ISIS Press Release 17/09/08
Close-up on Nuclear Safety
New report finds nuclear safety seriously amiss and there is no protection
against sabotage by terrorists Dr.
Mae-Wan Ho
A fully
referenced version of this article is posted on ISIS members’ website. Details here
An electronic version of this report with full references, can be downloaded
from the ISIS online store. Download
Now
Nuclear safety under the spotlight
While world leaders are falling over themselves signing up to the nuclear renaissance
[1] (Nuclear
Renaissance Runs Aground, SiS 40), critics have been quick to remind
them rightly of the accidents at Three Miles Island in 1979 and Chernobyl in
1986.
At the Three Mile Island power station near Harrisburg, Pennsylvania,
in the United States, a cooling malfunction caused part of the core of a nuclear
reactor to melt down, releasing an estimated 43 000 Curies of radioactive
krypton gas and under 20 curies of the particularly hazardous iodine-131 to
the environment [2].
The disaster at the Chernobyl plant near Pripyat in the Ukraine
of the former Soviet Socialist Republic was the worst nuclear accident in
history. A nuclear reactor exploded (several times) and caught fire, sending
a plume of highly radioactive fallout into the atmosphere that contaminated
an extensive geographical area [3]. The fallout was 30 to 40 times that released
by the atom bombs of Hiroshima and Nagasaki in Japan during World War II.
Some 336 000 people were evacuated and resettled. A 2005 report prepared by
the Chernobyl Forum, led by the International Atomic Energy Agency and World
Health Organization attributed to the Chernobyl incident 56 direct deaths
and an estimated 4 000 extra cancer cases among the approximately 600 000
most highly exposed, and 5 000 among the 6 million living nearby.
Given the poor safety records of the nuclear industry even in
the top nuclear nation France [1], who can guarantee that accidents on the
scale of Chernobyl will not happen again with the proliferation of new power
stations and especially while old power stations are being extended beyond
their intended, safe lifetimes?
Poor safety design offers no protection especially against malevolent acts
In response to the tabling of two new reactors and the refurbishing of old
ones in Ontario, Canada, a detailed assessment of nuclear accidents and malfunction
was carried out by Gordon Thompson of the Institute for Resource and Security
Studies at the Massachusetts Institute of Technology [4]. The assessment reveals
a litany of design faults in nuclear reactors that fail to protect the public
adequately against accidents and malfunction due to human error, mechanical
hitches, or external events such as tornados and earthquakes. In particular,
there is no protection against malevolent or terrorist attacks. This applies
to both existing nuclear reactors and “Generation III” reactors in the pipelines
or under construction.
Neither international nor national safety guidelines require such safe designs.
Thompson is especially critical of the regulator’s and industry’s concept of
“risk” defined as a product of a number indicating the consequence of an event
and another number indicating its probability of occurrence, arguing that equal
levels of risk should be equally acceptable to the public.
That argument is not a scientific statement, it is, instead,
dogma representing a particular set of values and interests.” Thompson writes.
The reason is that the public may be more concerned about the potential for
a high-hazard, low-probability event than a low-hazard, high-probability event
at the same level of risk. “That concern can reflect a legitimate set of values
and interests, scepticism about estimates of low probability, doubt about
the complexity of consequences can be represented by simple indicators, and
recognition that new phenomena can come into play when thresholds of consequence
are exceeded.”
(Thompson’s criticism applies to risk assessment in every field,
from genetically modified crops to mobile phones, as our readers will be fully
aware.)
Can nuclear power be safe, or safer?
In the 1980s, the reactor vendor ASEA-Atom developed a preliminary design
for an “intrinsically safe” commercial reactor known as the Process Inherent
Ultimate Safety (PIUS) reactor which was described as follows.
The basic design of today’s light water reactors evolved during
the 1950s when there was much less emphasis on safety. Those basic designs
held certain risks, and the control of those risks led to an increasing proliferation
of add-on systems and equipment ending up in the present complex plant designs,
the safety of which is nevertheless being questioned. Rather than to continue
into the ‘blind alley’, it is now time to design a truly ‘forgiving’ light
water reactor in which ultimate safety is embodied in the primary heat extraction
process itself rather than activated by add-on systems that have to be activated
in emergencies. With such a design, system safety would be completely independent
of operator actions and immune to malicious human intervention.”
