Japan Makes Progress at Troubled Nuclear Plant. Officials Regain Some Control.

TOKYO—Japanese officials appeared to have regained some control of northeast Japan's troubled nuclear power plant Tuesday afternoon, at least for now, after spikes in radiation levels that followed a new explosion at one reactor and a fire at another earlier in the day put the nation on high alert.

Officials stressed it was too early to say the worst has been averted at the Fukushima Daiichi nuclear power plant, which has suffered serious problems in four of its six reactors since Friday's massive earthquake and tsunami. Determining the cause of the earlier radiation leaks and checking what's happening inside the overheating reactors was difficult.

Authorities also signaled a new area of potential worry: temperature at the remaining two reactors, both not operating at the time of the earthquake and so far not the subject of concern, has risen slightly, prompting the need for close monitoring. Officials were also probing a report that boiling water had been spotted near where the fire broke out Tuesday morning, another potential worrying sign.

But the conditions at the plant appeared to have stabilized in some aspects Tuesday afternoon. While radiation levels at the plant remain elevated, they have dropped significantly from earlier in the day, ruling out the continuation of unstoppable large-scale leaks.

Radiation levels in downtown Tokyo—which had also risen earlier Tuesday, though they remained well below levels that could damage human health—also fell sharply later in the day.

Earlier Tuesday, Prime Minister Naoto Kan warned of the possibility of further increase in radiation levels, as he called on the Japanese people to "act calmly." Officials said radiation levels at the plant had surged to levels that would have impact on the human body.

For the science geeks out there.... here is the latest from Japan in terms of radiation strength...

* The Tokyo Metropolitan Government and other local authorities surrounding Japan’s capital city said Tuesday they have detected higher-than-normal radiation levels, but the amounts aren’t enough to cause immediate harm to the human body.

* They measured a radiation level of 0.809 microsievert per hour in the Shinjuku district in the western part of the city center at around 10 a.m. local time, about 23 times higher than normal. By late in the day it had fallen to 0.0682 microsevert an hour. The usual daily average is around 0.035 microsevert an hour.

* In Yokosuka, south of Tokyo, the radiation level hit as high as 0.212 microsievert per hour around 7 a.m., according to the Kanagawa Prefectural Government. But the level had fallen to around 0.1 microsievert per hour at around noon.

* The recorded level is a fraction of the 600 microsieverts that a human body receives from one x-ray.

* Exposure at the upper end of the range, at 400 millisievert, is equivalent to 40 rem. A single dose of 25 rem can cause temporary sterility in men. One hundred rems can cause radiation sickness and 500 rems likely will cause death. The U.S. Nuclear Regulatory Commission limits the exposure of U.S. nuclear workers to no more than five rem per year.

This is what I get on the IAEA newsfeed:

UPDATE AS OF 10:20 A.M. EDT, TUESDAY, MARCH 15:

The level of radioactivity at the Fukushima Daiichi nuclear power plant has been decreasing, according to the International Atomic Energy Agency.

At 8 p.m. EDT March 15, a dose rate of 1,190 millirem per hour was observed. Six hours later, the dose rate was 60 millirem per hour, IAEA said.

About 150 residents near the Fukushima Daiichi site have been checked for radiation and 23 have been decontaminated.

Japanese authorities have distributed potassium iodide tablets to evacuation center (see this page for more information on potassium iodide). If taken within several hours of ingesting radioactive iodine, potassium iodide can protect the thyroid gland.

UPDATE AS OF 9:15 A.M. EDT, TUESDAY, MARCH 15:

Fukushima Daiichi

Units 1 and 3 at Fukushima Daiichi are stable and cooling is being maintained through seawater injection. Primary containment integrity has been maintained on both reactors.

The Japan Atomic Energy Agency (JAEA) reported an explosion in the suppression pool at Fukushima Daiichi Unit 2, at 7:14 p.m. EDT on March 14. Reactor water level was reported to be at 2.7 meters below the top of the fuel. The pressure in the suppression pool decreased from 3 atmospheres to 1 atmosphere. Radiation readings at the site increased to 96 millirem per hour.

Dose rates at Fukushima Daiichi as reported at 10:22 p.m. EDT on March 14 were:

* Near Unit 3 reactor building 40 rem/hr
* Near Unit 4 reactor building 10 rem/hr
* At site boundary 821 millirem/hr.
* Kitaibaraki (200 km south of site) 0.4 millirem/hr.

We are working on getting updated information on radiation and dose rates at and near the plant.

Station personnel not directly supporting reactor recovery efforts have been evacuated, leaving approximately 50 staff members at the site. Operators are no longer in the main control room due to high radiation levels.

