Japanese Earthquake, Tsunami, and Nuclear Reactors

Nei

update as of 11:00 a.m. Edt, march 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 reactors 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. Tokyo electric power co. Is testing the cooling water pumps for reactor 3. External power was connected to the main control room at reactor 3 on tuesday.

Reactors 5 and 6, which were shut down for maintenance at the time of the earthquake, are in safe shutdown.

"the earthquake and tsunami may have inflicted considerable damage in addition to knocking out electricity supplies," the international atomic energy agency said. "since the extent of this damage (and therefore the extent of necessary repair) is unknown, it is not possible to accurately estimate a work schedule."

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.

The u.s. Department of energy has released the first radiation data from its aerial monitoring system and ground detectors in japan. The department will update the data regularly. For the latest information, click here.

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mot said:

Website collating misinformed, misleading and sensationalising journalism regarding the Great Tohoku Earthquake and the situation regarding Fukushima Nuclear Power Plant.
http://jpquake.wikispaces.com/Journalist+Wall+of+Shame

We're so lucky and thus grateful to have doris with us here in GS!

ETA: Olympia, I saw the press conference by some fire fighters from Tokyo on TV, after their first operation at the plant - one of them said when he'd text his wife to tell her that he'd volunteered, she had simply replied 'be a saviour of Japan'.

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I sure agree with you about Doris! She's been a great resource in the past few weeks.

That's an amazing quote about the firefighter's wife. And that's what those folks are doing--no less than saving their country.

TEPCO has their status for March 24th at 7 AM and an earlier status from March 23rd at 11 PM:

Changes are that

Unit 3

At around 4:20 pm on March 23rd, our staff confirmed light black smoke belching from the Unit 3 building. At approximately 11:30 pm on March 23rd and 4:50 am on March 24th, our employee found no signs of smoke.

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And at the Unit 3 spent fuel pool

Today's work for cooling the spent fuel pools -At approximately 10:00 am on March 23rd, we started spraying water to Unit 4 using the concrete pumping vehicle and completed at around 1:00 pm. And at around 11:00 am, sea water injection to fuel spent pool of
unit 3 was started by using Fuel Pool Cooling and Filtering(clean up) system (FPC) and finished at around 1:20 pm.

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Then later on March 24th, following seeing the smoke

-At approximately 5:35 am , we started injecting seawater into the fuel spent pool of Unit 3, using Fuel Pool Cooling and Filtering(clean up) system (FPC). -We are considering further spraying at other units and others subject
to the conditions of spent fuel pools.

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Unit 5

At around 5:24 pm on March 23rd, when we switched the temporary Residual Heat Removal System Seawater Pump, it automatically stopped. We will repair the pump and maintain the reactor water level and the temperature in the reactor properly.

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http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110323e6.pdf

There's a graph of TEPCO's measurements of seawater (above)

They took measurements at the plant's north discharge canal, south discharge canal, and at the Iwasawa Coast.

They checked for and found Iodine 131, Iodine 132, Cesium 134, Cesium 136, Cesium 137 and Cobalt 58 at the south discharge canal.

They checked for and found Iodine 131 (1.158 becquerel/cubic centimater), Cesium 134 (0.0463 becquerel/cubic centimeter), Cesium 137 (0.03962 becquerel/cubic centimeter) and Cobalt 58 at the north discharge canal. Iodine 132 and Cesium 136 were below the level of detection.

At the Iwasawa coast, they checked for and found Iodine 131 (0.66 becquerel/cubic centimeter), Cesium 134 (0.0393 becquerel / cubic centimeter), and Cesium 137 (0.046 becquerel /cubic centimeter). Iodine 132, Cesium 136, and Cobalt 58 were below the level of detection.

They also have information about radionuclides in the air around the Daini plant 10 km. from Daiichi for March 22:
In the most recent measurement they found Iodine 131 (0.00239 becquerels/cubic centimeter), Cesium 134 (0.0000151 becquerels / cubic centimeter) , Cesium 137 (0.0000189 becquerels /cubic centimeter), and tellurium 132 0.0000668 becquerels/cubic centimeter)

They report they found Cesium 134, Iodine 131, and Tellurium at Daiichi in the air, but I don't have the dose numbers.

JAIF has their NHK report

Status of Fukushima Daiichi nuclear power station as of 12:00, March 24, 2011
Here is information regarding the status of Fukushima Daiichi nuclear power station from the news reports aired by NHK in this morning of March 24.

Water is being injected to the reactor vessel at Unit-1, given the situation that the pressure is high inside the reactor pressure vessel. TEPCO decided to decrease injection volume based on its analysis that pressure inside the containment vessel increased as a result of increasing injection volume to the reactor vessel. Core cooling function has been enhanced at Unit-1 since March 23 after the core temperature exceeded design value of 302℃ and reached almost 400℃. (11:30, March 24)

All works at Unit-1, 2, 3 and 4 were suspended after black smoke rose from unit-3. TEPCO resumed water injection to the spent fuel pool of Unit-3 after 05:30 on March 24 after calming down the situation. (10:06, March 24)

Steam like substance rose from all unit-1, 2, 3 and 4 were observed from NHK’s helicopter. This is the first time that steam like substance rose from Unit-1. (09:30, March 24)
End

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JAIF's status says the following:

The Main Gate: 212.8 μSv/h at 06:00, Mar. 24

They comment on the seawater measurements

Monitoring results of seawater sampled at coasts in the surrounding area of the station within about 16km from the Fukushima Dai-ichi NPS in Mar. 22nd showed that radioactive Iodine, I-131, exceeding the regulatory limit and Cesium, Cs-134, 137, less than the regulatory limit were detected.

