47th Carnival of Nuclear Energy Blogs
Michele Kearney's Nuclear Wire - Major Energy and Environmental News and Commentary affecting the Nuclear Industry. Nuclear Activities
Saturday, April 9, 2011
World's Largest Concrete Boom Pumps en Route to Japan to Help Cool Nuclear Reactors
World's Largest Concrete Boom Pumps en Route to Japan to Help Cool Nuclear Reactors
Japan Orders Nuclear Plant Operators to Obtain More Emergency Generators
Japan Orders Nuclear Plant Operators to Obtain More Emergency Generators
Soil cesium limit set for rice / Some farmers won't be allowed to plant this season, possibly longer
Soil cesium limit set for rice / Some farmers won't be allowed to plant this season, possibly longer
Tepco Says Water Level Rises in Fukushima No. 2 Reactor
Tepco Says Water Level Rises in Fukushima No. 2 Reactor
Forget uranium, let's use thorium in nuclear reactors
Forget uranium, let's use thorium in nuclear reactors
Read more: http://www.vancouversun.com/news/Forget+uranium+thorium+nuclear+reactors/4587908/story.html#ixzz1J4W3Wg9c
Preventing a nuclear terrorist version of Fukushima
Preventing a nuclear terrorist version of Fukushima
Article Highlights
- The decision by the European Union to conduct nuclear safety "stress tests" on all of its 143 nuclear reactors sets an important precedent.
JAIF Updates 4/09
 | 2011-04-09 Earthquake Report 47  (119KB) |
| 2011-04-09 Reactor Status and Major Events Update 76 - NPPs in Fukushima as of 18:00 April ・・・ (280KB) |
| 2011-04-09 Reactor Status and Major Events Update 75 - NPPs in Fukushima as of 10:00 April ・・・ (280KB) |
| 2011-04-08 Earthquake Report 46 (146KB) |
| 2011-04-08 Reactor Status and Major Events Update 74 - NPPs in Fukushima as of 20:00 April ・・・ (273KB) |
| 2011-04-08 Reactor Status and Major Events Update 73 - NPPs in Fukushima as of 16:00 April ・・・ (273KB) |
| 2011-04-08 Trend of Radiation in the Environment around Fukushima Daiichi NPS (646KB) |
| 2011-04-08 Reactor Status and Major Events Update 72 - NPPs in Fukushima as of 10:00 April ・・・ (273KB) |
IAEA Briefing on Fukushima Nuclear Accident (9 April 2011, 15:00 UTC)
IAEA Briefing on Fukushima Nuclear Accident (9 April 2011, 15:00 UTC)
Presentation:→ Summary of Reactor Status
On Saturday, 9 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:
1. Current Situation
Earthquake of 7 April
The IAEA confirms that an earthquake occurred in Japan at 14:32 UTC 7th April. The IAEA International Seismic Safety Centre has rated it as a 7.1 magnitude, revised from an initial 7.4 magnitude. The epicenter of the earthquake was 20 km from the Onagawa nuclear power plant and approximately 120 km from the Fukushima Daiichi and Daini nuclear power plants. With the recovery of external power at the Rokkasho Reprocessing Plant, all sites reported on yesterday have external power.
Changes to Fukushima Daiichi Plant Status
In Units 1, 2 and 3, 60,000 tons of contaminated water need to be removed from the turbine buildings and trenches. This water will be transferred to the condensers of each unit and the Radioactive Waste Treatment facility. In addition, temporary storage tanks have been ordered to provide additional capacity for the water and will be located adjacent to the Radioactive Waste Treatment facility.
Nitrogen gas is continuing to be injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel is increasing due to the addition of nitrogen.
In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being continuously injected through the fire extinguisher lines at indicated rates of 8 m3/h and 7 m3/h respectively using temporary electric pumps with off-site power.
In Unit 1 the pressure in the RPV is increasing as indicated on both channels of instrumentation. NISA has indicated that some instruments in the reactor vessel may not be working properly. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.
RPV temperatures remain above cold shutdown conditions, typically less than 95 °C. In Unit 1 temperature at the feed water nozzle of the RPV is 246 °C and at the bottom of the RPV is 119 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 141 °C. The temperature at the bottom of the RPV was not reported. In Unit 3 the temperature at the feed water nozzle of the RPV is 89 °C and at the bottom of the RPV is 110 °C.
