Realizable Deposit for Radioactive Waste (RAW) (Site for intermediate storage, will later be sealed as permanent repository)
9.4.2018/ Hans J. Scheel, General Protection Engineering GmbH, Switzerland [email protected] www.general-protection-engineering.ch
Radioactive waste is generated by electricity generation in nuclear power plants (NPP) and by
the application of radioactive elements in medicine and research. There are different types of RAW:
- High-level waste ( HAA ) : spent fuel, vitrified fission products from spent fuel reprocessing,
alpha-toxic waste (more than 20,000 alpha decay per gram per second).
- Low (small) and intermediate level waste ( SMA ) : All other radioactive waste.
HAA reach the radiotoxicity of originally mined uranium after about 200'000 years,
SMA reach the radiotoxicity of granite rocks after about 30'000 years.
The desired inclusion time for RAW is 100’000 - 200’000 years, maximum 1 million years. Important condition is the retrieval possibility for later use of the large energy remaining in the fuel rods,
of which only 1.5% to 5% had been used. In the new NPP generation IV the remaining energy will be used.
Switzerland has about 8'000m3 HAA and 92'000 m3 SMA waste, Germany about 10'500 tons
HAA (1100+800 CASTOR containers) and 600'000m3 SMA waste (estimate Bundesamt für
Kerntechnische Entsorgungssicherheit BMUB 19.1.2017).-
The RAW handling should be evaluated and simplified. Can the fuel rods, after 50 to 80 years of
cooling, directly inserted into stainless-steel/lead/Ba-concrete containers, without being treated? The
huge CASTOR containers can be replaced by POLLUX or smaller containers for transport.
Deep Geological Deposit (Geologische Tiefenlager)
The concept of final storage in deep geological formations has become established according to
the principle that all rock types, that are on or near the earth's surface, are crushed by physical-
mechanical and chemical action (weathering, erosion), decomposed, converted and dissolved.
Therefore, deep geological deposits have been developed within chambers in granite, salt or in
claystone (Opalinus Clay, bentonite) at depths between 500m and 800m, with a geological barrier
closing these deposits upwards. Since the action of water (moisture) and gases, and thus the corrosion
of the steel drums, cannot be excluded, the HAA are "burned" in the reprocessing and vitrified into a
slag. These solids show reduced dissolution by reactive water at elevated temperatures and the
pressure in the ground. Then these slags are conditioned into metallic containers and filled into thick
cast-iron tanks. In deep repositories you have to basically count on rock movements and widespread
mountain water, because the deposits are below the groundwater level.
Salt mines as repositories are out of question, because salt is continuously recrystallizing and
permeable to water, and because saline water is very corrosive.
Clays (phyllosilicates) release water when the pressure or temperature increases, and swelling
occurs when water is absorbed. In addition, clay stones are dissolved much faster than framework-
silicate rocks like granite and gneiss. The construction of deep geological repositories is extremely
complex, requires enormous financial resources and is met with fierce resistance from the affected
population. The disposal costs for Switzerland's four nuclear power plants (NPP) are estimated at
CHF 20.7 billion (2011 study SWISSNUCLEAR), and the decommissioning of the four NPPs will
cost about CHF 3 billion.
Geologists have succeeded in getting deep geological repositories internationally accepted and
recognized by the International Atomic Energy Agency (IAEA) in Vienna. Also, this would secure
the young geologist formation for decades.
However, the knowledge of materials science and building technology of the past 60 years,
especially of improved building materials such as concrete and steel, but also of discovered new
materials, allow to conceive an alternative repository, which does not have the above-mentioned
problems and disadvantages and which can be built at significantly reduced costs in lonely
mountain places, where a small political resistance is expected.
Concept of High-Mountain Repository (“High-Deposit”, “Höhenlager”): Example Switzerland
Above the groundwater level there are numerous locations where a High-Deposit can be built on
solid bedrock. Due to their low water solubility, massive density and good mechanical strength,
silicate rocks (granite, gneiss, basalt, diorite, etc.) are recommended, which cover more than 60% of
the earth's crust. Preferred locations are isolated areas in the mountains, which can be conveniently
served by (new) rails and roads and are neither popular hiking areas nor will they be intensively used
for agricultural purposes. Furthermore, earthquake, volcanic and flood zones should not be chosen,
and also landslides and avalanche zones should not be considered. Furthermore, the next ice age in
41'000 to 100'000 years and the movement of glaciers should be considered. Figure 10 shows the
possible tracks of glaciers in Northern Switzerland, the earlier suggested area of Deep Geological
Deposits, during the next ice age. The glaciers may cause new valleys and lakes which could affect
the sites of Deep Geological Deposits in northern Switzerland.