Safety relief valves were able to be re-opened and seawater injection into the reactor core was restarted around 1 a.m. EDT on March 15 and is continuing.

At Unit 4 on March 14 at approximately 8:38 p.m. EDT, a fire was reported in the reactor building. It is believed to have been from a lube oil leak in a system that drives recirculation water pumps. Fire fighting efforts extinguished the fire. The roof of the reactor building was damaged.

Fukushima Daini

All four reactors at Fukushima Daini are being maintained with normal cooling using residual heat removal systems.

Per: http://www.iaea.org/newscenter/news/tsunamiupdate01.html.

(the IAEA previously reported events using the Cambodian Earthquake Time (CET) standard, have all been converted to Universal Time Coordinated standard (UTC) and will be used for all subsequent reports).

15 March 2011, 14:10 UTC
A 30-kilometre no-fly zone has been established around the Daiichi plant. The Japan Coast Guard established evacuation warnings within 10 kilometres of Fukushima Daiichi and 3 kilometres of Fukushima Daini.

15 March 2011, 11:25 UTC
at the main gate of the Fukushima Daiichi Nuclear Power Plant:.

00:00 UTC on 15 March a dose rate of 11.9 millisieverts (mSv) / hour
06:00 UTC on 15 March a dose rate of 0.6 millisieverts (mSv) / hour.

About 150 persons from populations around the Daiichi site have received monitoring for radiation levels measures to decontaminate 23 have been taken.

Evacuation of the population from the 20 kilometre zone is continuing. Residents out to a 30 km radius are requested to seek shelter indoors. Japanese authorities have distributed iodine tablets to the evacuation centres but no decision has yet been taken on their administration.

15 March 2011, 07:35 UTC
fire at the spent fuel storage pond at the Unit 4 reactor of Fukushima Daiichi nuclear power plant was extinguished on 15 March at 02:00 UTC.

15 March 2011, 05:15 UTC
spent fuel storage pond at the Unit 4 reactor of the Fukushima Daiichi nuclear power plant is on fire and 400 millisievert per hour radioactivity has been reported between Units 3 and 4. The Japanese authorities are saying that there is a possibility that the fire was caused by a hydrogen explosion.

non-indispensible staff were evacuated from the plant, in line with the Emergency Response Plan, and that the population around the plant is already evacuated.

14 March 2011, 14:35 UTC
Fukushima Daiichi Unit 2 has experienced decreasing coolant levels in the reactor core. Officials have begun to inject sea water into the reactor to maintain cooling of the reactor core.

Sea water injections into Units 1 and 3 were interrupted yesterday due to a low level in a sea water supply reservoir, but sea water injections have now been restored at both Units.

14 March 2011, 06:00 UTC
A hydrogen explosion occurred at Unit 3 on 14 March at 11:01 am local Japan time Six people have been injured. All personnel at the site are accounted for. The reactor building has been destroyed, although integrity of the primary containment vessel remains intact and control room for Unit 3 remains operational.

14 March 2011, 00:30 UTC - Clarified
IAEA can confirm the following information concerning status of following Fukushima Daiichi nuclear power plants:

being powered by mobile power generators on site, and work continues to restore power to the plant. There is currently no power via off-site power supply or backup diesel generators being provided to the plant. Seawater and boron are being injected into the reactor vessel to cool the reactor. Due to the explosion on 12 March, the outer shell of the containment building has been lost.
being powered by mobile power generators on site, and work continues to restore power to the plant. There is currently neither off-site power supply nor backup diesel generators providing power to the plant. The reactor core is being cooled through reactor core isolation cooling, a procedure used to remove heat from the core. The current reactor water level is lower than normal but remains steady. The outer shell of the containment building is intact at Unit 2.
does not have off-site power supply nor backup diesel generators providing power to the plant. As the high pressure injection system and other attempts to cool the reactor core have failed, injection of water and boron into the reactor vessel has commenced. Water levels inside the reactor vessel increased steadily for a certain amount of time but readings indicating the water level inside the pressure vessel are no longer showing an increase. The reason behind this is unknown at this point in time. To relieve pressure, venting of the containment started on 13 March at 9:20 am local Japan time. Planning is underway to reduce the concentration of hydrogen inside the containment building. The containment building is intact at Unit 3.

13 March 2011, 12:35 UTC
venting of the containment of reactor Unit 3 of the Fukushima Daiichi nuclear power plant started at 9:20 am local Japan time of 13 March through a controlled release of vapour. The operation is intended to lower pressure inside the reactor containment.

On 12 March, the Japanese Prime Minister ordered the evacuation of residents living within 10 kilometres of the Fukushima Daini nuclear power plant and within 20 kilometres of the Fukushima Daiichi nuclear power plant.

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.