Arkisto: 'energia'

Fukushiman onnettomuus jatkuu ja osoittautuu aina vain pahemmaksi

Perjantaina 19. elokuuta 2011

Vaikka valtamedia on ajat sitten lopettanut Fukushiman onnettomuuden seuraamisen, se ei ole lainkaan ohi vaan jatkuu tätä kirjoitettaessa 162. päivää. Johtavat tiedotusvälineet ovat päättäneet vaieta Fukushiman uusista käänteistä ja suojella ydinvoimateollisuutta ja myös Japanin muuhun teollisuuteen ja kiinteistöihin sijoittaneiden piirien rahoja. Japanilaisen ja vaihtoehtomedian välittämien tietojen mukaan onnettomuus oli toisaalta alunperinkin paljon pahempi kuin uskottiin ja toisaalta radioaktiivisen saasteen leviäminen jatkuu eikä reaktorien hallinnasta ole puhettakaan. Esimerkkinä alla Beyond Nuclear -verkoston välittämä uutinen:

http://www.beyondnuclear.org/nuclear-reactors-whatsnew/2011/8/18/reports-indicate-fukushima-nuclear-crisis-worsening-and-wide.html

Sen mukaan voimaloiden lähelle on avautunut suuri joukko halkeamia, joista pursuaa ulos korkeasti radioaktiivista kaasua. 100 km päässä onnettomuuspaikasta sijaitsevan oikeustalon edessä olevasta ojasta on löytynyt valtavan radioaktiivista lietettä. Osa Kiinan edustan merialueestakin on nyt vakavasti Fukushiman saastuttamaa.

Olli Tammilehto

Fukushimaan rakkaudella!

Torstaina 31. maaliskuuta 2011

Tässä käytännöllinen ehdotus Intiasta Fukushiman onnettomuusvoimalan ongelmien ratkaisemiseksi: Lähetetään kaikki ydinvoimaan ihastuneet asiantuntijat ympäri maailmaa paikan päälle laittamaan ydinvoimala kuntoon. He voisivat korvata nuo kaikki onnettomat japanilaiset tomppelit, jotka eivät ole vieläkään saaneet vuotoja tukittua. Suomesta voisi lähteä iso delegaatio maailman parhaita ydinvoima-asiantuntijoita säteilyturvakeskuksesta, Teollisuuden Voimasta ja Fortumista. Näille supermiehille korjaus olisi pikku juttu varsinkin, kun he tietävät, ettei ydinvoimaloissa koskaan voi sattua mitään todella vakavaa ja ettei säteily juuri koskaan voi olla vaarallista. Tarkemmin delhiläisen Satya Sagarin Counter Currents -nettilehdessä ilmestyneessä jutussa.
http://www.countercurrents.org/sagar300311.htm

Mitä pahimmassa tapauksessa Fukushimassa?

Sunnuntaina 27. maaliskuuta 2011

Vaikka Helsingin Sanomat ja monet muut tiedotusvälineet ovat siirtäneet Fukushiman sisäsivujen pikku-uutiseksi, ydinkatastrofi jatkuu. Jotkut tutkijat ovat pohtineet sitä, mitä pahimmassa tapauksessa tapahtuisi: jos vettä ei paineastiaan saataisi tarpeeksi, ydinvoimalan sydän sulaisi kokonaan, sula voimakkaasti radioaktiivinen aine höyrystäisi lopun vedestä ja sulattaisi paineastian pohjan. Kun sula sydän putoaisi reaktorin alaosassa olevaan vedentäyttämään betoniseen tilaan, seurauksena olisi valtava räjähdys, josta syntyisi erittäin radioaktiivinen pilvi. Kun tuuli sattuisi puhaltamaan maalle päin, laaja, mahdollisesti jopa Tokioon asti ulottuvan alue saastuisi asumiseen kelpaamattomaksi.
Suuren maa-alueen saastuminen voisi tapahtua myös muilla tavoilla varsinkin koska Fukushimassa on runsaasti myös ylikuumentunutta ja vaurioitunutta käytettyä polttoainetta. Asiasta tarkemmin alla.

http://motherjones.com/environment/2011/03/how-bad-could-japans-nuclear-crisis-get

How Bad Could Japan’s Nuclear Crisis Get?

As emergency workers begin “last-ditch efforts” to take control of the damaged power station, experts worry that a meltdown is still possible.

