Some details of the Fukushima nuclear accident
as reported by Wiki


After the March 11, 2011 earthquake, Nuclear Engineering International
reported that units 1, 2 and 3 were automatically shut down, while units 4,
5 and 6 were stopped for maintenance well before that.[8] Due to major
electric disturbances in the region, the electric power for the cooling
turbine was only available from the reactor working. After the stopping,
turbine was transferred to emergency diesel generators, however the
generators installed to provide backup power for the cooling systems for
units 1-3 were damaged by the tsunami;[9] they started up correctly and then
stopped abruptly about 1 hour later.[10] In Japan a nuclear emergency is
declared upon cooling problems. Because cooling is needed to remove residual
reactor heat, a nuclear emergency was declared-for the first time-when the
diesel engines failed. Batteries, which last about eight hours, were being
used to power the reactor controls and valves during the electrical
outage.[11][12][13] Japanese ground forces were said to be trucking
generators and batteries to the site.[14]

An evacuation order was issued to people living within 3 kilometres (1.9 mi)
of the plant, affecting approximately 5,800 residents. People living less
than 10 kilometres (6.2 mi) from the power plant were advised to stay
indoors.[15] Later the evacuation was expanded to a 10 kilometres (6.2 mi)
radius, and then to a 20 kilometres (12 mi) radius.[16][17][18]

On March 12, 2011, after midnight local time, it was reported that the Tokyo
Electric Power Company was considering venting hot gas from the reactor
vessel number 1 into the atmosphere, which could result in the release of
radiation.[19] The Tokyo Electric Company reported that radiation levels
were rising in the turbine building for reactor 1.[20] At 2:00 JST, the
pressure inside the reactor containment was reported to be 600kPa (6 bar or
87 psi), 200 kPa (2 bar or 29 psi) higher than under normal conditions.[10]
At 5:30 JST the pressure inside Reactor 1 was reported to be 2.1 times the
"design capacity",[21] 820 kPa (8.2 bar or 120 psi).[22] At 6:10 JST, the
IAEA reported that unit 2 was also experiencing cooling problems.[23]

Wikinews has related news: Earthquake-damaged Fukushima nuclear power
plant triggers evacuation

To reduce mounting pressure potentially radioactive steam has been released
from the primary circuit, into the secondary containment.[24] On March 12,
2011 at 6:40 JST, Chief Cabinet Secretary Yukio Edano stated that the amount
of potential radiation would be small and that the prevailing winds are
blowing out to sea.[25] Radiation levels recorded by the plant control room
were reported to be approximately 70 microsieverts (i.e., 7 millirem) per
hour.[26] Radiation levels measured at a monitoring post near the plant's
main gate were reported to be more than eight times above normal.[27][28] In
a press release at 7 am (local) March 12, TEPCO stated "Measurement of
radioactive material (Iodine, etc.) by monitoring car indicates increasing
value compared to normal level. One of the monitoring posts is also
indicating higher than normal level."[18] At 13:30 local time, radioactive
caesium was detected near reactor 1.[29][30] TEPCO reported that at 15:29
JST (06:43 GMT) radiation levels at the site boundary exceeded the
regulatory limits.[31] Fuel rods may have been exposed to the air.[32]

The Prime Minister of Japan, Naoto Kan, visited the plant for a briefing on
March 12, 2011.[33] The Tokyo fire department sent a special nuclear rescue
team to Fukushima.[34]

Over 50,000 have been evacuated during March 12.[35]

An announcement of TEPCO indicated that the gamma ray radiation recorded on
the main gate was increased from 69 nanogray/hour (nGy/h) (4:00 local time,
12 March) to 866nGy/h 40 minutes later and reached the peak of 385.5?Sv/h at
10:30am local time.[36]


NHK Sogo channel TV program screen shot image depicting before and after a
explosion of Fukushima. The collapse is visible from the height difference
of the structure behind the tower relative to the tower. I The news was
broadcast at 18:00 (JST) 12 March 2011.

At 15:36 JST (7:36 GMT) on March 12, there was an explosion at the plant and
that four workers were injured.[37] At 18:43 JST (9:43 GMT), officials had
confirmed that an explosion has occurred at the nuclear plant.[38] Chief
Cabinet Secretary Yukio Edano indicated -according to a Reuters report of
21:36 JST (7:36 ET), that the concrete outer structure had collapsed as a
result of a hydrogen explosion triggered by falling water levels. At 19:37
JST (10:37 GMT) Reuters reported that Mr Ian Hore-Lacy, communications
director at the World Nuclear Association, considered the same cause.[39]
Edano further indicated that the container of the reactor had remained
intact and there had been no large leaks of radioactive material.[40] An
increase in radiation levels has been confirmed following the
explosion.[41][42] ABC (Australia) reported "According to the Fukushima
prefectural government, the hourly radiation from the plant reached 1,015
microsievert [0.1015 rem], an amount equivalent to that allowable for
ordinary people in one year."[43][44]

The Guardian reported at 17:35 JST (8:35 GMT) that NHK advising residents of
the Fukushima area "to stay inside, close doors and windows and turn off air
conditioning. They were also advised to cover their mouths with masks,
towels or handkerchiefs" as well as not to drink tap water.[45] At 19:07 JST
(10:07 GMT) Reuters reported that the exclusion zone has been extended to 20
kilometres (12 mi) around the plant.[46] BBC correspondent Nick Ravenscroft
was stopped 60 kilometres (37 mi) from the plant by police.[47] Air traffic
has been restricted in a 20 kilometer radius around the plant, according to
a NOTAM.[48] The BBC has reported as of 22:49 JST (13:49 GMT)

"A team from
the National Institute of Radiological Sciences has been despatched to
Fukushima as a precaution, reports NHK. It was reportedly made up of
doctors, nurses and other individuals with expertise in dealing with
radiation exposure, and had been taken by helicopter to a base 5 km from the
nuclear plant."[38] The BBC has reported as of 23:27 JST (14:27 GMT) "More
than 300,000 people have now been evacuated from homes in northern Japan and
that number will rise as the government increases the exclusion zone around
the Fukushima nuclear power plant."[38]

http://en.wikipedia.org/wiki/Fukushi...ar_Power_Plant