Timeline
11th March
● (15.42): Going outside the MCR now required permission from the supervisor, groups of at least two
people, and there was a time limit of two hours, after which a rescue mission would be triggered
● 7:03 p.m: a nuclear emergency was declared
● 9.00m: an evacuation within 3 km of the NPP was announced.
● 21.15: Radiation in reactor one building reaches a point at which entry is prohibited
● 21.19: Reactor 1 operators can light up the indicator for water levels which shows 200 mm below
fuel, which is low but better than expected. The battery is disconnected to save the change
● At 21.28 some electric vehicles arrive, but they have the wrong connectors and cannot be used
● 22.00: the battery is reconnected, and it shows 550mm above the fuel
● 23.50: The pressure within the containment building of reactor 1 showed that it was already above
maximum operating pressure. The water level indicator was wrong, probably due to the ongoing
meltdown. Attention shifts to Reactor 1 and preparations for venting. Emergency operating
procedures for venting existed but did not cover the situation of not having electricity
12th March
● 00.06 (March 12th): venting preparations ordered from ERC. What usually requires the push of a
button now requires a trip to the reactor building to open two valves
● 1:30 a.m: the decision to vent Unit one, which would relieve pressure and allow water injection, but
venting was not begun.
● 02.24: ERC calculates the maximum exposure time to 17 minutes. Operators prepare by visualising
the task while waiting for evacuation to be complete
● 5:44 a.m: the prime minister ordered the evacuation extended to 10 km from the NPS boundary.
● 07.11: PM arrives and demands to know why venting has not happened yet; ERC assures him that
this will happen by 09.00
● 09.02: MRC informed that the evacuation is complete
● 09.04: First team leaves
● 09.15: The first team opens the target valve
● 09.24: First team returns, second-team leaves
● 09.30: Second-team returns, unable to even enter the room with the target valve due to radiation
levels
● While searching for the air compressor, ERC teams attempted to open the valve at 10.17, 10.23 and
10.24
● At 10.40, elevated radiation levels are registered, suggesting venting may have worked.
● But by 11.15, they had dropped again.
● 12.30: 4- ton truck transports air compressor and adapter to a connection site
● 14.00: Air compressor put into operation, and the team attempts to open the valve
● 14.30: pressure in the containment building measured at 0.75 absolut
● 14.59: measured at 0.58 absolute, and white steam was visibly escaping the building
,Earthquake
● On the 11th of March 2011, the great East Japan earthquake with a magnitude of 9.0, 130 km of
the coast, caused a major tsunami of approximately 14 meters that hit Japan's coast.
● 9-9.1 magnitude —> fourth-largest ever recorded
● Six reactors, of which three were operational at the time 'scrammed', as designed.
● Japan's main island moved 2,4 meters to the U.S.
● Severe damage to infrastructure
● Make it hard to respond to the disaster.
● As a result of the earthquake, the plant was disconnected from the power lines. This connection
to the power grid is needed to cool down the reactor core, making it entirely dependent on
backup power sources.
● When the external power was lost, the emergency diesel generators began operating to cool the
reactor cores. This was a built-in safety measure.
Tsunami
● Forty-five minutes after the Earthquake, the tsunami reached the coast. A series of waves
inundated the plant and caused serious damage
● 3,5 to 9,3 m Tsunami, in some places exceeding 12 meters
● 30m in certain places
● 500 km of coast destroyed
● Highest Japanese Tsunami on record
● They obliterated the 10-meter high concrete wall designed to stop Tsunamis up to 5.7 meters.
● It destroyed much of the cooling system, mostly constituting pumps responsible for pumping
seawater into the reactor building to cool the fuel rods.
● It caused eleven of the twelve emergency generators to stop working - diesel generator, batteries,
and circuit boards for the plant. The plant lost the capability to cool the reactors.
,During the accident.
New rules were introduced: The top priority was to figure out if emergency generators were working.
● No indicators or gauges are functioning in the control room.
● Some critical valves are inaccessible because they are inside the reactor; therefore, alternative
assessment methods were found.
● Mechanical indicators lit up intermittently, maybe as the batteries started to dry up; however, the
accuracy of the readings was uncertain
The search for alternative cooling functions
● Attempts to reconfigure the line for the diesel-driven fire pump
○ Because the power was out, they couldn't configure from the control room, so they had to
use the manual valves in the reactor building
○ For this, they had to check blueprints
○ This was an operator- driven mission
Searching for indicators
● Small generator restores lights to the control room, but connecting power to the indicator panel is
more changeling
● The ERC team clears debris so that electric trucks can get where they need to go; however, most
of the power centre transformers are damaged.
