The Browns Ferry Nuclear Plant is located on the Tennessee River near Decatur and Athens, Alabama, on the north side (right bank) of Wheeler Lake. The nuclear power plant is named after a ferry that operated at the site until the middle of the 20th century.
The site has three General Electric boiling water reactor (BWR) nuclear generating units and is owned entirely by the Tennessee Valley Authority.
It was the Tennessee Valley Authority’s (TVA) first nuclear power plant, and the largest in the world when it began operation in 1974.
TVA restarted Browns Ferry Units 2 and 3 in the 1990s. As part of a long-range integrated resource planning process, TVA deferred the decision in 1995 to recover Unit 1.
In 2002, TVA completed a number of detailed studies and determined that restarting the long idled reactor was the best business decision to help meet growing demand for electricity in its service area.
In 2002, when the TVA Board decided to authorize the restart project, TVA estimated Unit 1 would have to operate between seven and eight years in order to pay back the cost of recovery.
- Major construction on Browns Ferry began in 1967.
- Unit 1 began commercial operation on August 1, 1974.
- Unit 2 began commercial operation on March 1, 1975.
- Unit 3 began commercial operation on March 1, 1977.
- TVA shut down Browns Ferry and the rest of its nuclear fleet in 1985.
- TVA restarted units 2 and 3 in 1991 and 1995 respectively.
- TVA Board approved the restart of Unit 1 in May 2002.
TVA loses all power transmission lines in Alabama and Mississippi, Browns Ferry Nuclear plant forced into emergency shutdown
Wednesday’s storms took out all of TVA’s electric power transmission lines in Mississippi and North Alabama, and forced Browns Ferry Nuclear Plant onto diesel backup power and into emergency and automatic cold shutdown.
Bill McCollum, the chief operating officer of Tennessee Valley Authority, said it may be weeks before power can be restored to all of the 300,000 customers whose power is supplied by the federal utility.
“With the level of damage we have, it will be — we hope it will be days until we get most of the customers back on, but it will be weeks before we’ve fully repaired all of the damage,” he said.
McCollum said the reactors, now being cooled by backup diesel power, are safe. He also said the spent fuel pools also are being cooled by backup diesel power and are safe.
The transmission lines are the monster power lines that carry electricity from TVA power plants to power distributors such as EPB and Huntsville Utilities.
Now those utilities, along with a number of large industries that are wired directly to TVA transmission lines, will not have power until the lines are repaired, McCollum said.
The loss of those transmission lines also caused Browns Ferry Nuclear Plant to lose power.
When the plant generates power, it uses some of that power and the excess is sent out on the transmission lines. When those transmission lines can’t take power, it causes the reactors to trip, according to TVA officials.
The spent fuel is not as well protected as the fuel in the reactor. In Japan, the spent fuel is now open to the atmosphere in at least two plants. The danger posed by the pools is significant. A U.S. study showed that a drained spent-fuel pool delivers a lethal dose of radiation to a worker at its railing in 16 seconds.
Fuel rods in the pool are thermally hot and radioactive. They rely on water and circulation pumps to avoid reaching temperatures that melt the metal cladding around the fuel rods, a condition that releases radiation.
Browns Ferry is more vulnerable to problems with the spent-fuel pools than are the plants in Japan. Delays in constructing a storage facility for depleted fuel — planned at Yucca Mountain in Nevada — resulted in Browns Ferry and other plants stockpiling the fuel in the cooling pools.
TVA is gradually moving the spent fuel to on-site dry casks, but the pools remain near capacity. A capacity that was increased by request of the nuclear industry resulting in closer spacing of spent rods than was originally designed into the system.
That means they have more radioactive content than the pools at the Japan reactors, and they are more dependent upon electric pumps to circulate water within the cramped quarters.
“Our spent fuel pools in the reactors like the one in Japan are almost filled to the brim, and the risk from the spent fuel pools — either from an accident or from an act of malice — are about as high as you could possibly make them,” said Lochbaum, director of the nuclear safety program at the Union of Concerned Scientists, which describes itself as a watchdog group that neither supports nor opposes nuclear power.
Another issue that some experts fear will come into play in Japan involves the consequences of melting fuel rods within the reactor.
If cooling efforts fail, the fuel rods ultimately will melt into a lava-like substance. The heat would melt the steel reactor vessel, allowing the melted fuel to drop to the concrete containment vessel. In Mark I reactors, the containment vessel is concrete with steel at the edges.
“In the Mark I containment, there is a known vulnerability to containment failure known as liner melt-through,” said Ed Lyman, a physicist at Union of Concerned Scientists. “If that melt spreads to the corners, then it may be able to melt through the steel shell of the containment as it ate through the reactor vessel.”
If it happens, especially if the containment vessels are damaged as they are in Japan, “that would essentially mean large radiological release to the environment.”
McCollum said he is confident the authority’s reactors are safe, but TVA will seek to learn from the problems in Japan.
“TVA’s plants are designed, built and operated to be safe,” McCollum said. “That’s our No. 1 mission. Our plants are designed to be very robust against all types of occurrences.
“It’s far too early to assess the total impact of this,” McCollum said. “I believe we’ll have to wait to understand the facts and events as they’ve really occurred, and what actions may need to be taken and lessons to be learned out of this.”
Newly arriving data from NASA’s STEREO probes suggest that a coronal mass ejection (CME) might be heading toward Earth. The source of the cloud appears to be sunspot complex 1185-1186, which experienced an episode of magnetic instability during the early hours of April 9th and again on the 10th.
Since April 7th the active region has hurled massive clouds into space. High latitude sky watchers should be alert for auroras. NOAA forecasters estimate a 40% chance of geomagnetic activity during the next 48 hours, when a solar wind stream is expected to buffet Earth’s magnetic field.
This movie to the right shows a spherical map of the Sun as it currently appears, formed from a combination of the latest STEREO Ahead and Behind beacon images, along with an SDO/AIA image in between. The movie starts with the view of the Sun as seen from Earth, with the 0 degree meridian line in the middle. The map then rotates through 360 degrees to show the part of the Sun not visible from Earth.
STEREO consists of two space-based observatories – one ahead of Earth in its orbit, the other trailing behind. With this new pair of viewpoints, scientists are able to see the structure and evolution of solar storms as they blast from the Sun and move out through space.
