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Safer Nuclear Reactors: Dare we build them?
Citation-> Popular Science, April 1990 v236 n4 p68(10)
COPYRIGHT Times Mirror Magazines Inc. 1990
NEXT GENERATION NUCLEAR REACTORS
Between these antipodes of nuclear thinking lie shifting continents of
opinions. The arguments over nuclear power, dating back at least a
generation, have never been as turbulent and complex as they are today
because they have been stirred by the emergence of two powerful drivers,
each debatable in itself: an energy crisis and global warming.
Those concerns have spurred many in and out of the nuclear industry to
trumpet the merits of a proposed new generation of reactor designs, which
they claim will not only eke out our energy supplies but do so without
contributing to global warming via the greenhouse effect; nuclear reactors,
unlike plants that burn fossil fuels, do not belch carbon dioxide, the
greenhouse gas.
These new generation concepts range from somewhat improved versions of the
current reactor of choice in this country, the light water reactor (LWR),
so-called because the hot reactor core is cooled by ordinary (not heavy)
water, to one reactor cooled by liquid sodium and another cooled by helium
gas. What they promise is not only greater simplicity and lower operating
costs, but greater safety. Some are described as "passively safe" or
"inherently safe," meaning that they may not need active controls or
operator intervention in case of an emergency. In some designs, for example,
cooling water would not have to be pumped, but would automatically flow by
gravity where it was needed.
But the nuclear industry, in the words of Kenneth M. Carr, chairman of the
U.S. Nuclear Regulatory Commission, "is not in the best of health. In the
past several years, there have been many predictions that the industry is in
fact dying, and that it is just a matter of time before we throw on the last
shovel of dirt." Is it realistic to expect a nuclear renaissance in this
country?
To answer that question, it is necessary to ask why the nuclear option has
come to the moribund state it now occupies. In short, what went wrong?
The promise of energy from the atom once seemed limitless. In the heady days
after the first atomic bombs had exploded and the titanic power of nuclear
fission had been revealed, enthusiasm for the beneficial aspects of the atom
was unfettered. One journalist wrote that it could turn deserts and jungles
into "new lands flowing with milk and honey." Another wrote that "Africa
could be transformed into another Europe." In 1958, Lewis Strauss, then
chairman of the Atomic Energy Commission, made his famous prediction that
electricity from the atom would soon be "too cheap to meter."
Beginning with the impetus of President Eisenhower's "Atoms for Peace" plan
in 1953 and continuing for two decades, the march toward worldwide energy
salvation by splitting the atom seemed inexorable.
Then the nuclear passion began to pall. There were higher-than-predicted
construction and operating expenses, making nuclear electricity less
competitive with that from coal-fired plants. Then costly delays as the
procedures for getting a plant approved, built, and certified for operation
became lengthier and more onerous (from beginning to end the span eventually
stretched to a dismaying 14 years). Then a whole series of mishaps, some
minor, some potentially major. Troubling reports of negligent work,
inadequate inspections, cover-ups. Growing concerns about radioactive waste
storage, proliferation of bomb materials, terrorism, disposal of spent
reactors. Anxiety over the health hazards of exposure to radioactivity. And
the ultimate safety question: How could we be sure a reactor accident would
not result in a fuel meltdown and disastrous release of lethal
radioactivity? By the end of 1974, orders for more than 100 reactors were
either canceled or postponed.
Then in 1979 came the fuel meltdown at Three Mile Island-2 near Harrisburg,
Pa., the most serious nuclear-plant accident yet to occur in the United
States. Even though no lives were lost and measurements showed no one in the
vicinity was exposed to dangerous levels of radiation, the incident panicked
thousands, and the necessary cleanup job - at a cost of about a billion
dollars - is still not finished. Three Mile Island mortally wounded the
benign image of nuclear energy for a majority of the American people. The
far more serious 1986 accident at Chernobyl in the Soviet Union - which
killed 32, sickened hundreds, impelled the evacuation of 100,000, and spread
clouds of radioactive material over large areas of Europe - was the coup de
grace.