They then had to decide which reactor was most in danger
● Reactors 1 and two had different emergency response systems. Initially, there was more hope for
reactor 1
● It was estimated the water would reach reactor two at 21.40
Are the emergency cooling functions working?
● In an effort to find out whether Reactor two's RCIC cooling system is working, operators make the
hazardous journey to the mechanisms room twice and are unable to confirm whether it is working
Attempts to vent
● Emergency Operating procedures for venting existing but did not cover the situation of not having
electricity.
● In the ERC, attempts to understand venting were made, including off-limits buildings and
contracting sub- contractors.
● ERC ordered operators to decide on teams
○ Younger operators excluded
○ Shift leader volunteers, but others oppose urging consistent leadership.
○ Three teams of two chosen by discussion: one team for each valve plus backup and
consecutive not concurrent missions
Attempt to vent: option two
● The ERC teams try to open the suppression chamber using a compressed air valve.
● This requires an air compressor and an adaptor, which they do not have, and a small generator to
power it. They ask among th
Emergency management
● Why the Japanese government chose not to follow its established process for managing a
nuclear crisis revolved around personalities; a widespread distrust of TEPCO; and generally low
regard of the Japanese regulatory system, which was driven more by process than by analysis.
● The multiple-unit NPPs at the Fukushima Daiichi NPS and Fukushima Daini NPS posed unique
problems for the emergency managers’ concerns that the emergency planners assumed would
be controlled by the utility.
A station blackout.
● A complete loss of external power from electricity grids and the internal power of the diesel
generator
, ● Batteries are put in place that could continue the cooling of the reactor for several hours. This is a
redundancy measure.
● But the batteries of reactor one and two were flooded after the tsunami.
Seawater pumps were damages
● The tsunami destroyed the seawater pumps that were supposed to remove the extracted heat
from the reactors
● Even with electricity, accidents would have happened
Reactor 4
● It was not operational at the time of the accident.
● Reactors three and four were connected through their venting system. This was done with the
idea that two units could be vented simultaneously, making it more efficient.
● Hydrogen was also accumulating in reactor 4, leading to an explosion one day later.
● Hosted a large number of fuel rods in the spent fuel pools. These fuel rods are often kept there to
cool down before they could be shipped off.
● The evaporation of the water in the fuel rods was a big issue since it would speed up oxidation.
11th March
● (15.42): Going outside the MCR now required permission from the supervisor, groups of at least two
people, and there was a time limit of two hours, after which a rescue mission would be triggered
● 7:03 p.m: a nuclear emergency was declared
● 9.00m: an evacuation within 3 km of the NPP was announced.
● 21.15: Radiation in reactor one building reaches a point at which entry is prohibited
● 21.19: Reactor 1 operators can light up the indicator for water levels which shows 200 mm below
fuel, which is low but better than expected. The battery is disconnected to save the change
● At 21.28 some electric vehicles arrive, but they have the wrong connectors and cannot be used
● 22.00: the battery is reconnected, and it shows 550mm above the fuel
● 23.50: The pressure within the containment building of reactor 1 showed that it was already above
maximum operating pressure. The water level indicator was wrong, probably due to the ongoing
meltdown. Attention shifts to Reactor 1 and preparations for venting. Emergency operating
procedures for venting existed but did not cover the situation of not having electricity
12th March
● 00.06 (March 12th): venting preparations ordered from ERC. What usually requires the push of a
button now requires a trip to the reactor building to open two valves
● 1:30 a.m: the decision to vent Unit one, which would relieve pressure and allow water injection, but
venting was not begun.
● 02.24: ERC calculates the maximum exposure time to 17 minutes. Operators prepare by visualising
the task while waiting for evacuation to be complete
● 5:44 a.m: the prime minister ordered the evacuation extended to 10 km from the NPS boundary.
● 07.11: PM arrives and demands to know why venting has not happened yet; ERC assures him that
this will happen by 09.00
● 09.02: MRC informed that the evacuation is complete
● 09.04: First team leaves
● 09.15: The first team opens the target valve
● 09.24: First team returns, second-team leaves
● 09.30: Second-team returns, unable to even enter the room with the target valve due to radiation
levels
● While searching for the air compressor, ERC teams attempted to open the valve at 10.17, 10.23 and
10.24
● At 10.40, elevated radiation levels are registered, suggesting venting may have worked.
● But by 11.15, they had dropped again.