The concrete pump vehicle continued to spray fresh water to the spent fuel pool in Unit 3 on 8 April.
There has been no change in status in Units 4, 5 and 6 and the Common Spent Fuel Storage Facility
2. Radiation monitoring
On 8th April, low levels of deposition of both iodine-131 and cesium-137 were detected in 10 and 7 prefectures respectively. The values reported for iodine-131 ranged from 1 to 46 becquerel per square metre, for cesium-137 from 5 to 42 becquerel per square metre.
Gamma dose rates are measured daily in all 47 prefectures and the values continue to decrease. For Fukushima, on 8th April a dose rate of 2.3 µSv/h, for the Ibaraki prefecture a gamma dose rate of 0.15 µSv/h were reported. The gamma dose rates reported for the other 45 prefectures were below 0.1µSv/h.
Since the end of March, MEXT has set up an additional monitoring programme in cooperation with local universities. Measurements are made in 26 cities in 13 prefectures. As of 8th April, in 17 cities, the gamma dose rates were below 0.1 µSv/h. In 8 other cities, gamma dose rates ranged from 0.13 to 0.17 µSv/h, In Fukushima City, a value of 0.42 µSv/h was observed. Typical normal background levels are in the range 0.05 to 0.1 µSv/hr.
The IAEA Team in Fukushima made measurements on the 8th April at 8 different locations at distances of 24 to 42 km, in Northwesterly directions from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 1.6 to 56 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.2 to 5.0 Megabecquerel per square metre. The highest beta-gamma contaminations have been determined at distances of less than 30 km.
Since our written brief of yesterday, data related to food contamination has not been reported. However, on 8th April the Ministry of Health, Labour and Welfare reported that the Emergency Response headquarters had approved the lifting of restrictions on the distribution of unprocessed raw milk in certain locations in Fukushima prefecture (city of Kitakata and the towns of Aizumisato, Bandai, Inawashiro, Michima, Minamiaizu and Simogo) and on the distribution of spinach and kakina in Gunma prefecture.
As reported in the brief of 8th April TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations as illustrated in the Map 1
On 6th April at the near-shore sampling points TEPCO 1, TEPCO 3 and TEPCO 4 a decrease in the concentration of I-131 and Cs-137 have been reported. However, at the sampling point TEPCO 2 an increase in the concentration of I-131 (from about 20 kBq/l on 5th April to about 40 kBq/l) and Cs-137 (from about 15 kBq/l on 5th April to about 25 kBq/l) was observed.
For the six sampling points TEPCO 5 to TEPCO 10 on 6th April levels of I-131 below 0.4 kBq/l and Cs-137 below 0.2 kBq/l were measured.
MEXT Off-shore Monitoring Programme
As reported in the brief of 8th April, MEXT initiated the off-shore monitoring program on 23rd March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4th April, MEXT added two further sampling points to the north and west of sampling point 1. These are referred to as points A and B on the map below.
0n 9 April new data have been reported for samples taken on the 5th April. These data were for the sampling points MEXT3 and MEXT5. At MEXT3 there was an increase from about 3 Bq/l on 1st April to about 10 Bq/l on 5th April for I-131. At MEXT5 there was an increase from about 12 Bq/l on 1st April to about 65 Bq/l for I-131and from about 15 Bq/l to about 40 Bq/l for Cs-137 on 5th April.
No new data for the other sampling points have been reported.
3. IAEA Activities
A team of three agency experts in BWR technology continue to meet with TEPCO and NISA officials in Tokyo.
New Video Shows Disaster at Fukushima Nuclear Plant; Japan Tightens Regulations
New Video Shows Disaster at Fukushima Nuclear Plant; Japan Tightens Regulations
Newly released video of Japan's March 11 earthquake and tsunami is giving the world a better look at its devastating impact on the Fukushima Daiichi nuclear plant.The brief clip put out by the Tokyo Electric Power Company Saturday shows a wall of water slamming into the plant, easily overwhelming the facility's protective seawall.
The release of the video clip comes the same day Japanese officials announced they were requiring the country's nuclear facilities to take additional precautions.
The Nuclear and Industrial Safety Agency said Saturday all nuclear facilities will now have need two emergency backup generators instead of one.
