring and management. Tank leaks are also a symptom of the quick-fix – sacrificing quality for speed and quantity – that was never expected to serve as a long-term solution. They tend as well to trigger alarmist headlines, raising public anxiety. However, tank leaks actually contribute little to environmental pollution. The focus should be on the higher-impact groundwater issues.

To get to the heart of the matter, the government announced it will spend an additional $500 million on a three-pronged approach to address the groundwater issues: 1) Remove radioactive isotopes from contaminated water;  2) Keep tainted groundwater from entering the harbor and beyond; and 3) Keep untainted groundwater and radioactive water separate.

Removal of the radioactive particles is already an integral part of the makeshift cooling system discussed above – water cycled through the buildings to cool the fuel is passed through a filtration system that removes radioactive cesium. Radioactivity in the buildings’ basements is down a hundred-fold from its peak because of the constant dilutive effects of both this processed cooling water and the inflowing groundwater. Another filtration system called ALPS, an acronym for the Advanced Liquid Processing System, is being tested now and is intended to remove all the other radioactive elements except for tritium.

To prevent contaminated water from entering the harbor, a number of steps are being taken. These include redoubling efforts to seal off the trenches that run from the turbine buildings to the wharf (assumed to be the source of the most recent spikes in harbor radioactivity) and building a sea wall between the harbor and the groundwater adjacent to the stricken buildings.

The third prong is the most challenging: preventing the inflow into buildings of clean groundwater and the outflow of contaminated water. Engineering solutions considered include pumping out untainted groundwater before it flows beneath the damaged buildings and, more dramatically, building an ice wall around the affected reactor and turbine buildings. Weighing the potential benefit and likelihood of success of the measures tabled against their cost (and manpower), the ice-wall project, to which the government of Japan intends to commit $300 million, seems the most questionable.

Never has an ice wall been executed on such a scale and some experts question its potential efficacy. Indeed, it faces considerable challenges from the very outset. To start with, emplacement would be in an area of elevated radiation, making work difficult. Add to that the fact that care must be taken not to disrupt the more crucial makeshift cooling system, or the ongoing rubble-removal and spent fuel-pool defueling operations. Further, drilling operations will generate additional contamination that will also need to be processed and may actually increase groundwater contamination during construction. And once established, keeping the new web of hundreds of meters of coolant piping in operation will be manpower and energy intensive.

Assuming all goes as planned, the goal of the ice wall is actually fairly modest: to reduce the daily inflow of 400 tons of water into the basements, and to slow the underground flow of water below the reactor buildings. Finally, the ice wall is projected to take 18 months to build, during which time up to 200,000 tons more contaminated water will be added to the current inventory of almost 400,000 tons. Considering all of these factors, one wonders if an ice wall represents the best use of  $300 million.

Instead, the manpower and resources could be focused on strengthening or accelerating other key projects already in progress: reducing the contamination in the basements with the eventual goal of sealing them; erecting a sea wall to contain radioactive matter that makes it to the shore; managing the filters and screens in the harbor; emptying and sealing the contaminated trenches; and pumping out clean groundwater uphill of the stricken buildings. These projects, which have been used successfully elsewhere to control water for other purposes are essential parts of the recovery roadmap, independent of the existence of the ice wall.

Another matter that requires debate is the question of whether to store contaminated water or release it into the sea. Although the government has set stringent environmental containment standards in a (honorable) bid to reassure the public, doing so also raises expectations to an unrealistic level and entails greater difficulty and exponentially greater expense. As was the case with Waterworld, setting expectations so high encourages the impression of failure for falling short. Right now, water can only be discharged if it meets standards that are nearly as strict as those for drinking water. Drinking water standards for the radioisotope cesium are 10 Becquerels per liter (Bq/L). For Fukushima (only), the clean groundwater discharge limit is <1 Bq/L, and for all other discharges the limit has been set to 25 Bq/L. To help put this into context, the amount of natural radioactivity from potassium in the average person’s urine is on the order of 50 Bq/L. (No fear – there are no discharge limits for potassium.)

Because of these standards, even rainwater contaminated only slightly by cesium and already on the ground must be retained. This means putting money into building more tanks, using up more manpower and, by the laws of probability, having more leaks (with the anxiety-inducing news articles that tend to follow). Moreover, a recent scandal suggests a number of the tanks were built hastily using mechanical (bolted) fittings with poor quality control. These tanks have experienced some leakage and a major effort is underway to replace them with better tanks with welded fittings. Thus, there is a case to be made for lowering the discharge standards to international norms, attenuating the overall water burden. Focusing the overtaxed workforce on more important projects than tank farm expansion and maintenance will likely produce a better long-term result.

Some experts, including Lake Barrett, a former head of the U.S. Department of Energy’s Office of Civilian Nuclear Waste Management, and Joonhong Ahn, Professor of Nuclear Engineering at the University of California, Berkeley, argue that the water, filtered of the vast majority of radioactive isotopes (except tritium), could be diluted and safely discharged (or evaporated away). Once the discharge enters the sea, the concentrations of the contaminants dilute quickly – radioactive elements have rarely been detected in samples taken beyond half a kilometer from the harbor. Whereas the government has asked the international community for advice on how to stop contamination releases, it might be better served to seek out recommendations on more reasonable discharge standards specifically tailored for Fukushima, based on studies from other contaminated sites (such as outlined in the IAEA’s Worldwide Marine Radioactivity Studies (WOMARS)).

