N-waste burial in geological layers 'best option' by global standards

N-waste burial in geological layers 'best option' by global standards

JAPAN - The international community shares the common understanding that burying high-level radioactive waste in geological layers is the safest method for its final disposal.

In 2003, the International Atomic Energy Agency released a view that the burial of such waste in geological layers is among various options. They include burial in seabeds or Antarctic ice sheets.

In Japan, plutonium and uranium are extracted from spent nuclear fuel for reuse as fuel during reprocessing. The government plans to vitrify remaining high-level radioactive waste and bury the vitrified waste at a final disposal facility. The nation currently has spent fuel equivalent to 25,000 containers of vitrified waste. The government plans to store at least 40,000 such containers at a nuclear waste repository. The total project is expected to cost about ¥3.5 trillion.

High-level radioactive vitrified waste must be stored far from human habitation for tens of thousands of years. Therefore, the radioactive waste will be brought to pits at least 300 meters underground at the disposal facility before being placed inside thick iron containers, which will be buried with clay blocks packed tightly around each one.

The pits will then be buried completely and made inaccessible to humans. The method ensures that there will be no effects of radiation above ground.

The method is based on the idea confining the waste to a site deep underground is better than relying on manpower for its future management since the state of the nation and society in tens of thousands of years cannot be predicted.

In Finland and Sweden, locations for such nuclear waste repositories have been basically decided, and necessary studies and preparations for their construction are under way.

The construction is said to be relatively acceptable to residents in the two countries as there is great confidence in nuclear regulatory authorities and there are various ways to participate in the process to study the construction. In Finland, a test facility has already been built more than 400 meters underground, and the construction of a nuclear waste repository is ready to start.

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