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Risk Communication - Japan

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The Risk Communication Working Group is focused on providing risk communication to decision-makers and the public

The mission of the Risk Communication Working Group is to provide risk communication to decision-makers and the public.

Working Group email address:  ***@***.***

Members

AlMac99 bevcorwin Kathy Gilbeaux mdmcdonald

Email address for group

risk-communication-japan@m.resiliencesystem.org

New NRC Hazard Analysis Earthquake Study Released

submitted by Kay Goss

                 

US NRC study released today on "New Seismic Model Will Refine Hazard Analysis at U.S. Nuclear Plants" and performs studies at many central and eastern U.S. susceptible locations. The Central and Eastern United States Seismic Source Characterization for Nuclear Facilities (CEUS SSC) Project was conducted from April 2008 to December 2011 to develop a new, regional seismic source model for use in conducting and reviewing probabilistic seismic hazard analyses (PSHAs) for nuclear facilities in the CEUS. PSHA is a method for assessing site-specific seismic hazard that includes getting the best estimate of ground motions and a transparent quantitative accounting of uncertainty. The results of PSHA are used in seismic design and in calculating seismic risk. 

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Reactor Core Melted Fully, Japan Says

Reactors Monitor - (Click on image)

by Mitsuru Obe and Tom Fowler - The Wall Street Journal November 30, 2011

Fuel Breached Vessel Floor, Operator Says, In Its Gravest Fukushima Status Report

TOKYO—Japan's tsunami-stricken nuclear-power complex came closer to a catastrophic meltdown than previously indicated by its operator—who on Wednesday described how one reactor's molten nuclear core likely burned through its primary containment chamber and then ate as far as three-quarters of the way through the concrete in a secondary vessel.

The assessment—offered by Japan's government and Tokyo Electric Power Co., the operator of the Fukushima Daiichi nuclear complex—marked Japan's most sobering reckoning to date of the nuclear disaster sparked by the country's March 11 earthquake and tsunami.

IAEA Fukushima Daiichi Status Report - Full Update - November 4, 2011

                                        

The IAEA has received new information regarding the detection of xenon-133 and xenon-135 gases on 1 November inside the Primary Containment Vessel (PCV) of Fukushima Daiichi Unit 2.

Based on further analysis, Japanese authorities have concluded that the xenon concentrations are not due to a criticality event but rather from the spontaneous fission of curium-242 and 244. (Spontaneous fission is a form of radioactive decay that does not involve chain reactions and is characteristic of very heavy isotopes. Spontaneous fission occurs in low levels in all nuclear reactors.)

This conclusion is based on three key factors outlined and discussed in the report:

Xenon Means Recent Fission in Reactor 2

 

            

Graphic by The Asahi Shimbun

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By KAZUAKI NAGATA and MIZUHO AOKI - The Japan Times - November 3, 2011

Tepco claims level in gas too small to affect shutdown effort

Tokyo Electric Power Co. said Wednesday that some of the melted fuel in reactor 2 at the Fukushima No. 1 nuclear plant may have triggered a brief criticality event.

Although the Nuclear and Industrial Safety Agency said there have been no drastic changes in the reactor's temperature and pressure level, and the reactor itself is stable overall, the discovery may mean the goal of Tepco and the government to achieve cold shutdown of all three crippled reactors by the end of the year may not be possible.

Suggesting that criticality, or a sustained nuclear chain reaction, may have occurred temporarily, or partially, Tepco said one hundred thousandth of a becquerel per cubic centimeter of xenon-133 and xenon-135 was detected in gas samples.

New Trouble Reported at Japan Nuclear Plant

by Eric Talmadge - Associated Press (AP) - msnbc.com - November 1, 2011      

      

An aerial photo taken by a small unmanned drone and released by AIR PHOTO SERVICE, damaged Unit 3, left, and Unit 4 of the crippled Fukushima Dai-ichi nuclear power plant are seen in Okuma, Fukushima prefecture, northeastern Japan on March 24, 2011. (AP / AIR PHOTO SERVICE)

Officials detected a radioactive gas associated with nuclear fission at Japan's tsunami-damaged atomic power plant Wednesday, indicating there could be a new problem at one of its reactors. They injected a substance that neutralizes nuclear reactions as a precaution.

