As prefectures and municipalities that host or border nuclear plants upgrade their regional disaster prevention plans based on the nuclear disaster response guidelines for citizen evacuation protocols announced by the Nuclear Regulation Authority (NRA) in April, the problem of how to measure and prevent radiation exposure among evacuees continues to loom large.
“Reactor No. 1 (at the Fukushima No. 1 Nuclear Power Plant) had exploded, and the inside of the offsite center (which was established as the disaster response base of operations within Fukushima Prefecture) also had high radiation levels. The figures for the screenings we were conducting into whether or not residents had been exposed to radiation were raised immediately afterward.”
So recalls Tsuyoshi Ebine, 62, chief councilor in charge of nuclear power measures with the Nagasaki Prefectural Government. He was working for the secretariat of the Cabinet Office’s Nuclear Safety Commission at the time the nuclear accident occurred, and headed shortly thereafter to the town of Okuma in Fukushima Prefecture to begin engaging in disaster response measures at the offsite center amidst the unfolding chaos.
According to the Fukushima Prefectural Government and other bodies, standards that were in place prior to the nuclear accident held that decontamination procedures should be performed on anyone for whom radiation levels measured near the skin stood above 13,000 counts per minute (cpm). In the case of a one year-old child who had inhaled radioactive substances, this would be equivalent to the thyroid gland being exposed to 100 millisieverts of radiation. (The permissible level of radiation exposure for the average adult is one millisievert per year.)
Following the hydrogen explosion at the No. 1 reactor at the Fukushima plant, however, which took place on March 12, 2011 — dispersing enormous amounts of radioactive materials — screening centers for local evacuees were thrown into a state of total confusion. Escaping to safety became the top priority, and acceptable levels of radiation exposure were raised tenfold to some 100,000 cpm. Readings exceeded this level for a total of 102 residents — a figure, moreover, that represented only those cases that were recorded.
According to the NRA’s proposed measures for dealing with nuclear power disasters, the radiation exposure level at which decontamination is to take place is set at above 40,000 cpm for screenings conducted within one month following a nuclear accident.
“For residents, the objective is evacuation — and speed is top priority,” comments Shinichi Araki, who heads the department of nuclear emergency response and radioactive material protection at the NRA’s secretariat office. “Here, we are applying the lessons learned from the experience of evacuations following the nuclear accident in Fukushima.”
A manual was additionally compiled outlining guidelines for conducting examinations of residents leaving specific areas following exposure to radiation. Hair and shoes are identified in the manual as areas where such exposure generally occurs, and it is explained that if a water source is available, hair should be washed — and clothing should additionally be changed — in order to help bring radiation levels down. If subsequent testing reveals a figure below 40,000 cpm, the guidelines continue, the individual can then proceed to evacuate.
In cases whereby residents evacuate knowing that they have already been exposed to radiation, however, alleviating their concerns is difficult.
“I hope that trainings can be conducted in order to avoid the type of chaos that we saw following the Fukushima nuclear accident,” comments Araki. “The next step we must take is to allay the fears that exist among residents who have faced radiation exposure.”
Nagasaki Prefecture, where radiation exposure has been experienced from the atomic bombing, has been rapidly implementing measures for dealing with potential nuclear power accidents — with four of its cities lying within a 30-kilometer radius of the Kyushu Electric Power Company’s Genkai Nuclear Power Plant.
The prefecture revised its regional disaster prevention plan in June 2012, prior to the national government announcing its future disaster policy guidelines. Provisions were made within the prefectural supplementary budget for radiation-blocking stable iodine tablets, and revisions were made to its emergency radiation exposure medical manual the following year in 2013, including efforts such as increasing the number of medical facilities specializing in early-stage radiation exposure from two to at least three.
Still, however, Ebine comments, “Radiation prevention measures are lagging behind.” The number of medical team specialists remains insufficient, and plans are not in place for evacuations at social welfare facilities or other establishments of a similar nature.
“If there were to be an accident at the Genkai Nuclear Power Plant that resulted in residents being exposed to more than 40,000 cpm of radiation, it would not be enough to do as the government advises — which is to simply undertake decontamination until the figure falls below the target level,” Ebine adds. “It is preferable to continue decontaminating until the lowest possible radiation exposure levels are reached — but no (government) standards are in place in terms of the purpose and methods in this regard.”
The medical manual for radiation exposure that was put together by Nagasaki Prefecture includes information regarding concrete methods for decontamination, such as using moist towelettes to wipe away radioactive substances.
“Nagasaki Prefecture has experience with the eruption of the Fugen-dake peak of the Unzen volcano, and we also sent our employees to Fukushima Prefecture following the nuclear accident there,” notes Shinichi Yoshida, director of the prefecture’s crisis management department. “In addition, we have a framework in place based upon research conducted at Nagasaki University with respect to our history with the atomic bombing.”
“Following the Fukushima nuclear disaster, decontamination had to be undertaken with no available water source — and nobody there knew what was going on,” Yoshida added. “We must be ready for any possible contingency — and we have no choice but to make efforts to educate as many residents as possible about the realities of radiation.”