Investor Presentaiton
Topic
Seismic event
Tsunami
Loss of off-site power
|(LOOP)
SBO
Emergency Diesel
Generators (EDGs)
Switchgear
Procedure for notification
of a nuclear emergency
Known knowns
Known unknowns
Within the boundaries of the shared assumptions of main stakeholders
Design basis of the Fukushima Daiichi NPP and
prediction of its design basis seismic performance
Tsunamis are a co-related event to seismic events.
The Fukushima Daiichi NPP was designed for a loss
of off-site power, with the expectation that the grid
would be restored quickly.
Should SBO occur, the DC (batteries) would last for
about 4-6 hours. If AC was not restored in that time,
core damage was to be expected.
Expected to function on LOOP to provide AC power.
Endurance based on diesel stock replenishment
capability
Interconnections allow cross feeding of power from
one unit to its neighbour.
After NPP Site Superintendent is notified or discovers
the specific event defined in Article 10 (1) of the
Nuclear Emergency Preparedness Act of Japan,
he/she shall, within a targeted time frame of 15
minutes, simultaneously notify all relevant entities by
fax.
Response of the Fukushima Daiichi
NPP to a seismic event exceeding
its design margin
The prediction of tsunami heights
The extent of grid damage and
infrastructure disruption for a very
large earthquake and tsunami
Diesels can fail to start and
duration of service may be
unpredictable.
Availability of equipment and/or
staff to effect interconnection in a
severe accident
Site superintendent perception of
severity of event, communication
infrastructure available.
Unknown unknowns
Outside the boundaries of the shared
assumptions of main stakeholders
Staffing on site
Capability of staff for
accident response
Minimum number of staff available on site at the
beginning of an accident is known
Formal competences of staff to respond to an
anticipated type of accident is known (training,
experience)
Capability to relieve staff if severe
condition persists over prolonged
period in case of damage to outside
infrastructure
Psychological and physical
condition and ability of staff to
respond to an event under severe
conditions in a given moment
Etc.
Sum
Combination of all elements above =
Unknown unknownView entire presentation