Gas from inside the reactor indicated the presence of radioactive xenon, which could be the byproduct of unexpected nuclear fission. Boric acid was being injected through a cooling pipe as a countermeasure because it can counteract nuclear reactions.

Citizens’ Testing Finds 20 Hot Spots Around Tokyo

By Hiroko Tabuchi - The New York Times - October 14, 2011

      

Toshiyuki Hattori, who runs a sewage plant in Tokyo, surrounded by sacks of radioactive sludge.  Kazuhiro Yokozeki for The New York Times

TOKYO — Takeo Hayashida signed on with a citizens’ group to test for radiation near his son’s baseball field in Tokyo after government officials told him they had no plans to check for fallout from the devastated Fukushima Daiichi nuclear plant. Like Japan’s central government, local officials said there was nothing to fear in the capital, 160 miles from the disaster zone.

Then came the test result: the level of radioactive cesium in a patch of dirt just yards from where his 11-year-old son, Koshiro, played baseball was equal to those in some contaminated areas around Chernobyl.

The patch of ground was one of more than 20 spots in and around the nation’s capital that the citizens’ group, and the respected nuclear research center they worked with, found were contaminated with potentially harmful levels of radioactive cesium.

Residents Near Fukushima Mountains Face Nuclear Recontamination Every Rainfall

The Mainichi Daily News - October 12, 2011        

      

Workers decontaminate radiation from the roof of Yasawa Kindergarten in Minami-Soma, about 12 miles (20 kilometers) away from the tsunami-crippled Fukushima Dai-ichi nuclear facility, in Fukushima prefecture, northeastern Japan, Thursday, Aug. 18, 2011.  Photo - Associated Press (AP)

As the crisis at the Fukushima No. 1 Nuclear Plant drags on, worries are growing particularly among Fukushima Prefecture residents over drawn-out and in some cases apparently futile nuclear decontamination operations.

The unease is especially strong in areas in and around mountains that must be repeatedly decontaminated, as every rainfall brings a new batch of radioactive substance-contaminated leaves and soil washing down from the hills. Since some 70 percent of Fukushima Prefecture is mountainous, such instances of regular recontamination could occur over a broad area, while the same effect has also been observed in some undeveloped areas of cities.

IAEA Team in Japan; Fukushima Starts Thyroid Tests

by Eric Talmadge - Associated Press - boston.com - October 9, 2011

A boy is taken by his mother to Fukushima Medical University Hospital for a thyroid test in Fukushima, northern Japan, Sunday, Oct. 9, 2011. Local doctors began a long-term survey of children for thyroid abnormalities, a problem associated with radiation exposure. Officials hope to test some 360,000 people who were under the age of 18 when the nuclear crisis began in March, and then provide follow-ups throughout their lifetimes. Japanese on the board reads: a thyroid test entrance. (AP Photo/Kyodo News)

TOKYO—Experts from the International Atomic Energy Agency arrived in the Japanese city of Fukushima on Sunday to observe the massive decontamination effort following the world's worst nuclear disaster since Chernobyl.

Local doctors also began a long-term survey of children for thyroid abnormalities, a problem associated with radiation exposure. Officials hope to test some 360,000 people who were under the age of 18 when the nuclear crisis began in March, and then provide follow-ups throughout their lifetimes.

Cesium Fallout Map Illustrates Kanto Levels

by Mizuho Aoki - The Japan Times - October 1, 2011

                    

The science ministry's latest aerial monitoring over Chiba and Saitama prefectures in September confirmed that radioactive cesium released from the Fukushima No. 1 power plant has contaminated parts of the Kanto region.

A ministry report released Thursday revealed that contamination was found in northern Chiba, including the cities of Kashiwa, Matsudo and Abiko, and in the mountainous areas of Chichibu in Saitama Prefecture's west and Misato in the prefecture's east.

The highest contaminated areas contained between 60,000 to 100,000 becquerels of cesium-134 and -137 per square meter, it showed. Cesium-134 has a half-life of two years and the one for -137 is 30 years.

Radiation levels in the area were between 0.2 to 0.5 microsieverts per hour, the report said.

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