There are two kinds of solar storms, often related to each other: coronal mass ejections (CMEs) and solar flares.
A flare occurs when magnetic energy builds to a peak near the Sun’s surface and explodes. This intense, fast-paced event results in an intense burst of light, including X-rays, in the Sun’s lower atmosphere.
A much larger storm, a CME erupts when magnetic field lines snap, sending billions of tons of material into space at millions of miles per hour. The cloud expands to over 30 million miles by the time it reaches Earth. Both flares and CMEs can result in additional high speed particles being shot out into the solar system at close to the speed of light.
Click here to see the a composite of latest NASA LASCO C2 coronal images. Covering April 4-10, the GIF animation shows an amazing display of CME activity starting on April 7. This is a large file but worth downloading.
When the ejection is directed towards the Earth and reaches it as an interplanetary CME (ICME), the shock wave of the traveling mass of solar energetic particles causes a geomagnetic storm that may disrupt the Earth’s magnetosphere, compressing it on the day side and extending the night-side magnetic tail. When the magnetosphere reconnects on the night side, it releases power on the order of terawatt scale, which is directed back toward the Earth’s upper atmosphere.
This process can cause particularly strong auroras in large regions around Earth’s magnetic poles. These are also known as the Northern Lights (aurora borealis) in the northern hemisphere, and the Southern Lights (aurora australis) in the southern hemisphere. Aurora appear from Earth as shimmering, dancing lights in the night sky. Although green is the most common color, red and yellow hues are also observed.
Coronal mass ejections, along with solar flares of other origin, can disrupt radio transmissions and cause damage to satellites and electrical transmission line facilities, resulting in potentially massive and long-lasting power outages.
Humans in space or at high altitudes, for example, in airplanes, risk exposure to intense radiation. Short-term damage might include skin irritation. Long-term consequences might include an increased risk of developing skin cancer.
Japan may raise nuke accident severity level to highest 7 from 5
TOKYO [April 12, Kyodo News]
The Nuclear Safety Commission of Japan released a preliminary calculation Monday saying that the crippled Fukushima Daiichi nuclear plant had been releasing up to 10,000 terabecquerels of radioactive materials per hour at some point after a massive quake and tsunami hit northeastern Japan on March 11.
The disclosure prompted the government to consider raising the accident’s severity level to 7, the worst on an international scale, from the current 5, government sources said. The level 7 on the International Nuclear Event Scale has only been applied to the 1986 Chernobyl catastrophe.
The current provisional evaluation of 5 is at the same level as the Three Mile Island accident in the United States in 1979.
According to an evaluation by the INES, level 7 accidents correspond with a release into the external environment radioactive materials equal to more than tens of thousands terabecquerels of radioactive iodine 131. One terabecquerel equals 1 trillion becquerels.
Haruki Madarame, chairman of the commission, which is a government panel, said it has estimated that the release of 10,000 terabecquerels of radioactive materials per hour continued for several hours.
The commission says the release has since come down to under 1 terabecquerel per hour and said that it is still examining the total amount of radioactive materials released.
M 7.0 quake hits northeastern Japan
A strong earthquake struck north-eastern Japan at 5:16 PM, local time, on Monday, April 11. The earthquake’s magnitude was 7.0, and that its focus was in Fukushima Prefecture at a depth of 10 kilometers. Intensities of 6 minus on the Japanese scale of 0 to 7 were registered in some areas of Fukushima and Ibaraki prefectures, including Furudono Town, Nakajima Village and Hokota City. An intensity of 5 plus was registered in many areas in the southern Tohoku and northern Kanto regions.
Several minor quakes occurred following the major quake at 5:16. The agency is also warning of possible aftershocks with intensities of 6 plus or 6 minus. The operator of the crippled Fukushima Daiichi nuclear power plant, Tokyo Electric Power Company, says radiation figures at monitoring posts around the plant remain unchanged. The utility firm also says outdoor workers had been ordered to temporarily evacuate.
[Japan Atomic Industrial Forum Monday, April 11, 2011 18:46 +0900 (JST)
Expanded evacuation considered
The Japanese government is considering expanding its current 20-kilometer evacuation radius around the Fukushima Daiichi nuclear power plant, taking into account the risks of long-term accumulated radiation exposure. Chief Cabinet Secretary Yukio Edano said on Monday that the government may advise residents in areas between 20 and 30 kilometers from the plant to evacuate, based on accumulated radiation exposure levels. Currently such residents have been advised to remain indoors. Edano also said the government is considering advising residents to evacuate even from areas outside the zone where cumulative radiation exposure risks are higher. He said the possibility that the situation at the plant will worsen cannot be ruled out. Iitate Village
Water injection resumed at Fukushima Daiichi plant
The operator of Fukushima Daiichi nuclear power plant says water injection into the crippled reactors was briefly suspended after outside power lines were shut down by a magnitude 7.0 earthquake on Monday evening. Tokyo Electric Power Company said that outside power was restored for reactors No.1, 2 and 3. Water injection was resumed for these reactors after a suspension of about 50 minutes.
Monday, April 11, 2011 18:34 +0900 (JST)
Radiation dose higher than 1000 mSv was measured at the surface of water accumulated on the basement of Unit 2 turbine building and in the tunnel for laying piping outside the building on Mar. 27th.
Plutonium was detected from the soil sampled at Fukushima Dai-ichi NPS site on Mar. 21st, 22nd, 25th and 28th. The amount is so small that the Pu is not harmful to human body.
Radioactive materials exceeding the regulatory limit have been detected from seawater sample collected in the sea surrounding the Fukushima Dai-ichi NPS since Mar. 21st. On Apr. 5th, 7.5 million times the legal limit of radioactive iodine, I-131, was detected from the seawater, which had been sampled near the water intake of Unit 2 on Apr 2nd.
It was found on Apr. 2nd that there was highly radioactive (more than 1000mSv/hr) water in the concrete pit housing electrical cables and this water was leaking into the sea through cracks on the concrete wall. It was confirmed on Apr. 6th that the leakage of water stopped after injecting a hardening agent into holes drilled around the pit.
Release of some 10,000 tons of low level radioactive wastewater into the sea began on Apr. 4th, in order to make room for the highly radioactive water mentioned above.