By Kate Sheppard | Thu Mar. 17, 2011 4:46 PM PDT

Nuclear power experts and watchdogs warn that we’re entering uncharted territory. “The situation is worsening,” says Robert Alvarez, a scholar at the Institute for Policy Studies and a former senior policy advisor to the secretary of energy during the Clinton administration. “It seems to be slipping out of the control of authorities.” The situation at the Japanese plant is constantly changing and involves several reactors in various states of disrepair. The chairman of the Nuclear Regulatory Commission, Greg Jaczko, says it could be “possibly weeks” [2] before it is totally under control. Until then, the risk of a full meltdown still looms.

To recap: The Fukushima Daiichi Power Plant has six nuclear reactors. The power plant’s owner, Tokyo Electric Power Company, has been struggling to bring reactor units 1, 2, and 3 under control after last week’s earthquake and tsunami caused a massive power failure that disabled the cooling systems. On top of that, the spent nuclear fuel in Unit 4, which was down for maintenance at the time of the quake, has twice ignited and appears to be the source of the high levels of radiation released so far.

The spent fuel currently presents the biggest problem. On Wednesday, NRC chairman Jaczko testified to a Senate panel that he believed that the pool of water that the spent fuel is supposed to be submersed in had completely burned off. The Japanese government has said that there still is water in the pool, however. Keeping the spent fuel covered is essential for keeping it cool and preventing the release of radiation. Not all of the rods are completely spent, and ongoing reactions within them generate heat. Without a functioning cooling system, the rods heat up the water and cause it to boil off. The smoke coming from the unit indicates that the dry rods are likely causing their zirconium coating to corrode and ignite, allowing radiation to escape.
One expert describes what is currently happening as “last-ditch efforts.” If plant workers can’t regain control over the units, there could be a meltdown.

The spent fuel pool at Unit 4 is also particularly problematic, according to the Union of Concerned Scientists [3], because the rods in it were just removed in December 2010 and are still highly radioactive. The Unit 4 building has been severely damaged, and the spent fuel pools don’t have the containment infrastructure that the reactors do. “There’s no protection,” says Kenneth Bergeron, a physicist who previously worked on nuclear reactor accident simulations at the Department of Energy’s Sandia National Laboratories. “These things are burning in the open air virtually…Then the fission products are just there to be lofted into the atmosphere.”

The Japan Atomic Industrial Forum has released an updated status report [4] on all the units that shows that the water level in the spent fuel pool at Unit 3 is also critically low. Japanese officials have characterized this reactor as perhaps the most dangerous, because it uses some mixed oxide fuel, or MOX, which includes uranium and plutonium, and presents a more severe radiation threat. On Monday, there was an explosion at Unit 3 that appears to have damaged its reactor core and severely damaged its building. Responders have also been struggling to maintain the water level in its reactor, and as of Thursday evening it was only half full.

Life-threatening radiation levels have made it even harder to emergency workers to deal with the multiple problems at Fukushima. Fire engines, military trucks, and aircraft have been sent in to douse the units in hopes of cooling them down. The New York Times reports [5] that at least one helicopter turned back, likely due to the high radiation levels.

Alvarez describes what is currently happening as “last-ditch efforts.” If plant workers can’t keep the water levels up and regain control over the reactors, there could be a full meltdown. That means the overheated nuclear fuel will melt and pour into the bottom of the reactors. The question then becomes whether the reactors’ primary containment vessels can hold the melted fuel. Some nuclear watchdog groups have concerns that the Mark 1 model reactor used at Fukushima may be vulnerable to failures. The containment vessels at Units 2 and 3 are thought to be damaged, and the building integrity is compromised at all three units. Additional fires and explosions could further damage the containment system.

What might happen next was described to the Knoxville News Sentinel [6]by Michael Allen [6], who has run nuclear-accident simulations at Sandia National Labs:
If workers are unable to get additional cooling water into the reactor vessel, the molten fuel core will collapse into the water in bottom of the vessel. Eventually the heat from the decaying fuel would boil away the water that’s left, leaving the core sitting on the vessel’s lower head made of steel. Should that happen, “It’ll melt through it like butter,” Allen said.
That, in turn, would cause a “high-pressure melt injection” into the water-filled concrete cavity below the reactor. Because the concrete would likely be unheated, the reaction created by the sudden injection of the reactor’s ultra-hot content would be immense, he said.
“It’ll be like somebody dropped a bomb, and there’ll be a big cloud of very, very radioactive material above the ground,” Allen said, noting that it would contain uranium and plutonium, as well as the fission products.

