Comparison of Fukushima and Chernobyl nuclear accidents
The following table compares the nuclear accidents at Fukushima Daiichi (2011) and Chernobyl (1986) nuclear power plants.
| Plant Name | Fukushima Daiichi | Chernobyl |
|---|---|---|
| Location | Japan 37.6665°N 141.0208°E | Soviet Union (Ukrainian Soviet Socialist Republic) 51.38946°N 30.09914°E |
| Date of the accident | March 11, 2011 | April 26, 1986 |
| INES Level | 7 | 7 |
| Plant commissioning date | 1971 | 1977 |
| Years of operation before the accident | 40 years | 9 years |
| Electrical output | plant: 4.7 gigawatts; reactor 1 is rated 439 MWe, reactors 2-3 are 784 MWe each, and reactor 4 was in cold shutdown | plant: 4 gigawatts; 925 MWe rated power per reactor |
| Type of reactor | Boiling water reactor with containment vessel. Reactor 1 is a BWR-3; the rest are BWR-4. | RBMK-1000 graphite moderated, 2nd generation reactor without containment |
| Number of reactors | 6; 4 (and spent-fuel pools) involved in accident | 4; 1 involved in accident |
| Amount of nuclear fuel in reactors | 4 reactors - 1852 tons (274 tons in reactors + 409 tons in reactor storage pools and 1169 tons in central pool)[1] | 1 reactor - 245 tons[2] |
| Cause of the accident | Faulty design concerning the likelihood of tsunamis in that area. Loss of cooling systemdue to earthquake and tsunami destroying power lines and backup generators, leading tomeltdown. Failure to plan for total loss of off-site power and back-up power. | Faulty design leading to instability at low power (positive void coefficient), along with poor safety culture, leading to prompt criticality and steam explosion during an improvised experiment. |
| Maximum level of radiationdetected | 72.9 Sv/h (Inside Reactor 2)[3] | 300 Sv/h shortly after explosion in vicinity of the reactor core[4] |
| Radiation released | 900 PBq "into the atmosphere in March last year [2011] alone"[5][6] up from previous estimates of 370 PBq total. As of 2014, a peer reviewed estimate of the total was 340 to 800 PBq, with 80% falling into the Pacific ocean.[7] Radiation continues to be released into the Pacific via groundwater, as of 15 September 2013. | 5.2 EBq (5,200 PBq) [8][9] |
| Area affected | Radiation levels exceeding annual limits seen over 60 kilometres (37 mi) to northwest and 40 kilometres (25 mi) to south-southwest, according to officials. Plus Pacific Ocean (accurate data not available) | An area up to 500 kilometres (310 mi) away contaminated, according to the United Nations[citation needed] . |
| Exclusion ZoneArea | 20 km (30 km voluntary) | 30 km |
| Population relocated | 300,000 | About 115,000 from areas surrounding the reactor in 1986; about 220,000 people from Belarus, theRussian Federation and Ukraine after 1986 (335,000 people total) |
| Direct fatalities from the accident | 2 crew members (gone to inspect the buildings immediately after the earthquake and before the tsunami) due to drowning | 31; 64 confirmed deaths from radiation as of 2008[10] |
| Current status | Cold shutdown declared on 16 December 2011, but decommissioning is likely to take 30 to 40 years.[11][12] 85% of fuel rods in reactor 4 pool removed; completion expected by 31 December 2014. | All reactors were shut down by 2000. The damaged reactor is covered by a hastily built steel and concrete structure called the sarcophagus. A New Safe Confinement structure is under construction and expected to be completed in 2015, from which the plant will be cleaned up and decommissioned. |
Last update 4 September 2013.
