Bleak hardly does justice to assessments of Fukushima Prefecture's future over the long term.
A massive injection of government funds will be needed to remove soil contaminated by the nuclear disaster and to revitalize the local economy.
Decommissioning the Fukushima No. 1 nuclear power plant is another proposition altogether. The cost of doing that could run into trillions of yen, and the project would take decades to complete.
What is clear is that radiation levels will still be a problem in some areas 30 years from now, according to a study by the Research Center for Nuclear Physics at Osaka University.
There are a number of scenarios, none of them good. According to one calculation, it may be necessary to strip--and possibly remove--entire mountainsides to remove contaminated soil.
There are also serious concerns about whether depopulation is now a reality.
One estimate of radiation levels in March 2041 suggests that airborne contamination will be 85 percent less than at current levels.
According to the study, high radiation levels will likely persist in vicinities around the stricken Fukushima No. 1 plant as well as in an area some 30 kilometers northwest of the facility.
The calculations suggested there would be about 100 locations where radiation levels exceeded 1 microsievert per hour, which works out to 8.76 millisieverts on an annual basis.
The calculations were based on soil studies done last June at roughly 2,200 locations within a 100-kilometer radius of the Fukushima No. 1 plant in the prefectures of Fukushima, Miyagi, Ibaraki and Tochigi.
The study, carried out by universities and research institutes around Japan, found equal parts of cesium 134 and cesium 137. Cesium 134 has a half-life of two years, but cesium 137 has a half-life of 30 years.
This led researchers to conclude that cesium levels would fall significantly after a decade because of the cesium 134 with the short half-life.
Cesium levels are forecast to decrease by 60 percent after five years, by 70 percent after 10 years and by 85 percent after 30 years.
The figures could change because they were calculated on the basis that radiation would not spread further due to rain or wind and on the assumption that decontamination efforts would not be carried out.
After 30 years, it was forecast that the area with the highest radiation level would likely be the Chojahara district of Okuma in Fukushima Prefecture.
The district is located about 2 kilometers west of the Fukushima No. 1 plant and is forecast to have radiation levels of 10.32 microsieverts per hour, which works out to 90.4 millisieverts on an annual basis.
Researchers also estimated that it would take 126 years for the radiation level in that district to fall to 1 microsievert.
Twelve locations in the Fukushima Prefecture municipalities of Okuma, Futaba, Namie and Katsurao were estimated to have radiation levels of between 5 and 10 microsieverts per hour.
Researchers said an additional 80 locations in Fukushima Prefecture would have radiation levels of between 1 and 5 microsieverts per hour, which works out to 8.76 and 43.80 millisieverts on an annual basis.
Those spots are located in the four municipalities as well as Minami-Soma and Tomioka. All of those municipalities are located either close to the Fukushima No. 1 plant or northwest of the plant.
Those are the only six municipalities where radiation levels 30 years down the road are expected to exceed 1 microsievert per hour.
Isao Tanihata at the Osaka research center's Cosmonuclear Physics Division, said, "Even by looking at trends in the year after the nuclear accident, the cesium in the soil has generally remained in place so it is highly likely that most of the radiation will continue to remain in the same location in the future."
The center has posted the results of its calculations on its website (http://www.rcnp.osaka-u.ac.jp/dojo/).
An area in Fukushima Prefecture covering some 500 square kilometers currently has airborne radiation readings that exceed 20 millisieverts over the course of a year.
Radiation levels there will continue to be above a few millisieverts per year after 30 years if nothing is done. For this reason, decontamination offers the only hope of bringing down radiation levels to those that existed before the nuclear accident.
Under a road map for decontamination released by the central government, work will begin this year to remove topsoil from areas where radiation levels are between 20 and 50 millisieverts. However, no plans are in place for locations where radiation levels exceed 50 millisieverts.
An Environment Ministry official offered this explanation: "There is the possibility that radiation levels may not fall even if the area is decontaminated."