Regarding the influence of the low level radioactive waste release, TEPCO evaluated that eating fish and seaweed caught near the plant every day for a year would add some 25% of the dose that the general pubic receive from the environment for a year.
TEPCO and MEXT has expanded the monitoring for the surrounding sea area since Apr. 4th.
Radioactive materials were detected from underground water sampled near the turbine buildings on Mar. 30th.
Containment of radioactive material:
It is presumed that radioactive material inside the reactor vessel may leaked outside at Unit 1, 2 and Unit 3, based on radioactive material found outside.
NISA announced that the reactor pressure vessel of Unit 2 and 3 may have lost air tightness because of low pressure inside the pressure vessel.
NISA told that it is unlikely that these are cracks or holes in the reactor pressure vessels on the same occasion.
TEPCO started to inject nitrogen gas into the Unit 1 containment vessel to reduce the possibility of hydrogen explosion on Apr. 6th. The same measure will be taken for Unit 2 and 3.
Steam like substance has been observed rising intermittently from the reactor building at Unit 1, 2, 3 and 4. Injecting and/or spraying water to the spent fuel pool has been conducted.
Progress of the work to recover injection function:
Water injection to the reactor pressure vessel by temporary pumps were switched from seawater to freshwater at Unit 1, 2 and 3.
High radiation circumstance hampering the work to restore originally installed pumps for injection.
Discharging radioactive water in the basement of the buildings of Unit 1through 3 continue to improve this situation.
Water transfer work is being made to secure a place for the water to go.
Lighting in the turbine buildings became partly available at Unit 1 through 4.
Radioactive material was detected from milk and agricultural products from Fukushima and neighboring prefectures. The government issued order to limit shipment (21st-) and intake (23rd-) for some products.
Radioactive iodine, exceeding the provisional legal limit, was detected from tap water sampled in some prefectures from Mar. 21st to 27th.
Small fish caught in waters off the coast of Ibaraki on Apr. 4 have been found to contain radioactive cesium above the legal limit on Apr. 5th.
It was decided on Apr. 5th that as a legal limit of radioactive iodine, the same amount for vegetables should be applied to fishery products for the time being.
[ from Japan Atomic Industrial Forum.]
During the 7.1 aftershock on April 7, water sloshed out of spent fuel pools in the plant’s No.1, No.2 and No.3 reactors, which had been shut down after the 9.0 magnitude quake on March 11, and had also leaked in three other locations in the No.3 reactor complex.
Tohoku Electric said on Friday two out of three lines supplying off-site power to the Onagawa site — in so-called cold shutdown since the March 11 quake — were lost last night in the strongest aftershock so far of the earlier quake.
Cooling operations of its spent pool fuels resumed after they stopped due to the quake, it said, and there was still an emergency backup generator to fall back on.
“We detected a small rise in radiation levels inside the reactor buildings, and are trying to find the locations of the leaks,” a Tohoku Electric official said. “We see no change in radiation levels outside the reactor buildings.”
According to Tohoku Electric, the cooling systems for the temporary storage pools for spent nuclear fuel rods at the Nos. 1 to 3 reactors in the Onagawa plant stopped temporarily after the aftershock hit the area and water spilled out from each pool.
The cooling systems were manually reactivated about an hour later. The fuel rods were not exposed and no radioactive substance had been found to have leaked outside, the company said.
Tohoku Electric said it’s possible the malfunction of a pressure gauge attached to a pump might have caused the cooling system for the No. 1 reactor’s storage pool to stop. The company is investigating the reason for the temporary shutdown of the cooling systems for the Nos. 2 and 3 reactors’ storage pools.
Tohoku Electric is also investigating the cause of the power cuts. A transformer station that supplies electricity to the plant suffered no failures.
The Onagawa Nuclear Power Plant is a nuclear power plant located on a 432 acres in Onagawa in the Oshika District and Ishinomaki city, Miyagi Prefecture, Japan. It is managed by the Tohoku Electric Power Company. It was the most quickly constructed nuclear power plant in the world.
The International Atomic Energy Agency said off-site power was lost at some other nuclear facilities in the country after Thursday evening’s quake, and that emergency power supply was operating.
A cooling system at the Higashidori nuclear power plant in Higashidorimura, Aomori Prefecture, stopped temporarily after the aftershock, plant operator Tohoku Electric Power Co. said Friday.
According to the company, two external power sources for the Higashidori plant, which was not operating at the time due to a regular inspection, were cut off as a result of outages throughout the prefecture following the aftershock. An emergency generator was used to supply power to the plant.
The cooling system for a temporary storage pool for spent nuclear fuel rods, where all the plant’s nuclear fuel was stored, stopped automatically, but restarted about one hour later.
No leakage of radioactive substances has been found, the company said. Another external power source, which was under inspection at the time of the aftershock, was restored at about 3:30 a.m. Friday.
Tokyo Electric Power Co. said Friday that the aftershock did not cause any new problems at its Fukushima No. 1 nuclear power plant. Nitrogen injections into the No. 1 reactor and the transportation of contaminated water continued smoothly despite some disturbances in restoration work, TEPCO officials said.
At Japan Nuclear Fuel Ltd.’s nuclear fuel reprocessing plant in Rokkashomura, Aomori Prefecture, two external power sources were cut off due to outages after the aftershock, but an emergency power source was activated. The plant was conducting test operations.
According to Japan Nuclear Fuel, spent nuclear fuel rods and a system to cool radioactive waste solution were unaffected.
According to the Economy, Trade and Industry Ministry’s Nuclear and Industrial Safety Agency, it is extremely rare for an emergency generator or power source to be activated at a nuclear power plant.
Such systems are a last resort, meant to supply power only after regular external power sources became unusable. An emergency power source was lost at the Fukushima No. 1 nuclear power plant after tsunami ravaged the facility on March 11, making it difficult to cool down nuclear reactors in a stable manner.
Three of the four external sources for the Nos. 1 to 3 reactors at Tohoku Electric Power’s Onagawa nuclear power plant in Onagawacho and Ishinomaki, Miyagi Prefecture, stopped supplying power late night Thursday. As of Friday morning, however, one of the three sources was working again, the company said.