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Something like steam was seen rising from the reactor building of Unit 1through 4 (as of 7:00, Mar. 24). High-dose rate was measured in Unit 2 turbine building.

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Work to recover external AC power is in progress.
External AC power has reached to Unit 2.
External AC power is to be recovered on 24th in Unit 2 and by 26th in Unit 1, which is to receive the power from Unit 2. Integrity check of electric equipment is going on in both units.

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The NEI reports that at 7:00 PM EDT on March 23rd

Fukushima Daiichi
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.

Efforts are continuing to restore off-site electricity at reactors 1, 2, 3 and 4.

As reported earlier here, seawater injection continues to cool reactors 1, 2 and 3. Seawater is being sprayed into the reactor 3 spent fuel pool. Crews continued to use a truck to deliver high volumes of water into the spent fuel pool at reactor 4, IAEA said.

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They also report the the US's Nuclear Regulatory Commission is going through exercises to review lessons learned from Daiichi and the Japanese Tsunami & Earthquake in general.

And the IAEA says about the same things as TEPCO and JAIF and NEI.

Fukushima Daiichi Nuclear Accident Update (23 March, 20:00 UTC)
Brief update on state of Fukushima Daiichi reactors

Japanese authorities today announced a number of developments at Fukushima Daiichi nuclear power plant, where reactor cooling systems were disabled following the massive earthquake and tsunami on 11 March.

At Units 1, 2, 3, and 4, workers have advanced the restoration of off-site electricity, and the lights are working in Unit 3's main control room.

Black smoke was seen emerging from the Unit 3 reactor building, spurring the temporary evacuation of workers from Units 3 and 4. The emission of smoke has now decreased significantly.

Crews continued today to use a concrete pump truck to deliver high volumes of water into the Unit 4 spent fuel pool, where there are concerns of inadequate water coverage over the fuel assemblies.

At Units 5 and 6, workers have successfully restored off-site power to the reactor, which had previously reached a safe, cold shutdown status.

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Going through today's radiation readings at the Main gate at Daiichi and at Daina, the incident with the black smoke did not cause any jump in radioactivity, as did the event on the previous day.

Another earlier NHK report that I didn't post, translated by JAIF confirms that:

Status of Fukushima Daiichi nuclear power station as of 21:00, March 23,
2011
Here is information regarding the status of Fukushima Daiichi nuclear power
station from the news reports aired by NHK in this afternoon and evening of
March 23.

 Persons who were working to carry out test run of pumps, which are to inject
water into the reactor at Unit-3, were evacuated after black smoke rose and
the test run was suspended around 16:00. (19:05, March 23)

 TEPCO Fukushima office announced at the press briefing held at 17:30 that
black smoke rose from unit-3 around 16:20, and then it was gradually calmed
down as of 17:10. Radiation detected surrounding the power plant has not
changed. (18:05, March 23)

 Tokyo Fire Department was going to spray water to unit-3 from 16:30.
However, this operation was suspended concerning safety after black smoke
rose. (17:50, March 23)

 The operation of water injection to the spent fuel pool of Unit-4 with special
vehicle was finished around 13:00 after 3 hour operation. (14:15, March 23)
End

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JAIF has come out with their morning status, but in reformatting the chart, some things have become less clear-like whch wording goes with which Reactor or Spent Fuel pool. Here's what I get out of it

JAIF status, March 24th

Latest Major Incidents and actions

<March 23rd>
02:33 Feed Water Line was added to the Fire Extinguish Line to inject water into the Reactor Pressure Vessel in Unit 1.
also *Temperature in the reactor pressure vessel has been gradually dropping since March 23rd. (225 C at 9:00 am March 24th).

16:20 Black smoke erupted from Unit 3 (smoke settle around 23:30)
* from TEPCO monitoring data, no jumps in radiation measurements occurred this time)

17:24 Residual Heat Removal pump stopped automatically as the primary power supply [and was] replaced with the temporary power source.
Backup pump is to become in service on 24th.

<March 24th>
05:35 Water injection to Spent Fuel Pool via reactor water clean up system started
*it's not clear which pool from the chart.

Radiation at the Daiichi Main Gate: 209.4 μSv/h at 12:00, Mar. 24. Radiation at Daini is down to 10.0 μSv/h

Unit 1
Lighting has been recovered in the Unit 1 main control room.

*I think Unit 2 & 3 also have lights in the main control room now, but it's not clear from the chart.

TEPCO has issued a number of status reports.

Contract workers are back on the job, and it sounds like there might be a lot more people on site. There have been some new injuries. It must be remembered that Daiichi now looks like a war zone of wreckage. It is obviously very difficult working conditions.

Two workers were transferred to the hospital, after stepping in radioactive water in the turbine building. The actual dose they received from doing this will determine how serious injuries to them are. The file linked by let's talk listed the figure for radiation burns as 400mS/hour. TEPCO says more than 170 mS/hour. I hope the best for the injured workers.

