Japan struggling to 'cool down' nuclear plant, minister says

[Sukerkin]

What kind of radiation levels have been recorded at Fukushima?
The Kyodo news agency reports that a radiation level of 1,557 microsieverts per hour was registered on Sunday. At this level, one hour's exposure is roughly equivalent to one chest X-ray. Later measurements included 750 microsieverts per hour at 0200 on Monday, and 20 microsieverts per hour at 1145. On a long-haul flight, passengers are exposed to about five microsieverts per hour. However, after Tuesday's explosion, readings at the site rose again beyone safe limits - 400 millisieverts per hour and people living within 20 miles (32km) of the plant were told to stay indoors. Moving away from the source of radiation, measurements quickly tail off, and in Tokyo they were reported to have been higher than normal, but officials said there were no health dangers.

I would strongly suggest that the media is still getting behind the story and pushing for all it's worth rather than trying to actually report the news.

The situation is indeed fluid and dangerous but, until and if there is an explosion that breaches a reactors containment, there is no point talking it up to be worse than it already is (which is pretty bad but not catastrophic).

What made Chernobyl so bad was a huge blast that threw radioactive material up into the winds and spread it far and wide.

Have a read of this article which deals with things fairly matter-of-factly:

http://www.bbc.co.uk/news/health-12722435

This bit is particularly important for underlining the geographical scope of the danger:

What risk does Fukushima pose currently?
The Japanese authorities have recorded a radiation level of up 400 millisieverts per hour at the nuclear plant itself.
A sievert is essentially equivalent to a gray, but tends to be used to measure lower levels of radiation, and for assessing long-term risk, rather than the short-term acute impact of exposure.
Professor Richard Wakeford, an expert in radiation exposure at the University of Manchester, said exposure to a dose of 400 millisieverts was unlikely to cause radiation sickness - that would require a dose of around twice that level (one sievert/one gray).
However, it could start to depress the production of blood cells in the bone marrow, and was likely to raise the lifetime risk of fatal cancer by 2-4%. Typically, a Japanese person has a lifetime risk of fatal cancer of 20-25%.
Prof Wakeford stressed only emergency workers at the plant were at risk of exposure to such a dose - but it was likely that they would only be exposed for short periods of time to minimise their risk.
The level of exposure for the general population, even those living close to the plant, was unlikely to be anywhere near as high.

And for a bit of simple-terms video: http://www.bbc.co.uk/news/world-asia-pacific-12744973

 

[Empty Hands]

What kind of radiation levels have been recorded at Fukushima?
The Kyodo news agency reports that a radiation level of 1,557 microsieverts per hour was registered on Sunday. ...However, after Tuesday's explosion, readings at the site rose again beyone safe limits - 400 millisieverts per hour and people living within 20 miles (32km) of the plant were told to stay indoors.

Just to point out to those who may have missed it that the new reading, 400 millisieverts, is in different units than the previous reading, 1557 microsieverts. Putting them in the same units, the old reading was 1557, and the new reading is 400,000.

It's still a bit hard to grasp though, i'm used to working in cpm, dpm, curies and rems.

 

[Xue Sheng]

Ooops.

Isn’t that also what the captain of the Titanic, Robert Kagan of the Exxon Valdez and the CEO of BP said too

 

[LuckyKBoxer]

Isn’t that also what the captain of the Titanic, Robert Kagan of the Exxon Valdez and the CEO of BP said too

No I am pretty sure they all said "Oh ****"

 

[MA-Caver]

It keeps getting worse at the moment... http://news.yahoo.com/s/ap/20110315/ap_on_bi_ge/as_japan_earthquake fire broke out again...

in the midst of all that... a strange sound was heard...
http://www.godzillatemple.com/index2.htm
http://wavcentral.com/sounds/movies/godzilla/roar.mp3

sorry couldn't help it.

 

[5-0 Kenpo]

in the midst of all that... a strange sound was heard...

http://wavcentral.com/sounds/movies/godzilla/roar.mp3

sorry couldn't help it.

And just like Gilber Gotfried.... your fired....