In the very least, such a scenario would render the area around the Fukushima power plant uninhabitable for the foreseeable future—an area Alvarez says could possibly be as large as several northeastern states. Its wider impact would depend on where the resulting plume of radiation travels. Even then, fully understanding the accident’s environmental and public health impacts of could take years. Yet if the prevailing wind carries the radiation out to sea, there would be less impact on people living beyond the plant’s immediate vicinity. But that’s another big “if” in a situation whose final outcome remains unpredictable and potentially catastrophic.

Source URL: http://motherjones.com/environment/2011/03/how-bad-could-japans-nuclear-crisis-get

Links:
[1] http://motherjones.com/blue-marble/2011/03/japans-nuclear-emergency
[2] http://www.latimes.com/news/nationworld/world/la-fgw-japan-quake-nrc-20110318,0,2353640.story
[3] http://allthingsnuclear.org/tagged/Japan_nuclear?utm_&utm_medium=head&utm_campaign=sp-nuke-head-3%2F13%2F2011-pm
[4] http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300368041P.pdf
[5] http://www.nytimes.com/2011/03/18/world/asia/18nuclear.html?hp
[6] http://blogs.knoxnews.com/munger/2011/03/ex-sandia-engineer-talks-about.html


Fukushima jo Tshernobyl-luokkaa

Lauantaina 26. maaliskuuta 2011
Saksalaisen ydinvoima-asiantuntijan Helmut Hirschin mukaan Fukushimasta on päässyt ympäristöön jo niin paljon radioaktiivisuutta, että se on IAEA:n INES-asteikolla luokiteltava vakavuusasteeltaan 7:ksi eli kaikkein vakavimmaksi onnettomuudeksi. Fukushimassa on näin ollen tapahtunut saman luokan onnettomuus kuin Tshernobylissä vuonna 1986. INES-asteikolla onnettomuus on luokkaa 7, jos radioaktiivisia aineita pääsee ilmaan enemmän kuin 20 000 TBq (terabecquereliä) jodi-131:tä vastaava määrä. Fukushimasta oli 23.3. mennessä päässyt pelkästään radioaktiivista jodia ja cesiumia jo 500 000 TBq jodi-131-ekvivalenttia. Ja päästöt vain jatkuvat. Itseasiassa, jokaisesta Fukushiman kolmesta onnettomuusreaktorista on päässyt yli 100 000 TBq jodi-131-ekvivalenttia. Toisin sanoen Fukushimassa on tapahtunut kolme Tshernobyl-luokan onnettomuutta. Alla asiasta tarkemmin.

http://www.greenpeace.org/international/PageFiles/285388/greenpeace_hirsch_INES_report_25032011.pdf