● 12.30: 4- ton truck transports air compressor and adapter to a connection site
● 14.00: Air compressor put into operation, and the team attempts to open the valve
● 14.30: pressure in the containment building measured at 0.75 absolut
● 14.59: measured at 0.58 absolute, and white steam was visibly escaping the building
,Earthquake
● On the 11th of March 2011, the great East Japan earthquake with a magnitude of 9.0, 130 km of
the coast, caused a major tsunami of approximately 14 meters that hit Japan's coast.
● 9-9.1 magnitude —> fourth-largest ever recorded
● Six reactors, of which three were operational at the time 'scrammed', as designed.
● Japan's main island moved 2,4 meters to the U.S.
● Severe damage to infrastructure
● Make it hard to respond to the disaster.
● As a result of the earthquake, the plant was disconnected from the power lines. This connection
to the power grid is needed to cool down the reactor core, making it entirely dependent on
backup power sources.
● When the external power was lost, the emergency diesel generators began operating to cool the
reactor cores. This was a built-in safety measure.
Tsunami
● Forty-five minutes after the Earthquake, the tsunami reached the coast. A series of waves
inundated the plant and caused serious damage
● 3,5 to 9,3 m Tsunami, in some places exceeding 12 meters
● 30m in certain places
● 500 km of coast destroyed
● Highest Japanese Tsunami on record
● They obliterated the 10-meter high concrete wall designed to stop Tsunamis up to 5.7 meters.
● It destroyed much of the cooling system, mostly constituting pumps responsible for pumping
seawater into the reactor building to cool the fuel rods.
● It caused eleven of the twelve emergency generators to stop working - diesel generator, batteries,
and circuit boards for the plant. The plant lost the capability to cool the reactors.
,During the accident.
New rules were introduced: The top priority was to figure out if emergency generators were working.
● No indicators or gauges are functioning in the control room.
● Some critical valves are inaccessible because they are inside the reactor; therefore, alternative
assessment methods were found.
● Mechanical indicators lit up intermittently, maybe as the batteries started to dry up; however, the
accuracy of the readings was uncertain
The search for alternative cooling functions
● Attempts to reconfigure the line for the diesel-driven fire pump
○ Because the power was out, they couldn't configure from the control room, so they had to
use the manual valves in the reactor building
○ For this, they had to check blueprints
○ This was an operator- driven mission
Searching for indicators
● Small generator restores lights to the control room, but connecting power to the indicator panel is
more changeling
● The ERC team clears debris so that electric trucks can get where they need to go; however, most
of the power centre transformers are damaged.
They then had to decide which reactor was most in danger
● Reactors 1 and two had different emergency response systems. Initially, there was more hope for
reactor 1
● It was estimated the water would reach reactor two at 21.40
Are the emergency cooling functions working?
● In an effort to find out whether Reactor two's RCIC cooling system is working, operators make the
hazardous journey to the mechanisms room twice and are unable to confirm whether it is working
Attempts to vent
● Emergency Operating procedures for venting existing but did not cover the situation of not having
electricity.
● In the ERC, attempts to understand venting were made, including off-limits buildings and
contracting sub- contractors.
● ERC ordered operators to decide on teams
○ Younger operators excluded
○ Shift leader volunteers, but others oppose urging consistent leadership.
○ Three teams of two chosen by discussion: one team for each valve plus backup and
consecutive not concurrent missions
Attempt to vent: option two
● The ERC teams try to open the suppression chamber using a compressed air valve.
● This requires an air compressor and an adaptor, which they do not have, and a small generator to
power it. They ask among th
Emergency management
● Why the Japanese government chose not to follow its established process for managing a
nuclear crisis revolved around personalities; a widespread distrust of TEPCO; and generally low
regard of the Japanese regulatory system, which was driven more by process than by analysis.
● The multiple-unit NPPs at the Fukushima Daiichi NPS and Fukushima Daini NPS posed unique
problems for the emergency managers’ concerns that the emergency planners assumed would
be controlled by the utility.
A station blackout.
● A complete loss of external power from electricity grids and the internal power of the diesel
generator
, ● Batteries are put in place that could continue the cooling of the reactor for several hours. This is a
redundancy measure.
● But the batteries of reactor one and two were flooded after the tsunami.
Seawater pumps were damages
● The tsunami destroyed the seawater pumps that were supposed to remove the extracted heat
from the reactors
● Even with electricity, accidents would have happened
Reactor 4
● It was not operational at the time of the accident.
● Reactors three and four were connected through their venting system. This was done with the
idea that two units could be vented simultaneously, making it more efficient.
● Hydrogen was also accumulating in reactor 4, leading to an explosion one day later.
● Hosted a large number of fuel rods in the spent fuel pools. These fuel rods are often kept there to
cool down before they could be shipped off.
● The evaporation of the water in the fuel rods was a big issue since it would speed up oxidation.