| report- date | place | period of disposal | Iod-131 (TBq) | Caesium-137 (TBq) | source | ||
|---|---|---|---|---|---|---|---|
| from | to | from | to | ||||
| 2002 | Chernobyl | 25 April – June 1986 | 1 600 000 | 1 920 000 | 59 000 | 111 000 | NEA[13] |
| 22 March 2011 | Fukushima | 12 – 15 March 2011 | 400 000 | 3 000 | 30 000 | ZAMG[14] | |
| 2 April 2011 | Fukushima | 12 – 19 March 2011 | 10 000 | 700 000 | 1 000 | 70 000 | ZAMG [15] |
| 12 April 2011 | Fukushima | 11 March – 5 April[16] | 150 000 | 12 000 | NSC[17] | ||
| 12 April 2011 | Fukushima | 11 – 17 March 2011 | 130 000 | 6 100 | NISA [17] | ||
| 7 June 2011 | Fukushima | 11 – 17 March 2011 | 160 000 | 15 000 | NISA[18] | ||
| 24. August 2011 | Fukushima | 11 March – 5 April | 130 000 | 11 000 | NSC[19] | ||
| 15 September 2011 | Fukushima | March - September | 100 000 | 200 000 | 10 000 | 20 000 | Kantei[20] |
| report- date | place | period of disposal | amount (TBq) | source |
|---|---|---|---|---|
| 12 April 2011 | Chernobyl | 25 April – June 1986 | 5 200 000 | NISA[17] |
| 12 April 2011 | Fukushima | 11 March – 5 April 2011 | 630 000 | NSC[16][17] |
| 12 April 2011 | Fukushima | 11 – 17 March 2011 | 370 000 | NISA[17] |
| April 2011 | Fukushima | 4 April 2011 | 154 | NSC[16] |
| 25 April 2011 | Fukushima | 24 April 2011 | 24 | NSC[16] |
| 6–7 June 2011 | Fukushima | 11 – 17 March 2011 | 770 000 | NISA[21]>[18] |
| 7 June 2011 | Fukushima | 11 – 17 March 2011 | 840 000 | NISA[22] and published over press.[21] |
| 17 August 2011 | Fukushima | 3–16 August 2011 | 0.07 | Government[23] |
| 23 August 2011 | Fukushima | 12 March - 5 April 2011 | 630.000 | NISA[24] |
| report date | period of disposal release | entry into sea (TBq) | source | |
|---|---|---|---|---|
| direct | indirect | |||
| 21 May 2011 | 1 – 6 April 2011 | 4 700 | Tepco[25] | |
| End August 2011 | March – August 2011 | 3 500 | 16 000 | JMA[26] |
| 8 September 2011 | March – April 2011 | 15 000 | Scientist Group[27] | |
| 29 October 2011 | 21 March – 15 July 2011 | 27 100 | IRSN[28] | |
Food affected by Fukushima disaster harms animals, even at low-levels of radiation, study shows
Butterflies eating food collected from cities around the Fukushima nuclear meltdown site showed higher rates of death and disease, according to a study published in the open access journal BMC Evolutionary Biology.
Researchers fed groups of pale blue grass butterflies (Zizeeria maha) leaves from six different areas at varying distance from the disaster site, and then investigated the effects on the next generation. Feeding offspring the same contaminated leaves as their parents magnified the effects of the radiation. But offspring fed uncontaminated leaves were mostly like normal butterflies, and the authors say this shows that decontaminating the food source can save the next generation.
The 2011 meltdown at the Fukushima Dai-ichi nuclear power plant released substantial amounts of radiation into the surrounding area. Humans were evacuated, and no significant health effects have been reported, but the scientists from the University of the Rukyus, Okinawa, Japan, are studying the impact on the area's wildlife.
In a previous study, the group suggested that eating leaves with high levels of radiation seriously affected the pale grass blue butterfly. Their new study investigated the effect of eating leaves with much lower levels of radiation, which had been collected in 2012, a year after the disaster, from six areas that were 59km to 1760km from the site.
Their study showed that even in these comparatively low levels of radiation, there was an observable difference in the butterflies' lifespan, depending on the dose of caesium radiation in their food, which ranged from 0.2 to 161bq/kg. For comparison, leaves collected in the months after the disaster around 20km from the site had radiation in the thousands of Bq/kg. Butterflies fed leaves with higher caesium radiation doses were also smaller and some had morphological abnormalities such as unusually shaped wings.
Professor Joji Otaki, University of Rukyus, says: "Wildlife has probably been damaged even at relatively low doses of radiation, and our research showed that sensitivity varies among individuals within a species."
In the second part of the experiment, the researchers looked at the next generation of butterflies. These were split into groups fed an uncontaminated diet, and those fed the same diets as their parents.
The offspring fed an uncontaminated diet had a similar lifespan, irrespective of the amount of radiation their parents had been exposed to. The only effect seemed to be that those whose parents had been exposed to higher caesium diets had smaller forewings. But those fed the same contaminated diet as their parents showed magnified effects.
