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°39′59″N 141°01′15″E / 37.6665°N 141.0208°E / 37.6665; 141.0208 Soviet Union (Ukrainian Soviet Socialist Republic) 51°23′22″N 30°05′57″E / 51.38946°N 30.09914°E / 51.38946; 30.09914
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 (plant)
2 years (Reactor 4)[1]
Electrical output plant: 4.4 gigawatts; reactor 1 is rated 439 MWe, reactors 2-6 are 784 MWe each, reactor 4 was in cold shutdown plant: 3.7 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 on site; 4 (and spent fuel pools) involved in accident; one of the four reactors was empty of fuel at the time of the accident. 4 on site; 1 involved in accident
Amount of nuclear fuel in reactors 4 reactors - 1852 tons (274 tons in three reactors + 409 tons in reactor storage pools and 1169 tons in central pool)[2] 4 reactors - ??? tons[3]
Cause of the accident The plants were not designed with consideration of such a large tsunami. A major earthquake and tsunami caused the destruction of power lines and backup generators. Once the plants were without external power and the generators were flooded, a catastrophic decay heat casualty ensued, leading to major reactor plant damage including meltdowns and explosive loss of reactor containment. Proximate cause was human error and violation of procedures. The unsafe reactor design caused instability at low power due to a positive void coefficient and steam formation. When an improper test was conducted at 1:00 am at low power, the reactor became prompt critical. This was followed by a steam explosion that exposed the fuel, a raging graphite fire, and a core meltdown.
Maximum level of radiation detected 72.9 Sv/h (Inside Reactor 2)[4] 300 Sv/h shortly after explosion in vicinity of the reactor core[5]
Radioactivity released 900 PBq "into the atmosphere in March last year [2011] alone"[6][7] 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.[8]

Radiation continues to be released into the Pacific via groundwater, as TEPCO recognized that the Ice Wall strategy failed to effectively contain the underground water on August 19.

 5.2 EBq (5,200 PBq) [9][10]
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 .
Exclusion Zone Area 20 km (30 km voluntary) 30 km
Population relocated 154,000 [11] 335,000 (About 115,000 from areas surrounding the reactor in 1986; about 220,000 people from Belarus, the Russian Federation and Ukraine after 1986)
Direct fatalities from the accident 2 crew members (gone to inspect the buildings immediately after the earthquake and before the tsunami) due to drowning Two immediate trauma deaths; 28 deaths from Acute Radiation Syndrome out of 134 showing symptoms; four from an industrial accident (helicopter crash); 15 deaths from radiation-genic thyroid cancers (as of 2005)[12]
Current status Cold shutdown declared on 16 December 2011, but decommissioning is likely to take 30 to 40 years.[13][14] All fuel rods in reactor 4 pool removed. Fukushima disaster cleanup is ongoing. 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 was completed and installed in November 2016, from which the plant will be cleaned up and decommissioned.

Radioactive contamination discharge

Report date Place Period Iodine-131
(TBq) 		Caesium-137
(TBq) 		Source
from to from to
2002 Chernobyl 25 April – June 1986 1 600 000 1 940 000 59 000 111 000 NEA[15]
22 March 2011 Fukushima 12 – 15 March 2011 400 000 3 000 30 000 ZAMG[16]
2 April 2011 Fukushima 12 – 19 March 2011 10 000 700 000 1 000 70 000 ZAMG [17]
12 April 2011 Fukushima 11 March – 5 April[18] 150 000 12 000 NSC[19]
12 April 2011 Fukushima 11 – 17 March 2011 130 000 6 100 NISA [19]
7 June 2011 Fukushima 11 – 17 March 2011 160 000 15 000 NISA[20]
24 Aug. 2011 Fukushima 11 March – 5 April 130 000 11 000 NSC[21]
15 Sept. 2011 Fukushima March - September 100 000 200 000 10 000 20 000 Kantei[22]
Report date Place Period Amount
(TBq) 		Source
12 April 2011 Chernobyl 25 April – June 1986 5 200 000 NISA[19]
12 April 2011 Fukushima 11 March – 5 April 2011 630 000 NSC[18][19]
12 April 2011 Fukushima 11 – 17 March 2011 370 000 NISA[19]
April 2011 Fukushima 4 April 2011 154 NSC[18]
25 April 2011 Fukushima 24 April 2011 24 NSC[18]
6–7 June 2011 Fukushima 11 – 17 March 2011 770 000 NISA[23]>[20]
7 June 2011 Fukushima 11 – 17 March 2011 840 000 NISA,[24] press printing[23]
17 August 2011 Fukushima 3–16 August 2011 0.07 Government[25]
23 August 2011 Fukushima 12 March - 5 April 2011 630 000 NISA[26]
Report date Period Into the sea
(TBq)		 Source
direct indirect
21 May 2011 1 – 6 April 2011 4 700 Tepco[27]
End of August 2011 March – August 2011 3 500 16 000 JMA[28]
8 September 2011 March – April 2011 15 000 Scientist Group[29]
29 October 2011 21 March – 15 July 2011 27 100 IRSN[30]

