R. Testonia, S. Segantina,b, M. Zucchettia,b

a DENERG, Politecnico di Torino, Italyb Plasma Science and Fusion Center, MIT, Cambridge (MA), US

Overview

Progress in nuclear energy

Radiation induced degradation of Polychlorinated Biphenyls (PCBs)

Conclusion

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Overview

Progress in nuclear energy

Radiation induced degradation of Polychlorinated Biphenyls (PCBs)

Conclusion

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Technical Aspects

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Energy studies

=

Interdisciplinary

studies

Environmental Aspects

Politic and Social AspectsEconomic Aspects

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From the purely technological point of view, two directions can be followed:

• Simple solutions that make it possible to reduce the growth of energy

needs in developing countries, focusing on efficiency, savings and

conversion, and that will lead to the reduction of social and geographical

disparities in its availability and its use.

• Most advanced technological innovation, that aim to seek new

energy sources and high-tech energy-intensive approach, in developed

countries.

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Four main actions can be pursued to face the energy issue:

• rationalize the use of energy;

• abandoning a development model based on endless growth;

• equalize the per capita consumption in the world;

• innovate and develop new energy sources.

The current energy economy based on fossil fuels is not sustainable at long

term. Alternatives must be concrete, and able to withstand the economic,

environmental and social issues that provide the current boundary

conditions. One solution to the energy problem does not exist.

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Two case studies

Nuclear energy in the framework of

energy issue and the development of a

new technology in the fusion nuclear

field.

The environmental impact of PCBs

and the use of irradiation techniques to

degrade them as possible solution to

reduce their environmental impact.

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Overview

Progress in nuclear energy

Radiation induced degradation of Polychlorinated Biphenyls (PCBs)

Conclusion

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The role of nuclear energy in the field of development of new energy source

is recognized by the world scientific community. However, an open debate

on nuclear energy concerns the solution of the problem of radioactive

waste, reinforcing nuclear safety and developing research into reactors of

the future.

Fission energy Fusion energy

Acceptance by the public is doubtful

and depends on:

• the safe continuing operation of

existing plants,

• the trends in energy demand, in

particular electricity,

• the ability to meet a share of demand

in a competitive way.

It is seen as a candidate long-term

solution for the following reasons:

• a clean energy,

• no core melting risks,

• no proliferation,

• very low amount of radioactive

waste.

The scientific community is devoting many efforts in fusion development.

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Most of the studies and experiments on nuclear fusion

are currently devoted to the Deuterium-Tritium (DT) fuel

cycle.

Roadmap to fusion power

Fusion energy is one of

the most challenging and

complicated fields for

Engineering and Physics.

The next milestone is ITER, but some of the engineering challenges still have

to be solved.

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Tokamak Main Component

First Wall

It is the inner layer of the vacuum vessel,

it faces the plasma column therefore it is

subjected to high thermal loads and high

energetic particles, such as neutrons.

Magnets

They are surely the most

expansive and conceiving part of a

machine based on magnetic

confinement of plasma.

Vacuum vessel

Its main objective is to maintain the

vacuum inside its volume where

plasma is supposed to run and

fusion reactions are supposed to

take place.

Cooling system

It is a key component also for the energy

supply: it removes thermal energy from

plasma and transfer it to the turbine letting

us get electricity.

Biggest challenge: keep the cryogenic temp. for cooper super-conduction.

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• It is the flagship of a new generation of

fusion devices

• It is a tokamak conceptual design

proposed by Massachusetts Institute of

Technology (MIT)

• It represents a cheaper, smaller but

even more powerful, faster way to

achieve fusion energy

• Its design is always changing and every

new idea is applied and integrated to the

design

ARC development is based on forefront technologies

Technological development such as High Temperature Superconductors,additive manufacturing, new diagnostics allowed to think to a new concept:Affordable Robust Compact (ARC) fusion reactor

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Affordable Robust Compact (ARC) fusion reactor –

Main innovations

1. The idea of ARC’s concept began when a

new generation of superconducting materials

became available on industrial scale. The most

important innovation are its magnets, that are

made of Rare Earth Barium Copper Oxide

(REBCO). This material shows a quite high

critical temperature ~ 80K, which is almost

twenty times higher than copper’s critical

temperature, and is able in a very thin tape to

generate a magnetic field of tens of Teslas.

2. A second innovation integrated in this device is the approach to blanket, cooling

system and tritium breeder all of them: a single material (FLiBe) satisfies all

functions done by those components.