 

[dowan50]

Having worked in a nuclear plant as a civil engineer certified to work in red zones that's as hot as it gets the plant I worked in was one of the safest and generated power at 5 cents per Kilowatt hour. The power company finally shut it down just tired of the bad PR and guess what replaced it a coal fired plant releasing all kinds of toxins and contributing to global warming.

I find it interesting how people do not calculate total numbers of sick and dead from a data point of view compare in a real sense how many people in the thousands have died in the pursuit of Oil and the impact of fossil fuels. Whole communities women children schools are being ruined and made sick by large scale coal mining that pollutes ground water and covers living areas and air quality with waste products. All this so 80% of the country can waste utilities at the cost of those less fortunate. Not to mention the total number of dead mining coal from unsafe conditions.

I have known from the start that Japan was in trouble related to the plants refusing to tell the truth or just not willing to realize how bad it was but given that unless the fires can find enough material to put up to the jet stream it is doubtful we will be impacted here seriously.

At worst case the whole plant sight becomes unusable even contaminated for a 20 mile radius for the next 30 years. So the premise will be end all Nuclear plants? Really? Coal is doing the same thing to vast areas never usable again. Difference is its happening to people of low income and people desperate for jobs to supply the needs of the majority who see no impact to them because its not happening in their back yard. The US needs to rebuild its infrastructure to conserve and reuse/store energy. We need to do what France has done since the 80's recycle our Nuclear spent fuel rods so there are no spent fuel rods left to store and valuable energy is reclaimed.

We kill 50,000 people a year here on the roads and accept that as the cost of travel? The worst radioactive contamination you can get is to ingest it. Every pack of cigarettes is equal to 30 millerems of exposure so when the do a bio of your body to get your exposure tag you have to tell them so they up your allowable exposure your lungs glow in the dark. Even when you quite smoking you have a half life of 15 to 30 years cooking away that is why second hand smoke is so bad it gets on your clothes and radiates you and your children you have to wash the clothes or they continue doing damage you inhale second hand smoke its just as bad for you as the smoker.

But people are nut running around end all cigarettes and we are killing thousands of people a year. We need to learn from the Japan crisis and apply realistic plans for the future. We need to end corporate greed in America or we are circling the drain.

 

[Empty Hands]

Every pack of cigarettes is equal to 30 millerems of exposure so when the do a bio of your body to get your exposure tag you have to tell them so they up your allowable exposure your lungs glow in the dark.

Uh, no, 15-20 millirems per year with a 1/pack a day habit. 30 mrem is 10% of the typical yearly dose, if one pack gave you a 30 mrem dose, you would have health effects from the radiologicals alone.

 

[LuckyKBoxer]

Uh, no, 15-20 millirems per year with a 1/pack a day habit. 30 mrem is 10% of the typical yearly dose, if one pack gave you a 30 mrem dose, you would have health effects from the radiologicals alone.

NO your wrong he was specifically talking about the tobacco blend called Chernobyl Brown... It has a strong kick, and delivers niccotine better then any other tobacco on the market... just that pesky millirem problem to deal with......

 

[Empty Hands]

NO your wrong he was specifically talking about the tobacco blend called Chernobyl Brown... It has a strong kick, and delivers niccotine better then any other tobacco on the market... just that pesky millirem problem to deal with......

:lol:

From the same manufacturers as:

 

[MA-Caver]

We need to end corporate greed in America or we are circling the drain.

Well the only way it seems to do that is to do what the French did in 1793-94.... okay maybe not quite as bloody.

 

[elder999]

So, this comes from discussion with some colleagues and former-colleagues, a few of whom are directly involved in the DOE and NRC efforts to aid the Japanese, a few of whom are retired, and condensed to a "Mom the shrink" explanation so that we can all tell our various relatives and friends what we think is going on over there.

The 3 units that were operating at the Fukushima nuclear power complex at the time of the earthquake are not in a safe, stable condition. The units shutdown during the earthquake, and were relying on onsite emergency diesel generators, as the quake also took down the power grid. The emergency diesel generators failed about an hour later due to seawater intrusion caused by the tsunami. Unit 1 was being successfully cooled using reactor core isolation cooling (RCIC). RCIC shutdown when control power from the station batteries was lost due to battery depletion. At this point the plant had no electrical power of any kind. At some point the drywell was vented to secondary containment to relieve pressure in the drywell. On 3/12 there was an explosion that breached the secondary containment building, probably caused by a rapid hydrogen burn.