See also

References

  1. ↑ "PRIS - Reactor Details". www.iaea.org. Retrieved 2016-07-14.
  2. ↑ Fukushima: Background on Reactors (Technical report). February 2012. Retrieved 4 September 2014.183.3 kg / assembly * (400 assemblies in reactor 1, 548 in reactors 2 and 3, 0 in 4, 2229 bundles in pools 1-4, 6375 bundles in central storage
  3. ↑ Malko, Mikhail V. The Chernobyl Reactor: Design Features and Reasons for Accident (PDF) (Technical report). p. 13. Retrieved 4 September 2014.1661 fuel channels x 147.5 kg U per fuel assembly
  4. ↑ Minoru Matsutani (March 29, 2012). "Reactor 2 radiation too high for access". Japan Times. Retrieved April 1, 2012.
  5. ↑ B. Medvedev (June 1989). "JPRS Report: Soviet Union Economic Affairs Chernobyl Notebook" (Republished by the Foreign Broadcast Information Service ed.). Novy Mir. Retrieved 27 March 2011.
  6. ↑ "TEPCO puts radiation release early in Fukushima crisis at 900 PBq". Kyodo News. May 24, 2012. Archived from the original on May 24, 2012. Retrieved May 24, 2012.
  7. ↑ Kevin Krolicki (May 24, 2012). "Fukushima radiation higher than first estimated". Reuters. Retrieved May 24, 2012.
  8. ↑ "Comparison of the Chernobyl and Fukushima nuclear accidents: A review of the environmental impacts Science of The Total Environment Volumes 470–471, 1 February 2014, Pages 800–817".
  9. ↑ "Three Mile Island, Chernobyl, and Fukushima, A comparison of three nuclear reactor calamities reveals some key differences". IEEE. Nov 1, 2011. Retrieved Nov 4, 2013.
  10. ↑ "Chernobyl Accident 1986". World Nuclear Association. Jun 1, 2013. Retrieved Nov 4, 2013.
  11. ↑ "Reconstruction Agency". www.reconstruction.go.jp. Retrieved 2016-05-25.
  12. ↑ Health effects due to radiation from the Chernobyl accident (Annex D of the 2008 UNSCEAR Report) (PDF) (Technical report). UNSCEAR. 2011.
  13. ↑ Kaushik, Kavyanjali (7 April 2011). "UPDATE 1-Toshiba proposes to scrap Fukushima nuclear plant-Nikkei". Reuters. Retrieved 27 July 2013.
  14. ↑ Justin Mccurry (10 March 2014). "Fukushima operator may have to dump contaminated water into Pacific". The Guardian. Retrieved 10 March 2014.
  15. ↑ Chernobyl: Assessment of Radiological and Health Impact, Chapter 2. 2002, archived from Original on 20 April 2011, retrieved on 6 April 2011.
  16. ↑ Unfall im japanischen Kernkraftwerk Fukushima (German). ZAMG, 22 March 2011, archived from Original on 20 April 2011, retrieved on 20 April 2011.
  17. ↑ Aktuelle Lage nach Unfall in Fukushima (Update: 2. April 2011 12:00) (German). In: www.zamg.ac.at. Zentralanstalt für Meteorologie und Geodynamik, 2 April 2011, archived from Original on 20 April 2011, retrieved on 2 April 2011.
  18. 1 2 3 4 Earthquake Report – JAIF, No. 64: 20:00, April 26. JAIF / NHK, 26 April 2011, archived from Original on 27 April 2011, retrieved on 27 April 2011.
  19. 1 2 3 4 5 INES (the International Nuclear and Radiological Event Scale) Rating on the Events in Fukushima Dai-ichi Nuclear Power Station by the Tohoku District – off the Pacific Ocean Earthquake. NISA/METI, 12 April 2011, archived from Original on 12 April 2011, retrieved on 12 April 2011.
  20. 1 2 Report of Japanese Government to the IAEA Ministerial Conference on Nuclear Safety / VI. Discharge of radioactive materials to the environment. NISA/Kantei, 7 June 2011, archived from Original, retrieved on 8 June 2011.
  21. ↑ NSC Recalculates Total Amount of Radioactive Materials Released. In: Atoms in Japan. JAIF, 5 September 2011, archived from Original, retrieved on 20 December 2011.
  22. ↑ Additional Report of the Japanese Government to the IAEA. Kantei, 15 September 2011, archived from Original, retrieved on 17 December 2011. Spent fuel pool measurement on page 205, 207, 210 and 214; total release on page 449. Archived January 18, 2012, at the Wayback Machine.
  23. 1 2 No.1 reactor vessel damaged 5 hours after quake. NHK, 6 June 2011, archived from Original, retrieved on 6 June 2011.
  24. ↑ Abstracts of the cross check analysis on the evaluation of the cores of Unit 1, 2 and 3 of Fukushima Dai-ichi NPP reported by TEPCO. NISA/Kantei, 7 June 2011, archived from Original, retrieved on 14 June 2011.
  25. ↑ Earthquake Report – JAIF, No. 177. JAIF / NHK, 18 August 2011, archived from Original, retrieved on 21 August 2011. Converted from 200 MBq/h in a two-week period.
  26. ↑ Earthquake Report – JAIF, No. 182. JAIF / NHK, 23 August 2011, archived from Original, retrieved on 31 August 2011.
  27. ↑ Report regarding the impact due to the discharge of drained water with concentrations of radioactive materials exceeding discharge standard to the ocean (summary). Tepco, 21 May 2011, archived from Original, retrieved on 23 May 2011.
  28. ↑ Dagmar Röhrlich: Die Havarie und das Meer - Wie sich die radioaktive Belastung in den Weltmeeren ausbreiten wird (German). In: dradio.de, Forschung Aktuell. Deutschlandfunk, 5 September 2011, archived from Original, retrieved on 7 September 2011; 1 000 000 000 000 Becquerel = 1 TBq.
  29. ↑ Earthquake Report – JAIF, No. 199. JAIF / NHK, 9 September 2011, archived from Original, retrieved on 11 December 2011.
  30. ↑ Earthquake Report – JAIF, No. 250. JAIF / NHK, 30 November 2011, archived from Original, retrieved on 20 December 2011.
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