The authors say that this shows that the effects of eating contaminated food can be significant, and that they can be passed on, but are minimized if the next generation have an unaffected diet.
Professor Otaki says: "Our study demonstrated that eating contaminated foods could cause serious negative effects on organisms. Such negative effects may be passed down the generations. On the bright side, eating non-contaminated food improves the negative effects, even in the next generation."
Story Source:
The above story is based on materials provided by BioMed Central. Note: Materials may be edited for content and length.
Journal Reference:
- Chiyo Nohara, Wataru Taira, Atsuki Hiyama, Akira Tanahara, Toshihiro Takatsuji, Joji M Otaki. Ingestion of radioactively contaminated diets for two generations in the pale grass blue butterfly. BMC Evolutionary Biology, 2014; 14 (1): 193 DOI:10.1186/s12862-014-0193-0
Radiation exposure linked to aggressive thyroid cancers, researchers confirm for the first time
For the first time, researchers have found that exposure to radioactive iodine is associated with more aggressive forms of thyroid cancer, according to a careful study of nearly 12,000 people in Belarus who were exposed when they were children or adolescents to fallout from the 1986 Chernobyl nuclear power plant accident.
Researchers examined thyroid cancers diagnosed up to two decades after the Chernobyl accident and found that higher thyroid radiation doses estimated from measurements taken shortly after the accident were associated with more aggressive tumor features.
"Our group has previously shown that exposures to radioactive iodine significantly increase the risk of thyroid cancer in a dose-dependent manner. The new study shows that radiation exposures are also associated with distinct clinical features that are more aggressive," said the paper's first author, Lydia Zablotska, MD, PhD, associate professor in the Department of Epidemiology and Biostatistics at UC San Francisco (UCSF). The paper will be published online in the journal Cancer.
Zablotska said the findings have implications for those exposed to radioactive iodine fallout from the 2011 nuclear reactor incidents in Fukushima, Japan, after the reactors were damaged by an earthquake-induced tsunami.
"Those exposed as children or adolescents to the fallout are at highest risk and should probably be screened for thyroid cancer regularly, because these cancers are aggressive, and they can spread really fast," Zablotska said. "Clinicians should be aware of the aggressiveness of radiation-associated tumors and closely monitor those at high risk."
Chernobyl studies led by Zablotska also showed for the first time that exposures to the radioactive iodine after the Chernobyl nuclear plant accident are associated with a whole spectrum of thyroid diseases, from benign to malignant. Benign encapsulated tumors of the thyroid gland are called follicular adenomas, and are treated in the same way as thyroid cancer -- by removing the thyroid gland, then giving patients pills to replace the hormones that are lost. Lifelong hormone supplementation treatment is both costly and complicated for patients.
Thyroid cancer is ordinarily rare among children, with less than one new case per million diagnosed each year. Among adults, about 13 new cases will be diagnosed each year for every 100,000 people, according to the Surveillance, Epidemiology and End Results (SEER) Program of the National Cancer Institute (NCI). But in the Belarus cohort, the researchers diagnosed 158 thyroid cancers among 11,664 subjects during three rounds of screening. Those who had received higher radiation doses also were more likely to have solid or diffuse variants of thyroid cancer, as well as to have more aggressive tumor features, such as spread to lymphatic vessels and several simultaneous cancer lesions in the thyroid gland.
Story Source:
The above story is based on materials provided by University of California, San Francisco (UCSF). The original article was written by Laura Kurtzman. Note: Materials may be edited for content and length.
Journal Reference:
- Lydia B. Zablotska, Eldar A. Nadyrov, Alexander V. Rozhko, Zhihong Gong, Olga N. Polyanskaya, Robert J. McConnell, Patrick O'Kane, Alina V. Brenner, Mark P Little, Evgenia Ostroumova, Andre Bouville, Vladimir Drozdovitch, Viktor Minenko, Yuri Demidchik, Alexander Nerovnya, Vassilina Yauseyenka, Irina Savasteeva, Sergey Nikonovich, Kiyohiko Mabuchi, Maureen Hatch.Analysis of thyroid malignant pathologic findings identified during 3 rounds of screening (1997-2008) of a cohort of children and adolescents from belarus exposed to radioiodines after the Chernobyl accident. Cancer, 2014; DOI:10.1002/cncr.29073
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