U.S. Health-Care System Unprepared For Major Nuclear Emergency, Officials Say -- Washington Post
U.S. officials say the nation’s health system is ill-prepared to cope with a catastrophic release of radiation, despite years of focus on the possibility of a terrorist “dirty bomb” or an improvised nuclear device attack.
A blunt assessment circulating among American officials says, “Current capabilities can only handle a few radiation injuries at any one time.” That assessment, prepared by the Department of Homeland Security in 2010 and stamped “for official use only,’’ says “there is no strategy for notifying the public in real time of recommendations on shelter or evacuation priorities.”
Read more ....
Update: U.S. Health System Judged Unready For Nuclear Disaster -- Global Security Newswire
Did the Graphite in the Windscale Reactor Burn?
Did the Graphite in the Windscale Reactor Burn?
It is not entirely clear what happened in the Windscale reactor fire. The Windscale reactor has not yet been entirely dismantled, so how much damaged was done to its core graphite is still open to question. There is little doubt that metals in the core - Aluminum and Uranium - burned.
The hastily prepared 1957 Penney report stated that the Windscale core graphite caught fire, but did it? When The UK Nuclear Safety Advisory Committee (NuSAC) meet in 2009 to examine evidence from the Windscale reactor, it found, • Inspections have shown that there was NOT a graphite fire: damage to graphite, caused by severely overheated fuel assemblies, was localised.The NuSAC report added,
Some members of NuSAC may be aware that recent attempts to burn GLEEP graphite (block form) in a high temperature incinerator succeeded only in making it hot.
China to ban imports of farm products from Japan
China to ban imports of farm products from Japan
(Reuters) - China will ban the import of farm produce, including food, edible agricultural products and feedstuff, from 12 areas in Japan, the country's quarantine authorities said, as concerns about radiation contamination mount.Fukushima Nuclear Plant Threatened by Rising Water Before Drainage Starts
Fukushima Nuclear Plant Threatened by Rising Water Before Drainage Starts
Leaked Docs Show U.S. Regulators Doubt Nuclear Safety
Leaked Docs Show U.S. Regulators Doubt Nuclear Safety
Newly disclosed documents show U.S. regulators privately doubt that some of the nation’s nuclear power plants can withstand a disaster akin to Japan’s following the earthquake and tsunami. In internal emails and memos, Nuclear Regulatory Commission members have questioned backup plans to maintain cooling systems in case main power sources fail. A July 2010 memo assessing Exelon Corporation’s Peach Bottom nuclear plant in Delta, Pennsylvania, concludes that contingency plans "have really not been reviewed to ensure that they will work to mitigate severe accidents." The messages were released by the Union Concerned Scientists. In a statement, UCS nuclear expert Edwin Lyman said, "While [regulators] and the nuclear industry have been reassuring Americans that there is nothing to worry about … it turns out that privately NRC senior analysts are not so sure."
Tepco Installs Barrier to Prevent Sea Contamination
Tepco Installs Barrier to Prevent Sea Contamination
TOKYO—Tokyo Electric Power Co. on Saturday began installing a steel barrier at the crippled Fukushima Daiichi nuclear plant to prevent highly radioactive water from leaking into the Pacific Ocean, as Japan's trade minister became the first member of the government to visit the site since the March 11 earthquake and tsunami.Earthquake in Japan
Regulatory Limits on Radiation Dose
Regulatory Limits on Radiation Dose
Safety Limits: What are they? How are they determined?Much of the discussion concerning radiation levels and radioactive material releases has been presented in the context of safety limits set by a regulator. Examples of such limits include the I-131 limit for drinking water (210 Bq/L) or an annual occupational radiation dose limit (0.05 Sv). What is often left out of these discussions is how these limits were determined and what exceeding a limit implies. This post is intended to provide a general description of the implications of safety limits.
What is a Safety Limit and how are Safety Limits determined?
Safety limits are designed to protect the public from a potential harm and are often set well below the point of potential danger to prevent that point of danger from being accidentally reached. Safety Limits are determined in two steps. First, by identifying the amount of exposure to any given agent, above which causes a health effect to be observed. This amount is determined for the most vulnerable members of the population, and considers the effects of both short and long-term exposure. That resulting number is then divided by a safety factor to ensure that the public is never exposed to dangerous levels. The reason for the safety factor is so the regulator will have time to fix the problem before the levels reach a point that can cause harm to the public, if for whatever reason, the safety limit is exceeded. The more uncertain the dividing line between safety and harm is, the larger the safety factor used to protect the public.
