A Current View of Public Health and Safety Consequences of the
Fukushima Nuclear Event
Published in the RMEL Electric Energy Magazine, June 2011
By: Dr. K. Ronald Laughery Former President and founder of Micro Analysis and Design, Inc. and member of the American Nuclear Society Public Policy Committee
From the standpoint of public perception and, therefore, the future of the nuclear power, the central issue arising from the Fukushima nuclear power event will be how it affected public health and safety.
The Radiation Releases Examined
In an attempt to categorize and address radiation release issues, I reviewed the print and online media from the period of March 11 – April 10, 2011. I then gathered and analyzed radiation level and dispersion data from a variety of data sources including print and on-line media as well as Tokyo Electric Power Company (TEPCO) reporting sites. As appropriate, I compared these to different criteria for radiation exposure levels to make a determination of whether the radiation to which the public and workers at the site are being exposed presents health risks. From data collected, I developed the following five major categories of radiation issues:
o Increased Airborne Radiation Levels: based on Fukushima City Health Office’s radiation exposure data, I estimated a total of 4.2 milliSieverts (mSv) of radiation exposure outdoors from March 11th through April 12th. Using the conservative 65 percent shielding factor, I estimated that the highest radiation level that an individual who stayed indoors outside of the evacuation zone was exposed to was 3.7 mSv as of April 12th. While the Fukushima event is not over and future radiation levels will drive these exposure levels higher, my conclusion was that there will be minimal health effects to the public from airborne radiation barring some unforeseen radiation release event.
o Radiation Inside the Plant: Highest reported level was 1,000 mSv/h at a pool of water in turbine room of reactor two; Annual dose limit raised for workers during Fukushima emergency to 250 mSv/year; On April 1st, 21 workers were reported to have been exposed to levels of over the generally accepted limit of 100 mSv, but none over the 250 mSv limit. To date, there have been no reports of radiation-caused incapacitation from plant workers.
o Radiation Contaminated Food: On March 19th, tainted milk was found 30 km from the plant and tainted spinach was collected as far as 100 kilometers to the south. However, it was reported that the levels were such that, if a person consumed these products continuously for a year, their radiation exposure would be about that of a single CT scan (about 7mSv). Radiation levels were not found in all food tested. Past and future risk to public health from the food supply appears to be very small.
o Tokyo Water Supply Contamination: On March 22nd, 210 Becquerels of radioactive iodine per kilogram of water (Bq/kg) were measured in part of the Tokyo water supply. The limit for infants under 1 year old is 100 Bq/kg; the limit for humans > 1 year old is 300 Bq/kg. This led to a recommendation to infants and nursing mothers to stop drinking Tokyo tap water until dehydration concerns caused Japan's leading obstetrics and gynecological organization to say pregnant and nursing women should continue to drink tap water even if the levels of radioactive iodine rise up to 500 Becquerels.
o Release of Radioactive Water into the Ocean: An example of the data at all measurement locations on April 4th is presented in Figure 4. After the leak was plugged on April 6th, ocean radiation levels dropped rapidly. However, on April 5th, fish were caught near the plant that showed Cs-137 levels at twice the limit, and on April 10th, other fish were caught with lower amounts of Cs-137, but still over the limit. The Japanese government is monitoring the fish caught in this area of Japan to ensure that tainted fish do not make it into the food supply. Overall, the likely public health consequences of this radiation release appear minimal. The second source of seawater radiation contamination is from the release by TEPCO of low level radioactive wastewater into the sea to make space for storage of more radioactive wastewater. TEPCO officials estimated that adults who eat fish and seaweed exposed to this seawater daily for a year would receive approximately 0.6 mSv. As such, the public health and safety consequences of this second radiated water release appear minimal.
Summary
This is an ongoing event and the above analysis should be seen as a status report, not as the final word on radiation effects on the public from Fukushima. However, assuming radiation levels continue to drop and the government continues to be vigilant with respect to monitoring the food and water supplies, the net effect of the Fukushima event on the general public should be very small. Workers at the plant face the greatest risks, though with increased use of robots, careful staff management, and continued reductions in radiation levels at the facility, I believe that even these consequences will be limited.
Given the age of these reactors and the severity of the event that precipitated this – a 9.0 earthquake and the ensuing tsunami – I suggest that these limited effects on public health and safety are extremely encouraging with respect to the underlying safety of nuclear power.