(Sorbom et.al, 2015)

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Affordable Robust Compact (ARC) fusion reactor –

Main innovations

3. Thanks to new manufacturing systems such as 3D printing,

this tokamak is also designed to be quickly demounted and

reassembled since the number of components is allowed to be

very low.

4. The most innovative characteristics of ARC, in

our opinion, is the load-following capability.

Since plasma can quickly change its power

output, a load following power plant can be

connected to a grid characterized by several

other intermittent energy input, such as solar and

wind based power plants. In this case, the ARC

reactor could be not only the base-load energy

producer, but also a load-following one, capable

to cover peak requests and other plant

shutdowns.

Example of electric energy stratification divided by type of plants and their role

(Sorbom et.al, 2015)

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Overview

Progress in nuclear energy

Radiation induced degradation of Polychlorinated Biphenyls (PCBs)

Conclusion

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Chemical properties Chlorinated aromatic hydrocarbons

209 isomers

tech. PCBs containing up to 80 isomers

Physical properties High chemical and thermal stability (>1000°C)

Low flammability

High heat conductivity

Electrical insulator

High solubility in rubber

High solubility in fat

No solubility in water

PCBs characteristics

• dielectric fluids,

• heat transformer fluid,

• lubricants,

• vacuum pump fluids,

• etc.

PCBs use in energy field

The widespread use of PCBs in

such applications presents a major

environmental issue because of

the toxicity and long lifetime of

these compounds in ambient

conditions.

Banned in developed countries, but still widely used in developing countries.

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Incineration

PCBs can be effectively destroyed by Incineration at more than 1000 degC.

Drawback: process that converts some of the PCBs into more toxic materials

(dioxins) wherever the flame temperature is lower than 1000 degC.

Radiolytic degradation

Radiolytic degradation of PCBs is expected to overcome the disposal problems.

PCBs in the organic solvents, such as transformer oils, may be reduced into benign

inorganic chloride and practically non-toxic biphenyl, without formation of any

dioxins. Such treatment leaves the solvents practically unchanged so that they can

be recycled instead of incinerated.

This approach may be adapted to remove PCBs in sediments and soils by

combining it with extraction or other treatment methods.

Methods for PCBs disposal

Radiolytic degradation is the most sustainable PCBs disposal technique.

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Gamma-ray degradation of PCBs in oil

In general, it is known that gamma irradiation of chlorinated hydrocarbons in alkaline

polar solvents results in the production of free radicals via chain dechlorination to

the next less chlorinated species.

It is not expected to lead to dechlorination by direct reaction of the solvated

electrons with the PCBs, because the oil contains substantial quantities of other

aromatic compounds, which also react with solvated electrons very rapidly.

PCB transformation occurs primarily through reductive dechlorination, forming lower

chlorinated PCBs and biphenyl. The highest degradation rates of PCBs can be

achieved by solubilizing PCBs in water using a surfactant prior to irradiation.

Radiolytic degradation techniques

Gamma degradation effectiveness is dependent on PCBs solvent.

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Beta-irradiation

Beta-emitting radioactive sources may be used, while industrial application

processes mainly use electron beams (EB) accelerators. In general, an industrial

pollutant is irradiated with beta particles in order to induce in it chemical

transformations (or biological sterilisation) in such a way that the pollutant itself

could be more easily treated with conventional techniques for its environmental

processing, or it could be easily recycled.

The technique that is being investigated uses an EB linear accelerator (Linac) with a

3 MeV electron energy. The main safety and radioprotection problems that deal with

the use of EBs are the following: particle-man interaction (accidental irradiation),

shielding of gamma and beta diffuse radiation, device maintenance operations,

decommissioning of the apparatuses.

The activity is focusing on the safety and environmental aspects, and also on the

studies of interaction between beta particles and matter, applied to the proposed

case.

Radiolytic degradation techniques

A complete chemical destruction of PCB occurs with electrons of this energy.

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Overview

Progress in nuclear energy

Radiation induced degradation of Polychlorinated Biphenyls (PCBs)

Conclusion

Energy studies involve not just technical aspects, but also environment,

material science, and politics (interdisciplinary studies).

In this work, two case studies on advanced technological innovation as a

part of simple solutions for the energy problem were reported.

The first case study involves the progress of nuclear energy in the framework

of energy issue and a new generation of fusion reactors: Affordable Robust

Compact fusion reactor.

The second case study concerns the environmental impact of

polychlorinated biphenyls (PCBs). The use of beta-irradiation technique to

degrade PCBs is presented as one feasibility solution in order, both from the

technological point of view and from the economical convenience to reduce the

environmental impact of these compounds.

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Thank you for your

attention!