Key Principles of Radiation Protection at Low Radiation Exposure
The probabilistic nature of low-dose radiation health effects makes it impossible to derive a clear distinction between ‘safe’ and ‘dangerous’ level of radiation. This also creates difficulties in explaining the control of radiation risks. The major policy implication is that some finite risk, however small, must be assumed and a level of protection established based on what is deemed acceptable. This leads to a system of protection based on three key principles recognized by the International Commission of Radiation Protection (ICRP) and endorsed by the US National Council on Radiation Protection and Measurement (NCRP) and all other national agencies:
- Principle of Justification, based on the analysis of benefit versus risk of exposure;
- Principle of Optimization of Exposure, based on the ALARA (As Low As Reasonably Achievable) principle;
- Principle of limitation of exposure to any person;
The ICRP, in its latest Recommendations on Radiological Protection, stated that for radiation doses below around 100 mSv in a year, the increase in the incidence of stochastic effects is assumed to occur with a small probability and in proportion to the increase in radiation dose over the background dose. The use of this so-called linear-non-threshold (LNT) model is considered by the ICRP and by NCRP the best practical approach to managing risk from radiation exposure and commensurate with precautionary principle, being a prudent basis for radiological protection at low doses and low dose rates. However, uncertainties on the over-conservatism on this judgment are recognized by the ICRP and the NCRP, which have stated the need for further evaluation based on new research results.
Despite the fact that the actual onset of latent cancer and other long term effects in relationship to radioactivity exposure is unknown, we do know that those effects are not statistically significant at very low doses. In simpler terms, the number of cancers caused by exposure to low doses of radiation is so small that we can’t sort it out from the noise – the natural rate of cancer incidence.
In 1980, the US National Council on Radiation Protection and Measurement (NCRP) published a report examining and quantifying the dose rate effect. In examining all laboratory data regarding tumor induction published at that time, they found that lowering the dose rate from acute (eg 180 mSv/hr) to about 4.8 mSv/hr reduced the rate of tumor generation by an average factor of 4. They called this the ‘dose rate effectiveness factor’, DREF. When the irradiations were much longer term irradiations, comprising “a significant or sizeable fraction of the life span” an even larger reduction in effect was observed, an average of a factor of 10; this was called the ‘protraction factor’ (PF). With few exceptions, the dose rates used in all of the laboratory studies cited in NCRP 64 used ‘low dose rates’ at least a factor of 4000 times higher than normal background dose rates. It is the results of these experiments and others like them, plus corresponding safety factors, which are used to establish regulatory limits on dose and dose rate to the general public.
However, what is of interest today in Japan are dose-rates more like 10, 30, or 100 times background. What about these dose rates? The problem noted by the NCRP was that deleterious effects of these very low dose rates could not be observed. In fact, low doses and low dose rates led to increased longevity rather than the decreased lifespan seen at higher doses and dose rates. In addressing the apparent life lengthening at low dose rates, the NCRP interpreted this effect as reflecting “a favorable response to low grade injury leading to some degree of systemic stimulation.” They go on to state that “…there appears to be little doubt that mean life span in some animal populations exposed to low level radiation throughout their lifetimes is longer than that of the un-irradiated control population.” In the future, the accurate examination of residents of high background radiation areas around the world might generate the needed information on this phenomenon, which is termed “radiation hormesis”. Based on the presently available data, residents of high background radiation areas (sizeable population is exposed up to 20 mSv per year from natural background) do not appear to suffer adverse effects from these doses.
Areas characterized with background radiation significantly higher than average can be found in Iran, Brazil, India, Australia and China. In the U.S., the population of Denver receives more than 10 mSv per year from natural background.
BNC Fukushima Daiichi nuclear saga - 2 to 9 April overview
 | Fukushima Daiichi nuclear saga - 2 to 9 April overview Barry Brook | 9 April 2011 at 10:45 PM | Categories: Hot News, Nuclear | URL: http://wp.me/piCIJ-18V |
The nuclear crisis at Fukushima Daiichi has, alas, now evolved into more of a saga. The last seven days of events has been acted out in slow motion compared to the first dramatic week (dating back to almost a month ago), but there continues to be plenty of headaches for TEPCO -- and no clear sign of things being locked down any time soon. The economic cost of the earthquake and tsunami has now been put at ~$300 billion, and will probably rise further in the coming months.I last wrote an update post a week ago (although I've also been providing daily updates in the comments section), so it's best to start this one by looking at what's happened, day by day, since then. Here is my somewhat potted update summary, with just the main points highlighted.