The result was to becalm a once vigorous industry. There are now 108
operating commercial nuclear plants in the United States, generating 18 to
20 percent of the nation's electricity, with 14 more under construction. But
since 1978, not a single one has been ordered by any utility. Indeed, in the
last decade, 60 reactors that had been ordered or were already being built
were actually canceled. Three plants - Rancho Seco in California (pictured
on the opening pages of this article). Seabrook in New Hampshire, and the
$5.3-billion Shoreham on Long Island, N.Y. - are built and ready to operate,
but stand idle, mute witnesses to the industry's troubles. As one nuclear
contractor said recently, "Anyone suggests a nuclear reactor to a utility
board of directors, they will send for the guy with the net and with
reason."
Can there be a born-again nuclear industry here, based on so-called
"advanced" reactor designs? That will depend on the answers to three
questions: Does the United States really need more nuclear power to cope
with an impending energy crisis? Do any of the newer designs guarantee
acceptable levels of economy, reliability, and safety? Can such thorny
problems as radioactive waste storage, still intractable after more than 30
years of effort (see box, Radioactive Waste Disposal), be resolved?
Controversy rages on each of these points.
Take energy. Most proponents of an expanded role for nuclear power agree
that we face an energy crunch in the future. So do many die-hard opponents
of nuclear in any form. After all, U.S. production of oil has shrunk 13
percent since the Arab oil embargo in 1973, and in 1989 we relied on oil
imports for 46 percent of our needs - the highest in a decade. And even
though energy demand is notoriously difficult to predict accurately, future
shortfalls seem inevitable, especially if there is a real effort to cut back
on greenhouse gas emissions. One of the biggest problem areas may be
electricity.
"We're living off the fat of the land as far as our electrical capacity
reserves for the last ten years are concerned," says David J. McGoff of the
Department of Energy. (His title, remarkably, is associate deputy assistant
secretary for reactor deployment, and he is the main man in the DOE's
advanced reactor program.) "We've worked down from about thirty-five-percent
excess capacity to about twenty percent. At about eighteen percent, you're
really on the jagged edge - you get into brownout and blackout situations.
We haven't been able to build much base-load capacity of any sort, much less
nuclear, in the last ten year. The arithmetic shows that even with a modest
growth in electricity demand, we're going to have to build a lot of
base-load-capacity plants of some kind by the early or mid-1990s. You have
two choices - coal or nuclear."
Coal, of course, is the dirtiest possible fuel when it comes to carbon
dioxide emissions.
Many in the environmental movement dispute the need for nuclear. They
believe that energy needs probably can be met - even while reducing carbon
dioxide emissions - by a reliance on energy conservation and the promotion
of non-polluting renewables such as solar, wind, and geothermal.
Christopher Flavin, vice president of the prestigious Worldwatch Institute,
says, "If it were either use nuclear or destroy the climate . . .I would
have to reconsider my opposition [to a nuclear option]. But I believe there
is a whole range of other options that have been pursued only in a very
half-hearted way.
"When it is clear that we have rejected nuclear technology, something I
think will be apparent in the mid-1990s, that will free public opinion and
the investment funds needed to really move ahead on those options. So we
won't, for example, be spending just twenty million dollars a year on solar
thermal - that's peanuts. Despite what you hear from DOE, there's no real
commitment to energy efficiency in this country. The end of nuclear energy
will mean a real commitment to an alternative-energy future."
Representative Claudine Schneider of Rhode Island laments that the DOE's
nuclear-power budget for fiscal 1990 is more than $700 million, whereas
research and development for energy efficiency gets less than $200 million,
and research and development for all solar and renewable technologies is
awarded a paltry $100 million.
The other side of the coin is epitomized by a report published in the
journal Science, written by a six-man energy task force headed by William
Fulkerson of Oak Ridge National Laboratory. "Even if energy is used much
more efficiently," it stated, "a sustainable reduction in carbon dioxide
emissions will require better non-fossil sources. None of these non-fossil
energy sources [nuclear, solar thermal, photovoltaics, wind, geothermal,
ocean thermal, wave and tidal power, fusion] are ready to be put into use at
the level of performance, cost, and social acceptance required to be
competitive.
"Nuclear power is perhaps the nearest to being ready, but a significantly
expanded deployment is constrained by concerns over reactor safety,
accidental reactor damage, and diversion of nuclear fuel to weapons; by
problems with managing waste; and by escalating capital and operating
costs."