Injuries:

-At approximately 10 pm on March 22nd, 1 worker who had been working on
setting up a temporary power panel in the common pool was injured and
transported to Fukushima Daini Nuclear Power Station where the industrial
doctor is.
-At approximately 1 am on March 23rd, 1 worker who had been working on
transporting a temporary power panel in the common pool was injured and
transported to Fukushima Daini Nuclear Power Station where the industrial
doctor is.
-On March 24th, it was confirmed that 3 workers from other companies who
were in charge of cable laying work in the 1st floor and the underground
floor of turbine building were exposed to the radiation dose of more than
170 mSv. 2 out of 3 are being transferred to the hospital as it was
confirmed that their leg skin were contaminated. They were transferred to
FUKUSHIMA Medical University Hospital.

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Unit 5

Yesterday, the pump broke, today it's fixed.

At around 4:14 pm, March 14th, we started replaced pump and at around 4:35 pm, cooling of reactor has restarted

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Additonally
Spent Fuel Pool Activities
(for some time JAIF has considered the spent fuel pools at Daiichi to be the most criticial items on site at Daiichi.

Today's work for cooling the spent fuel pools
-At approximately 5:35 am, we started injecting seawater into the fuel
spent pool of Unit 3, using Fuel Pool Cooling and Filtering(clean up)
system (FPC) and finished at 4:05 pm.
-At around 2:35 pm, spraying to unit 4 by concrete pump track and finished
at around 5:30 pm.
-We are considering further spraying at other units and others subject to
the conditions of spent fuel pools.

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-At 3:37 pm, March 24th, electricity supply to common spent fuel pool has started from external power.

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And TEPCO reminds us that they have other power issues than Daiichi

We are announcing the status of major inspections and restoration works and nonconformances at TEPCO's Kashiwazaki-Kariwa Nuclear Power Station after the Niigata-Chuetsu-Oki Earthquake.

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JAIF and TEPCO have issued their usual late night updates for March 24th (Japanese time)

We learn that the upper bound of the radiation dose received by the injured workmen transferred to Fukushima Hospital was 180 milleSievert/hour.

Tokyo has a shortage of bottled water, due to the announcement that babies should not be given tap water. However, today, the concentrations of radionuclides in Tokyo tap water returned to normal.

Meanwhile, people in China have bought up all the iodized salt to be had, as ad hoc Iodine pills. Chinese customers of a US manufacturer who is a friend of mine have been requesting salt to be sent in orders.

And in Groton, CT, my home, people are still going to the Town Clerk to stock up on Iodine pills (You can get them at town hall for free, since Groton is within 5 miles of Millstone Point, and the US Submarine Base)

TEPCO

Radiation at Daiichi Main Gate continues to drop slowly

March 24, 11:50 PM 199.6 microSievert/Hour

Radiation at Daina Measuring Point four continues to drop slowly

March 24, 11:50 PM 9.3 microSievert/Hour

JAIF UPDATE as of 11:00 PM March 24

<March 24th>
05:35 Water injection to SFP via reactor water clean up system started in Unit 3.
Around 11:30 Lighting has been recovered at Unit 1 Main Control Room.
16:14 Residual Heat Removal pump of Unit 5, which had stopped automatically, was restarted and then the system was put into shutdown cooling mode.

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JAIF translation of NHK report of March 24, 2011at 21:00

Status of Fukushima Daiichi nuclear power station as of 21:00, March 24,
2011
Here is information regarding the status of Fukushima Daiichi nuclear power
station from the news reports aired by NHK in this afternoon and evening of
March 24.
l The 2 workers sent to the hospital are suspected to get burned by beta-ray. 3
workers were working to lay electrical cables at the first basement level
when they were exposed. To secure safety of workers under high radiation
environment becomes an issue. (19:25, March 24)
l Nuclear and Industrial Safety Agency announced that 3 persons who were
exposed to radiation. These were working in the turbine building of unit-3 at
that time. The amount of radiation that they were exposed is from 170mSv/hr
to 180mSv/hr. It is found that radionuclide adheres to foot skin of 2 workers
and these 2 workers were sent to the hospital for cure. (15:50, March 24)
l The work to recover external AC power for units-1, 2, 3 and 4 is in progress.
External AC power to the main control room of unit-1 became available at
11:30 of today. Now the lights are working in the main control room at unit1
and 3. (13:20, March 24)
End

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NEI has its afternoon updates:

Things that JAIF, NHK and TEPCO haven't mentioned are in bold.

UPDATE AS OF 1:30 P.M. EDT, MARCH 24
In a sign of progress, Tokyo Electric Power Co. (TEPCO) is working to switch from seawater to borated freshwater to cool uranium fuel at three reactors at the Fukushima Daiichi nuclear power plant.

All reactors now have access to off-site power, and work is under way to inspect, repair and connect equipment needed to cool the reactors. Testing by TEPCO indicates that many pumps are inoperable because of flood damage.

Restoring regular cooling to the used fuel pools at Fukushima Daiichi remains a high priority. The used fuel pools at reactors 5 and 6 are being cooled using heat removal systems with electric power. Workers continue to spray seawater on the reactor buildings and spent fuel pools at reactors 1, 3 and 4. Cooling water to the spent fuel pool at reactor 2 is being supplied by a fire hose connection.

