Here’s the latest of our news bulletins from the ongoing crisis at Japan’s Fukushima Daiichi nuclear power plant.

State of the Fukushima Reactors

Sunichi Tanaka, Chairman of Japan’s Nuclear Regulation Authority (NRA), said this week that his agency is prepared to inspect reactor #1 at the Fukushima Daiichi plant for damage sustained during a magnitude 9.0 earthquake in March 2011. “We want to begin an investigation soon,” Tanaka confirmed, but he acknowledged that high radiation levels in the building might provide challenges with that task.

His statement came after a former member of the parliament’s Fukushima Nuclear Accident Independent Investigation Commission, Kiyomi Tsujimoto, charged TEPCO with intentionally obstructing the investigation. In recorded conversations with members of the panel, TEPCO officials said that a cover constructed over the reactor to prevent radiation from entering the atmosphere rendered the area so “pitch-black” dark that it would be too dangerous for humans to navigate the building. In fact, the reactor cover did allow sunlight to filter in, and the cover was equipped with five mercury bulbs equivalent to the light emitted by 40 automobiles, as well as backup lighting.  

Earlier in the week, TEPCO president Naomi Hirose apologized for the incident but insisted that it was the fault of one official who got his facts wrong, rather than a coordinated, institution-wide effort to mislead the Diet panel. If earthquake damage is discovered, it will have a major impact on reactor restarts nationwide, in a country that is riddled with seismic fault lines.

Meanwhile, TEPCO is insisting that the spent fuel pool at Fukushima Daiichi’s reactor #4 will be safe even if more earthquakes strike the region, despite major damage incurred by the building during the March 2011 hydrogen explosion, including one wall that is now bulging. The reactor building stores over 1500 fuel rods on the fourth floor; if an earthquake struck and water leaked from the pool, the rods could overheat and cause a massive nuclear disaster. Collapse of the entire structure is also a concern. TEPCO said that the seismic fitness assessment was done by a single external expert, but failed to identify the person by name, prompting some journalists, including at public news network NHK, to question whether or not the recommendation was objective and can be trusted.

Nuclear Regulation Authority

The NRA has begun an onsite investigation at the Monju fast-breeder reactor in Fukui Prefecture—by the agency’s own admission, a serious acknowledgement of significant concerns—after more safety issues surfaced last week. The Monju reactor has had a long history of expensive problems since construction first began in 1986, including in 1995, when sodium coolant leaked and the fuel reached dangerously high temperatures.

The move comes in response to an admission to the NRA by the reactor’s operator, Japan Atomic Energy Agency (JAEA), that it submitted erroneous reports to the NRA, claiming that safety checks had been conducted on five pieces of equipment at the reactor when, in fact, they had not. Some of the neglected equipment includes an emergency diesel generator, crucial for keeping fuel cool in case external power is lost, and an electromagnetic flow meter for sodium, which is used to monitor whether coolant is flowing through the reactor at an appropriate rate. Last year, JAEA failed to perform checks on 9,847 pieces of equipment. A team of eight NRA officials are currently doing onsite interviews at the facility and reviewing documents.

Nuclear Politics in Japan

Japan is planning to revamp its Basic Act on Disaster Control Measures, in order to better monitor and manage the safety and evacuation of populations who need assistance in time of disasters, including the elderly and handicapped. In particular, officials hope to establish mandatory registration of all residents unable to evacuate on their own, so that welfare organizations can provide assistance if needed. During the Fukushima nuclear crisis, many municipalities were unable to identify those who required help. Current government guidelines advise creating and maintaining such directories, but the recommendation is not legally binding, and only 60% of cities and towns have done so. In response to privacy concerns, officials are discussing only allowing social welfare organizations to use the contact information in case of disaster, and are considering working with electronic privacy companies to safeguard personal data.

Radiation Contamination, Including Human Exposure

A panel appointed by Fukushima prefectural officials studying the effects of radiation on children who were younger than 18 years old when the nuclear disaster there first began to unfold announced this week that they have now confirmed three cases of thyroid cancer in children who have undergone health screenings. Approximately 360,000 young people are eligible for the health checks, but only 38,000 were examined through fiscal year 2011. An additional seven cases of other forms of cancer have also been identified. That number could rise; Shinichi Suzuki, a panelist and professor at Fukushima Medical University, cautions that thyroid cases did not begin to appear until four to five years following the Chernobyl disaster in 1986.

However, some researchers are now questioning the study methods used to determine the thyroid doses, which are based on estimates of exposure to radioactive iodine, rather than actual measurements. Earlier this year, researchers from the National Institute of Radiological Sciences (NIRS) estimated that 90% of the prefecture’s children were exposed to less than 30 millisieverts of iodine, lower than the international limit. Because iodine has such a short half-life, scientists had to make estimates of how much the children’s bodies absorbed and the amount that might have accumulated in their thyroid glands. There are various schools of thought on the best way to calculate that data, including whether or not just one ratio should be applied to all children.