To bring improved nuclear power on-line, the study suggests, will take some
$3 billion to $4 billion over the next 10 years.
Ironically, it is this last factor - cost - and not safety or global warming
that may be the most important inducement in the nuclear industry's search
for a "new generation."
For the utilities, at least, the resistance to acquiring new nuclear plants
has been in large part economic. Carl H. Seligson, managing director of
Kidder, Peabody & Co., raised that concern in an address to the Nuclear
Energy Forum in San Francisco last November: "Investor experience with
utilities that have built nuclear plants in the past has been less than a
happy one. Billions of dollars supplied by investors have been written off
the utility books, and some forty percent of the companies with nuclear
generation have had to reduce or omit their dividends on common stock, not
characteristics expected by the typical utility investor. This history does
not suggest that new investment will be easy to come by."
One of the key players in the nuclear industry today is Richard Slember,
head of Westinghouse's Energy Systems Division. He is frank to say: "The
driving force behind the new generation of nuclear reactor designs is not
safety. It is economics.
"If I had to pick a single villain responsible for the state of the nuclear
industry in this country, it would be the way we approached the construction
of plants. We have ten to fourteen architect-engineering firms, five reactor
vendors, and many utilities that each had enough ego or whatever to demand a
custom-designed-and-built plant. As a result, the United States now has
about one hundred ten nuclear plants of which every one is different. There
is no standardization."
Slember and many others both in and out of the industry contrast this
situation with the one in France, a country where nuclear has run a
relatively much easier course. The French have licensed essentially one
technology, by Westinghouse, and have but one electric utility, Electricite
de France. The result is a large number of standardized plants that are now
up to 1,300 megawatts in size.
"Construction crews can go from plant to plant," says Slember, "start-up
crews can follow through, and everything is replicated in a very
disciplined, well-ordered program. That includes the pooling of spare parts,
the training of crews, the simulators to train the operators... This program
is much easier to regulate than ours because instead of 110 different
designs you have one basic design at three different power levels."
The French also have a political infrastructure that centralizes control
over their nuclear power program. That allows them to tackle the whole fuel
cycle - the front and back end, emcompassing uranium supply, reprocessing of
spent fuel, and waste disposal.
"They did this as a national objective to achieve energy independence for a
nation with poor fossil-fuel resources," says Slember. "They have been
successful. You can get into an argument about whether the United States has
an energy policy or not; it's all in the eye of the beholder."
In the eye of the DOE, at least, the policy toward new generation reactors
seems fairly close to jelling. The DOE is spending hundreds of millions of
dollars on a number of these advanced concepts. Last year, for example,
contracts for $50 million each were awarded to groups headed by Westinghouse
and General Electric for work on designs that are improved variants of
current LWR designs. The concepts are dubbed the AP (Advanced Pressurized)
600 and the SBWR (for Simplified Boiling Water Reactor), respectively. Other
funding for this reactor research comes from the Electric Power Research
Institute, a utility consortium.
In his Washington, D.C., office, the DOE's David McGoff outlined a
time-table of reactor developments as they are currently foreseen.
"We're projecting a renewed need for nuclear power in the early 1990s. If a
utility manager is going to go out and mortgage his future to buy a nuclear
plant, he's going to want - at least initially - something he's comfortable
with, something that's been operating in the past and has a proven track
record. So I think it's generally accepted that in the near-term - 1990 to
the end of the century - any new nuclear generation is going to be some sort
of advanced light water reactor. You'll get agreement on that from both the
utility industry and the government."
The next generation beyond current ones, McGoff says, are therefore what he
terms "evolutionary LWRs." They will use essentially the same concepts as
present LWRs, except that "people will apply some common sense to them:
Let's not run them quite so hot Let's lower the power rating. Let's increase
the ratio of the amount of cooling water to the amount of fuel, so we have
more time before things get bad in case of upset conditions. Let's
renegotiate the geometry so there aren't large penetrations in places below
the core, so if there are any leaks we'll always have water above the core.
These are simple things, but they result in a probability of fuel failure
ten times smaller than in the present LWRs."
GE has designed such a reactor, the Advanced Boiling Water Reactor, or ABWR.