Overnight, steam was rising from the secondary containment buildings that house reactors 1 through 4.

Radiation dose rates at the site boundary range from 1 to 3 millirem per hour.

NEI has updated the brochure "Understanding Radiation: Its Effects and Benefits," which includes facts about monitoring and protection against radiation.


UPDATE AS OF 9:30 A.M. EDT, MARCH 24:
Two workers were hospitalized for radiation exposure Thursday, even as Tokyo Electric Power continued to make progress in stabilizing reactors at the Fukushima Daiichi nuclear power plant.

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.

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.

In Tokyo, the level of radioactive iodine in tap water has dropped to within safety limits Thursday. Yesterday, the Japanese government had advised against giving tap water to infants under one year old.

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You will notice that guidelines for an emergency for those workers were not exceeded. You would have thought from the way this was reported on TV that these guys were going to die immediately of radiation poisoning.

I suppose this is why NEI has updated its brochure on Understanding Radiation & given a link to it.

http://www.nei.org/filefolder/Understanding_Radiation_1.pdf

Page 7 on putting Radiation dose in context is useful:

ACTIVITY ANNUAL DOSE

Smoke detector in the home 0.008 millirem

Living within 50 miles of a nuclear power plant 0.009 millirem

Living within 50 miles of a coalfired power plant* 0.03 millirem

Roundtrip flight from New York City to Los Angeles 5.0 millirem

Medical X-ray 10.0 millirem

Food and water consumed throughout the course of one year 30 millirem

Mammogram 100 millirem

Average annual exposure for a nuclear power plant worker 120 millirem

Average annual exposure from natural radiation 300 millirem

CT scan 1000 millirem

NRC’s annual limit for occupational exposure 5000 millirem

Cardiac catheterization or coronary angiogram 5,000 millirem

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For more context, fall of 2009, Mr. Ski was very, very sick.

He had 7 catherizations (35,000 millirem) in interventional radiology and 1 CT (1,000 millirem) scan. He had a chest x ray (10 millirem) on being admitted to the hospital.

1 rem is 1000 millirem, so Mr. Ski had more exposure to radiation (36 rem, in addition to his annual exposure) than the guys in the hospital. He had no radiation burns, and is alive and well.

On the other hand, the IAEA report contradicts this, and says they may have burns on their feet. IAEA is seeking more information. I hope we actually hear how they are doing.:

Fukushima Daiichi Nuclear Accident Update (24 March 17:25 UTC)
Japanese Workers Treated for Radiation Exposure

Japanese authorities today reported that three workers at the Fukushima Daiichi nuclear power plant were exposed to elevated levels of radiation. The three were working in the turbine building of reactor Unit 3 and have received a radiation dose in the range of 170-180 millisieverts.

Two of the workers have been hospitalized for treatment of severely contaminated feet, which may have suffered radiation burns. The workers had been working for about three hours in contact with contaminated water.

The IAEA is seeking additional information.

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IAEA got the saltwater data we saw yesterday.

Fukushima Daiichi Nuclear Accident Update (24 March, 17:30 UTC)
Japanese Seawater Samples Show Signs of Radioactive Materials

Japanese authorities today provided the IAEA with data on seawater samples they collected on 22 and 23 March, after detecting iodine and cesium in the water near the Fukushima Daiichi nuclear power plant. (See earlier update.)

A vessel from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) collected water samples at several points 30 kilometres from the coastline and found measurable concentrations of iodine-131 and cesium-137. The iodine concentrations were at or above Japanese regulatory limits, and the cesium levels were well below those limits.

The IAEA's Marine Environmental Laboratory in Monaco has received the data for review.

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And has more information on the very interesting (to me) subject of Japanese Spent Fuel pools:

Fukushima Daiichi Nuclear Accident Update (24 March 14:00 UTC)
Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant - Updated

Spent fuel removed from a nuclear reactor is highly radioactive and generates heat. This irradiated fuel needs to be stored for one to three years in pools that cool the fuel, shield the radioactivity, and keep the fuel in the proper position to avoid fission reactions. If the cooling is lost, the water can boil and fuel rods can be exposed to the air, possibly leading to severe damage and a large release of radioactive materials.

Nuclear power plants must replace fuel every one to two years, and the Fukushima Daiichi reactors typically remove about 25 percent of the reactor's fuel -- to be replaced with fresh, or unirradiated, fuel -- during each refuelling outage. The spent fuel, which is hottest immediately after it is removed from the reactor, is placed in the spent fuel pool until it is cool enough to be moved to longer-term storage.

The concern about the spent fuel pools at Fukushima Daiichi is that the capability to cool the pools has been compromised. See diagram below for location of the pool in each reactor building.

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http://www.iaea.org/newscenter/images/spent-fuel-pool-820.jpg

(Hint: the spent fuel pool is on the upper story)

A Running Status of the Spent Fuel pools & their problems, according to IAEA:

Unit 1

Unit 1 experienced an explosion on 12 March that destroyed the outer shell of the building's upper floors. No precise information has been available on the status of the spent fuel pool.