IMHO, the presence of abundant hydrogen in the vented gas implies that significant zirconium hydriding has occurred. and the condition of the reactor core is uncertain. Additional backup generators for all the units were brought on site, and the Unit 1 reactor was flooded with seawater. The other 2 units that were operating appeared to be in somewhat better shape than Unit 1 because they were provided with backup power first. The 3 units that were shutdown are better off, if only by virtue of being at lower temperatures with lower decay heat power. The earthquake strength and tsunami height exceeded plant design basis.

On 3/13 high pressure injection on Unit 3 shutdown and could not be restarted. Unit 3 core is now being cooled with seawater. Reactor vessel water level indication on Units 1 & 3 is being questioned. Radiation levels don't support the amount of core uncovery the level indicators are displaying. Unit 2 is presently stable. There was an explosion at Unit 3, I assume that the process that caused it was similar to what occurred on Unit 1.

It's important to note again that Unit #3 is using MOX fuel, that's mixed-oxide fuel. The important part is that the "mix" includes significant quantities of plutonium, making any releases from a cladding breach far more serious than those from the other units.

3/14/11 2300: Unit 2 experienced varying periods of core uncovery throughout the day. The utility resorted to seawater injection on this unit, as well. Radiation levels at the site increased significantly. At 5:20 pm EDT, an explosion occurred near the suppression pool. This is more significant than the explosions at Units 1 & 3 because it affected primary containment.

3/15 1120: A fire occurred at Unit 4, apparently in proximity to the spent fuel pool. TEPCO has stated that the fire was caused by an oil leak from a cooling pump, not the spent fuel. Fire duration 140 minutes. Radiation levels spiked to 40 Rem/hr at Unit 3, 10 Rem/hr at Unit 4, 831 mRem/hr at the site boundary. IMHO, these numbers would be consistent with either core damage and a breach of containment integrity or fuel damage in the spent fuel pool, which I gather is inside secondary containment. Control rooms were evacuated. All site personnelwereevacuated except for about 50 people that are directly involved with cooling the cores.

3/15 2320: At 4:45 pm EDT the fire at Unit 4 reignited and was extinguished in 2 hours. Plans to dump water into the Unit 4 spent fuel pool from helicopters has been scrapped as the hole in the roof of secondary containment isn't aligned with the pool. TEPCO plans on opening up the roofs of secondary containments on Units 5 & 6 to avoid the hydrogen buildup that occurred on the other units. TEPCO has said that seventy percent of the fuel rods in Unit 1 and one-third in Unit 2 have been damaged. The cooling water levels in those units are being maintained. And, sometime during the day there was another earthquake.

3/16reparations begun to restore offsite power via temporary feeders.
Reactors 1, 2 and 3 at the plant are being cooled with seawater.
There is some degree of core damage at Units 1, 2, and 3.
Containment structural damage is suspected at Units 2 and 3.
Preparations are being made to pump water into the fuel storage pool using a high-capacity spray pump. There have been two fires inside the secondary containment building at Unit 4, but they have been extinguished. Although the secondary containment at Unit 4 was damaged, the primary containment remains intact.

3/16-17:Crews still working to restore offsite power.
Water being sprayed on Unit 3 reactor from helicopters.
TEPCO says the Unit 4 reactor has been stable throughout the day, and insists that there is water in the Unit 4 spent fuel pool. USNRC believes the pool is dry (satellite information? pure speculation?). Temperature in the spent fuel pool was reported to be 84 degrees C (183.2 degrees F) at 7 PM EDT. Radiation levels at the site boundary have been decreasing. 75 mRem at 0400 to 33 mRem at 1600.

Even at its worse, though, given the distance, the U.S. isn't in any real danger-though it's more than likely we'll see detecatable amounts of contaminants, just as we did from Chernobyl.