For the realization of the High-Deposits there are the variants a) of an artificial hill, b) of a new
building, c) the partial dismantling of an existing mountain and (after completion of the High-Deposit)
subsequent restoration of the original form, or d) the use of a military mountain fortress (Bunker).
Efficient construction of the High-Deposit can be achieved when the cost of connection to the railway
network is low and when the transport of construction equipment and later the radioactive waste does
not take too much time. A rack railway in closed gallery, with connection to the railway network with
matching gauge, will be useful.
By chance, about 50 years ago, the author made a hike in an area that largely meets these requirements: Together with Dieter Schwarzenbach
(about 1963 PhD student ETH Crystallography, now Prof. emer.) from Ambri-Piotta TI climb on foot to the Ritom lake, 6-lake hike, Cadlimo -SAC hut (was closed) onto the Piz Blas (3019m) and then through the Cadlimo-valley, covered with bomb craters, to the Lucomagno-Pass.
First transport option: Piz Blas is a mountain 3019m high, the slopes covered with rock debris,
which can be reached south of Sedrun/Rueras with a new rack railway by Val Nalps. Construction
machinery and later the HAA and SMA waste can be transported directly from “Zwischenlager
Würenlingen” via SBB Göschenen and via Andermatt and Oberalp-Pass with the Matterhorn-
Gotthard- Bahn (MGB) and then by the rack railway to the Piz Blas, see Figure 1. With reactivation
of the factory track Tscheppa -Las Rueras the empty freight wagons can return via Disentis / SBB.
Variant c): With blasting and large saws a part of the mountain is removed as shown
schematically in Figure 2. The rock debris is partly used for the construction of the road to
Lucomagno -pass (Δ H ~ 200m). Some fraction of the rock can be crushed and sieved to gravel and
sand for the concrete mix. In the formed chamber stone platforms are created or poured concrete
platforms onto which the RAW containers are placed, the HAA container in the center surrounded
by SMA barrels, see Figure 2. With cast-in stones and granite slabs, the original shape of the
mountain is restored at the end. Workers accommodation is provided by a simple hotel, which will
be set up for tourism including a museum after the work has been completed. As compensation for
the affected communities (Andermatt, Rueras, Sedrun) the Val Nalps can be developed as a ski area
with 6 .5 km descent from Pass Nalps ( ΔH=750m ) to the Nalps Lake, the intermediate station of the
Val Nalps rack railway , and would have connection to the Andermatt -Sedrun Ski Arena of Samih
Sawiris (Orascom Development Holding AG). The new road to the Lukmanier pass will be useful. An alternative transport option can be obtained with the Gotthard Base Tunnel. Building materials and later the
RAW containers are assembled onto transport trains in Erstfeld and driven to the multifunctional station (PAS) Sedrun
and where they are simultaneously unloaded by controlled cranes in a quick action (see Figure 3) within 3 minutes **.
After transport to the lift of the Porta-Alpina-Station (PAS), they will be hoisted 800m by the elevator in 2 to 3 minutes.
The carrying capacity of the elevator system with unhooked basket is 116t, with basket payload approx. 40t. On top, the
RAW containers are stored in a hall until they can be driven by the rack railway to the Piz Blas. Sedrun and Surselva
would be interested in the PAS later on as a tourist station with 1 train per day to be able to expand and thus to amortize
the on-investment of 15.8 million CHF. At the two PAS stations at Sedrun (north and south line) of the Gotthard base
line there are halls of 38 x 10m 2 each and a height of 5.5m for intermediate storage of RA containers and later for tourism,
each up to 240 people. Figure 4 shows schematically this transport variant.
** If the Erstfeld-PAS travel time is 14 minutes, the base tunnel will be used for about 32 minutes per day.
For the variant a) the repository consists of an artificial hill, which is built on a relatively flat
terrain with rocky ground and after completion is adjusted to the landscape, see Figure 5. To use the
described transport possibilities, a place with a small slope on the south side of the Cadlimo valley
could be chosen, e.g. on the northern slope of the mountain Schenadüi (2678 or 2747m) or north of
the Laghetti di Miniera east of the streambed, but this needs preliminary clarifications. Figure 6
shows the detailed geography of Piz Blas-upper Val Nalps with discussed repository sites and ski
descent. The rack railway can drive directly to the final position to deposit the RAW waste.