Fukushima – INES scale rating
23 March 2011
Helmut Hirsch
_________________________________________________________
Aim and structure of the INES scale
In 1990 the International Nuclear and Radiological Event Scale (INES) was developed
through international experts, summoned via the IAEA and the nuclear agency of the
OECD (OECD / NEA). The aim of the INES scale is to provide prompt and consistent
information covering the relevance of an event connected to radioactive material.
The INES scale covers eight levels:
level 7 major accident
level 6 serious accident
level 5 accident with wider consequences
level 4 accident with local consequences
level 3 serious incident
level 2 incident
level 1 anomaly
level 0 no safety significance
Chernobyl in 1986 was rated an INES 7 event, Three Mile Island in 1979 an INES 5 event.
The rating follows three main criteria areas: offsite radiological effects, onsite radiological
effects, impairment of safety measures.
For accidents (level 4 – 7) the radiological effects outside the plant are primarily relevant.
Criteria for INES event rating
According to the INES handbook the radiological impacts outside a nuclear complex can
be described through (a) the release of radioactive material into the atmosphere and (b)
the radiation doses.
Following (a) will be applied. This is because releases can be estimated more precisely
compared to received radiation doses. Besides this an INES rating of 6 is the maximum
when based on radiation doses only.
For the rating the releases into the atmosphere are in J-131 equivalents. Specific factors
for different nuclides are given to specify the J-131 equivalent. The factor for rare gases,
for example, is 0, for Cs-137 it is 40 and for Pu-239 the factor is 10,000.
INES level 7 – more than a couple of 10,000 J-131 equivalents
INES level 6– some 1,000 to a couple of 10,000 TBq J-131 equivalents
INES level 5– some 100 to a couple of 1,000 TBq J-131 equivalents
INES level 4– some 10 to a couple of 100 TBq J-131 equivalents
The IAEA states it not being appropriate to use exact numbers to define ratings as early
estimations are inevitably rough estimations only. To provide some orientation the IAEA
suggests 50,000, 5,000 and 500 TBq.
Adaptability to a number of reactors
The handbook suggests the IAEA generally assuming that the INES scale of is applied to
an event in one specific block of a nuclear power station. In general practical experience
confirms this.
How to deal with a combination of evens (like in Fukushima) remains open in the
handbook.
As mentioned above, the aim of the INES scale is to provide prompt and consistent
information covering the relevance of an event. Without doubt the overall release during
an event is the most important part of information for the public. The overall release is
relevant for air, ground, water, foodstuff contamination. Therefore it reflects the idea of the
INES scale to take into account all events in a nuclear complex (like Fukushima Daiichi)
where releases of a number of reactors overlap within a short time period, and rate them
together. Additionally the course of events interlink through contamination, explosions,
fires, direct radiation.
Beside this an individual rating can also be reasonable approach to add transparency to
the course of events.
Fukushima releases to date
There have been estimations on releases from Fukushima Daiichi reactors, two are
known to the author.
On 22.03.2011 the French Institut de Radioprotection et de Sûreté Nucléaire (IRSN)
(www.irsn.fr) published an estimation covering reactors 1 – 3 and the time period between
12.03.2011 and 22.03.2011: 90,000 TBq j-131, 10,000 TBq Cs-137 (plus specification
covering other nuclides).
On 22.03.2011 the Austrian Zentralanstalt für Meteorologie und Geodynamik (ZAMG)
(www.zamg.ac.at) published estimations covering the total release of J-131 and Cs-137 in
the first four days. This estimation has been specified on the 23.03.2011: 400,000 TBq J-
131, 85,000 TBq Cs-137.
For J-131 the author did further estimations. Based on core inventory specifications and
medium burn up (source: WNIH 2010) a J-131 inventory of 1,000,000 TBq for block 1 at
the time of the shutdown due to the earthquake and for bocks 2 and 3 1,800,000 TBq
each seems to be reasonable.
A release of 2.75% (equalling a non-filtered release during containment venting) results in
an overall release of approx. 125,000 TBq J-131 (summing up the three blocks).
These numbers closely represent IRSN numbers and will be used as the base for further
estimations. It is not to be assumed that this results in any kind of overestimation.
Radioactive decay is not taken into account by the author. It remains unclear whether it
was taken into account by IRSN or ZAMG. Radioactive decay is – having the time period
in mind – only relevant for J-131 (half life: eight days), not for Cs-137 (half life: 30 years).
Fukushima
The release of J-131 and Cs-137 alone (as stated through IRSN) corresponds to a
500,000 TBq J-131 equivalent.
Taken all Fukushima Daiichi reactors into consideration this is obviously an INES 7 event.
Each reactor considered individually results in more than 100.000 TBq per block (all
releases divided by three and proportionally to the inventory) – three INES 7 events. If the
release is not divided proportionally different ratings are possible.
As the Cs-137 release is the biggest share the above assessment remains unchanged,
even when the radioactive decay is taken into consideration.

Lääkärien sosiaalinen vastuu: ei turvallista säteilytasoa

Perjantaina 25. maaliskuuta 2011

Alla on Lääkärien sosiaalinen vastuu -järjestön tiedote, jossa se ilmaisee huolensa ruoan saastumisesta Japanissa. Lääkärijärjestö oikoo myös suomalaistenkin viranomaisten levittämää harhaa tulvallisesta säteilytasosta. Tiedotteessa esitetään myös hyvin se, mitä säteilyriskin suoraan verrannollisuus säteilyannokseen käytännössä tarkoittaa.

http://www.psr.org/news-events/press-releases/psr-concerned-about-reports-increased-radioactivity-food-supply.html

Physicians for Social Responsibility Deeply Concerned About Reports of Increased Radioactivity in Food Supply
Home > News & Events > Press Releases
March 23, 2011
Topic: Nuclear Power, Safe Energy, Safe Food

Washington, DC - March 23, 2011 – Physicians for Social Responsibility (PSR) expressed concern over recent reports that radioactivity from the ongoing Fukushima accident is present in the Japanese food supply. While all food contains radionuclides, whether from natural sources, nuclear testing or otherwise, the increased levels found in Japanese spinach and milk pose health risks to the population. PSR also expressed alarm over the level of misinformation circulating in press reports about the degree to which radiation exposure can be considered “safe.”