Unit 2

Precise information on the status of the spent fuel pool was unavailable in the days following the earthquake, but Japan's Nuclear and Industrial Safety Agency began to release temperature data on 20 March:
20 March, 23:00 UTC: 49 °C
21 March, 05:25 UTC: 50 °C
21 March, 21:20 UTC: 51 °C
22 March, 02:20 UTC: 53 °C
22 March, 06:30 UTC: 50 °C
22 March, 19:20 UTC: 51 °C
23 March, 00:00 UTC: 51 °C
23 March, 06:00 UTC: 51 °C
23 March, 16:00 UTC: 52 °C
24 March, 00:00 UTC: 47 °C

Workers conducted an operation to spray 40 tonnes of seawater to the spent fuel pool on 20 March, and they added another 18 tonnes on 22 March.

Unit 3

Unit 3 experienced an explosion on 14 March that destroyed the outer shell of the building's upper floors. The blast may have damaged the primary containment vessel and the spent fuel pool. To address these concerns, authorities began spraying water into the building, first by helicopter on 17 March and then by fire trucks and other vehicles through 22 March. Starting 23 March, seawater was injected into the spent fuel using the cooling and purification line. By midday 24 March, 4-5 tonnes of seawater had been injected through this line.

Unit 4

This reactor was shut down 30 November 2010 for routine maintenance, and all the fuel assemblies were transferred from the reactor to the spent fuel pool, before the 11 March earthquake. The heat load in this pool is therefore larger than the others.

On 14 March, the building's upper floors were severely damaged, possibly causing a reduction of cooling capability in the spent fuel pool. Emergency workers began spraying water into the building on 20 March, and have continued daily since then. On 22 March, workers began using a concrete pump truck that can deliver water more effectively, placing 150 tonnes of water on 22 March and 130 tonnes on 23 March.

Units 5 and 6

Instrumentation at these reactors began to indicate rising temperatures at their spent fuel pools starting on 14 March. Three days later, Japanese technicians successfully started an emergency diesel generator at Unit 6, which they used to provide power to basic cooling and fresh-water replenishment systems. Workers created holes in the rooftops of both buildings to prevent any hydrogen accumulation, which is suspected of causing earlier explosions at Units 1 and 3.

A second diesel generator came online on 18 March, and the next day, the higher-capability Residual Heat Removal (RHR) system recovered full function. External power was restored to Units 5 and 6 on 22 March. Temperatures in the spent fuel pools of Units 5 and 6 have gradually returned to significantly lower temperatures, although the Unit 5 pool temperature increased somewhat on 23 March after pumps for the RHR system were stopped when the diesel generators were removed from service.

Common Use Spent Fuel Pool

In addition to pools in each of the plant's reactor buildings, there is another facility -- the Common Use Spent Fuel Pool -- where spent fuel is stored after cooling at least 18 months in the reactor buildings. This fuel is much cooler than the assemblies stored in the reactor buildings. Japanese authorities confirmed as of 18 March that fuel assemblies there were fully covered by water, and the temperature was 57 °C as of 20 March, 00:00 UTC. Workers sprayed water over the pool on 21 March for nearly five hours, and the temperature on 23 March was reported to be 57 °C.

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IAEA also has replicated a version of the JAIF block diagram status of the Daiichi reactors:

http://www.slideshare.net/iaea/table-summary-of-reactor-unit-status-at-of-24-march0600-utc

And other slide shows at

http://www.slideshare.net/iaea/technical-briefing-on-the-situation-in-japan-23-march-2011

Including modelling of the path the contamination from the plant took. It shows most everything on the 17th and 18th went out to sea.. The modelling was done by a group in Montreal.

TEPCO issued further info about the workers sent to the hospital:

- On March 24th, it was confirmed that 3 workers from cooperative companies who were in charge of cable laying work in the 1st floor and the underground floor of turbine building were exposed to the radiation dose of more than 170 mSv. 2 of them were confirmed that their leg skin were contaminated. Although they were decontaminated, since it is judged that there is possibility of beta ray burn injury, they were transferred to Fukushima Medical University Hospital. After medical examination at Fukushima Medical University Hospital, they will be transferred to National Institute of Radiological Sciences in Chiba Prefecture today (March 25) and stay for around four days to survey the situation. Inspection result of the water that the workers stepped in will be announced when it is reported.

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And in case you've yearned to see how US Spent Fuel pools look:

NEI has put up two videos

Fuel Assemblies
http://www.youtube.com/watch?v=Zp7jAhMIWD8

US Spent Fuel Pools
http://www.youtube.com/watch?v=QO-daVysLH8

Golly, if ever there were an incentive to give up butter, it's reading what a cardiac catheterization costs in millirems! It makes me want to become a vegan.

Doris, I hope you're reading frivolous things as well as all this material. While I'm sure you're finding it helpful to immerse yourself in the details--and we're certainly glad to have such an expert informant helping us through it!--the stress can build up in you. This is a tough time for anyone with links to the situation. Make sure you're eating, sleeping, and rocking on.

Too much eating and not enough sleeping mostly

As to reading, after I finished "Wormwood Forest" and have started on "Power to Save the World" by Gwyneth Cravens, a very good book, very pertinent reading right now.