The design is now going through a new (as of 1989) Nuclear Regulatory
Commission certification procedure which will cut years from the whole
licensing process. It should be complete by the end of 1991. But in a
parallel move. GE is actually building two of these reactors in Japan in
conjunction with Hitachi and Toshiba. The plants will be purchased by the
Tokyo Electric Power Co., the world's largest private utility, and should
begin operating in the late 1990.
At a hefty 1,356 megawatts (electric) the evolutionary ABWR design does not
meet the lower-power goals of the truly "advanced" concepts. But GE claims
that it will make reactor maintenance and operation easier by using 10
internal circulation pumps instead of the external pumps used in most LWRs.
This will greatly reduce the amount of piping required and cut about 50
percent of the welds in the reactor assembly. And the placement of large
water-injection nozzles above the top of the core rather than below it means
that even in the case of a loss-of-coolant accident, the fuel in the core
will remain submerged in liquid.
If an ABWR or other evolutionary design were built in the United States,
when could it start operating? "No new nuclear plant can operate here before
1998 in my view," says McGoff. "Even if you took one of the evolutionary
designs and ordered it after its certification, you still get to 1998 or
1999."
Oddly enough, an advanced LWR might be ready to generate power by the same
time, even though certification for one of these "passive" designs is
further off, perhaps 1995 or 1996.
Passively safe or inherently safe reactors (many in the industry loathe
these terms because they seem to imply that current reactors are by
definition unsafe) would rely on natural forces, such as gravity, to keep
the reactor safe during a loss of cooling accident, such as a pipe break.
There would be no need for immediate intervention by human operators or for
an automatic kick-in of complex, massive emergency systems that may require
copious amounts of electric power - supplied by standby diesel generators if
all external power to the plant were interrupted.
For example, a passive LWR would have an emergency core cooling system whose
water would move under the influence of gravity and compressed gas rather
than being driven by an elaborate system of pumps.
For various reasons, such passive systems mate well with smaller reactors
rather than larger ones. "As a simple-minded example," says McGoff, "if you
want to rely on rejecting excess heat from a reactor just by letting it flow
by conduction into the ground, the bigger the reactor is the harder it gets.
The same is true for natural circulation: The head of water you need depends
a great deal on the geometry and the power level."
By coincidence, the utility industry and the DOE realized about five years
ago that a reactor much smaller than the 1,200- to 1,300-megawatt behemoths
- around 600 megawatts, say - would be welcome.
"The average utility size in the United States is about 6,000 megawatts,"
says McGoff. "If the utility wants to add capacity, it often doesn't want to
get an extra 1,200 megawatts; that's too big a bite. And the capital cost of
one of these plants is about 1,500 dollars per kilowatt. For a big plant
we're talking about two billion dollars. So we settled on about 600
megawatts both to meet utility needs and to allow the use of passive safety
systems. And we ended up with designs for the passive, mid-sized, advanced
light water reactor."
McGoff believes that such designs, including the Westinghouse AP600 and the
GE SBWR, could be built in just six years after certification and site
approval. "They are not only passive and simpler, but modular, in the same
sense that shipbuilding is. Ships are built in sections, carted to a site,
and then assembled."
The Westinghouse AP600 uses both gravity and pressurized nitrogen gas in its
reactor coolant safety systems.
Heat can be removed passively through the steel containment vessel, which is
cooled by both a water jacket on the shell and by natural air circulation
around baffles between the vessel and an outer concrete shield. These
systems provide enough of a heat sink to last several days.
The AP600 also uses an advanced digital information and control system,
based on microprocessors, with booth electrical and fiber-optic links.
GE's SBWR has similarly passive features, such as gravity feed and natural
circulation. It is designed so that it needs no intervention by an operator
for 72 hours after a loss-of-coolant accident. After that interval, the
operator would need only to add sufficient water.
The ancestor of these passively safe light water reactor concepts is the
Swedish PIUS (for Process Inherent Ultimate Safety) from the 1970s. It
relies on a hydraulic pressure balance to separate the water in the coolant
loop, which normally cools the reactor, from a large tank of borated water.
In case of an accident, this balance is upset, and the borated water surges
into the react
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