ENS President's contributions
High Level Wastes
Bertrand Barré, President European Nuclear
Society
February 2005
1. Achilles’ heel ?
All the citizen of Europe, with the unique exception
of Austria, would at least keep the nuclear option open if they
were convinced that nuclear waste can be safely managed. That
was according to a EUROBAROMETER survey of November 2002, but
I doubt the results would differ today in our EU25. And for the
man-in-the-street, nuclear waste means High Level Wastes, or a
mixture of High Level and Long Lived radioactive wastes when the
two streams are actually segregated. I will refer to both under
the acronym HLW.
The lack of industrial implementation of a disposal
method for HLW constitutes undoubtedly nuclear industry’s
Achilles heel. In the whole world, only one disposal site is in
operation, the Waste Isolation Pilot Plant WIPP near Carlsbad,
New Mexico, but it is devoted to alpha-contaminated wastes issued
from the US Defense programs, and its military nature played a
significant role in its local acceptance. We all know that the
process is more painful for the Yucca Mountain civilian project.
As far as nuclear power HLW are concerned, Finland is the most
advanced country, having democratically decided upon a disposal
method - the geologic disposal of encapsulated spent nuclear fuel
assemblies, selected a site, and began work in Olkiluoto. Many
others, including France, are in the throes of the decision process.
2. And we thought it was simple…
In the 60s and early 70s, HLW was not a public
issue and the nuclear community was confident: disposal of spent
fuel or HLW issued from its reprocessing would be by deep geological
disposal after proper conditioning. It was just a matter of selecting
the proper geological stratum combined with the proper packaging,
and there was no urgency to it because the volumes concerned were
trivial1 and, anyway, it was better to let the waste
cool down for a few decades before putting it underground. A number
of underground labs were implemented in Canada, Switzerland, Belgium
and Sweden, to name a few.
It was rather late in the game, when exploratory
drillings were actually taking place, that it appeared the issue
was much more sensitive than anticipated by the scientific and
technical community and that populations which were willing –
with a various degree of enthusiasm - to accept the location of
a nuclear power plant nearby, opposed very strongly the siting
of a HLW disposal facility in their backyard. An when we thought
the issues to elucidate and settle were corrosion rates, complexation
with humic acids, migration factors, rock porosity and how it
was affected by the heat generated by the waste packages, depth
of the water table, geological modifications over hundreds of
thousands of years and so on, the real issues were commercial
on the one hand and ethical, almost metaphysical, on the other
hand :
In France, where we almost rediscovered in the late 80s the meaning
of the word jacquerie2, another issue was
clearly raised:
3. Focus on France
The French case is interesting because, contrary
to some other countries, the HLW issue erupted in a context where
nuclear power as a whole was reasonably accepted by the public.
By the end of the 80s, with very few exceptions like Plogoff,
power plants had met good local acceptance and the same could
be said for the Low Level disposal site being built in Soulaines
by ANDRA, then an autonomous branch of the CEA. Furthermore, since
1990, the N4 plants have been put on line in Chooz and Civaux;
so have Soulaines and the Marcoule MOX fabrication plant MELOX,
without controversy, and the recent decision to build a 3rd
generation EPR in Flamanville has met little public opposition.
When Superphénix was terminated by the government in 1997,
it was certainly not to answer any vast public outcry! But the
HLW issue remains today a special case.
Following the troubles, sometimes violent, on
the locations where ANDRA was drilling, Prime Minister Michel
Rocard decreed a moratorium on any attempt of HLW disposal. Representative
Christian Bataille was missioned to crisscross France to shed
some light on the issue. The result of this mission was a Law
enacted by the French Parliament on December 30th 1991.
The “Bataille” law extended for 15 years the moratorium
on actual disposal, 15 years to be devoted to R&D along three
so-called axes:
The French Parliament will revisit the issue
before the end of 2006. As a matter of fact, all the R&D teams
have almost completed their reports and the OPECST, the French
Parliamentary Office for science and technology assessment, is
holding its hearings on the results of these studies while the
special blue ribbon panel CNE, appointed under the Law, is busy
preparing its synthesis.
