Japan Earthquake: nuclear plants

|Fred

Quote by Cire

2. A reactor pressure vessel is a massive heat sink. I believe the drywell on both reactor 1 and 2 where flooded early on in the process; providing addition temperature relief. This doesn't include the water that has been injected since the start of the accident..

Thank you Nuceng and Cire for those anwsers, you mention that the drywell (primary containment in concrete if I'm not mistaken) Has been flooded. I've seen this "idea" on the paper writen by or for Areva.
But I haven't seen any statement , indications or explanation by the Japanese authorities or tepco that they did so ...
Is is a standard procedure ? how did they get some water there and when..

E.g. to receive a dose of 1 mSv in 50 years it requires about ingestion of about 80000 Bequerel of Caesium 137 but only about inhalation of 15 Bq of Plutonium. The activity in Bq in the environment is relatively simple to determine.

I think this statement is wrong there is a 20 factor ponderation between alpha and beta, please correct me a dose of 1mSv it would require contact with a 10 000 Bq source of 137Cs or a 500 Bq source of Pu

Bodge

So, is it currently feasable for there to be a large steam explosion in (under) any of reactors 1-3?

Could there be corium in an unbreached RPV, suspended above a saturated area?

Bodge

I'm looking at Reactor 1 in particular.

But, in any reactor, could the conditions above still conceivably develop in the next few days?

Astronuc

Quote by |Fred

Thank you Nuceng and Cire for those anwsers, you mention that the drywell (primary containment in concrete if I'm not mistaken) Has been flooded. I've seen this "idea" on the paper writen by or for Areva.
But I haven't seen any statement , indications or explanation by the Japanese authorities or tepco that they did so ...
Is is a standard procedure ? how did they get some water there and when..

A contact at GE indicate that flooding containment is standard op in the case of a LOCA.

I would expect that TEPCO flooded containments on Units 1, 2 and 3 - in addition to getting water into the pressure vessel in order to reflood the core as much as possible.

Cire

Quote by |Fred

Thank you Nuceng and Cire for those anwsers, you mention that the drywell (primary containment in concrete if I'm not mistaken) Has been flooded. I've seen this "idea" on the paper writen by or for Areva.
But I haven't seen any statement , indications or explanation by the Japanese authorities or tepco that they did so ...
Is is a standard procedure ? how did they get some water there and when..

Here is a 1995 Paper by ECN on the IAEA website about flooding the drywell.. It's a good read.[Link to Paper]

Quoted from the abstract:

In case of a severe reactor accident inside a Nuclear Power Plant (NPP), the
worst case scenario includes melt-down of a significant part of the core.
Without any counter measures, this will lead to failure of the Reactor
Pressure Vessel (RPV). In order to prevent failure of the RPV, the decay heat
generated by the corium pool has to be removed from the vessel at such rates
that excessive temperature rise of the vessel wall is averted.
Recently, flooding of the lower drywell or external (ex-vessel) flooding has
been suggested as a possible accident management strategy, with the purpose
to cool the relocated heat generating corium pool in such a way that vessel
failure is prevented.

My understanding is you flood the dry well by activating the fire suppression system in that area and not turning it off until you flood the area. I'm looking for the source material I read that stated the dry well was flooded. When I find it I'll be sure to link to it.

Astronuc

Quote by M. Bachmeier

I was thinking more about unit #4, wondering if a solution could have been in the core at the time of the quake? And, if so, would the solution (if leaked back into SFP through failed gate seal) contribute to more rapid heating by dissolving or weakening the cladding on the spent fuel rods?

In a BWR, there would be no solution in SFP water or the reactor cavity. It's flooded with clean water, which is cooled and filtered.

I would expect that the gate was open, but I don't know as I'm not familiar with their procedures. Unit 4 was shutdown since Nov 30, 2010, and for whatever reasons, they do exceptionally long maintenance outages. The core had been cooling for 101 days at the time of the quake. The thermal burden should have been about 2.75 MW.

Most US plants try to minimize outage length. Some utilities have it down to about 15-17 days every 18 mo or 24 mo depending on the unit, although many units probably do it more like 20-30 days.