Naturally, you folks in Australia, Europe and the rest of Asia aren't in any danger as long as the wind keeps blowing the way it is.....we should see the plume reaching the Aleutians in another 4 or 5 days, though, maybe a little more....

What this really points to is the likely uninhabitability of part of Japan for quite some time.....

 

[5-0 Kenpo]

You know, I can understand warp drive, matter-antimatter technology from Star Trek better then I can seem to grab this stuff....

 

[Empty Hands]

Radiation levels spiked to 40 Rem/hr at Unit 3, 10 Rem/hr at Unit 4, 831 mRem/hr at the site boundary.

Ouch. I hadn't seen the actual numbers, that's not good at all.

 

[jks9199]

I'm not trying to make light of this at all...

But isn't there something a little ironic or funny about an electrical generating plant falling apart because there's not enough electricity?

 

[Sukerkin]

From the BBC:

"We are right to be worried by need to put the risks in context" said Gerry Thomas, Professor of Medical Pathology at Imperial College London. She is concerned that the dangers to human health are being exaggerated by some in the international media and could cause "psychological damage" to the Japanese.

She said that, even in the worst-case scenario, with a large release of radioactive material from Fukushima, the health dangers would be minimal.
"The Japanese are doing the right things - giving people iodine tablets, setting up an exclusion zone and asking people to stay indoors". Even if radiation from Fukushima reached Tokyo she believes the long-term health risks would be minimal.

Gerry Thomas is an expert in the health effects of radiation and has been studying tissue samples from many of the cancer patients affected by the Chernobyl disaster. Like other experts she said Fukushima was in no way as serious as Chernobyl and she urged those reporting the situation not to overplay the situation.

Even tho' this is present on the BBC website and I credit them for actually including it, it is tucked away near the bottom of an article that is still showing all the media's predisposition to make things even worse than they are i.e. 'story' rather than news.

Yes, things are bad and no I would not like to be one of the engineers working on the site. Also, it is possible that things could indeed get much worse but this seeming pressure from the media 'willing' it to happen is galling.

EDIT: Found the sequence of articles that quote came from:

http://www.bbc.co.uk/blogs/thereporters/ferguswalsh/

 

[Sukerkin]

I'm not trying to make light of this at all...

But isn't there something a little ironic or funny about an electrical generating plant falling apart because there's not enough electricity?

Such things happen .

I was once trapped in a blockhouse inside a GIS (gas insulated switchgear) compound of a substation for a while because there was a power cut :lol:. 400kV busbars running nearby and I had no lights .

 

[elder999]

· Update, 3/19: Diesel generators are powering spent fuel pool cooling pumps on Units 5 & 6.
· Firefighters added water (seawater) to the spent fuel pool at Unit 3, using a high pressure pump for 13 hours. TEPCO plans on adding water to the Unit 4 spent fuel pool tomorrow.
Temporary offsite power feeds are connected to Units 1 & 2. TEPCO plans on energizing them tomorrow.
Holes have been drilled into the roofs of secondary containments of Units 5 & 6 to prevent the accumulation of hydrogen in those buildings and subsequent explosion They have been using every means possible to get water into the reactors and spent fuel pools: pumping seawater, dumping seawater from helicopters, spraying water from crowd control water cannons. Some reactor cooling capacity has been restored at Units 5 and 6 after the installation of temporary generators at those reactors.
Offsite power is expected to be restored to Units 1 & 2 today. (They have been having problems with this).
Radiation levels at the site remain at levels that permit onsite recovery efforts. Offsite doses outside the 30 kilometer (18.64 miles) zone require no protective action. Levels of radionuclides have been found to exceed Japanese government limits in certain foods, notably milk and spinach. That seems fast to me (transit time-wise).
The Japanese government has now requested U.S. help. Bureaucrats? Perhaps if they had asked days ago we could have put together a volunteer crew of linemen and engineers to work on restoring offsite power. I'm sure their people are quite overloaded with trying to restore power to the population, besides the nuclear plant issue. Also, I doubt that their emergency response organization is sized for an accident on more that 1 or 2 units at the same time.
For those that can stand the dry and technical, to get an idea of what is happening inside the reactors go to: http://www.libraries.psu.edu/tmi/images/TMIStreamingWeb.mov