4. A personal view on the technical State-of-the-Art
4.1 Interim Storage
The first fact to underline is that HLW are
actually managed today. They are not orphaned, nor are they
disseminated in the environment. They are accounted for and gathered
under surveillance in licensed interim storage facilities. Spent
fuel assemblies are in storage pools at the plant sites, in dry
storage, or in centralized underwater storage facilities, waiting
for reprocessing. Vitrified wastes and long lived medium activity
wastes are in dedicated dry storage facilities. Wherever they
are, HLW occasion today no nuisance whatsoever to anybody.
Quite frankly, they may be too well managed:
if they are safe in their interim storage facilities for 30 or
40 years, why not simply leave them there a few decades more?
Why rush to disposal - at a significant political cost - when
there is no actual urgency? Because! Because if we believe nuclear
power has a future, if we believe it will be necessary to develop
it further if we want to solve our energy–environment dilemma,
if we want to increase our energy production while reducing our
greenhouse gases emissions, then we cannot be content with interim
solutions. Disposal is an ethical obligation. But which disposal?
Source : ANDRA
As the official assessments are still in preparation phase, allow
me to offer you my own personal evalution, as one individual expert
among many others: this is not an official statement of ENS or
any other organisation I may belong to.
4.2 P&T
Based on results obtained mainly by the CEA
teams with significant contributions from JRC’s Transuranians
Institute, partitioning is now proven on the laboratory scale.
Its extrapolation to pilot scale could be started if so decided.
Of course, partitioning makes only sense if we know how to manage
the diverse waste streams this opearation would generate! For
example, separating americium today would be pointless since we
know we won’t transmute it in LWRs.
Because of the untimely demise of Superphénix
and the longer than expected revamping of Phénix, transmutation
still relies mostly on the Superfact experiments carried out in
Phénix in a European framework in the mid 80s. We know
its works. It works better in fast neutrons reactors, but even
in FBRs, transmutation ratios are never 100%. Any significant
results would involve a series of recycling.
My own reservations about P&T is that it
would add complexity to the spent fuel reprocessing-recycle for
a quite questionable benefit in terms of human health, balancing
actual additional operational doses today against hypothetical
reduced public doses in the far future. I do believe, though,
in long lived waste minimization, but not as a sophisticated add-on
to our existing systems: rather as a part of the design specifications
of generation 4 systems. The transition period between generation
3 and 4 might be a special case. Let me explain why:
The recycling in LWRs of the plutonium issued
from spent MOX fuel is not very attractive, but spent MOX is a
good way of storing plutonium before it is needed for future fast
breeders. When time comes to extract this plutonium to constitute
the FBR initial inventory, one might want to separate the minor
actinides - that can be transmuted such plants, in order not to
increase above the current accepted level the amount of minor
actinides to be vitrified.
4.3 Long-term Storage
Long term Storage is not a matter for science
or even R&D: it is a matter of engineering, it could be decided
and implemented today. As a matter of fact, the Vitrified Waste
storage buildings of La Hague or Rokkasho are very good examples
of such facilities, as are many dry spent fuel storage facilities
around the world. Can they be qualified as “very long-term”?
May be not, but, at worst, three successive 60-year facilities
is equivalent to a single 180-year facility… as long as
you guarantee retrievability of the packages, which is the basis
of “storage” versus “disposal”.
Sub-surface storage may be preferred to surface
facilities in order to increase the physical protection: there
again, it is purely a matter of engineering.
The only problem I find with long term storage
is of ethical nature: I would find distateful to simply leave
the legacy to my grandchildren, even if it is done cleanly and
safely.
4.4 Geological Disposal
More and more, there is a kind of international
consensus in favour of the disposal of HWL in a facility built
in a stable underground geological stratum located at medium depth,
around 500 meters. I will not discuss the respective merits of
cristalline or sedimentary strata: I may have my preferences,
but I am convinced that in every case one can find the right conditioning
and packaging to fit the specific requirements of a given geologic
medium, as long as this medium has proven to be reasonnably stable
over geologic periods. The high integrity copper container design
adopted in Sweden and Finland for disposal in granite is a good
example of such a fit. This disposal should remain reversible
at least for a significant period.