Health Canada’s Fixed Point Surveillance Network Data
As part of routine operations, Health Canada’s Radiation Protection Bureau conducts 24/7 environmental monitoring across Canada using the Fixed Point Surveillance (FPS) network. Unlike the particulate and noble gas systems, these detectors do not concentrate radioactive material but rather report on the radiation levels from all gamma-emitting isotopes around the detector in near-real-time. As a result, they are less sensitive to low levels of radiation in air, but are better able to indicate changes in environmental radiation exposure. This information is being reported as a gamma radiation dose per day.
The following charts depict the average daily radiation dose from the environment for the month of April. In order to compare the actual daily values and account for normal fluctuations, the chart includes measured baseline values from 2010 (minimum, maximum and average over the entire year). Numbers are micro-Seiverts per day.
Canadian Comprehensive Nuclear-Test-Ban Treaty Station Radioisotope Concentrations
Under the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS), Health Canada’s Radiation Protection Bureau operates four certified IMS particulate monitoring stations (Sidney, BC; Yellowknife, NWT; Resolute Bay, NU; and St John’s, NL), two experimental noble gas systems (Yellowknife and St. John’s), and one station in Ottawa, ON.
All systems collect air over 24-hour sampling periods and concentrate radioisotopes so that they can be measured by gamma radiation detectors. By concentrating the material, it is possible to detect much lower quantities of radioactivity in air than with a real-time monitoring system, such as the Fixed Point Surveillance Network. In fact, it was the monitoring station in Sydney BC that detected the first radioactive isotopes coming from Japan.
The measurements in the following charts show the concentrations of radioisotopes in the air.
All of the Canadian CTBT stations collect data for cesium-137, iodine-131, and tellurium-132. These data are reported in milliBecquerels per cubic meter (mBq/m3).
Only Yellowknife, Ottawa, and St John’s are equipped to collect data for xenon-133, which is a noble gas. Noble gases do not react with other elements in the environment. As a result, they do not settle out of the plume but travel long distances in the atmosphere and are detected in relatively high concentrations.
Because the activities are relatively high, xenon-133 measurements are reported in Becquerels per cubic meter.
Several states have reported finding Iodine-131 in surface water (e.g., lakes, rivers, and reservoirs) and rain water. What does this mean for the public’s health?
Highly sensitive radiation monitors operated by EPA and others have detected very low levels of radioactive material in the air in the United States. These levels are consistent with estimated releases from the damaged nuclear reactors.
These findings were expected, given the sensitivity of our monitors and the fact that radioactive material is known to travel in the atmosphere. Federal, state, and local authorities will continue to monitor levels.
Will contaminated rainwater hurt me? Is it okay for my kids to play in the rain?
The very low levels of radioactive material currently being measured in surface water and rain water are far below those of public health concern.
Is it okay for my pet to drink the rainwater?
Drinking rainwater contaminated with radioactive material at the levels currently being detected is unlikely to harm your pet.
Since contaminated rain may have fallen in my area, is it okay to eat food from my garden or use rain water to irrigate it?
Yes. Keep in mind that it is always a good idea to wash food from your garden before you eat it.
Are there any groups of people that should be especially sensitive to radiation?
Infants, pregnant women and women who are breastfeeding are particularly sensitive to radiation. However, levels being measured now are still many times below the risk for even these groups, even for people who drink rainwater. Drinking water levels are many times below this. At this time, there is no need to take extra precautions with regard to drinking water.
Is it okay to take a shower or bath? Swim in a pool? In a river or lake?
Showering, bathing, or swimming in water with the amount of radioactive material that is currently being measured will not harm your health.
Should I drink bottled water instead of tap water?
At this time, there is no reason to switch to bottled water. State and local authorities will provide information for your community if this situation changes.
Should I be testing my water?
At this time, there is no need to take extra precautions with regard to drinking water.
States and the federal government routinely conduct water monitoring for safety and are working to ensure that drinking water does not pose a health risk to people in the US.
Is this likely to be a long-term problem?
Given the uncertainty related to the nuclear reactors in Japan, we don’t know how levels of radiation currently seen in surface water and rain water will change in the immediate time period. However, we do know that Iodine-131 disappears relatively quickly in the environment.
Who can I contact for the best information about my community?
The best source of information about your community is your local drinking water program or department, or your state environmental protection division or program.
Content source: Radiation Studies Branch (RSB), Division of Environmental Hazards and Health Effects (EHHE), National Center for Environmental Health (NCEH), Coordinating Center for Environmental Health and Injury Prevention (CCEHIP)
From The EPA’s Envirofacts Site – RadNet Overview
“RadNet is a national network of more than 200 monitoring stations distributed across all 50 states and the American Territories. These stations regularly sample the nation’s air, precipitation, drinking water, or pasturized milk for a variety of radionuclides.
RadNet normally samples radiation in all media on a regularly defined schedule. In the event of a threat of a significant radiation release RadNet typically will increase the frequency of sampling and generate many more data records for a given period of time compared to its routine operation.
RadNet data provides a means to estimate levels of radioactivity in the environment, including background radiation as well as radioactive fallout from atomic weapons testing, nuclear accidents, and other intrusions of radioactive materials. RadNet also provides the historical data needed to estimate long-term trends in environmental radiation levels.”
THEN WHERE’S THE DATA?
For more information on the EPA’s Failed RadNet radiation monitoring system click on the two stories below:
A 7.1-magnitude earthquake rattled Japan today according to the AP.
The quake, which occurred during the Japanese night on Thursday, hit 60 miles east of the city of Sendai and about 90 miles from Fukushima, where the beleaguered Daiichi nuclear plant is located; Tepco, the plant’s operator, released a statement noting none of its facilities received further damage from the quake.
A bright bluish flash is seen in the video. Earthquake Lights or electrical transformers are two possible explainations.
Characteristics of Earthquake Lights
Earthquake lights occur before, during and after earthquakes. They are cool and quiet, colored white or blue or red. They are usually dim, but sometimes are brighter than moonlight.
They take various forms: globes, bands, rays, sheets, clouds. They tend to rise from the ground. They have been reported at sea. They may flicker or shine steadily. They may be silent or accompanied by a crackling or bristling sound. Sometimes light boils from the ground like flames. They may be as brief as lightning or glow for several minutes.
Earthquake lights have been accompanied by low-frequency radio noise in the 10 to 20 kHz range.
Earthquake lights have been seen weeks before or after earthquakes and hundreds of kilometers from the epicenter. They are more common in areas of hard, crystalline rocks and near dip-slip rather than strike-slip faults.