·
· 3/21:
· TEPCO continued efforts on Monday to restore power to its Fukushima Daiichi plants as well as stabilize cooling in the spent fuel pools of some reactors.
· Reactors 1, 2 and 3 are in stable condition and reactors 5 and 6 are stable and being cooled by systems powered by electricity that was restored over the weekend.
· The Tokyo Fire Department sprayed cooling water into the reactor 3 spent fuel pool for 4.5 hours, ending early Monday morning.
· At reactor 4, Japan’s Self-Defense Force sprayed water into the pool for about two hours. Overall, 13 fire engines have been used in the spraying. Efforts to spray water into the spent fuel pools at reactors 3 and 4 was stopped on Monday while TEPCO assessed the effectiveness of these efforts.
· Workers were evacuated from the area around reactors 2 and 3 Monday when smoke was observed coming from both reactors
· Electricity is expected to be restored to both reactors 3 and 4 by March 23.
· Radiation dose rates at monitoring posts are slightly higher than on past days. Rates at the plant site boundary range from 1 to 3 millirem per hour. Radiation dose rates in the area where fire trucks have been located are reported to be 2 to 3 rem per hour, with some isolated areas as high as 30 rem per hour.
3/22:
· U.S. EPA says U.S. radiation levels remain at background, same levels as before the quake and tsunami.
· Offsite power feeders have been established to all 6 Fukushima Daichi units. Onsite power distribution at Units 1 & 2 need repairs before they can be energized. TEPCO expects to energize the feeds to Units 3 & 4 tomorrow.
· Offsite power is supplying the spent fuel cooling pumps at Units 5 & 6.
· TEPCO reports that radiation levels at the plant's main gate have decreased to 25 mRem/hr.
· Fire companies have continued to spray seawater into Units 3 & 4's spent fuel pools, roughly 900,000 gallons.
· Low levels of I131 and CS137 (radioactive isotopes of iodine and cesium) have been detected in seawater near the plants.
· Shipments of milk and spinach have been suspended from specified areas.
3/23:
· Workers continued efforts on Wednesday to restore offsite power to six reactors at the Fukushima Daiichi nuclear power plant. External power was available Wednesday at Units 2, 3, 5 and 6, the Japan Atomic Industrial Forum said, but has not yet been re-established to reactor safety systems.
· The next step before fully connecting external power is to test and repair the equipment that it will power. Cooling pumps for reactors 1 and 2 were covered by seawater and will require maintenance to bring them online. TEPCO is testing the cooling water pumps for reactor 3. External power was connected to the main control room at reactor 3 on Tuesday.
·
· Japanese authorities have detected high levels of radioactive cesium 137 in soil about 40 kilometers northwest of the Fukushima plant. Surveys of radioactive substances in soil at six locations found levels of cesium 137 that are 1,600 times typical for that area. Japan's government is expanding offshore monitoring for radioactive nuclides to 30 kilometers.
·
· Japanese authorities have advised Tokyo residents not to provide municipal drinking water to infants or use it in mixing powdered milk for infants because of abnormal levels of radioactive iodine (I-131) detected in the drinking water. One water sample (5,700 picocuries per liter) indicated approximately twice the Japanese government guideline and prompted the restriction for infants. In an emergency in the United States, state and local officials would closely monitor food and drinking water supplies and quarantine any contaminated supplies as needed to prevent public exposure. U.S. officials use pre-established guidelines for safe consumption of food and water set by the U.S. Food and Drug Administration.
·
· TEPCo. reported Tuesday afternoon (U.S. time) that it has restored electricity to the control room at the Fukushima Daiichi reactor 3. Lights in the control room were switched on for the first time since the earthquake 11 days ago. Electricity to the reactor 4 control room is expected to be restored shortly.
· Power restoration to the control rooms will help technicians as they seek to repair the two reactors' cooling systems. Workers are seeking to reactivate control room monitoring systems for reactor parameters, such as reactor coolant temperatures and water levels. The company also reported that temperature indicators at reactors 1, 2 and 3 are working again.
·
· Workers at the Fukushima Daiichi plant also continued to spray water Tuesday into the spent fuel pools of reactors 3 and 4. A 160-foot long extension arm normally used to pour concrete for high-rise buildings was used to more accurately spray water into the used fuel pool area of reactor 4. Workers also pumped 18 tons of seawater into the reactor 2 used fuel pool.
·
· Elevated levels of radioactive iodine and cesium were detected in soil about 25 miles from Fukushima Daiichi, but the levels do not pose a health risk, according to Japan's science ministry.