As to the cardiac cath, the health consequences of "low dose" radiation (and yes people argue about what dose is "low dose") are a "hot" topic of discussion, and not just now, among people interested in having more and having less nuclear power, and among health professionals that fall on either side of that debate. Most people these days end up with their biggest doses from medical procedures, and that will be true in Japan, because other than the workers at the plant, no one has gotten anything but a very small dose, as the surrounding people were evacuated well in advance of any release of radiation or radioactive materials.

Cardiac cath is a lot less than what people receive for radiation therapy (I had radiation therapy for uterine cancer back in 2000)

Everyone agrees that a "large dose" is catastrophic, and causes death. However, after that there are people who believe any dose may be harmful (and I hope they never need a cardiac cath), those that believe small doses actually improve health, those that believe doses below a certain threshold cause no problems, and a few other even strager theories.

There are several groups of people whose long term health have been followed:

Women who used to paint the numbers on radium watch and alarm clock faces. In fact many of them used to lick their brushes to get a finer point. The last of them recently died at 100.

A group of men in the US who ingested massive doses of plutonium in the 1950's, from one of the US national labs, and who call themselves the UPPU club (If you have had a high dose of plutonium (chemical symbol Pu), it is excreted in your urine.) The survivors are in their 80's.

The survivors of Hiroshima and Nagasaki. In 2006, when Cravens wrote her book, about 40% of them were still alive.

The people who actively worked at the effort to clean up after Chernobyl were followed very closely, and areas affected by Chernobyl, (although that is significantly more difficult). Many of the people who cleaned up have better health than the average for the areas in which they live, mostly because they get lots of medical checkups compared to other people living in the region. People's ability to withstand radiation varies greatly.

Radiation is most destructive to fast growing tissue in your body, which is why it is disruptive to cancer, and why it is much more dangerous for babies and children than for adults.

The cancers most closely associated with it are thyroid (mostly avoidable with iodine tablets, and generally curable.)

The overall five-year relative thyroid cancer survival rate from 1995-2001 was 96.6 percent. The five-year relative survival rates by race and sex were:

•94.4 percent for Caucasian men
•97.7 percent for Caucasian women
•89.2 percent for African American men
•95.4 percent for African American women.

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And of course, better if you are diagnosed early than late.

The other cancers most closely associated with radiation are blood cancers, including the different forms of leukemia. In the 1960's, this was considered a quick death sentence. Survival rates are now 85% for children and 50% for adults.

http://en.wikipedia.org/wiki/Leukemia

As Cravens cites in her book, explaining the difficulties of doing statistics on the subject of large scale radiation exposure, like Chernobyl, looking at the population of New York City, even if you accept that some 5000 odd additional cancers might develop in a situation that she cites, that is hard to tell when the same population has more than 1,000,000 cancer cases from other causes.

And the excessive number cancers started appearing some five years after Hiroshima/Nagasaki, so this is something that does not appear at once. If any of the workers at Daiichi gets cancer due to radiation exposure, it will be after a number of more years of medical research have improved survival rates still further. And you may be sure, those plant workers' health will be tracked, as the Hiroshima/Nagasaki survivors were tracked.

TEPCO has more info about the radiation exposure of the two men who were sent to the hospital:

It appears they continued working, even though their dosimeter alarms went off, and stayed standing in the puddle for three hours. They were decontaminated by "laundering", which is typical.

The puddle has been analyzed.

Radiation dose rate of surface of the water is approximately 400 mSv/hr.

Result of gamma-ray nuclide analyses based on sampling of puddle

Name of nuclide Concentration (Bequerel / cubic centimeter)

Cobalt 60 Conc 700
Technetium 99m Conc 2,500
Iodine 131 Conc 1,200
Cesium 134 Conc 1,800
Cesium 136 Conc 23,000
Cesium 137 Conc 180,000
Barium 140 Conc 52,000
Lanthanum 140 Conc 9,400
Cerium 144 Conc 220,000

Total dose 390,000

We are assessing radiation dose of 2 worker's leg skin by beta ray.

We guess that this incident was caused because the workers regarded radiation dose of working area as low from survey result of radiation dose on March 23 and continued working without recognizing change of working conditions of the day although alarm of their dosemeter rang.

We thoroughly instruct our employees and workers of cooperative companies to recognize alarm of their dosemeter and evacuate when the alarm rings.

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More detail on the scale of pumping sea water to reactors and spent fuel pools:

*In total 13 fire engines are lent for spraying water to the spent fuel pools and water injection to the nuclear reactors by various regional fire departments* as well as Tokyo Fire Department. Also, instruction regarding the setting and operation of large scale decontamination system was provided.