UPDATE (Apr 7) -TEPCO Completes Nitrogen Injection At Unit 1
An operation to reduce the risk of a hydrogen explosion at the crisis-hit Fukushima Daiichi atomic power station’s No. 1 reactor by injecting it with nitrogen has gone smoothly, the plant’s operator Tokyo Electric Power Co. said Thursday. Pressure in the reactor’s containment vessel has risen as expected, indicating the success of the operation.
In its operation to prevent a hydrogen explosion at the No. 1 reactor, TEPCO plans to insert nearly 6,000 cubic meters of nitrogen, an inert gas, into the reactor over six days and estimates that about 200 cubic meters were injected between 1:30 a.m. and 9:50 a.m. Thursday.
The firm and the government’s Nuclear and Industrial Safety Agency said they believe chances are slim that another hydrogen explosion will occur immediately or that high volumes of radioactive substances will be emitted following the nitrogen injection operation. – Kyodo News (April 7)
UPDATE – Nuclear and Industrial Safety Agency – Seismic Damage Information (the 74th Release)
The Nuclear and Industrial Safety Agency stated that at Units 1 through 4 at Fukushima Daiichi NPS , “White smoke was confirmed to generate continuously.” Reported on April 6.
TEPCO Press Release (Apr 6) – Measures Taken To Prevent Explosion
Injection of Nitrogen to Reactor Containment Vessel of Fukushima Daiichi Nuclear Power Station Unit 1
“Regarding Fukushima Daiichi Nuclear Power Station Unit 1, taking into account the possibility of hydrogen accumulating inside, we have been considering encapsulation of hydrogen by injecting nitrogen to the reactor containment vessel.
Today, we received an order from minister of economy, trade and industry to report on matter such as necessity of encapsulating nitrogen, method for implementation, and impact assessment of safety.
Accordingly, we have compiled related matters and reported to minister of economy, trade and industry today. The report was approved after the deliberation in the Ministry of Economy, Trade and Industry.
Based on the report, we will begin injecting nitrogen to the reactor containment vessel of Unit 1 today, around 10:30pm”. END
Update [Apr.9] – TEPCO announced 0n 4_9 that they would perform an additional operation to inject nitrogen gas into the containment vessel of the Number 1 reactor to prevent a possible hydrogen explosion, TEPCO plans to increase the purity of nitrogen gas from 98 percent to 99.98 percent.
UPDATE – TEPCO Press Release (April 4) – Seawater at Unit-2 7.5 Million Times Limit
It has recently been reported in a number of blogs that Xe-131 has “blanketed” The US. There is enough to worry about during this event and Xenon is not one of them.
Pacific Northwest National Laboratory measured and reported the Xenon. Their lab has the most sensitive instrument in the world measuring specifically for Xenon around-the-clock. They are set up to provide Nuclear Test Treaty verification. They are not set up to warn for un-healthful levels during a radiation event.
Here is a report from the lab that first measured the very miniscule levels. PACIFIC NW LABS XENON-131 STATEMENT
Most of the “articles” include a moving map from WeatherOnline as proof of the blanket of Xe-131 covering us all. These are predictive dispersion models of where radioactive isotopes might go if they were in the atmosphere at that time. They are basically weather maps – not radiation predictors and should be treated as such.
Here is a disclaimer from the WeatherOnline website to amplify my assertion: “ATTENTION: These products are highly uncertain based on limited information for the source terms. Please use with caution and understand that the values are likely to change.”
HALF-LIFE: 5.29 days
Hazard category: C- level (low hazard ) : 0.100 to 10 mCi
B – level (Moderate hazard) : > 10 mCi to 1000 mCi
A – level (High hazard) : > greater than 1000 mCi
EXTERNAL RADIATION HAZARDS AND SHIELDING:
The gamma exposure rate at 1 cm from 1 mCi of Xe133 shielded for betas is 150 mR/hr, and at 1 foot will be 0.17 mR/hr. The half and tenth values of lead for this gamma are 0.003 and 0.015 cm respectively. This means that lead sheets or regular lead shipping pig will be sufficient for shielding the material.
The maximum range of the betas is about 0.002 inches in lead. Therefore, the use of the lead shield for storage will provide adequate shielding for the beta particles. If skin is uniformly contaminated with Xe133, 1 microcurie /cm2 deliver a dose of 4200 mrems/hr to the basal cells of the skin.
HAZARDS IF INTERNALLY DEPOSITED:
It is important to avoid ingestion, inhalation and/ or skin contamination.
The NCRP MPC for Xe133 is 10E-5 uCi/ml for 40 hr/wk.
SPECIAL PROBLEMS AND PRECAUTIONS:
1. Xe133 is heavier than air and hard to be kept in solution form, therefore, one should work in well ventilated areas.
2. Survey frequently. Change gloves often.
3. Limit of soluble waste to sewer: 100 microcuries per day per lab
TEPCO Press Release – Apr 6
“As part of monitoring activity of the surrounding environment, we conducted analysis of plutonium contained in the soil collected on March 21st and 22nd at the 5 spots in Fukushima Daiichi Nuclear Power Station.As a result, plutonium 238, 239 and 240 were detected. (previously announced)
Subsequently, from the 3 spots where periodic sampling was conducted on March 25th and 28th and from another spot which was supplemented on 25th, we conducted analysis of plutonium contained in the soil. As a result, plutonium 238, 239 and 240 were detected.
In addition, we conducted nuclide analysis of gamma ray contained in the soil collected on March 21st and 22nd at the 5 spots in Fukushima Daiichi Nuclear Power Station. Such analysis was also conducted on soil collected on March 25th and 28th at the 4 spots. As a result, radioactive materials were detected as described in the exhibit.
Accordingly, we have reported the result of analysis to Nuclear and Industrial Safety Agency and Fukushima Prefecture. We will continue the radionuclide analysis contained in the soil.”
UPDATE – TEPCO Press Release – April 7
“Additionally Iodine, Cesium, Tellurium, Barium, Niobium, Ruthenium, Molybdenum, Technetium, Lanthanum, Beryllium, Silver have been detected from the sample of soil at the site of Fukushima Daiichi Nuclear Power Station collected on 21st, 22nd, 25th and 28th of March.”
