Radiation Disaster at Fukushima Daiichi Nuclear Power Plant

Photo from the Institute for Science and International Security

The March 11 earthquake and tsunami was enough of a disaster in itself. One of the effects of 10 meter tsunami was to knock out the system that cooled the nuclear facility at Fukushima. The plants automatically shut down with an earthquake - but a tsunami of that size was not anticipated. Without cooling, there has been explosions and some amount of melting and release of radiation.

The presence of radiation has made it difficult to have people working at the plant to fix the problems because of the high levels of radiation around the plant. Based on the sievert level (see below) - there are limits to how much a person should be exposed to in an hour, in a day, in a year.

From the BBC ->"After Tuesday's explosions and fire, radiation dosages of up to 400 millisieverts per hour were recorded at the Fukushima Daiichi site, about 250km north-east of Tokyo. Later, a reading of 0.6 millisieverts (mSv) per hour was recorded at the plant's main gate, the International Atomic Energy Agency (IAEA) said."

Radiation has spread out app. 15 miles. The US advised an evacuation of 50 miles out. France advised it's citizens to leave the country. Tokyo is about 150 miles away. People have been concerned about the wind direction - as far as radiation spread. It has mostly gone out over the ocean so far.

Summary of conditions put together by Greenpeace as of March 18th:

Overall, with possible exception of spent fuel pool of reactor #3, the status of all facilities is very similar to yesterday, which is a bad thing. Major uncertainty relates to amount of radiation already being released to air and sea, to risk of a violent fire in the cladding of the fuel rods as the spent fuel pools are exposed for hours, as well as to the behavior of the reactor cores as water levels remain low.

Good news is that the violent release of radioactivity due to fire or explosion feared yesterday has not happened yet. Power is still not restored to the facility, but some progress has made to bring off site power and more equipment. This means more effective cooling could be established in some days. At least until that happens, the situation remains critical and unpredictable.

Reactors 1-3: water level in reactors low (about half of fuel rods exposed), no grid power, seawater injection apparently ongoing. Fuel rods have certainly damaged and are releasing radioactive substances.

Fire department has brought in 30 more trucks, at least one reported to be a “Super Bomber” able to shoot to a distance of 2 kilometers. Yesterday police trucks were unable to operate close to plant because of high radiation levels, only SDF (Self Defense Force) trucks that can be operated from inside the cabin were used.

Spent fuel pools of units 1&2: Water levels in Unit 1 are decreasing. Steam was reported from unit 2, expected to be boiling.

Spent fuel pool of unit 3: Water in #3 almost depleted, but Tepco hopes some water is left. Fuel rods have certainly damaged, releasing radioactive substances. The reactor buildings are heavily damaged, allowing releases directly to outside air.

Spent fuel pool of unit 4: Water level very unclear.

Spent fuel pools of units 5&6: Temperatures still rising, water left but level unclear.

Worst case scenarios

* The zirconium contained in the fuel rod cladding can react violently with air, if exposed for hours. This fire would release and spread very large amounts of radioactivity high up in the air. Wide disagreement on the probability of this happening.

* A large amount of molten fuel accumulates at the bottom and a nuclear reaction starts. Very low probability and can be prevented if there is any borated water in the pool.

* Reactor boils dry, molten core breaches reactor pressure vessel and comes in contact with the water in the containment, which boils rapidly causing a steam explosion.

* A major risk is an event (e.g. increased release of radioactivity from a spent fuel pool due to overheating) that raises local radiation levels to completely intolerable levels - preventing further work to restore cooling.

Tepco seemed to suggest that encasing the plant in concrete is an option if cooling efforts fail (according to Reuters live feed).
Wind

Local wind speed slowed down considerably in the morning but direction remained towards the sea. Winds towards Tokyo are still feared for Sunday.
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A more detailed summary can be found @ Reuters

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There was 3 Mile Island, there was Chernobyl, and now this. This situation has made it clear that all nuclear plants need to have their systems and possible catastrophic scenarios more thought out. There are many plants of the same type in the US - where people have warned of this and this sort of possible problem and yet - nothing has been done to fix and avert the potential problem.

Clearly more people need to accept that nuclear energy poses very extreme risks to people and the environment.

