Update: This post from March 15 have been moved to the top, as Japan’s nuclear crisis continues — and the radiation spreads. I recommend using the links in section 3 to learn what’s happening.
Summary: We might be reading much about radiation during the next few days. Most of these articles will provide little context. Here’s some useful background information, and links to reliable news sources. This is a follow-up to News about the earthquake in northeastern Japan.
- About radiation: units and definitions
- Effects of radiation
- For more information about the crisis in Japan’s nuclear reactor crisis
- For more information about nuclear power
- Other articles on the FM website about the future of energy
(1) About radiation (from the Encyclopedia Britannica)
(a) Gray (Gy), a unit of absorbed dose of ionizing radiation.
One gray is equal approximately to the absorbed dose delivered when the energy per unit mass imparted to matter by ionizing radiation is one joule per kilogram. The gray replaced the rad; one gray equals 100 rads. The gray was defined in 1975, named after Louis Harold Gray (1905–1965).
(c) Sievert (Sv), a unit measuring absorption of radiation by tissue (equivalent doses)
The sievert is the … replacement for the rem, the long-standing special unit for measuring biological absorption of radiation. Like the rem, the sievert takes into account the relative biologic effectiveness (RBE) of ionizing radiation, since each form of such radiation — e.g., X rays, gamma rays, neutrons — has a slightly different effect on living tissue. Accordingly, one sievert is generally defined as the amount of radiation roughly equivalent in biologic effectiveness to one gray (or 100 rads) of gamma radiation. … It is named after Rolf Sievert (1896-1966).
- Exposures can be expressed as totals, or as flows (units/time, such as gray/hour).
- Common prefixes are milliSievert (one-thousand, mSv) and hecot-gray (hGy), using the The International System of Units (SI; see Wikipedia).
(2) Effects of radiation
(a) Standard definitions in grays (from the Encyclopedia Britannica)
- sublethal dose range: (1–2 Gy): sore throat, pallor and diarrhea; no fatalities (except for complications)
- midlethal dose range: (2.5–5 Gy): nausea, vomiting, loss of hair, fever, hemorrhages, and emaciation; death for 50% of the population
- supralethal dose range: (6–10 Gy): diarrhea, vomiting, inflammation of throat, and emaciation; death for 100% of the population
(b) Exposures in Sv, from the World Nuclear Association (via the BBC)
- 2 mSv/yr: Typical background radiation experienced by everyone (average 1.5 mSv in Australia, 3 mSv in North America)
- 9 mSv/yr : Exposure by airline crew flying New York-Tokyo polar route
- 20 mSv/yr: Current limit (averaged) for nuclear industry employees
- 50 mSv/yr: Former routine limit for nuclear industry employees. It is also the dose rate which arises from natural background levels in several places in Iran, India and Europe
- 100 mSv/yr: Lowest level at which any increase in cancer is clearly evident
- 350 mSv/lifetime: Criterion for relocating people after Chernobyl accident
- 1,000 mSv single dose: Causes temporary radiation sickness such as nausea and decreased white blood cell count, but not death. Above this, severity of illness increases with dose
- 5,000 mSv single dose: Would kill about half those receiving it within a month
For more detail about exposures in terms of sieverts, see Wikipedia.
(c) “How much radiation is dangerous?“, Reuter’s Factbox article, 15 March 2011 — Excerpt:
- People are exposed to natural radiation of about 2 mSv a year.
- Airline crew flying the New York-Tokyo polar route are exposed to 9 mSv a year.
- Exposure to 100 mSv a year is the lowest level at which any increase in cancer is clearly evident. A cumulative 1,000 mSv would probably cause a fatal cancer many years later in five out of every 100 persons exposed to it.
- Exposure to 350 mSv was the criterion for relocating people after the Chernobyl accident, according to the World Nuclear Association.
- A single 1,000 mSv dose causes radiation sickness such as nausea but not death. A single does of 5,000 mSv would kill about half of those exposed to it within a month.
Also see “Chernobyl fallout not as bad as first feared“, The Times,7 September 2005.
(d) For more information see Acute Radiation Syndrome: A Fact Sheet for Physicians, Centers for Disease Control and Prevention.
(e) Update: from the International Atomic Energy Agency (IAEA) Tsunami Update page:
The Japanese authorities have informed the IAEA that the following radiation dose rates have been observed on site at the main gate of the Fukushima Daiichi Nuclear Power Plant. At 00:00 UTC on 15 March a dose rate of 11.9 millisieverts (mSv) per hour was observed. Six hours later, at 06:00 UTC on 15 March a dose rate of 0.6 millisieverts (mSv) per hour was observed. These observations indicate that the level of radioactivity has been decreasing at the site.
As reported earlier, a 400 millisieverts (mSv) per hour radiation dose observed at Fukushima Daiichi occurred between units 3 and 4. This is a high dose-level value, but it is a local value at a single location and at a certain point in time.
(f) Update: Estimated condition of each reactor in the Fukushima complex, Japan Atomic Industrial Forum, as of 11:00 local time on 16 March 2011 — Excellent graphic!
(3) For more information about the crisis in Japan’s nuclear reactors, and nuclear power
- Nuclear Energy Institute
- Most detailed: Japan Atomic Industrial Forum
- Best source: International Atomic Energy Agency updates on Japan Earthquake
News articles about the crisis in Japan:
- Experts pore over contaminants in Japan’s radioactive spill“, Reuters, 22 March 2011
- “Behind Reactor Battle, a Legion of Grunts“, Wall Street Journal, 24 March 2011
- “First pictures emerge of the Fukushima Fifty as steam starts pouring from all four reactors at the stricken nuclear power plant“, Daily Mail, 24 March 2011
Articles about nuclear power:
- Yes, it can happen here: “Nuclear Hubris: Could Japan’s Disaster Happen Here?“, Christian Parenti, The Nation, 13 March 2011
- More evidence it could happen here: “After Three Mile Island: The Rise and Fall of Nuclear Safety Culture“, Christian Parenti, The Nation, 22 March 2011
- “When the steam clears“, The Economist, 24 May 2011 — “The Fukushima crisis will slow the growth of nuclear power. Might it reverse it?”
- An interactive map of current and future nuclear-power producers, The Economist, 24 May 2011
(4) For more information about nuclear power
From the FM reference page Peak oil and energy – studies and reports:
- “The Future of Nuclear Power“, MIT, 29 June 2003 — An interdisciplinary MIT study
- “The Economics of Investment in New Nuclear Power Plants in the US“, Paul L. Joskow (MIT), EIA, 12 April 2005 — PDF, 19 slides
- “Nuclear Power Reactors: A Study in Technological Lock-in“, Robin Cowan, The Journal of Economic History, Sepember 1990
- “Nuclear Power’s Role in Generating Electricity“, CBO, May 2008 (46 pages)
- “Nuclear power will be added faster than wind power“, posted at Next Big Future, 25 August 2008 — List of nukes under construction
- “Breeder Reactors, Uranium from Phosphate and Near Term Thorium usage“, posted at Next Big Future, 22 September 2008
- ”Update of the MIT 2003 Future of Nuclear Power Study“, MIT, 2009
(5) Other articles on the FM website about the future of energy
The full archive is listed here.
- Fusion energy, too risky a bet for America (we prefer to rely on war), 4 May 2008
- An urban legend to comfort America: crash programs will solve Peak Oil, 5 September 2008
- A long-shot project for fusion power: the Polywell, 30 September 2008
- An atomic solution to the energy crisis, 11 November 2008
- Eventually we’ll have unlimited cheap clean energy. But that will not help us or our kids., 15 February 2011