Street Roots • Aug. 28-Sept. 3, 2015
Allowing
plants to
restart would
ignore lessons
learned from
Fukushima,
expert says
B Y RIE M A TS U O K A
made the external power more earthquake
resistant, but for them our idea looks
senseless.”
ore than four years after the
Ino points out that cost is also a big factor
Fukushima disaster, no nuclear
playing out behind the scenes: “In order to
power plants have operated in
enhance the entire plant’s level of
Japan. At least that was the case until
earthquake resistance, you must make the
August 2015, when the Sendai nuclear plant
whole system within and around the
in southern Japan became the first to begin
premises earthquake resistant, including
operation since the 2011 Fukushima
pylons, wiring and the thermal power plant
meltdowns, despite anti-nuclear protests.
itself, which would cost a huge amount of
An additional 23 units in 14 nuclear
power plants are applying for the green light money. That is why power companies are
not willing to do it.”
to resume operations. To do this, tiiey must
Nuclear power plants are built taking into
pass a safety review conducted by Japan’s
consideration not only safety but al^o the
Nuclear Regulation Authority.
balance of safety, costs (economic <
But the plan to resume nuclear | .
efficiency), performance and environmental
operations fails to reflect on the lessons we
burden, among other factors. “This sense of
have learned from Fukushima, warns
balance applies not only to a nuclear power
Hiromitsu Ino, a former Tokyo University
plant, but also to many other things,” says
professor and specialist in metallic material
engineering.
Ino. “However, if and when a nuclear power
“At the moment, the Abe government is
plant has an accident, the damage is
attempting to revive nuclear power stations
enormous. We need to emphasize safety by
arid trying to return the evacuated
all means. But they evaluate the balance at
inhabitants to their home. However, we do
the same level as in any other technology. It
hot have any clear plan to restore the
is both ridiculous and dangerous to resume
damaged area yet. We must use our
a nuclear power plant in this situation.”
Commenting on the nuclear power plants
experience of the Fukushima accident as
the base when we consider the future,” says built in the 1970s, Ino says, “The design
Ino, who has already raised major concerns
concept is bad and the materials are also
over the risks involved in resuming nuclear
bad. They are built based on the assuinption
operations across the country.
of an operating life of 30 to 40 years. Such
“First.of all, I want to emphasize that the
common material as stainless steel were
common sense of the nuclear power
used. The material of pressure containers
community is senseless for citizens, and the
contains copper impurities. When neutrons
common sense of citizens is senseless for
hit the containers, copper fuses together
the nuclear power community,” says Ino.
and forms clusters, making that part stiff,
“During the Fukushima accident, all the
brittle and therefore easier to break.”
external power was cut down and the
The boundary temperature before a
internal emergency diesel generators were
material breaks is called “brittle transition
also damaged. We wonder why they had not
temperature.” For example, copper’s brittle
C O N T R IB U T I N G W R IT E R
M
transition temperature is usually about
minus 20 degrees centigrade, but as the
material gets older the brittle transition
temperature rises. The worst is 99 degrees
in Unit 1 of Takahama Nuclear Power Plant,
followed by 98 degrees in Unit 1 of Genkai
Nuclear Power Plant.
The higher the brittle transition
temperature; the higher the risk of the
container breaking. Additionally, when the
core cooling system functions as an
emergency measure and cold
water flows into the
container, only the inside
" li t e common sense of
part of the container is
the xstxclear power com*
rapidly Cooled down. The
oioaity Is senseless for
temperature difference
citizens,
and the com*
between inside and outside
moa
sense
of citizens Is
could generate some force
senseless
fo
r the nuclear
and break the container from
inside.
power com m unity."
“If the pressure container
H ie o M iT s w im o ,
EXPERT IN METALLIC: M A T E R IA L
is broken, we can no longer
ENGINEERING
cool it down with water,”
explains Ino. “The meltdown
will surely start. If there ir hydrogen
around, there is a risk of explosion as well.
When the containment vessel is blown away,
the radioactive substances will disperse in
the area of 250 kilometers in radius, causing
damage much more serious than the
Fukushima Daiichi accident.”
Unit 1 of Genkai Nuclear Power Plant has
been officially decommissioned, but there
are still hopes that Unit 1 of Takahama
Nuclear Power Plant could once again
become active. “The reason is that while
the output power of Genkai is relatively
small, 50 kW, that of Takahama is nearly
See NUCLEAR, page 7