By: Dr. K. Ronald Laughery Former President and founder of Micro Analysis and Design, Inc. and member of the American Nuclear Society Public Policy Committee
From the standpoint of public perception and, therefore, the future of the nuclear power, the central issue arising from the Fukushima nuclear power event will be how it affected public health and safety.
The Radiation Releases Examined
In an attempt to categorize and address radiation release issues, I reviewed the print and online media from the period of March 11 – April 10, 2011. I then gathered and analyzed radiation level and dispersion data from a variety of data sources including print and on-line media as well as Tokyo Electric Power Company (TEPCO) reporting sites. As appropriate, I compared these to different criteria for radiation exposure levels to make a determination of whether the radiation to which the public and workers at the site are being exposed presents health risks. From data collected, I developed the following five major categories of radiation issues:
o Increased Airborne Radiation Levels: based on Fukushima City Health Office’s radiation exposure data, I estimated a total of 4.2 milliSieverts (mSv) of radiation exposure outdoors from March 11th through April 12th. Using the conservative 65 percent shielding factor, I estimated that the highest radiation level that an individual who stayed indoors outside of the evacuation zone was exposed to was 3.7 mSv as of April 12th. While the Fukushima event is not over and future radiation levels will drive these exposure levels higher, my conclusion was that there will be minimal health effects to the public from airborne radiation barring some unforeseen radiation release event.
o Radiation Inside the Plant: Highest reported level was 1,000 mSv/h at a pool of water in turbine room of reactor two; Annual dose limit raised for workers during Fukushima emergency to 250 mSv/year; On April 1st, 21 workers were reported to have been exposed to levels of over the generally accepted limit of 100 mSv, but none over the 250 mSv limit. To date, there have been no reports of radiation-caused incapacitation from plant workers.
o Radiation Contaminated Food: On March 19th, tainted milk was found 30 km from the plant and tainted spinach was collected as far as 100 kilometers to the south. However, it was reported that the levels were such that, if a person consumed these products continuously for a year, their radiation exposure would be about that of a single CT scan (about 7mSv). Radiation levels were not found in all food tested. Past and future risk to public health from the food supply appears to be very small.
o Tokyo Water Supply Contamination: On March 22nd, 210 Becquerels of radioactive iodine per kilogram of water (Bq/kg) were measured in part of the Tokyo water supply. The limit for infants under 1 year old is 100 Bq/kg; the limit for humans > 1 year old is 300 Bq/kg. This led to a recommendation to infants and nursing mothers to stop drinking Tokyo tap water until dehydration concerns caused Japan's leading obstetrics and gynecological organization to say pregnant and nursing women should continue to drink tap water even if the levels of radioactive iodine rise up to 500 Becquerels.
o Release of Radioactive Water into the Ocean: An example of the data at all measurement locations on April 4th is presented in Figure 4. After the leak was plugged on April 6th, ocean radiation levels dropped rapidly. However, on April 5th, fish were caught near the plant that showed Cs-137 levels at twice the limit, and on April 10th, other fish were caught with lower amounts of Cs-137, but still over the limit. The Japanese government is monitoring the fish caught in this area of Japan to ensure that tainted fish do not make it into the food supply. Overall, the likely public health consequences of this radiation release appear minimal. The second source of seawater radiation contamination is from the release by TEPCO of low level radioactive wastewater into the sea to make space for storage of more radioactive wastewater. TEPCO officials estimated that adults who eat fish and seaweed exposed to this seawater daily for a year would receive approximately 0.6 mSv. As such, the public health and safety consequences of this second radiated water release appear minimal.
Summary
This is an ongoing event and the above analysis should be seen as a status report, not as the final word on radiation effects on the public from Fukushima. However, assuming radiation levels continue to drop and the government continues to be vigilant with respect to monitoring the food and water supplies, the net effect of the Fukushima event on the general public should be very small. Workers at the plant face the greatest risks, though with increased use of robots, careful staff management, and continued reductions in radiation levels at the facility, I believe that even these consequences will be limited.
Given the age of these reactors and the severity of the event that precipitated this – a 9.0 earthquake and the ensuing tsunami – I suggest that these limited effects on public health and safety are extremely encouraging with respect to the underlying safety of nuclear power.