The earthquake certainly could have caused a structural failure somewhere in the pool or containment structure.

Some of the Kashiwazaki-Kariwa units sustained damaged from the Niigata earthquake, and Chubu's Hamaoka Units 1 & 2 were shutdown and decommissioned prior to the Suruga Bay earthquake of Aug 11, 2009.

AtomicWombat

Quote by jlduh

An other question, I've heard this sentence: "because Plutonium is so dense and heavy, IT CANNOT go very far and be transported to a great distance from its source point, so it should stay around the vicinity of the plant".

I know it's a very dense element, but is this sentence 100% true?

Plutonium oxide is insoluble in almost everything, so it wont get into the food or water supply.

Plutonium (in its oxide form) is most dangerous when it is in fine particles of airborne dust. I see it as a little like asbestos. If in some accident a large amount of asbestos dust was to spread over an inhabited area, there would be a long term expectation of elevated rates of mesothelioma. The mechanisms and resulting cancers are different with plutonium (lung & bone cancers and leukemia) but it's that form of risk.

A medical look at plutonium

"If somebody inhales plutonium dust, he won't notice anything special. Only 10 to 50 years later is it possible that lung and bone cancer may develop. "

"Plutonium is not dangerous outside the body."

"...during fires in the US nuclear weapons complex Rocky Flats near Denver in 1957 and 1969 clouds of smoke containing plutonium dust spread over the town. However, the expected "epidemic" of lung cancer and congenital defects did not occur. Probably the plutonium dust did not reach the population because it came down quickly and became firmly adhered to the soil. Besides, extra cases of cancer or birth-defects in babies are difficult to distinguish from what people acquire "naturally". "

"Atmospheric testing between 1945 and 1963 brought 4.2 tons of plutonium dust directly into the environment. ... In theory 7,900 cases of cancer may have been caused by this plutonium. "

"Plutonium can go off when it is piled up, a 'criticality' disaster. ... The smoke coming out of the burning pile may lodge tiny particles containing plutonium deep in the lungs. Fall-out from an explosion of an atomic bomb also contains plutonium dust, and so does the smoke of a nuclear disaster like 'Chernobyl' and 'Windscale' "

Astronuc

About 15 years ago, I met one to two guys who experienced glove box explosions while working with Pu. The accidents has happened in the 70's, and he was still doing well in the 90's. He had had glass and Pu solution embedded in his face, neck and chest. As far as I know he's still alive, but I'll have to check.

rhody

Quote by Astronuc

About 15 years ago, I met one to two guys who experienced glove box explosions while working with Pu. The accidents has happened in the 70's, and he was still doing well in the 90's. He had had glass and Pu solution embedded in his face, neck and chest. As far as I know he's still alive, but I'll have to check.

Astronuc,

If someone suspects they have inhaled plutonium, are there medical or radiological tests to confirm it ?

Rhody...

AtomicWombat

Michio Kaku trying to calm fears and reassure people:

http://www.youtube.com/watch?v=qdq4l...yer_detailpage

rhody

Quote by AtomicWombat

Michio Kaku trying to calm fears and reassure people:

http://www.youtube.com/watch?v=qdq4l...yer_detailpage

AW,

He stirs the masses and at the same time putting himself front and center... Wait, did I just say that !!! Doesn't he have a new book out as well, Wait, did I say that too !!!

Rhody...

Astronuc

Quote by AtomicWombat

Michio Kaku trying to calm fears and reassure people:

http://www.youtube.com/watch?v=qdq4l...yer_detailpage

If they abandon ship?!!! Free fall?!!!!

Um - we don't do that.

Incidentally from JNES BWR_Safety_Design

*AntonL*

KYODO 11:04 30 March
NEWS ADVISORY: Radioactive iodine 3,355 times legal limit found in seawater near plant

So the trenches are overflowing

for the past detailed seawater analysis up to 28 march can be found in this 15MB pdf file

and here are the latest results supporting the news advisory

and again Tc-99m 6 hour half life is detected - I hope measuring error

ailog

Any news on the fresh water that the US navy is/has barged to the site? Is it being put to use? I havn't seen anything about it recently.