The PIUS design goal was “complete protection against core melting
or overheating in case of any credible equipment failure, natural events such
as earthquakes and tornadoes, reasonably credible operator mistakes, and combination
of all those. In addition, the design should protect against inside sabotage
by plant personnel completely knowledgeable about reactor design, terrorist
attacks in collaboration with insiders, military attack, as by aircraft with
‘off-the-shelf’ non nuclear weapons, and abandonment of the plant by the operating
personnel.
Such a PIUS light-water reactor was indeed designed by ASEA-Atom
that would cost no more than a conventional plant with the same generation
capacity. But to-date no PIUS plant has been ordered.
Another attempt at improving nuclear reactor safety was made
in 1991 in a study conducted at the US Oak Ridge National Laboratory, which
put together a list of characteristics of ‘PRIME’ reactors, with safety features
that are passive, resilient, inherent, malevolence-resistant, and extended,
i.e., remaining in a safe state for an extended period after an accident or
attack. The study identified several types of reactors in various states of
development as PRIME, but did not set a framework of indicators and criteria
that could be used to assess the comparable merits of those reactors to determine
if it belonged in the PRIME category.
During the past decade, Generation IV reactors have been proposed that use
‘closed fuel cycles’ to extend the life of uranium reserves, but these remain
on paper as long-term strategies to be developed over the next several decades
while Generation III reactors are constructed. The European Commission concedes
that Generation III reactors would not meet criteria for sustainability [5]
(see The Nuclear Black
Hole, SiS 40), let alone safety.
The reactor is not the only source of serious hazard in case
of accidents. The Canadian Environmental Assessment Agency (CEAA) identifies
three categories of accidents and malfunctions: those directly involving the
nuclear reactor such as serious damage to the reactor core; conventional accidents
and malfunctions that result in chemical or radioactive releases not directly
involving the reactor core and may include those associated with nuclear fuel,
and malevolent acts involving fires, explosions, punctures, aircraft crashes
that could result from sabotage or terrorist actions..
Major hazard involving spent fuel
The spent nuclear fuel now stored on site in nuclear power stations is another
source of major hazard. Large amounts are stored under water in pools next to
the reactors. Those pools currently use high-density racks to maximise the storage
space. Unfortunately this makes cooling less effective especially if water were
lost from a pool. Several studies, including one from the US Nuclear Regulatory
Commission (NRC) [6] (see Old
Nuclear Cash Cows Exposed, SiS 40) have come to the conclusion that
loss of pool water could lead to spontaneous ignition of the zirconium alloy
cladding of the most recently discharged spent fuel assemblies. The resulting
fire would spread to adjacent fuel assemblies and propagate across the pool.
It would be difficult if not impossible to extinguish the fire once it had started.
Spraying water would make it worse because of an exothermic (heat producing)
reaction between steam and zirconium. A fire in the spent fuel storage pool
would release huge volumes of radioactive gases to the atmosphere, just as in
the case of fire in the reactor core, including a large proportion of the radioactive
cesium-137, which is water-soluble and extremely toxic in minute amounts. Loss
of pool water could happen in various ways, such as the failure of pumps or
valves, piping failures, an ineffective heat sink, a local loss of power, and
malevolent acts. According to the NRC Report [7], a fire in the spent fuel
pool at a reactor like Vermont Yankee in Pennsylvania, USA, which stores 488
metric tonnes of spent fuel, would cause 25 000 fatalities over a distance of
500 miles if evacuation were 95 percent effective. But that evacuation
rate would be almost impossible to achieve.
It gives us little comfort to know that none of the commercial
nuclear power plants now operating around the world can resist malevolent
attacks, not because it is impossible to design such plants, but because the
industry has simply chosen not to do so, and the International Atomic Energy
Agency, responsible for among other matters, the development of criteria for
the safety and security of nuclear power plants, does not explicitly require
plants to be safe against malevolent attacks. The Canadian Nuclear Safety
Commission’s criteria are no better. Neither agency addresses potential releases
from stored spent fuel.
Not surprisingly, none of the proposed Generation III nuclear
reactor designs in Ontario or elsewhere gives adequate protection against
malevolent attacks and may also fail other safety design criteria.
There is practically no defence against a range of “credible”
attacks on existing nuclear plant. Among the possibilities mentioned is [4]
“a small, general aviation aircraft laden with explosive material, perhaps
in a tandem configuration in which the first stage is a shaped charge.” A
shaped charge is one that is shaped to deliver all the energy of explosion
in one direction.
Devastating as they are, it won’t be safety concerns that aborts the nuclear
rebirth, but the economics [8] (see Nuclear
Industry’s Financial and Safety Nightmare, SiS 40).
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