Subsequently, a hill is designed (Figure 7) or a structure desired by the architect that adapts to the
environment. A central chamber can be set up for the storage of HAA waste with a concrete channel
exit, which can be used later for the retrieval of the HAA containers with fuel rods. Initially this exit
is specially secured and closed (Figure 8). Also, temperature and humidity probes and pipes for gas
measurements are connected from the RAW-chamber to the externally accessible control room. The
initial heat generation of HAA waste can be used by means of heat transfer fluid and external heat
exchangers (heating of buildings, electricity). The structure of the RAW chamber will be made with
optimized materials (special reinforced concrete, steel, granite plates, etc.) so that it can withstand all
impacts (e.g. rockets, weather) for at least 100,000 years. A building concept for a High-Deposit has
been presented at Technical University Karlsruhe 2017 [H. S. Müller & N. Herrmann at 13. Symposium Baustoffe
und Bauwerkserhaltung “Sicherheit durch Beton” March 16,2017 at KIT, Zeitschrift Beton- und Fertigteiltechnik Heft 2, 2017].
By dry storage, the corrosion of the RAW containers can be largely prevented. Nevertheless, the used fuel rods should be packed and sealed so that their oxidation can be prevented. Theoretically the best
materials for encapsulation would be the noble metals silver, gold and platinum but their high value would make them too attractive
and thus cause a risk for the storage site for radioactive waste. Figure 11 shows the temperature dependence of the thermodynamic
stability of oxides of metals which could be applied as container for radioactive material. This Ellingham-type diagram, extended for
CO-CO2 and for H2-H2O gas ratios by Richardson and Jeffes (1948), is discussed in the book of L.S. Darken and R.W. Gurry: Physical
Chemistry of Metals (McGraw-Hill 1953). Practical values for temperature can be obtained by a straight line passing from one of the
three points (O, H, C) on the left margin to the oxygen partial pressure or the gas ratios on the scales on the right side of the diagram,
and hitting the stability line of the specific metal. Iron-nickel-chromium alloys (stainless steel) and lead could be considered. Copper
is foreseen for enclosing radioactive material in Sweden.
A large size of the High- Deposit can be chosen (see Figure 9) so that other countries such as
Germany, Belgium and France can also deposit their RAW for a charge under the condition that the
waste (controlled by Switzerland) has been perfectly conditioned and that the transport routes (e.g.
Deutsche Bahn Basel to Karlsruhe) are sufficiently developed.
The Cadlimo Valley and Piz Blas meet the requirements of isolation and accessibility by train,
even with separate feeder and return traffic (Göschenen/Erstfeld and Disentis), and have the benefit
of tourist attraction in future. Of course, there are other places in the Alps suitable for High-Deposits,
with an important factor being the (financially compensated) approval of the canton and of the
municipalities. In the case of Piz Blas these are Tujetsch / Sedrun GR and Quinto TI, where Sedrun
had positive experience during the construction of the Gotthard Base Tunnel and would also be
interested in the subsequent tourist use and possibly museum about High-Deposit of RAW. Many of the research findings of NAGRA, which was founded in 1972 (with a typical annual budget of up
to CHF 3 million), may also be useful in the high-altitude concept and some NAGRA specialists should be
involved in this project. Possibly AlpTransit AG or NAGRA or a general contractor could lead the realization
of this High-Deposit concept. Candidates for the rack-railway system are Stadler Rail and Siemens.
Both the Geological Repositories as well as the High-Deposit proposed above are safe from
human, belligerent and terrorist acts and plane crashes. However, the High-Deposits are also safe
from the effects of water and corrosion and are much easier and less expensive to build in places
where low political resistance is to be expected. Of crucial importance is the possibility of retrieval.
In future, repositories for radioactive waste should only be constructed far above groundwater
levels. However, geologists, geophysicists, civil engineers, chemists and material scientists need to
create a report for the IAEA Vienna to receive acceptance.
A similar detailed RAW concept has been developed for Germany and could be presented (after
compensation for the development efforts). Hans J. Scheel 9.4.2018
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