The fourth anniversary of the multiple meltdowns at the Fukushima Daiichi no. 1 power plant passed in relative quiet, but events there have hardly become less troubling. The good news first: TEPCO and its contractors have now completed the move of all spent and fresh fuel from the high and wide-open secondary containment of reactor Unit 4 to a safer ground-level location. They performed the work on time and almost without incident, despite the fears of many nuclear scientists and policymakers. Removal of molten fuel debris in Units 1, 2, and 3 will be more challenging, but Japan’s extensive experience with robotics should be helpful there, says Dr. Dale Klein, former chairman of the US Nuclear Regulatory Commission and now chair of TEPCO’s Nuclear Reform Monitoring Committee.
A team of 15 experts from the International Atomic Energy Agency looked on the bright side in the draft of its recent third review of decommissioning efforts at Fukushima. They found progress in the following areas as well as the fuel maneuver:
- The creation in 2014 of an exclusive new branch of TEPCO, Fukushima Daiichi Decontamination and Decommissioning Engineering Company, to manage on-site radioactive waste management and decommissioning activities.
- The establishment of the Nuclear Damage Compensation and Decommissioning Facilitation Corporation.
- Improvements in the situation on-site:
Improvement and expansion of systems to clean contaminated water;
- Installation of new, improved tanks to store contaminated water;
- Operation of an underground water bypass system; and
- Cleanup of the site, reducing radiological dose to the workforce.
The report also cited some of the remaining challenges:
- Persistent underground water ingress to main buildings and the accumulation of contaminated water on-site;
- Need for a more sustainable solution than the current practice of storing contaminated water ;
- Long-term management of radioactive waste; and
- Removal of spent nuclear fuel, damaged fuel, and fuel debris.
Late in February, a fresh leak developed near a gutter that pours rain and groundwater to a bay adjacent to the Japan nuclear facility. It generated a contamination level reportedly between 50 and 70 times higher than the regular readings. Plant personnel blocked the gutter. Ditch water around tanks at the plant showed a relatively high level of radioactivity several weeks later. This water may have spilled into the sea. In March, 750 tons of strontium 90-contaminated water is said to have seeped from the tank area into the ground. A couple of days ago, technicians found a tiny leak under a storage tank measuring 70 millisieverts per hour of beta ray-emitting radioactivity.
About 160 million gallons (600,000 cubic meters) of contaminated water are now stored in tanks at the Fukushima site. The amount grows by 300 cubic meters daily because engineers have not been able to stop groundwater seeping into the damaged reactors. As we reported in an earlier story, attempts have even included even trying to freeze the ground around them. TEPCO and its contractors have installed several systems to treat this now-contaminated water and have had some success with many radioactive materials, including cesium and strontium. The company has said that 90% of stored water would be processed through those systems by the end of May, two months later than the original deadline.
Radioactive tritium is another concern. The existing systems can’t remove tritium, which is not as dangerous as cesium or strontium but still causes concern in both the fish industry and its customers. The US Environmental Protection Agency views tritium as one of the least dangerous radionuclides, and the UN nuclear watchdog IAEA even recommended releasing the tritiated water into the ocean. Release has some potential international repercussions also, notably with South Korea and China. Japan currently regulates both the concentration of tritiated water that can be released and the annual total volume. The amount of tritium it has on hand now is 40 times the annual release limit. The government has formed a task force to study the issue.
The Los Angeles Times quotes Edwin Lyman, coauthor of Fukushima: The Story of a Nuclear Disaster and a nuclear expert at the Union of Concerned Scientists, as saying that the post-accident management of water “has been a lot more complex than anyone imagined. If they are going to be restarting plants in Japan, they need to think harder about it.”
Kurion, a California company that TEPCO contracted with last year on water contamination, says it has a system that can separate tritium from water, but it must be scaled up to deal with volume present at Fukushima. Its president believes that the process would take 5-8 years. Setup would cost about $1 billion and operating costs would be several hundred million dollars a year.
TEPCO now estimates that decommissioning will involve an additional unforeseen $8.7 billion over the next 10 years for “unanticipated” expenses. About 7,000 people onsite are at work on it. High radiation precludes any human entry to some structures. In April, two robots were sent into the Unit 1 reactor to examine and record the condition around the pressure vessel, and this summer, another small bot will explore the center of the inner containment vessel of Unit 2 to assess the condition of melted fuel there. Sixteen robots have been used to date.
So far, TEPCO has been able to reduce contaminated water production by about 100 tons per day. Review TEPCo’s 199th news release (May 1) for more information on the current state of accumulated radioactive water storage and treatment.
Making matters worse for Japan’s nuclear industry on the whole is this development reported by Kyodo News:
“The nation’s nuclear regulator determined… that a reactor at Japan Atomic Power Co.’s Tsuruga nuclear plant on the Sea of Japan coast sits right above an active geological fault, a conclusion that may force the operator to permanently shut down the unit.”
Another April development occurred in Fukui prefecture, where a court blocked Kansai Electric Power from restarting two reactors at its Takahama site, warning of “imminent danger” to the surrounding area if the reactors were restarted. But on April 22, a court on Kyushu, third-largest of the country’s four main islands, rejected vociferous attempts to block restarting of two reactors at Kyushu Electric’s Sendai plant because of active earthquake faults and a nearby volcano.
TEPCO has also been working on a restart of its seven-reactor Kashiwazaki-Kariwa nuclear plant, the world’s largest nuclear generating station by net electric power rating. Its last two units were the first advanced boiling water reactors ever built. At full power, the plant could generate enough electricity to supply 2.7 million households.
An offshore earthquake at Chūetsu in 2007 stressed the KK facility beyond its design limitations, which necessitated further earthquake-proofing for almost two years. (Poor communications about this event and measures to mitigate it preceded the distrust surrounding TEPCO’s management of the Fukushima disaster site.) Four reactors (Units 1, 5, 6, and 7) at Kashiwazaki-Kariwa then restarted. Power generation halted again in the general post-Fukushima disaster shutdown. The company has been working since then on massive improvements to the seawall and other aspects of the facility. Klein claims that these changes will make KK “the safest nuclear plant in the world.”
The Economist summarizes the situation: all of Japan’s 48 usable reactors are still offline, the country’s Nuclear Regulation Authority is reviewing about 20 reactors for regulatory compliance, and all are under suit by local interests. Although Prime Minister Shinzo Abe and his conservative Liberal Democratic Party would like to recoup the nuclear losses and limit the fossil fuel expenses, the government is now formulating a more modest energy plan that sees nuclear as a source of up to 20% of Japan’s electricity needs by 2030. We’ll see how it goes.
For ongoing news and background about Japan’s nuclear situation, link here.