According to the National Academy of Sciences, there are no safe doses of radiation. Decades of research show clearly that any dose of radiation increases an individual’s risk for the development of cancer.

“There is no safe level of radionuclide exposure, whether from food, water or other sources. Period,” said Jeff Patterson, DO, immediate past president of Physicians for Social Responsibility. “Exposure to radionuclides, such as iodine-131 and cesium-137, increases the incidence of cancer. For this reason, every effort must be taken to minimize the radionuclide content in food and water.”

“Consuming food containing radionuclides is particularly dangerous. If an individual ingests or inhales a radioactive particle, it continues to irradiate the body as long as it remains radioactive and stays in the body,”said Alan H. Lockwood, MD, a member of the Board of Physicians for Social Responsibility. “The Japanese government should ban the sale of foods that contain radioactivity levels above pre-disaster levels and continue to monitor food and water broadly in the area. In addition, the FDA and EPA must enforce existing regulations and guidelines that address radionuclide content in our food supply here at home.”

As the crisis in Japan goes on, there are an increasing number of sources reporting that 100 milliSieverts (mSv) is the lowest dose at which a person is at risk for cancer. Established research disproves this claim. A dose of 100 mSv creates a one in 100 risk of getting cancer, buta dose of 10 mSv still gives a one in 1,000 chance of getting cancer, and a dose of 1 mSv gives a one in 10,000 risk.

Even if the risk of getting cancer for one individual from a given level of food contamination is low, if thousands or millions of people are exposed, then some of those people will get cancer.

Recent reports indicate the Japanese disaster has released more iodine-131 than cesium-137. Iodine-131 accumulates in the thyroid, especially of children, with a half-life of over 8 days compared to cesium-137, which has a half-life of just over 30 years. Regardless of the shorter half-life, doses of iodine-131 are extremely dangerous, especially to pregnant women and children, and can lead to incidents of cancer, hypothyroidism, mental retardation and thyroid deficiency, among other conditions.

“Children are much more susceptible to the effects of radiation, and stand a much greater chance of developing cancer than adults,” said Dr. Andrew Kanter, president-elect of PSR’s Board. “So it is particularly dangerous when they consume radioactive food or water.”

All food contains some radioactivity as a result of natural sources, but also from prior above-ground nuclear testing, the Chernobyl accident, and releases from nuclear reactors and from weapons facilities. The factors that will affect the radioactivityin food after the Fukushima accident are complicated. These include the radionuclides that the nuclear reactor emits, weather patterns that control the wind direction and where the radionuclides are deposited, characteristics of the soil (e.g., clays bind nuclides, sand does not) and the nature of the food(leafy plants like spinach are more likely to be contaminated than other plants like rice that have husks, etc.).However, radiation can be concentrated many times in the food chain and any consumption adds to the cumulative risk of cancer and other diseases.

“Reports indicate that the total radioactive releases from the Fukushima reactor have been relatively small so far. If this is the case, then the health effects to the overall population will be correspondingly small,” said Ira Helfand, MD, a member of the Board of Physicians for Social Responsibility. “But it is not true to say that it is “safe” to release this much radiation; some people will get cancer and die as a result.”

Resources

Health risks of the releases of radioactivity from the Fukushima Daiichi nuclear reactors: Are they a concern for residents of the United States?

ABOUT PHYSICIANS FOR SOCIAL RESPONSIBILITY (PSR)

Founded in 1961 by physicians concerned about the impact of nuclear proliferation, PSR shared the 1985 Nobel Peace Prize with International Physicians for the Prevention of Nuclear War for building public pressure to end the nuclear arms race. Since 1991, when PSR formally expanded its work by creating its environment and health program, PSR has addressed the issues of global warming and the toxic degradation of our environment. PSR educates and advocates for policies to curb global warming, ensure clean air, generate a sustainable energy future, prevent human exposures to toxic substances, and minimize toxic pollution of air, food, and drinking water. More information is available at www.psr.org.