3/24:
· Three workers received radiation exposure of 17 to 18 rem from standing in contaminated water while laying cable in the reactor 3 turbine building, TEPCO said. One of the workers did not require hospitalization. The exposures were less than the 25 rem emergency dose limit established by the Japanese government. IMHO: While this dose level is significant, it doesn't produce any observable changes other than being creeped out from knowing you got that much dose. I presume the hospitalization of the 2 workers was for decontamination.
·
· External electric power was restored to reactor 1 and lights were on in the control room. Lighting was restored to the reactor 3 control room Wednesday. Electric power also has been connected to some of the instruments in all reactors except unit 3. While external electricity is available at all six units, it is not in wide use as workers inspect and repair cooling equipment before it can be energized. Reactors 5 and 6 have been safely shut down with cooling systems running on offsite power.
·
· Seawater is being injected to cool the cores of reactors 1, 2 and 3. Workers continue to spray water into the spent fuel pools of reactors 3 and 4.
· Smoke seen coming from the reactor building at reactor 3 at 4:20 p.m. on Wednesday (Japan time) "decreased significantly," the International Atomic Energy Agency said. On Wednesday, smoke from reactor 3 caused the temporary evacuation of workers from reactors 3 and 4.
·
· In Tokyo, the level of radioactive iodine in tap water has dropped to within safety limits Thursday.
·
· Commissioners at the U.S. Nuclear Regulatory Commission on Wednesday voted to launch a two-pronged review of U.S. nuclear power plant safety in the aftermath of the March 11 earthquake and tsunami and the resulting events at the Fukushima Daiichi nuclear power plant
UPDATE AS OF 9 P.M. MST, MARCH 24
Restoration of electric power at reactors 1, 2 and 4 at the Fukushima Daiichi nuclear power plant has led to the reconnection of important reactor instrumentation, the International Atomic Energy Agency said.Cooling water continues to be injected into reactors 1, 2 and 3. Reactors 5 and 6 at Fukushima Daiichi remain safely shut down. Both reactors were undergoing maintenance at the time of the earthquake. Radiation dose rates inside the containment vessels of reactors 1 and 2 have decreased slightly, IAEA said. External power has been reconnected to the common used fuel storage pool at the plant and cooling started on March 24 at 5:05 a.m. EDT, according to Japan's Nuclear and Industrial Safety Agency. About 60 percent of the used uranium fuel rods at Fukushima plant are stored at this facility.
Radiation Monitoring Continues
Air samples collected at on-site monitors at the Fukushima Daiichi plant March 19-23 show that only iodine-131 was found to be in excess of Japanese government limits. Radiation dose rates measured on site March 21-23 have decreased from 193 millirem to 21 millirem per hour. Radiation dose rates at the plant's site boundary ranged from 1 millirem to 3 millirem per hour on Thursday. At distances between 34 and 73 kilometers to the west of the Fukushima Daiichi nuclear power plant, the dose rate ranged from .06 millirem to .69 millirem per hour.Considerable variation in the levels of reported iodine-131 and cesium-137 continues in 10 prefectures, IAEA said. Food, milk and drinking water sampling has been most thorough and extensive in the Fukushima and Ibaraki prefectures, IAEA said.Seawater samples collected at several points 30 kilometers from the coastline near the Fukushima Daiichi nuclear power plant found measurable concentrations of iodine-131 and cesium-137, IAEA said. The iodine concentrations were at or above Japanese regulatory limits. The cesium levels were well below those limits.