Today we have received a letter of protest from National Federation of Fisheries Cooperative Associations (NFFCA) with regard to the discharge of the low level radioactive wastewater from Fukushima Daiichi Nuclear Power Station to the sea. We, as the operator of the power station, received the letter with sincerity, being painfully aware of the feelings and concerns of people in the fishery industry.
While the water discharge was an unavoidable emergency measure implemented after the consultation with the national government in order to prevent the spread of high level radioactive substances, protect the essential safety facilities from inundation and maintain the cooling functions of Units 5 and 6, we would like to make our deepest apologies for the concerns and anxieties caused by our insufficient explanation in advance.
With regard to the compensations related to the water discharge and other issues, we will follow the Act on Compensation for Nuclear Damages and sincerely address them with support from the government. We would highly appreciate it if NFFCA could understand the above.
Working closely with the government, we will make every effort toward the earliest resolution of the situation.
April 6, 2011
The Tokyo Electric Power Company, Incorporated
LATEST RESULTS UPDATED DAILY
Scientists Say NO SAFE LEVEL of Radiation
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.”
The father of Health Physics, Dr. Karl Morgan stated, “There is no safe level of exposure and there is no dose of radiation so low that the risk of a malignancy is zero”
“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 FDA and EPA must enforce existing regulations and guidelines that address radionuclide content in our food supply here at home.”
EPA Statement on Rainwater Results
Elevated levels of radioactive material in rainwater have been expected as a result of the nuclear incident after
the events in Japan since radiation is known to travel in the atmosphere – precipitation data collected by EPA in
the states of California, Idaho and Minnesota have seen elevated levels of radiation in recent precipitation
In all cases these are levels above the normal background levels historically reported in these areas.
While short-term elevations such as these do not raise public health concerns – and the levels seen in rainwater
are expected to be relatively short in duration – the U.S. EPA has taken steps to increase the level of monitoring
of precipitation, drinking water, and other potential exposure routes to continue to verify that.
EPA’s “About the Rainwater Data”
EPA scientists routinely test precipitation samples from more than 30 sites in the U.S. The stations submit
precipitation samples to the EPA lab as rainfall, snow or sleet occurs. Under routine circumstances, samples are
composited and analyzed by EPA scientists monthly. In response to the Japanese nuclear incident, gamma
analyses are being performed on the precipitation samples as they’re received.
It may take up to five days for results because of the number of samples being directed to the laboratory. This is
to ensure the proper analysis and quality assurance measures takes place before the results are released.
EPA expects to see radioisotopes consistent with the Japanese nuclear incident during sample analysis. EPA
expects the measured levels to be extremely low as this air mass disperses across our planet. All results are in
picocuries per liter (pCi/L). A picocurie is one trillionth of a curie.
EPA’s “About the Milk Data”
As part of our efforts to ensure that there is no public health concern in the U.S. related to radiation exposure, EPA routinely samples cow’s milk at more than 30 stations every three months.
EPA has accelerated our quarterly milk sampling across the nation to collect the samples immediately. This action is precautionary, to make sure that we are gathering as much data as possible, informing our scientists and the public.
The milk samples are analyzed by gamma spectrometry, looking for fission products such as iodine-131 (I-131), barium-140 (Ba-140), and cesium-137 (Cs-137), which could become present in the event of a nuclear accident. All results are measured in picocuries per liter (pCi/L). A picocurie is one trillionth of a curie.
In a previous article it was argued that the EPA’s RadNet radiation detection network suffers from a lack of maintenance, improper calibration and zero credibility. That article also named the company responsible for the proper maintenance of RadNet and showed the political ties that may have helped land the no-bid contract.
A system so essential to informing and protecting Americans during a radiation event fails at a time of need. Why is this? Just how hard is it to maintain what is essentially an Ethernet computer network with a few dozen workstations connected to a radiation sensor and a few servers ?
The “amateurs” over at the Radiation Network set up a simple version of the system with all volunteers in response to the emergency and at last check they were 27 stations strong.
In order to understand the current situation it is necessary to first explore the hows, whats and whys of RadNet.
Air monitoring stations are sited throughout the United States, designed to detect and record various types of airborne radiation. According to the EPA, RadNet provides near real-time monitoring. The RadNet air network uses two different types of monitors, fixed (stationary) and deployable (mobile):
Fixed Air Monitors: Permanently mounted and continuously operating, each fixed monitor contains a high-volume air sampler, gamma and beta radiation detectors, and a computer that controls the monitor and sends data to a central database at least once an hour. The individual detectors within each monitor can discriminate between different types of radiation, including those that are naturally occurring. See the left side of Figure 1.
Deployable Air Monitors: Deployable monitors are portable and can be used for exercises and for rapid deployment in response to real events. The monitors have high- and low-volume air samplers, a gamma radiation level monitor, a data logger, and telecommunication systems that send data to the central database. Although deployable monitors do not discriminate the energy of gamma radiation, they do provide gamma exposure rates. See the right side of Figure 1.
The monitoring stations are in constant contact with a central server through telephone, ethernet, cellular and satellite links depending on the location and circumstances. Collected data is sent to the central server at prescribed intervals and is incorporated into a database that contains data from all stations. Historic and current data can be compared and viewed in numerical or graphical format.
When a monitoring station fails to send data to the server at a prescribed time the software is designed to make a notification.
When a station sends data over a predetermined limit a notification should be sent.
If a self-check of the computer at the station determines there is a malfunction, a notification should also be sent.
This can be accomplished by an entry into a computerized log or an email/page to an on-call technician.
Either none of these notification systems were in place or the EPA knew of the problems and did nothing to resolve them.
It is evident that the EPA is having a hard time presenting any useful data for the public. A map of fixed stations currently providing useable data downloaded from EPA’s RadNet site on 4/2 shows the following:
And the same map downloaded on 4/4:
And again on 4/7:
Legend for map color scheme
- Dark blue pins show recently updated data.
- White pins show monitors that are temporarily out of service.
- Light blue pins mean the data is being reviewed at EPA’s National Air and Radiation Environmental Laboratory.
It is evident from the three maps above, downloaded over a period of five days, that there are a high number of stations where “data is being reviewed”. Quite a few are the same stations all three days. The stations in Fort Wayne, Indiana and Raleigh, N.C. have been out of service for multiple days during this period.