About that Radiation and Sieverts:

The sievert (symbol: Sv) is the SI derived unit of dose equivalent. It attempts to quantitatively evaluate the biological effects of ionizing radiation as opposed to the physical aspects, which are characterised by the absorbed dose, measured in gray. It is named after Rolf Sievert, a Swedish medical physicist renowned for work on radiation dosage measurement and research into the biological effects of radiation.

Frequently used SI multiples are the millisievert (1 mSv = 10−3 Sv = 0.001 Sv) and microsievert (1 μSv = 10−6 Sv = 0.000001 Sv).

An older unit of the equivalent dose is the rem. In some fields and countries, the rem and millirem (abbreviated mrem) continue to be used along with Sv and mSv, causing confusion. Here are the conversion equivalences:

1 Sv = 1000 mSv (millisieverts) = 1,000,000 μSv (microsieverts) = 100 rem = 100,000 mrem (millirem)

Single dose examples:

Eating one banana: 0.0001 mSv
Sleeping next to a human for 8 hours: 0.0005 mSv[1]
Dental radiography: 0.005 mSv[2]
Average dose to people living within 16 km of Three Mile Island accident: 0.08 mSv; maximum dose: 1 mSv[3]
Mammogram: 3 mSv[2]
Brain CT scan: 0.8–5 mSv[4]

International Commission on Radiological Protection recommended limit for volunteers averting major nuclear escalation: 500 mSv
International Commission on Radiological Protection recommended limit for volunteers rescuing lives or preventing serious injuries: 1000 mSv

Hourly dose examples:

Approximate radiation levels near Chernobyl reactor 4 and its fragments, shortly[clarification needed] after explosion are reported to be 10–300 Sv/hr

Yearly dose examples:

Living near a nuclear power station: 0.0001–0.01 mSv/year
Living near a coal power station: 0.0003 mSv/year
Cosmic radiation (from sky) at sea level: 0.24 mSv/year
Natural radiation in the human body: 0.40 mSv/year
New York-Tokyo flights for airline crew: 9 mSv/year
Total average radiation dose for Americans: 6.2 mSv/year

Current average limit for nuclear workers: 20 mSv/year

Lowest clearly carcinogenic level: 100 mSv/year

Elevated limit for workers during Fukushima emergency: 250 mSv/year

Dose limit examples:

Criterion for relocation after Chernobyl disaster: 350 mSv/lifetime

Public dose limits for exposure from uranium mining or nuclear plants are usually set at 1 mSv/yr above background.


Symptom benchmarks

Symptoms of acute radiation (within one day):

0 – 0.25 Sv (0 - 250 mSv): None

0.25 – 1 Sv (250 - 1000 mSv): Some people feel nausea and loss of appetite; bone marrow, lymph nodes, spleen damaged.

1 – 3 Sv (1000 - 3000 mSv): Mild to severe nausea, loss of appetite, infection; more severe bone marrow, lymph node, spleen damage; recovery probable, not assured.

3 – 6 Sv (3000 - 6000 mSv): Severe nausea, loss of appetite; hemorrhaging, infection, diarrhea, peeling of skin, sterility; death if untreated.

6 – 10 Sv (6000 - 10000 mSv): Above symptoms plus central nervous system impairment; death expected.
Above 10 Sv (10000 mSv): Incapacitation and death.

Radioactive Waste Shipments

From the St. Petersburg Times:
Cargo of Toxic Waste Arrives in City’s Port

A cargo of 650 tons of depleted uranium hexafluoride arrived at the city’s port on Monday. The radioactive load, which is due to travel on by rail to the Siberian Chemical Factory in the Siberian town of Seversk for reprocessing, was brought in by The Captain Kuroptev ship, a vessel that has repeatedly come into conflict in the past with ecological groups trying to prevent it from docking.

The French company AREVA, one of the largest exporters of depleted uranium to Russia, along with the German-Dutch holding URENCO, is responsible for the radioactive cargo. During the past 15 years, the companies have jointly sent to Russia nearly 140,000 tons of radioactive material, according to Greenpeace Russia.

Radioactive loads on board foreign ships have been arriving at the port of St. Petersburg on a regular basis for a decade, being sent on by rail to factories in Siberia and the Urals.

The trains carrying the hazardous loads set off from Avtovo railway station — located in the south of the city close to residential areas — according to the local branch of the ecology group Bellona. Bellona’s research has shown that most residents in the area have no idea about the risks to which they are regularly exposed as a result of these toxic cargoes.