It was 2nd of April (Saturday) that it was first reported that a stream of contaminated water was flowing into the ocean, leading to extremely high radiation levels immediately offshore of the plant. The water appeared to be coming from the vicinity of Unit 2, and after some diagnostics, including the use of a coloured tracer (dye), the source was identified as a 20 cm crack in a maintenance pit which lies between Unit 2 and the sea. The pit is used to hold cables to power the seawater pumps. Its radiation was measured as ~1 Sv/hr.
In the evening of 2 April, concrete injection was trialled as a means to seal the crack, but this failed. Throughout 3 April, a second attempt was made, this time via injection of a water-absorbing polymer, mixed with sawdust and shredded paper (to aid in the swelling process). This also did not set. To mitigate the leaks to the ocean, plans were then made to try and pump a large amount of the contaminated water out of the pit and into storage, including some barges that had been anchored offshore.
It was also announced by TEPCO that the bodies of the two workers who had been missing in the turbine building of Unit 2 since the tsunami struck had been recovered on March 30. They'd apparently been drowned when the site had been innundated. The image above illustrates just how devastated the landscape around the plant is after the monster wave (14 m in this area of the coastline) wreaked its havoc.
Along with the crane operator at Fukushima Daiini, WNN reports...
Read more of this post
Editorial How Much of a Threat?
Editorial
How Much of a Threat?
Radiation from Japan must be carefully monitored, but, so far, Americans are in no danger.
TEPCO won't take Chernobyl approach to resolving nuclear power plant crisis
It may take 10 years to start removing damaged nuclear fuel from the Fukushima No. 1 Nuclear Power Plant, but the plant's operator is adamant not to bury the damaged reactors while fuel remains in them, a company official has told the Mainichi.
"We will not bury the site while radioactive materials remain. We will definitely remove the fuel," Tokyo Electric Power Co. (TEPCO) adviser Toshiaki Enomoto told the Mainichi in an interview, stressing that the company would not bury the reactors in concrete in a "stone tomb" approach like the one adopted at Chernobyl.
"We will not bury the site while radioactive materials remain. We will definitely remove the fuel," Tokyo Electric Power Co. (TEPCO) adviser Toshiaki Enomoto told the Mainichi in an interview, stressing that the company would not bury the reactors in concrete in a "stone tomb" approach like the one adopted at Chernobyl.
Status of nuclear facilities after Thursday's strong aftershock
Status of nuclear facilities after Thursday's strong aftershock
TOKYO, April 8, Kyodo
The following is the known status of nuclear power facilities as of Friday night following the aftershock that rattled Miyagi Prefecture and elsewhere late Thursday night, the strongest since the magnitude 9.0 earthquake on March 11.Tomari nuclear power plant in Hokkaido
Failure to supply electricity to Tohoku region, output at reactors Nos. 1 and 2 temporarily cut to 90 percent of capacity, operation restored by 6:30 a.m. Friday.
Higashidori nuclear power plant in Aomori Prefecture
Part of outside power source temporarily lost at reactor No. 1 undergoing regular checkup, spent nuclear fuel pool cooled down with emergency power generator, external power source restored at 3:30 a.m. Friday, no problem found.
Rokkasho spent nuclear fuel reprocessing plant in Aomori Prefecture
Part of external power source temporarily lost, restored at 9:44 a.m. Friday.
Onagawa nuclear power plant in Miyagi Prefecture
Suspension of operation continuing, part of external power source lost, cooling system for nuclear fuel pool temporarily suspended, water leakage found.
Fukushima Daiichi nuclear power plant in Fukushima Prefecture
No new problem found at reactors Nos. 1 to 6, no change in radiation levels.
Fukushima Daini plant
No problem found, no change in radiation levels.
Tokai Daini nuclear power plant in Ibaraki Prefecture
Suspension of operation continuing, no problem found.
JAIF Reactor Updates 4/09
Subscribe to:
Posts (Atom)