During the first week after the radiation started spewing from Fukushima there were almost a dozen stations that were out of service and at least 5 of them were on the west coast. Any attempt to access data from the “online” stations oftentimes resulted in bogus data or no data at all.
Just as disturbing is the EPS’s claim that if a station is offline another nearby station would pick up the slack. The RadNet stations sample air that is available locally. They do not scan at any distance. If a station in Idaho Falls goes offline (which it has) the next nearest station is in Salt Lake City which is 200 miles away. The air nor the weather is the same in these two places.
A section of the EPA RadNet website is devoted to publishing data collected from the stations via quarterly reports, however this has not been done for some time. The first report published at the site is July – September 1991. The last report available on the site is July – September 2009!
According to the site: Environmental Radiation Data (ERD) is an electronic and print journal compiled and distributed quarterly by the Office of Radiation and Indoor Air’s National Air and Radiation Environmental Laboratory (NAREL) in Montgomery, Alabama. It contains data from RadNet (previously known as ERAMS.)
Where is the data from September 2009 to March 2011?
EDI, (the company with the EPA contract to maintain RadNet maintenance) should be investigated and the owners should be held responsible for allowing America to be unprotected from a radiation event such as Fukushima.
NO-BID MAINTENANCE CONTRACT TO FORMER DEPARTMENT OF DEFENSE UNDER-SECRETARY
SYSTEM NOT READY ON 3/11
RadNet – the EPA’s front-line, radiological detection network is severely flawed and suffers from maintenance and reliability issues.
The lack of consistent data and the number of units offline (a techie term for broken) at the time they were most needed shows that the EPA was not prepared for this emergency.
Besides that fact the broken system left us all unprotected; the confusion, apprehension and fear witnessed as people try to wade through the incomplete and inaccurate data online is evidenced by an exchange on the UC Berkely website over this RadNet graph:
The graph shows that this monitoring station was one of the units actually running on 3/11 . The readings were significantly higher prior to 3/11 and drop to a much lower level afterwards. This is an indication that the units were running in an uncalibrated condition and were adjusted only after the events at Fukushima.
Who is responsible for assuring that the system is up and running? The EPA contracted this responsibility to a private company, Environmental Dimensions, Inc.
Environmental Dimensions, Inc (EDI) has provided maintenance for EPA’s RadNet monitoring systems under a sole source contract which can be viewed at the end of this article. The base amount of the contract is $238,000.00. This does not include materials and travel, which is billed back to the government as needed.
The contract was awarded to what is stated as a “Woman-owned 8(a) Small Disadvantaged Business“. The disadvantaged woman in this case is EDI company president Patricia S. Bradshaw, former Deputy Under Secretary of Defense appointed by George Bush.
Could it possibly be that the corporate management at EDI formed the company not out of an altruistic sense of patriotic duty but to cash in on inside information and connections? Did Mrs. Bradshaw’s former DOD employment open the door? Did the fact that she heads a woman-owned business give her company a competitive edge?
EDI’s revenues have doubled in each of the past three years and they currently have 90 employees spread across offices in Albuquerque, Denver and Oak Ridge.
The New Mexico Corporations Division website lists the corporate address as : 1901 CANDELARIA NW ALBUQUERQUE, NM.
A quick Google maps check revealed this building at that location:
This same company also performs radioactive waste remediation and decontamination services for a number of government-funded projects. Do they follow the same cost-cutting, profit-maximizing philosophy as it appears that their maintenance and calibration division practices?
CURRENT NO-BID CONTRACT TO MAINTAIN RADNET MONITORING STATIONS
It’s all over the media. 104 nuclear reactors in the US. But that is just commercial plants. Did you know there are dozens and dozens of other reactors in the US that aren’t included in this list?
Well there are and they might be in your hometown. They are called “Research Reactors” and a full list of North American Research reactors can be found here.
To date approximately 670 Research reactors (RR) have been built, and of those, 246 reactors in 56 countries continue to operate. Half are now over 45 years old. Many do not meet today’s technological and safety standards.
Their fuel requirements include uranium with much higher enrichment than that of commercial power reactors (typically ~20% U-235). Some still use “highly enriched uranium fuel” (HEU) containing 93% U-235!
Storage of spent fuels is a problem just as it is with commercial reactors . Currently, spent fuels which will be dangerous for 100,000 years are stored in pools and tanks at the reactor location. The US has no centralized off-site program for storing radioactive waste from research reactors, just as it has none for commercial reactors.
While the International Atomic Energy Agency (IAEA) has expressed concern with the spent fuel issue, they are still entertaining plans by Member States to build new RRs with little or no experience in this domain.
One issue that has been known since the early 1990s is corrosion induced degradation of the fuel cladding. This was observed in many of the pools.
According to a recent IAEA report (IAEA-TECDOC-1637 – 2009) “Corrosion of research reactor aluminum clad spent nuclear fuel stored in light water filled basins has become a major concern.”
Download the full list of North American Research reactors here and check to see if there is one active in your state. Even if one is listed and has been decommissioned, it is likely that spent fuel is still stored at the site.
Start making calls to your state EPA and ask who is responsible for overseeing the safety of the research reactors in your state. Ask for written reports.
Call your state elected officials and express concern. It is likely that they are not aware of the issue – email them a copy of the list that I have provided. Educate yourself and demand accountability.
In a recent CNN report, correspondent Elizabeth Cohen described an experience she had while waiting in the TSA screening line at an airport. She was behind a man in line who opted for the “pat-down” in lieu of the scanner. Having never seen this happen before, Cohen was intrigued.
When she asked the man about his choice he said, “I’m a doctor at M.D. Anderson, and I don’t want radiation if I can avoid it.”
Cohen goes on to poll a number of doctors to find out what they would do – the results were mixed. I know that I wouldn’t go any where near back-scatter scanners, which emit x-ray radiation – who needs an extra dose in these times, right?
If the TSA feels it is necessary to virtually strip down American citizens to protect the homeland, than they should at least provide a safer technology at all checkpoints.
That alternative is active millimeter wave (MMW) radio frequency technology that uses radio signals, no x-rays or radiation.
I’m not saying I agree at all with the ongoing extreme government reaction to 9/11 – but if they are going to do it it they might as well use safe technology.
Here’s a quick video showing the MMW technology in action. It is produced by L3 Communications – makers of the ProVision.