The science ministry and the Cabinet Office will decide if it is technically feasible to decontaminate after assessing the outcome of an experimental project to cleanse areas with high radiation levels.
The results of that project will likely not be known until next year at the earliest.
Meanwhile, there is some hope for removing cesium from the soil by using chemicals. But this could have unintended side effects.
Mamoru Fujiwara, an associate professor at the Experimental Nuclear Physics Division at the research center who was also involved in the calculations of radiation levels after 30 years, said chemical processing would destroy nutrients in the soil.
"There would be no use for the soil that remained since not even grass would grow on it," Fujiwara said.
Even if the soil on plots where private homes stand was completely decontaminated, there would still be the issue of radioactive materials contaminating the sites from surrounding areas within a radius of several dozens of meters.
The effects from surrounding areas will be especially high for mountainous ones, where radiation levels are high.
Tanihata said, "There may be a need for drastic action, such as removing large sections of mountains and valleys, including the vegetation found there."
However, if such steps were taken, it would greatly increase the volume of decontaminated waste.
Before these calculations were made, the Environment Ministry estimated that the maximum volume of decontaminated waste would reach 28 million cubic meters.
It would require a rethink on the size of the intermediate storage facility for the waste, which is now estimated would cover an area of between 3 and 5 square kilometers.
It would also require far greater government expenditures than the 1 trillion yen ($12.3 billion) or so now earmarked for decontamination purposes, leaving aside the cost of constructing that storage facility.
Other estimates also predict a gloomy picture for the future population of Fukushima Prefecture.
The Great East Japan Earthquake and the Fukushima nuclear disaster caused 63,000 residents to flee the prefecture.
By age group, the largest outflows were among women who are in their child-bearing years as well as children who 30 years from now will be having their own families.
Even before last year's disasters, the population of Fukushima Prefecture had been declining from a peak of 2,138,454 reached in January 1998.
The question now is whether the evacuees will eventually return. If they do not, the pace of population decline will increase dramatically compared with the situation before the disasters occurred.
Kyoko Deguchi, an associate professor specializing in economic statistics at the National Graduate Institute for Policy Studies, estimated what Fukushima Prefecture's population would likely be in 30 years time by comparing population shifts between March and November 2011 among all prefectures with similar changes in the same period of the previous year.
If the effects from the natural disasters are included, Fukushima Prefecture's population is expected to decrease by 49.2 percent from the level in 2010 of 2,029,064. If the natural disasters had not occurred, the population decrease would only have been 36.2 percent. Her calculations suggest that the pace at which the prefecture's population declines will move up by about 10 years.
In addition, the graying of the prefecture's population is bound to become more marked.
The ratio of residents aged 65 and above in 2010 was 25 percent for Fukushima Prefecture, placing it about mid-range among all prefectures.
However, by using Deguchi's estimate for population decline, the ratio after 30 years would be 44.7 percent, much higher than the national average of 33.8 percent and making Fukushima Prefecture the most aged prefecture in the nation.
The prefecture's economy is now propped up by post-disaster growth in personal consumption and spending on public works projects.
However, that special demand will not last in the opinion of Shigeru Kuwahata, a researcher at the NLI Research Institute.
Kuwahata calculated economic growth rates based on the assumption that Fukushima Prefecture's working population decreased by 2 percent in fiscal 2011 and would not recover even after 30 years.
Given this scenario, he estimated that Fukushima's economy would have zero growth over the next decade, much lower than the national average of 0.6 percent annual growth.
Kuwahata said it was possible that Fukushima's economy would continue to be stagnant even 30 years in the future, with negative growth of 0.1 percent by that time.
"It will be impossible to have positive economic growth in the long term unless a work force is gathered," Kuwahata said. "There is a need to utilize special economic zones for rebuilding and consider such policy measures as bringing young people from the Tokyo metropolitan area who cannot find jobs because of a mismatch in the jobs available and their skills."
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