What follows (after the line of asterisks) is a half-serious
essay on the same subject. This piece of science fiction was
my entry in the essay contest organized by Physics Today
to celebrate its 50th anniversary. The contest announcement
(October 1997) contained the following invitation: "Imagine
that you are writing in 2048. Your essay should report on
an exciting discovery, advance in physics or in a new
technology." As a physics teacher interested in nuclear
technology, I decided to focus on the decline of that
technology in the first decades of the 21st century and on
its subsequent reawakening. My essay was not among the
three which were published in the journal. But here it is,
just for fun. Feel free to show it to your students.
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NUCLEAR ENERGY INITIATIVES, 2048
Submitted by Ludwik Kowalski
Global production of electricity has more than tripled in the last fifty years, but contrary to predictions, the
dominant fuel is still coal, not uranium. In fact, the nuclear industry was essentially defunct by the first decade of
the century. The reactor accident in Chernobyl, discoveries of coal reserves in China, and public opposition to the
long-term storage of radioactive waste were the main reasons. Even in France, where 80% of electricity was nuclear in
the year 2000, no new reactors were built after that date. The world's last operating nuclear plant was decommissioned
in Sweden in 2031. At that time not a single school in the world offered a training program for nuclear engineers. The
profession was dying, with only several hundred reactor experts still alive. But the situation changed suddenly after
2033 when undeniable evidence linked the rise of the sea level to the catalytic effects of atmospheric contamination,
mostly by CO2. Use of coal had to be curtailed to prevent global calamities. An international tax of 4% of GNP was
imposed by the World Union of Nations, WUN, to support all climate-related activities.
Reforestation and artificial clouding were among the first tasks undertaken. In 2035 chemical transformers of CO2 were
installed at several coal-burning plants. Preparations for the induced absorption of CO2 by the oceans were in progress.
Solar energy, already used in many countries to heat water and to produce modest amounts of electricity in isolated
areas, had never been tapped on a large scale due to high costs and technical difficulties. Several technological
initiatives were undertaken to improve the situation using a "mission-oriented" approach. The success of the Manhattan
project during World War II, the moon landing mission of the 1960’s, the elimination of the AIDS epidemic, and, more
recently, the first human habitat on Mars, were sufficiently persuasive to justify global mobilization.
A return to nuclear energy was unavoidable; nuclear plants had demonstrated that electricity could be produced without
contaminating the atmosphere with CO2. About 24% of the world's electricity (325 GW) was generated from 350 reactors at
the end of the last century. Even environmentalists, who formerly opposed nuclear energy, now began to promote it. They
insisted, however, that everything possible should be done to make reactors safer than in the past. In 2037 the
International Nuclear Power Laboratory, INPL, was created by WUN in Grenoble, France, to coordinate all nuclear
activities. It was there that the famous "Two Generations Meeting" took place. All reactor engineers were invited to
help formulate nuclear policy. Two hundred of them, mostly from France and Japan, were brought out of retirement. About
one hundred young physicists and engineers were also invited to promote transfer of knowledge.
Numerous discussions took place and several options were debated. Reactors of the old design were at once rejected
because their operation depended on 235U, a rare isotope of natural uranium. The attention focused on so-called
breeders, reactors which were known to utilize uranium more efficiently. The Integral Fast Reactor was at first
considered as a possible powerhouse of the resurrected nuclear industry. Then attention shifted to so-called "hybrid
systems" in which large accelerators and subcritical reactors could be used together to produce nuclear fuel (233U from
common 232Th), to generate electricity and to transmute radioactive waste, all at the same time. The favorable neutron
economy of hybrid systems was quickly recognized. The reactor could be operated well below the level of criticality, for
example, at k=0.95. Under such conditions a Chernobyl-like runaway chain reaction would be impossible. Furthermore,
running reactors on 233U, instead of traditional 235U, had long been known as an attractive alternative; the lower rate
of producing transuranium elements was one of the benefits.
The main advantage of reactor-accelerator systems, as opposed to traditional stand-alone reactors, was their operational
safety and, above all, their ability to destroy long-lived components of radioactive waste. Spent fuel from hybrid
systems was expected to decay in several centuries. This was much more acceptable than tens of thousands of years during
which unprocessed fuel from old reactors had to be isolated in geological depositories. Additionally, the reactors could
be stopped instantly without mechanical control rods. The so-called "passive cooling" technology, which was promoted
earlier to minimize dangers of meltdowns in some old reactors, could be incorporated into new devices. The advantages of
accelerator-driven systems had been known for a long time; many old engineers were familiar with the pioneering work of
Carlo Rubbia, from CERN, Switzerland, and of Charlie Bowman from LANL, USA.
The experts felt that homogeneous reactors, in which nuclear fuel is dissolved in a molten salt (LiF-BeF2), as outlined
by Bowman, and heterogeneous reactors in which solid fuel assemblies are embedded in a liquid metal (Bi-Pb), as outlined
by Rubbia, were equally promising and should be developed. They also recognized the need for reactors which produce
hydrogen from water instead of electricity. The H2, a non-pollutant fuel, would be used as a replacement for gasoline
and natural gas. The electrolytic decomposition of water was too expensive; a direct transformation of thermal energy
into chemical energy was a better alternative. This approach, proposed in 1980s by American and Japanese engineers, was
never implemented. New non-corrosive materials would now facilitate the decomposition of water (via the Iodine-Sulfur
process), if a temperature higher than 900 oC could be maintained in a vessel heated by a nuclear reactor.