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Radiation measurements at Daini are still declining slowly at Meauring Point 4 and at the Daiichi Main gate

8.9 microSieverts/hour at 3:00 PM, March 25, Daina MP4
202.5 microSieverts/hour at 3:30 PM, March 25, Daiichi Main Gate

JAIF has translated the noon March 25th NHK news on Daiichi

Status of Fukushima Daiichi nuclear power station as of 12:00, March 25,
2011
Here is information regarding the status of Fukushima Daiichi nuclear power station from the news reports aired by NHK last night and in this morning on March 25.

l The work to recover external AC power for units-1, 2, 3 and 4 is in progress. External AC power to the main control room at unit-2 will be available today. According to Tokyo Electric Power Co. (TEPCO), the reactor surface temperature at unit-1 increased to approx. 400 degrees C once (design assumption maximum 302 degrees C). Now it dropped to 204.5 degrees C (as of 06:00 on March 25). Meanwhile, in the turbine building at unit-3, drainage work is also in progress. (10:45, March 25)

l On March 24, 2 workers, who were working to lay electrical cables in turbine building at unit-3, were sent to the hospital. TEPCO suspected that the nuclear fuel in the reactor or spent nuclear fuel at the pool was damaged and water contaminated with high radioactivity was leaked to the workspace. Further investigation is now carrying on. These 2 workers were not wearing boots. Another worker wearing boots is safe. (07:15, March 25)

l As for the coolant of reactors at Fukushima Daiichi, TEPCO would like to switch from seawater to fresh water as fast as possible. The first switch will be carried out at unit 3. (04:30, March 25)

l Ministry of Defense announced that the Self-Defense Force helicopter measured the surface temperatures of Fukushima Daiichi units-1, 2, 3 and 4 from the air by using infrared rays and found that the temperature of each units are below 20 degrees C.
Unit-1:17 degrees C;
Unit-2: 13 degrees C;
Unit-3: 11 degrees C;
Unit-4: 17 degrees C (as of the morning on March 24).
Especially, the surface temperature of the spent fuel pool at unit-3 dropped significantly to 31 degrees C, compared to 56 degrees C on the previous day. (21:15, March 24)

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And JAIF has produced the following report, from their "Atoms in Japan" newsletter

http://www.jaif.or.jp/english/aij/member/2011/2011-03-25a.pdf

Lights Back On in Central Control Room at Fukushima Daiichi Unit 3
after External Electricity Reconnected (as of March 23)

As seawater injection continued to the spent fuel pool at the Fukushima Daiichi Nuclear Power Station, owned and operated by the Tokyo Electric Power Co. (TEPCO), a temporary cable for external power was connected, making electricity again available to Units 1 through 6. Test runs of each item of the electrical and other equipment will now be carried out, with recovery work to proceed as expeditiously as possible.

At 10:45 p.m. on March 22, lights came back on in the Central Control Room in Unit 3.

At Units 5 and 6, meanwhile, all power has been switched to external sources, with a
water feeding line having been added to the water-injection line to the reactor pressure
vessel in Unit 1.

Earlier, on March 21, the Japanese government held a joint meeting – the 13th meeting
of the Tohoku Region Pacific Ocean Offshore Earthquake Emergency Response Headquarters and the 11th meeting of the Nuclear Emergency Response Headquarters - at the Prime Minister’s Official Residence in Tokyo. In his remarks, Prime Minister Naoto Kan said that there was “now light at the end of the tunnel in this critical situation,” thanks to the strenuous efforts of the many people involved. He thereby showed his recognition that progress, though little and slow, was being made.

On the morning of March 17, six days after the government had issued declaration of nuclear emergency, Self-Defense Force (SDF) helicopters dropped water four times at the Unit 3 of Fukushima Daiichi, the reactor building of which had shown white smoke belching the previous day. Thereafter, water injection began to be carried on the ground by various parties: SDF fire trucks, police water-cannon trucks, high-pressure watercannon trucks provided by U.S. Forces, special fire trucks of the Tokyo Fire Department’s Hyper-Rescue Team, and others. Unit 3 received most of the injection. By 10:00 a.m. on March 23, the amount of water injected into Unit 3 had reached 3,900 tons.

In the cooling operations at the spent fuel pools – another key to containing the damage – a special vehicle (concrete-pumping truck with 50-meter-long arm, normally part of construction work) was used at Unit 4 on March 22, in addition to the fire trucks of the SDF and that provided by U.S. Forces.

Regarding the restoration of external electric power at Units 5 and 6, where states of cold shutdown had been achieved on March 20, the power was switched from emergency diesel generators to an external source on March 21 and 22, respectively. Electricity was restored at Unit 2 on March 21 and at Unit 4 on March 22. At Unit 3, where gray smoke emerging on March 21 was a cause for fresh concern, lights were restored in the Central Control Room. At Unit 1, which is receiving electricity from Unit 2, equipment is currently being checked. Excluding Unit 4, which was not in operation when the earthquake occurred, Units 1 through 3, with their fuel assemblies loaded in their cores, must still achieve cold shutdown. Injections of seawater are continuing at those reactors.

25 March 2011

At the start of the joint meeting on March 21, Prime Minister Kan expressed his recognition that “truly life-risking efforts are enabling the situation at Fukushima Daiichi to move forward.” Heroic work by the SDF and Tokyo Fire Department has delivered 3,000 tons of water to the reactors, primarily Unit 3, and recovery of power has made significant progress primarily at Units 1 and 2. Although we have not escaped this critical situation, there is now “light at the end of the tunnel,” according to the Prime Minister.

Describing the Fukushima NPS accident as one of the worst in Japan’s history, the prime minister said “we still must bring it under control before it causes enormous damage.” He said that the SDF, TEPCO, the Tokyo Fire Department and other firefighting parties were doing everything in their power. He urged them to continue, and to “provide even greater help.”