Astronuc

From World Nuclear News:

A good description of the Fukushima event - http://www.world-nuclear.org/info/fu...nt_inf129.html

I've been wondering about the ground motion and accelerations. Apparently not all the data are collected and/or processed, but from WNN,

http://www.world-nuclear-news.org/RS...i_2303113.html

More detailed data of the ground acceleration rates caused by the magnitude 9.0 earthquake have also been made available by Tepco. Although not all the data has yet been collected, they record very powerful tremors that exceed the design basis in one dimension.

At Daiichi there is still no data for units 1, 2 and 5, but available figures put the maximum acceleration as 507 gal from east to west at unit 3. The design basis for this was 441 gal. Other readings were below design basis, although east-west readings at unit 6 of 431 gal approached the design basis of 448 gal.

At the Daini plant, ground accelerations ranged from 186 gal in the vertical plane at unit 1 to 277 gal from north to south at unit 3, as recorded by sensors in the reactor building foundation. The range of design basis figures is a spread from 415 gal to 512 gal.

No mention of unit 4.

From - http://www.world-nuclear.org/info/inf18.html

Japan's Nuclear & Industrial Safety Agency eventually declared the accident as Level 5 on INES scale - an accident with wider consequences, the same level as Three Mile Island in 1979. The design basis acceleration for both Fukushima plants had been upgraded in 2008, and is now quoted at horizontal 441-489 Gal for Daiichi and 415-434 Gal for Daini. The recorded data for Daiichi are still being analysed, but it appears that 507 Gal was the maximum for it, and 251 Gal for Daini. (Ground acceleration was around 2000 Gal a few kilometres north, on sediments.)

*AntonL*

New idea - wrap the structures in special cloth to filter radio-activity

I suppose Christo and Jeanne-Claude will be asked to help with the design - nobody more experienced.

From below info graphic:
But more important the highly radio-active water unit 2 to be shipped off-site - and then?

Quote by www.asahi.com/special/10005/TKY201103290495.html (machine translated)

　Fukushima Daiichi nuclear power plant at TEPCO, 1,3,4 a rocket blew the building, Kan, the Cabinet is considering measures to prevent radioactive material dispersal of a special cloth to cover it. To ensure that working conditions for recovery and stable power supply to cool the reactors. Water pollution measures, including high levels of radioactivity leaking into the turbine building basement, is also out with a plan to collect contaminated water tankers. TEPCO has struggled to win work, they need to recognize more ambitious plans.

Yes a neat "out of the box idea" as an example of ambitious plan

Reno Deano

BWRs have an astounding number of penetrations (CRDMs and reactor instrumentation) coming through the bottom of the reactor vessel. A CRDM ejection is a remote possibility. But if the CRDM seismic supports failed, that could be the breach.

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Bodge	So, is it currently feasable for there to be a large steam explosion in (under) any of reactors 1-3? Could there be corium in an unbreached RPV, suspended above a saturated area?

Astronuc Admin	About 15 years ago, I met one to two guys who experienced glove box explosions while working with Pu. The accidents has happened in the 70's, and he was still doing well in the 90's. He had had glass and Pu solution embedded in his face, neck and chest. As far as I know he's still alive, but I'll have to check.

AtomicWombat	Michio Kaku trying to calm fears and reassure people: http://www.youtube.com/watch?v=qdq4l...yer_detailpage

AntonL	KYODO 11:04 30 March NEWS ADVISORY: Radioactive iodine 3,355 times legal limit found in seawater near plant So the trenches are overflowing for the past detailed seawater analysis up to 28 march can be found in this 15MB pdf file and here are the latest results supporting the news advisory and again Tc-99m 6 hour half life is detected - I hope measuring error

ailog	Any news on the fresh water that the US navy is/has barged to the site? Is it being put to use? I havn't seen anything about it recently.

Reno Deano	BWRs have an astounding number of penetrations (CRDMs and reactor instrumentation) coming through the bottom of the reactor vessel. A CRDM ejection is a remote possibility. But if the CRDM seismic supports failed, that could be the breach.