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Updated: February 3, 2011 16:49 IST

Finland far ahead in nuclear waste management

K S Parthasarathy
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A general view of the Olkiluoto 3 European Pressurised Reactor (EPR) being built by France's Areva and Germany's Siemens in Finland on June 15, 2010. EPR reactors are currently being built in Finland, France and China. Launched in 1992, the EPR, a third generation nuclear reactor, was designed by French power giant EDF and German counterparts EON and RWE to be safer, more fuel efficient and generate less nuclear waste.
AFP
A general view of the Olkiluoto 3 European Pressurised Reactor (EPR) being built by France's Areva and Germany's Siemens in Finland on June 15, 2010. EPR reactors are currently being built in Finland, France and China. Launched in 1992, the EPR, a third generation nuclear reactor, was designed by French power giant EDF and German counterparts EON and RWE to be safer, more fuel efficient and generate less nuclear waste.

Finland consumes nearly 17,000 units of electric power per capita annually; its share of nuclear electricity is about 28 per cent. Though its nuclear power programme is very modest compared to that of U.S. or U.K. it is far ahead in its universally applauded plans for nuclear waste management.

The general refrain of lay public (often reinforced by antinuclear rhetoric) is that there is no ultimate solution for managing high level nuclear waste. Finland demonstrates that it has in place a popularly accepted technological solution.

Finnish programme

Currently, Finland operates four nuclear power reactors with a total installed capacity of 2716 MWe. It produces about 70 tonnes of spent fuel annually. Finland has no plans to reprocess the spent fuel.

Finland started its preliminary preparations for its nuclear waste management shortly before the first reactors started operation 1n 1977-1978. In 1978, the first lot of spent fuel entered the facility for interim storage at Loviisa.

The Nuclear Energy Act 990/1987 passed by its parliament stated that nuclear waste generated in connection with or as a result of the use of nuclear energy in Finland shall be handled, stored and permanently disposed of in Finland.

In 1983, Finland started screening of potential sites for spent fuel disposal. Within the next four years, Finnish scientists started field research in five municipalities for selecting the final disposal site.

Final repository

In 2000, they chose Olkiluoto. They plan to dispose of spent fuel in an underground geological repository. Posiva, a Finnish company which is entrusted with the job has drilled a 6.5 metre –high, 5 m- wide and 5000m long Okalo tunnel. It has removed over 100,000 cubic metre of rock.

The company successfully located the place where no one would ever be likely to dig a deep hole later for exploiting minerals because the place is not mineral-rich. The idea is to abandon forever, the mostly natural, and partly engineered underground repository after filling it.

Canister design

After a few decades of interim storage, the levels radioactivity and heat of spent fuel reduce to about 0.1 per cent of the original values.

It is then encapsulated in a cast iron insert which in turn is covered by a 5 cm thick copper canister. Each insert may carry up to 12 fuel bundles.

They will be placed in neatly bored holes a few metre apart in the underground repository. The gaps between each canister and the hole will be filled with bentonite clay, which swells by absorbing water.

This clay provides cushioning to the canister in case of geological movements and ensures that there are no voids through which water can enter and corrode the container.

Finland hopes to start filling the repository by 2012 and completing it by 2120. They can cover the mouth of the tunnel and forget about it.

Canister integrity

Most of the radioactivity in the spent fuel is due to fission products.

They have a half life of about 30y. In 100,000 years, the radioactivity remaining in the fuel will be negligible. Finnish scientists proved that 1.5 cm of copper cladding would last over 100,000 years. Evidently, 5 cm of copper cladding will be more than adequate.

During the period, an ice age may come and cover the area under 2-3 km of ice. The pressure on the canister due to ice, tightly gripping bentonite clay and ground water may equal that experienced by it at an ocean depth of 4.5 km. Finns proved that their copper cylinders will withstand a pressure three times that before failing.

Waste management cost is manageable. Finland collects a few percentage of the electricity cost per unit of power to manage the waste and deposits it in an independent National Nuclear Waste Management Fund, controlled and administered by the Ministry of Trade and Industry.

The agency estimates and assesses the liability annually.

Finland's nuclear waste management programme was accepted by people because the Government took them into confidence at every stage.

Finland demonstrates that nuclear waste can be managed safely. This issue need not come in the way of harnessing nuclear power.

Raja Ramannna Fellow, Department of Atomic Energy

(ksparth@yahoo.co.uk)

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I would question the excessive conservatism represented in the Finnish design described in this article. They foresee enormous compressive loads on the waste container at some time in the future and have provided sufficient copper thickness to withstand that load. If, instead, the container were allowed to be crushed, and even breached in some way, at what rate might radionuclides leave the container and make their way to the ecosystem? How much of a dose might any plant, animal or human ever receive from substances released, transported and uptaken (if there is such a word) from a breached container? A comprehensive risk assessment ought to be the basis for selecting any design. Money is not an infinite resource. If Nevadans are too stupid to accept all that money and great jobs to dispose of America's commercial waste, I hope New Mexico is stepping up their efforts to assign a share of their great WIPP salt bed to a commercial (reprocessed) waste repository.

from:  Martin Bensky
Posted on: Feb 4, 2011 at 04:25 IST
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