At the end, the Prime Minister raised his voice when saying, “We must make a visionary restoration plan. We must realize a society where people feel that Japanese communities have improved and become more vigorous after overcoming this unprecedented natural disaster – communities in which they can live again with peace of mind.”
Editor: Mio Kimuro, JAIF

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NEI has their evening report up

UPDATE AS OF 7 P.M. EDT, 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.

For more information on iodine-131, see NEI's fact sheet Health Impacts of Iodine-131.

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IAEA has the following daily status:

Fukushima Nuclear Accident Update (25 March 2011, 05.15 UTC)
Update on Conditions of Fukushima Daiichi Nuclear Power Plant

At Unit 1 workers have advanced the restoration of off-site electricity and lighting in the Unit's main control room was recovered as of 24 March, 11:30 UTC. They are now checking the availability of the cooling system.

While the pressure in the reactor vessel remains high, Japanese authorities are reporting that it has stabilized.

At Unit 2 engineers are working for the recovery of lighting in the main control room, and the instrumentation and cooling systems.

At Unit 3, around 120 tonnes of seawater was injected in the spent fuel pool via the cooling and purification line. The operation was carried out between 23 March, 20:35 UTC and 24 March, 07:05 UTC.

Work was under way for the recovery of the instruments and cooling systems. However, it had to be suspended because three workers were exposed to elevated levels of radiation on 24 March.

At Unit 4, the spent fuel pool was sprayed with around 150 tonnes of water using concrete pump truck. The operation was carried out between 24 March, 05:36 UTC and 06:30 UTC of the same day.

At Units 5 and 6, repair of the temporary pump for Residual Heat Removal (RHR) was completed as of 24 March, 07:14 UTC, and cooling started again 21 minutes later.

At the Common Spent Fuel, the power supply was restored as of 24 March, 06:37 UTC and cooling started again 28 minutes later. Work is now under way for the recovery of the lighting and instrumentation systems.

As of 24 March, 09:40 UTC, the water temperature of the pool was around 73 °C.

As of 24 March, 10:30 UTC workers continue to inject seawater into the reactor pressure vessels of Units 1, 2 and 3 and are preparing to inject pure water.

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The IAEA also reports on the workers who were sent to the hospital, and adds this info:

As of 24 March, 19:30 Japan time, the number of workers at the Fukushima Daiichi nuclear power plant found to have received more than 100 millisieverts of radiation dose totalled 17 including the three contract workers. The remaining fourteen are TEPCO's employees.

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100 milliSieverts is 10 mrem, the amount of one chest xray. Each worker has a dosimeter, which records what dose he has received. So the above is actually good news, that it is not worse.

The reason the worker with boots had no problem was that beta radiation is stopped by clothing. The two workers without boots had the water on their bare skin.

Veen Oui YOKOSUKA, Japan (Mar. 25, 2011) - Barge YOGN-115, carrying 1.04 million litres (275,000 gallons) of fresh water, departs Commander, Fleet Activities Yokosuka (CFAY) to support cooling efforts at the Fukushima Daiichi nuclear power plant. CFAY port operations cleaned and filled two barges, totaling nearly 1.89 million litres (500,000 gallons) of fresh water. (U.S. Navy photo by Mass Communication Specialist 3rd Class Mikey Mulcare)

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The above from IAEA's facebook, which I thought was interesting.

There are of course, concerns about where the radioactive water in the basement of Unit 3 came from.

However, there are several things to know:

It was a puddle, that was deep enough to go over someone's shoes, but not deep enough to go over the top of a pair of boots, and the workers involved stood in it for 3 hours, so it wasn't getting deeper very fast.

Unit3 is a building that has had water sprayed into it by the ton, over and over. And there have been doubts about the integrity of the suppression chamber, spent fuel pool, and the reactor pressure vessel since the explosion.

The containment vessel is a separate structure.

http://www.iaea.org/newscenter/images/spent-fuel-pool-820.jpg



If there were a sizable hole in the bottom of the spent fuel pool or the reactor, there would be a lot more water in the basement, in the space of 3 hours.

Furthermore, the concentration of radioactive material in the water in the puddle is higher than JAIF expects for reactor water.

JAIF says:

Radioactive fission products were detected in the pool at the work area. Their concentration was about 3.9 million Bq/cc, ten thousand times higher than the reactor water in
normal operation. NISA indicated the possible damage of the Reactor Pressure Vessel of Unit 3. With these three workers, so far seventeen workers have been exposed to more than 100 mSv of radiation.

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Stuff is still going on in the other 5 units, but no workers are hauling cables through the basement of Unit 3.

<March 25th>
06:45-10:20 Water injection to SFP via reactor water clean up system started in Unit 4
10:30-12:19 Water injection to SFP via reactor water clean up system started in Unit 2
11:00 Switching the water source for injecting into RPV from seawater to freshwater was started at Unit 2 and 3. That has become ready at Unit 1.

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This is not affecting radiation outside the site:

And

The Main Gate: 202.5 μSv/h at 15:30, Mar. 25

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And, I suspect that what this will do is make it much harder both to cleanup and to stabilize Unit 3.

Even the TV expert says that there is very little chance of a Chernobyl event at Daiichi. The risk is to the immediate site.

http://roseparsley.iobb.net/hotart/radiation.html
Granite and marble can have natural radiation of 0.5. Both materials are very popular ones in the historical centers in Europe. So, I am immune, I guess.