Ecologists have difficulty monitoring the cargoes, as officials restrict information concerning the transportation of nuclear material, and often prevent independent experts from gaining access to the trains. When volunteers have been able to get close to the trains they say they have often registered increased radiation levels.

AREVA is not the only French company that regularly sends uranium hexafluoride to Russia. EURODIF also continues to send regular shipments of radioactive loads. Russia’s contracts with both AREVA and EURODIF expire in 2014, and ecologists are actively campaigning in France against their renewal...

Ecologists have questioned the ethics of these deals. It has been calculated that it is at least three times cheaper for Western European companies to send depleted uranium for reprocessing to Russia than to do the job at home.

In 2008, Russia also signed contracts with India, Pakistan and China to receive spent nuclear fuel and highly toxic uranium hexafluoride in addition to the regular shipments of radioactive cargoes from Western Europe.

In November last year, environmentalists trumpeted their first major success in years when the German-Dutch company URENCO announced that it would end the practice of sending spent nuclear fuel to Russia for reprocessing and storage...

And From the Japan Times:
The world's radioactive rubbish is piling up

The Pacific Sandpiper, a specially built cargo ship with safety features far in excess of those found on conventional vessels, left Britain's Barrow port bound for Japan the other day.

In the Pacific Sandpiper's hold on this journey to Japan via the Panama Canal is only one item of cargo — a giant cylinder weighing more than 100 tons. Inside are 28 containers, each made of stainless steel nearly one-third of a meter thick. They are packed with 14 tons of highly radioactive waste that has been turned into solid glass form to make it safer and easier to handle.

It is the first of a series of such shipments planned for next few years to Japan from Britain's Sellafield nuclear storage and reprocessing complex. Three years ago, a dozen similar shipments from France to Japan were successfully completed. Used fuel from nuclear power reactors that generate about one-third of Japan's electricity has been shipped to Europe for reprocessing since 1969, while vitrified waste has been sent back to Japan by sea since 1995.

There have been over 170 of these ocean shipments covering more than 8 million km without any incident involving the release of radioactivity, according to the Euro-Japanese company that operates the fleet of purpose-built vessels.

But the elaborate and costly arrangement casts light on two of the most problematic and controversial aspects of civilian nuclear power — how to prevent the spread of nuclear weapons material and knowhow to terrorists and rogue states, and how to store nuclear waste safely for the long-term when it can remain radioactive for hundreds of years.

With the number of power reactors expected to rise from 435 in 31 countries to nearly 570 in 42 countries by 2020, and with much of this expansion expected to take place in Asia and the Middle East, the need for safeguards on uranium or plutonium processing that could be used to make nuclear weapons is obvious.

Recycling fuel from nuclear reactors under strict national and international regulations is one method being developed. When uranium oxide fuel has been used in a reactor for three or four years, it becomes less efficient and is replaced with fresh fuel.

The spent fuel can then be chemically treated to recover usable uranium, associated plutonium and radioactive waste, a system known as reprocessing. Although expensive, this cycle provides up to 25 percent more energy from the original uranium. It also reduces the volume of high-level waste to about one-fifth of what it would otherwise be...

So far, about 90,000 tons of used fuel from commercial power reactors have been reprocessed, mainly in Britain, France and Russia. By 2030, another 400,000 tons of used fuel is likely to pile up, an average of 20,000 tons a year.

At present, annual global reprocessing capacity is about 3,800 tons per year for normal uranium oxide fuel, and about 1,700 tons for other nuclear fuels, according to the World Nuclear Association.

Much of the spent fuel piled up by 2030 will be in Asia. Japan, India, China and South Korea aim to emulate the main reprocessing centers in Europe and Russia. They see the technology as the key to a lucrative nuclear service industry as well as being one that is vital to their own energy security...

High-level radioactive waste is accumulating at a rate of about 12,000 tons per year worldwide. When used fuel is removed from a reactor, it must cool for up to 50 years under water in secure pools or in dry storage, where circulating air gradually removes the heat.

The level of both radioactivity and heat from spent fuel, or from the dangerous waste material extracted from the fuel during reprocessing, fall rapidly in these years down to about one-thousandth of the level when the fuel was removed from the reactor...

Without a long-term solution, the pile of radioactive "rubbish" will become so big and so widely dispersed that it may be impossible to manage safely.