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 hans.scheel@bluewin.ch 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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