Significant domestic opposition to any discharge of contamination will likely continue, even if scientific public-health risk assessments were to support such measures. Local fishermen are particularly vocal and understandably concerned. Contributing to the public’s fear is the persistence of radioactive cesium on the local seabed and the impact on bottom-dwelling fish and crustaceans, as well as the frequent distorted news stories in the press. Some of these fish have been found with radioactive cesium concentrations exceeding food radiation standards, causing reluctance to buy any fish from this region (South Korea, for instance, has recently banned its import). Even some migrating tuna far across the Pacific have presented minute cesium levels, though well below food radiation limits and far eclipsed by radioactivity from naturally occurring polonium. An important and oft overlooked point is that food radiation limits are established not as safety limits, but are derived to keep a person’s overall exposure low and within conservative radiation exposure limits.

Hosting the 2020 Olympics imposes an additional level of pressure on the Japanese government. The image Japan projects overseas is critically viewed through this lens, and discharging radioactive water from Fukushima – irrespective of the concentration – would be heavily scrutinized.

This extraordinarily difficult water situation puts the Japanese government in a quandary. In an ideal world, the government would be able to retain all the nuclear plant’s contamination and win back the public’s confidence. But in reality there are limits – in money, time, and people, among other areas. As the guardian of the people’s health and economic welfare, the government should weigh the positive impact on public health of these measures against the monetary cost, plant workers’ health and the chances of success. Clearly the public must be involved in this debate.

Contrary to how we widely remember Waterworld as a flop, the story was not over in 1995; steady gains in the longer term made up for the short-term box office losses. Waterworld, as it turns out, was a success – it just took time. In the two and half years since the accident at Fukushima, steady improvement has been made and the most dangerous aspects seem to be under control. Certainly there is a long, hard and costly journey ahead towards solving these complex water issues. However, if the public is brought fully on board, the effort need not end in failure.

Reid Tanaka, who has more than 25 years of experience in nuclear issues in the U.S. Navy, served as a nuclear advisor to the commander of the U.S. military forces in Japan and to the U.S. Ambassador to Japan during the Fukushima nuclear crisis. David Roberts, a former academic physicist, served as the science advisor to the U.S. Ambassador to Japan during the post-Fukushima recovery.

This story, and the sidebar that follows, appeared in the November issue of Newsweek Japan.

Getting a Sense for Radiation

As described in the accompanying article, the Fukushima Daiichi Nuclear Power Plant is struggling with water contamination problems. Much time and resources are being spent on the extraordinarily difficult task of controlling and containing the water at the stricken site, but decisions to undertake such resource-intensive projects should be opened for informed public debate.

One difficulty here is that radiation (by which we mean ionizing radiation in this article) incites a particular brand of fear, one that arises from our inability to detect it with our five senses. Quite different from a hot stove, where we can feel the heat and can withdraw before being burned, we receive no such immediate indication with growing levels of radiation. Science (and history) tells us that very high levels of radiation are harmful or even fatal and also that, at the other extreme, we live our everyday lives in low-level radiation from natural sources. We can accept both of these book-end concepts; it is the range in between where our inability to sense radiation handicaps our understanding.

Thus we offer a rough analogy to chlorine in the hope that it will help give a sense of the impact of different levels of radiation and how the contamination disperses or dilutes. However, we suggest that readers be skeptical of this and all Fukushima analogies, given how, in this sensitive topic, comparisons tend, wittingly or not, to distort.

Chlorine, like radiation, is fatal in high concentrations, and innocuous in low concentrations. We live normally in the low concentration world of chlorinated drinking water (and naturally occurring background radiation). Between high and low is a wide range of concentrations that have varied effects on our health – skin burns from a bleach spill, dry hair from a chlorinated swimming pool, and a funny taste in some drinking water are familiar experiences. A range of effects is also true of radiation.

Of course, there are numerous ways in which the analogy with chlorine does not work. For instance, radiation can’t be directly sensed, while chlorine can be detected by smell well before it is harmful; unlike various radioactive isotopes which persist, chlorine is a reactive chemical; and in contrast to higher levels of radiation known to have carcinogenic affects, chlorine is not thought to be carcinogenic (although many of its by-products, such as chloroform, are).

With this in mind, we apply the analogy to get a rough idea of the effects of dose and dilution. Imagine deadly chlorine gas when thinking of the stricken reactor buildings: worker access is severely limited. Think of industrial-strength and household bleach when dealing with water processing systems and storage tanks: workers should wear protective clothing and masks, and risk burns or asphyxiation if handled improperly, but the chlorine is otherwise manageable with the appropriate precautions. In the vicinity of the sea-intake pipes in the harbor, think of a heavily chlorinated swimming pool.

Although there is much to be learned regarding the long-term impacts the contamination might have on the marine environment (particularly the seabed), the sea area within 1 km outside the harbor periodically contains barely detectable levels. To continue with the analogy, think of this sea area like chlorine in drinking water – sometimes it has a distinctive taste, other times it is undetectable. Thus, a chlorine leak may start in quite concentrated form, but will diffuse and dilute as it gets into the ground or is washed by rain and drains to the sea. The water-borne radioactive matter at Fukushima behaves similarly.

The leaks and spills at Fukushima have some features in common with a major chemical spill. Initial fear is natural and, as information rolls out, the public becomes rightfully alarmed, concerned and even angry. More often than not, however, we learn that the direct and immediate risks of these leaks and spills are primarily to the workers and not to the public at large.

Reid Tanaka, who has more than 25 years of experience in nuclear issues in the U.S. Navy, served as a nuclear advisor to the commander of the U.S. military forces in Japan and to the U.S. Ambassador to Japan during the Fukushima nuclear crisis. David Roberts, a former academic physicist, served as the science advisor to the U.S. Ambassador to Japan during the post-Fukushima recovery.

This sidebar, and the main article that preceded it, appeared in the November issue of Newsweek Japan.