Large water desalination plants were also recommended. The engineers pointed out, however, that existing spallation
sources were not powerful enough for large industrial installations. Accelerators able to sustain proton currents larger
than 100 mA, at the output energy of 1000 MeV, had to be designed and tested. The importance of effective beam focusing
was emphasized. A beam which is not sufficiently focused would contaminate the pipes above the limit of acceptability.
Other recommendations referred to spallation chamber windows, to corrosion-related problems and to the reliability of
convection cooling.
Six departments were created at the INPL to implement the agenda outlined in the proceedings. Working relations were
established with numerous national laboratories within a year. The prototype of a homogeneous reactor, supported by two
linear accelerators, was constructed in Japan in 2039, exactly 100 years after the discovery of fission by Meitner, Hahn
and Strassman. That small plant is still producing electricity at the rate of 60 kW. One third of the output is used to
run the accelerator; the rest is delivered to the commercial grid. The extrapolated costs of electricity (assuming much
larger units are used worldwide) turned out to be 30% less than the average from coal burning plants. The Canadian
prototype of a 200 MWe heterogeneous system has been operating successfully since 2042.
The technological initiative undertaken by WUN coincided with the work of a German scientist from Hamburg, Hans Wagner.
In 2043 he visited a Moroccan friend, a geologist supervising the construction of a near-surface depository of
radioactive waste in the Sahara Desert. At the construction site Wagner saw huge blocks, made from reinforced cement,
pulled slowly by cables over a multirail track. "These are containers in which spent fuel will be kept", explained the
geologist. "We are testing them for mobility, in case we have to transfer them to another location for some unforeseen
reasons. Spent nuclear fuel, mostly 90Sr and 137Cs, will remain inside for about 400 years. Don't worry about leaks," he
joked, "our desert will keep the container intact for as long as the Pyramids have lasted."
Wagner knew that 90Sr and 137Cs were beta emitters whose half-lives were close to 30 years. The beta decay theory was
his specialty; he was interested in its astronomical applications. The indirect effect of photons on quark gluon
structures (via quantum fluctuations) was constantly on his mind in those days. A few weeks later, upon his return from
Morocco, he suddenly realized that beta decay could be speeded up artificially. Ten years earlier such an idea would
have been considered a heresy; in 2044, however, it could be defended on the basis of what was already known about
condensed nuclear matter. Wagner was familiar with American and European experiments in which ultra-relativistic heavy
ions compressed nuclei and created quark-gluon plasma. Many unusual reactions were observed in compressed nuclear
matter. An Argentinean scientist, Eduardo Cania, theorized that similar reactions would take place in atomic nuclei
subjected to strong magnetic fields.
It turned out that a large megamag was under construction at MIT. Wagner was not familiar with the intended purpose of
this device but he knew that it would produce extremely strong and extremely short magnetic pulses. That is exactly what
was needed to test his induced-beta-decay theory. What happens when a neutron decays into a proton inside of 137Cs? The
nucleus turns instantaneously into the non-radioactive 137Ba. And the same process in 90Sr produces 90Y. The half life
of that isotope is only 64 hours and it decays into the non-radioactive 90Zr. At a deeper level, however, each process
can be viewed as a spontaneous transformation of a down-quark into an up-quark accompanied by the emission of a W-
boson. The boson instantly decays into an electron and an antineutrino.
Wagner was excited by thinking that the megamag might speed up the decay of fission products. Doing this in a couple of
months, or days, would certainly be better than keeping them in containers for several hundred years. And what if a
megamag is incorporated into an accelerator-reactor system? Acting upon this idea, he contacted the MIT scientists and
suggested some experiments. They liked the proposal and a request for a research grant was prepared. The grant was
awarded to Wagner and his MIT colleagues by the INPL. Preparations for the experiment started three months later.
Meanwhile the theoretical paper on quantum fluctuations was finished; it was submitted to Physical Review Letters and
published within six months.
The megamag, slightly modified to accept radioactive material, was nearly ready and the first experiments were scheduled
for December, 2046. But everything changed in October after Cania came to MIT unexpectedly to discuss an urgent matter.
The elaborate post-standard-model calculations, which he outlined at the informal gathering, were indeed alarming.
According to Cania, magnetically induced transformations of quarks, in solid materials, can be very dangerous. Started
artificially at one place the reaction may spread quickly over the entire planet and destroy all living matter. This did
not happen when relativistic ions collided in a vacuum but might happen during an experiment with a solid sample.
Wagner and his colleagues listened carefully but were not convinced. They asked for time to think and arranged to meet
again a week later. Cania, however, feared that they might start experimenting and wanted to prevent this at any cost.
His open letter to the Secretary General of WUN, urging a moratorium on induced-beta-decay experiments, was received by
the members of the team on the same day on which it was released to the press. The research project was suspended at
once. Cania and Wagner, however, are now working together at the Atomic Energy Institute in Buenos Aires; their goal is
to find a safe way of inducing beta decay in gases. They are also exploring ways of speeding up alpha decay and of
lowering fission barriers in heavy nuclei. Similar investigations are in progress in England and in Rusia.
Can a device, based on the megamag principle, be used to release nuclear energy in a better way than in a
reactor-accelerator system? What fraction of liberated energy will it need to sustain the operations? Looking back, we
see that Fermi, who formulated beta-decay theory, went on to construct the first nuclear reactor. Looking forward we see
a possibility of another great contribution that theoretical scientists can make in the area of practical engineering.