Higher levels of radioactive iodine were detected in seawater at water outlets near the Fukushima Daiichi nuclear power plant. "Iodine 131 was detected at a level 1,250 times the national safety limit," Hidehiko Nishiyama of the Nuclear and Industrial Safety Agency said during a news conference. Officials said there is no immediate danger to residents near the plant from these levels.

Samples taken on Friday were significantly higher than those taken on Wednesday, which had 147 times the legal concentration of I-137. Authorities said the concentration of radioactive materials in the water will decrease as the water is diluted by ocean currents. A sample taken at 8:50 a.m. on Friday had one-fifth the concentration of I-131 as the earlier measurement. Three subsequent measurements that morning showed fluctuation. All were below the highest level found at 8:30 a.m. on Friday.

"As of now, there is no report of adverse impact on the marine life, especially beyond kilometers [of the plant]," said Chief Cabinet Secretary Yukio Edano. "Experts say there is a very low possibility, but we must strengthen our monitoring."


Efforts to cool the reactors and fuel pools continues at the Daiichi site. Fresh water is now being used to cool reactors 1, 2 and 3 instead of seawater. Workers began injecting fresh water at reactors 1 and 3 on March 25 and at reactor 2 on March 26. Meanwhile, two U.S. Navy barges carrying 500,000 gallons fresh water are en route to a port 37 miles south of the Fukushima plant.
UPDATE AS OF 7:00 P.M. EDT, MARCH 25:
Fresh water is being injected into the reactor pressure vessel at reactor 3 at Fukushima Daiichi nuclear power plant, Japan's Nuclear and Industrial Safety Agency said.

TEPCO said that radioactive materials discovered at the reactor 3 turbine building possibly came from water from the reactor system, not the spent fuel pool. TEPCO made that statement after collecting samples of contaminated water in the reactor 3 turbine building and conducting a gamma-emitting nuclide analysis of the sample. The reactor pressure and drywell pressure at reactor 3 remained stable on Friday, leading TEPCO to believe that "the reactor pressure vessel is not seriously damaged.

Cooling efforts at Reactor 1 already had switched back to fresh water cooling. Reactor 2 is still being injected with seawater, but is expected to switch to fresh water soon.

Tokyo Electric Power Co. said that crews continued spraying water into the used fuel storage pools at reactors 3 and 4 on Friday to keep the used uranium fuel rods safe. Also on Friday, the heat removal system at reactor 6 was switched to a permanent power supply, NISA added.

TEPCO said it was assessing the radiation dose to two workers who were contaminated while laying cable in the turbine building of reactor 3. TEPCO said it had instructed its employees and contract workers to pay attention to their personal radiation dosimeter alarms and evacuate when necessary.

On-site radiation monitoring at the Fukushima Daiichi nuclear power plant indicates that radiation dose rates continue to decrease, the International Atomic Energy Agency said.

Radiation Monitoring Update

Air and seawater sampling continues by the Japanese government. Measurements in the ocean were taken 30 kilometers off-shore and 330 meters from the discharge points on March 23 and March 24. Results indicate concentrations of iodine-131 at 2,162 picocuries per liter and cesium-137 at approximately 703 picocuries per liter. Adult consumption of 1,000 picocuries (1 picocurie is one-trillionth of a curie) per liter concentration for 30 days will result in 24 millirem of radiation dose. For comparison, a typical dose from a chest x-ray is 10 millirem.

The concentrations found in the seawater samples are most likely "due to atmospheric fallout rather than just ocean currents," IAEA said. Dilution is expected to rapidly decrease this surface contamination, IAEA added.

Iodine-131 was detected in drinking water in 13 prefectures and cesium-137 was detected in drinking water in six prefectures. All results remained below the limits set by the Japanese government, IAEA said. Iodine-131 levels in drinking water in Tokyo are now below limits for consumption by infants set by the Japanese authorities and restrictions have been lifted.

On March 25, the IAEA radiation monitoring team made additional measurements at distances from 34 to 62 kilometers from the Fukushima Daiichi nuclear power plant. At these locations, the radiation dose rate was at extraordinarily low levels, ranging from 0.073 millirem per hour to 0.88 millirem per hour.