It might be a good time to buy some L3 stock and hope it goes back over $100.00 a share based on increased sales to replace the more dangerous scanners currently in use.
The Fukushima Daiichi plant has seven pools for spent fuel rods assemblies.
Six of the pools are located at the top of each reactor building and contained 3,450 fuel rod assemblies between them in 2010.
There is one common pool building housed in a dedicated building. The common pool contains 6,291 fuel rod assemblies.
A dry cask is used to store another 408 assemblies. This is a reported total of 10,149 as of March, 2010.
Add another 700 units for the period of March 2010 to 2011 and the current estimated total of fuel rod assemblies at the reactor site is 10,849.
Each assembly contains 63 fuel rods. So at the time of the accident there were almost 640,000 spent fuel rods being stored on site.
A total of 1,760 metric tons of spent nuclear rods are stored above and around the reactors.
Sometime prior to 2010 the holding capacity of the pools above the reactors was increased by re-racking the existing rods. It is unclear if this increase was anticipated in the original design.
What has become clear is that the added storage of spent fuel rods at the Fukushima reactors is greatly increasing the scale and mortality of this current, world-class emergency.
The practice of re-racking is not limited to Japan. Here in the US, the Nuclear Regulatory Commission (NRC) has increased the number of spent-fuel rods allowed per pool partly because a national disposal site for nuclear waste has not been established.
But the main reason that federally sanctioned re-racking has been allowed is because plant operators avoid millions of dollars in costs by delaying moves to safer but expensive dry cask storage. The concerns of the plant operators drown out any opposition bolstered by the immense amount of money and manpower marshaled by the various lobby groups and PACs – most notably the Nuclear Energy institute (NEI).
The NRC insists the practice is safe but many scientists and engineers say the practice is dangerous and warn that the sheer volume of radioactivity in the pools could turn an accident or natural disaster into a cataclysm. JUST LIKE FUKUSHIMA.
A 1997 study by the Brookhaven National Laboratory concluded that a pool fire at a plant like Millstone Nuclear Power Station in Connecticut or Pilgrim Nuclear Generating Station in Massachusetts could kill 100 people instantly and another 138,000 people eventually. Some $546 billion in damage would result, the study said, and 2,170 square miles of land could be contaminated.
After uranium fuel has been used in a reactor for a while, it is no longer as efficient in splitting its atoms and producing heat to make electricity. It is then called “spent” nuclear fuel. About one-fourth to one-third of the total fuel load is spent and is removed from the reactor every 12 to 18 months and replaced with fresh fuel.
Spent nuclear fuel is still highly radioactive and potentially very harmful. Ten years after removal from a reactor, the radiation dose 1 meter away from a typical spent fuel assembly exceeds 20,000 rems per hour. A dose of 5,000 rems would be expected to cause immediate incapacitation and death within one week.
Many of the radioactive elements in spent fuel have long half-lives. For example, plutonium-239 has a half-life of 24,000 years, and plutonium-240 has a half-life of 6,800 years. Because it contains these long half-lived radioactive elements, spent fuel must be isolated and controlled for thousands of years.
Currently, most spent nuclear fuel is stored in specially designed pools at individual reactor sites around the country. The water-pool option involves storing spent fuel in rods under at least 20 feet of water, which provides shielding from the radiation for anyone near the pool.
The fuel pools vary in size from a capacity of 216 to 8,083 fuel assemblies. Most pools were originally designed to store several years worth of spent fuel.
A second hazard of spent fuel, in addition to high radiation levels, is the remote possibility of an accidental “criticality,” or self-sustained fissioning and splitting of the atoms of uranium and plutonium.
The original design and construction of US nuclear plants planned for used fuel storage over a decade or two, not long-term storage.
The nation’s 104 nuclear power plants are now storing some 63,000 metric tons of spent fuel rods, according to 2010 numbers compiled by the Nuclear Energy Institute.
All of these concerns sit atop a shaky foundation where most plants in the US are re-licensed automatically way past their originally designed lifetime.
We know that in the days after the Fukushima nuclear plant began releasing radioactive materials into the atmosphere, all of the “weather readers” on the networks and local channels appeared to be reading from the same script. Soon after “experts” were paraded in front of the camera to dismiss the possibility. We all know now that they were dead wrong!
Examples of this:
March 15, Dr. Perry Kendall (public health officer – British Columbia) said, “winds from Japan take five or six days to reach B.C. and by then any radioactive particles would have dispersed over the Pacific Ocean.“
“Japan has an evacuation area of about 12 miles from the nuclear plants. Washington state is 5,000 to 6,000 miles away from Japan,” Tim Church, a spokesman for the Washington State Department of Health, told the Wall Street Journal in a March 15th article.
March 18, a Baltimore Sun article stated, “There’s just one problem with all this panic: It’s completely irrational. Nuclear radiation can extend around 12 miles from the point of meltdown — not 12-friggin’-thousand miles. ”
“Worst-case scenario, there is no threat to public health in California,” said the California Emergency Management Agency Secretary Mike Dayton.
“Based on the type of reactor design and the nature of the accident, we see a very low likelihood — really, a very low probability — that there’s any possibility of harmful radiation levels in the United States or in Hawaii or any other U.S. territories,” Nuclear Regulatory Commission Chairman Gregory Jaczko stated .
And now that it is here they are all now saying that the levels aren’t harmful.
What I haven’t heard discussed much is whether or not the massive amounts of material flowing into the Pacific Ocean can make it to the US shores.
Fig. 1 is a map of the ocean currents in the Pacific. Much like the jet stream, gulf currents follow fairly predictable seasonal paths.
As you can see, just as with the jet stream there is ample opportunity for ANY material to be transported thousand of miles.
Recently in Bloomberg Business Week, Ken Buesseler, senior scientist at Woods Hole Oceanographic Institute in Massachusetts said, “The ocean can absorb significant increases in cesium and iodine, the two most common radioactive isotopes coming from the plant, before it becomes unsafe for humans or marine animals.”
“For cesium and iodine, they are soluble,” Buesseler said “This time of year off the coast of Japan, they would mix with water down 100 feet to 300 feet, and be diluted by a factor of about 100. The currents there would move it to the south, just north of Tokyo, and then out to sea.”
OUT TO SEA???? AND THEN WHERE???
More to come on this issue in a latter post.