The rationale for going underground is to provide
an additional barrier to the eventual dissemination of the radioactive
species as well as to protect the facility against intrusions
and other agressions, be they voluntary or involuntary. Opinion
polls and studies tell us that the general public is usually wary
of the underground, often associated with seisms or infernal powers…
but experience tells us that – as long as you avoid risk-prone
areas – geology is vastly more stable and “smooth”
that the history of human societies! Disposed of at depth, in
a proper conditioning and packaging, radioactive species can only
manage to reach the surface through a series of very slow mechanisms
(corrosion, leaching, diffusion, migration) giving radioactive
decay ample time to play its cleansing role. Radioactive wastes
are not biodegradable, as some antinuclear pamphlets rightfully
state, but they are indeed “chronodegradable”!
In France, for instance, we have choosen to reprocess
our spent fuel both to recover the recyclable materials and to
condition the final HLW under a physico-chemical form especially
stable and corrosion resitent. Physico-mathematical models qualified
on experiments of accelerated corrosion and globaly validated
on several “natural analogues” have convinced us that
even immersed bare in pure water, the HLW glass blocks would lose
only 0.1% of their mass in 10 000 years. Even if you neglect the
packaging, the retention capability of the engineered barrier
and, further on, of the geologic media will further delay the
migration of the species very slowly released by the glass matrix.
All international modelling round robins conclude that, when they
finaly reach the biosphere, the most mobile surviving species
exhibit a radio-toxicity the level of which lies orders of magnitude
below those considered acceptable by the present regulations.
That is to say: if we choose the geological disposal, we impose
upon our inheritors, as far as we can figure, no nuisance we would
not accept upon ourselves. This is for me the definition of an
ethically as well as technically acceptable solution.
Saying that it appears today a good solution
is not the same as pretending it is and will remain the best ever.
That is why a minimal amount of reversibility is needed.
But if you look carefully into it, the degree of reversibilty
to insure is not something to decide today. The decision will
have to be taken when it is time to close the disposal, i.e. in
one century at least, assuming we – or rather our successors
– decide to operate it till saturation. This decision will
be taken based upon all the additional knowledge accumulated during
those hundred years, not only about the site itself, its behaviour
and its environment, but also about eventual alternative management
processes which are not mature or even available today. And even
if, when time comes, it is decided to close the site “irreversibly”,
thousands of years will elapse before irreversibility actually
takes place. For centuries after a “leaktight” closure,
it will be possible to retrieve the packages, but only through
a complex and costly mining operation.
5. Conclusion
Let me conclude on a note of optimism. In the
60s, disposal appeared to be a simple scientific issue. In the
80s, we learned painfully that it was a difficult social issue.
But a lot has happened since 1990. The WIPP has been put to operation;
Yucca Mountain has made progresses even though the road is still
long before it is licensed. Finland has made its choices, both
technical and political, and Sweden appears to be close behind.
Alternatives to geologic disposal have been scrutinized and assessed
anew within comprehensive and multinational R&D programs.
I really believe that in a few decades, geologic disposal will
be routine. And if, with time, we design a better mousetrap, a
better way to dispose of HLW, we, or our successors shall gladly
implement it.
Therefore, since the title of this Workshop is
Fact and choices, let me summarize my choices for HLW management
(and once again let me emphasize the “my”):
-
We can and should dispose of pat, present and committed
HLW with our best available techniques (our grand children
may dispose of their waste differently)
-
There is no technical reason to delay the
decision to create a geologic disposal site for HLW. As there
is no hurry to put hot glasses underground, we should begin
with IL-LL-W (Intermediate level Long lived waste)
-
The “reversibility” issue is
moot.
-
We must keep studying other options (P&T) in the frame
of the 4th generation, and not wait for the results before
implementing the solution for today.
1Even
in France, where three quaters of the electricity is generated
by nuclear plants, conditioned HLW amount to ~100 grams per capita
and per annum, while highly toxic non-radioactive wastes total
100 kg/cap/a.
2 Peasants’ uprising,
in reference to an historical episode during the 100 year Anglo-French
War (1258).
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