[3-16]Problems for units 3 and 4

Problems for units 3 and 4

16 March 2011

FIRST PUBLISHED 0.25am GMT
UPDATE 1:14am GMT Information from TEPCO spokesman and video feed

UPDATE 2: 4:10am GMT Update title from ‘Second fire reported at unit 4’ and information on Unit 3 and 4 from Chief Cabinet Secretary Edano

Chief Cabinet Secretary Yukio Edano has described problems that occurred on the morning of 16 March with Fukushima Daiichi 3 and 4. He also outlined plans to pump water into unit 4.

At 8:34am local time white smoke was seen billowing out of Fukushima Daiichi 3. Efforts to determine the cause of this development were interrupted as all workers had evacuated to a safe area due to rising radiation readings. Readings from a sensor near the front gate had fluctuated for some time, although Edano said that on the whole there was no health hazard. Earlier in the morning readings had ranged between 600-800 microsieverts per hour, but at 10am readings rose to 1000 microsieverts per hour. Readings began to fall again from around 10:54.

Why I am not worried about Japan’s nuclear reactors.

Modified version of original post written by Josef Oehmen

Posted on March 13, 2011 by mitnse

This post originally appeared on Morgsatlarge. It has been migrated to this location which is hosted and maintained by the MIT Department of Nuclear Science and Engineering. Members of the NSE community have edited the original post and will be monitoring and posting comments, updates, and new information. Please visit to learn more.

***Note that the title of the original blog does not reflect the views of the authors of the site.  The authors have been monitoring the situation, and are presenting facts on the situation as they develop.  The original article was adopted as the authors believed it provided a good starting point to provide a summary background on the events at the Fukushima plant.***

The original post written by Dr Josef Oehmen “Why I am not worried about Japan’snuclear reactors.” are being reposted in different languages. They have not been checked / verified.

•Japanese
•German
•Spanish

We will have to cover some fundamentals, before we get into what is going on.

Construction of the Fukushima nuclear power plants

The plants at Fukushima are Boiling Water Reactors (BWR for short). A BWR produces electricity by boiling water, and spinning a a turbine with that steam. The nuclear fuel heats water, the water boils and creates steam, the steam then drives turbines that create the electricity, and the steam is then cooled and condensed back to water, and the water returns to be heated by the nuclear fuel. The reactor operates at about 285 °C.

静岡県富士宮市で震度６強…津波の心配なし

静岡県沼津市の中古本店では、マンガ本が本棚から落ち、床に散らばった＝黒羽泰典撮影

１５日午後１０時３１分頃、静岡県東部を震源とする地震があり、同県富士宮市で震度６強、山梨県忍野村、山中湖村、富士河口湖町で震度５強、神奈川県小田原市、山梨県南アルプス市、富士吉田市、静岡県御殿場市、富士市などで震度５弱を観測した。

この地震の影響で、東海道新幹線は品川―浜松駅間、東海道線は東京―熱海駅間の上下線で運転を見合わせている。東名高速は、大井松田―清水インターチェンジ間の上下線で通行止めとなっている。

気象庁によると、震源の深さは約１０キロ、マグニチュードは６・０と推定される。

この地震による津波の心配はないという。

その他の主な震度は次の通り。

▽震度４　甲府市、山梨県笛吹市、甲州市、中央市、都留市、大月市、横浜市中区、戸塚区、港南区、川崎市中原区、神奈川県平塚市、茅ヶ崎市、海老名市、綾瀬市、厚木市、千葉県館山市、東京都町田市、国分寺市、長野県諏訪市

（2011年3月15日22時36分  読売新聞）

 

Radiation decreasing, fuel ponds warming

Radiation decreasing, fuel ponds warming

15 March 2011

FIRST PUBLISHED 1.22am GMT
UPDATE 1: 1.58am GMT Information from TV appearance, change of headline from ‘Possible damage to Fukushima Daiichi 2′
CORRECTION: 1.58am GMT Removal of potential inaccuracy on torus’ status in containment
UPDATE 2: 2.19am GMT Information from government, change of headline from ‘Damage to Fukushima Daiichi 2’
UPDATE 3: 3.20am GMT Details on fire from PM’s spokesman
UPDATE 4: 3.44am GMT Fire reported put out

UPDATE 5: 8.36am GMT More on torus, Containment shows ‘no change’
UPDATE 6: 1.52pm GMT Radiation data from IAEA, status of fuel ponds

Loud noises were heard at Fukushima Daiichi 2 this morning and a major component beneath the reactor was confirmed as damaged. Evacuation to 20 kilometres is being completed, while radiation levels decrease from a high in the morning. Concern is growing over the status of fuel cooling ponds at units 4, 5 and 6.

Confirmation of loud sounds at unit 2 this morning came from the Nuclear and Industrial Safety Agency (NISA). It noted that “the suppression chamber may be damaged.” It is not clear that the 6am sounds were explosions in the usual sense.

This cutaway diagram shows the central reactor vessel, thick concrete containment and lower torus structure in a typical boiling water reactor of the same era as Fukushima Daiichi 2

Also known as the torus, this large doughnut-shaped structure sits in the centre of the reactor building at a lower level than the reactor. It contains a very large body of water to which steam can be directed in emergency situations. The steam then condenses and reduces pressure in the reactor system. One effect of this is that the water and steam in the torus will exist alongside a range of gases produced by the nuclear processes in the reactor.
The pressure in the pool was seen to decrease from three atmospheres to one atmosphere after the noise, suggesting possible damage. Radiation levels on the edge of the plant compound briefly spiked at 8217 microsieverts per hour but later fell to about a third that.

In line with the theory that non-condensed gases in the torus will be released fairly promptly and not replenished at the same rate, it is possible that the radiation release – at least via this route – will dimininsh and stabilise.