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  • Cryolines | Another day, another spool

    Having wedged his body and equipment into the cramped space between the ceiling and the massive pipe, a worker is busy welding two cryolines spools. A few metre [...]

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  • Image of the week | Bearings unveiled

    The construction teams are in the last stages of preparing the Tokamak pit for the first major operation of ITER machine assembly: the lowering of the cryostat [...]

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  • Technology | Perfecting tritium breeding for DEMO and beyond

    While ITER will never breed tritium for its own consumption, it will test breeding blanket concepts—the tools and techniques that designers of future DEMO react [...]

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  • Fusion world | Japan and Europe complete the assembly of JT-60SA

    The JT-60SA fusion experiment in Naka, Japan, is designed to explore advanced plasma physics in support of the operation of ITER and next-phase devices. After s [...]

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  • Manufacturing | Thermal shield milestone in Korea

    Six years after the start of fabrication, Korean contractor SFA has completed the last 40° sector of vacuum vessel thermal shield. The stainless steel panels, c [...]

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Of Interest

See archived entries

Rethinking the unthinkable

Robert Arnoux

A seasoned folk and blues guitar player, the CEA-Cadarache director has long played the semi-professionnal circuit. (Click to view larger version...)
A seasoned folk and blues guitar player, the CEA-Cadarache director has long played the semi-professionnal circuit.
In the weeks that followed Fukushima a few things changed at CEA-Cadarache. "We had to ask ourselves new questions," explains Director Maurice Mazière. "Nuclear safety has always been about thinking the unthinkable. Now, after Fukushima, the unthinkable must be redefined ..."

It had gone without saying, for instance, that in the case of a power failure in a nuclear installation, redundant diesel generators would automatically provide electricity wherever it was needed. This safeguard, however, did not work in Fukushima where the generators were drowned by 15-metre-high waves from a monster tsunami.

Tsunamis, of course, are unlikely to happen in Cadarache. "Still," confides Mazière, "what happened in Japan has led us to ask ourselves some hard questions." Some of these "hard questions" have led to swift action: on the Jules-Horowitz Reactor (RJH) work site, diesel generators were moved to higher grounds—some 15 metres above the original location.

Also, more-or-less-dormant research projects on severe accidents have been revived. For years CEA-Cadarache had been conducting studies and accumulating data on the behaviour of corium, the molten lava that results from core meltdown; this project, termed "Vulcano," is now receiving high priority.

Interest in "passive system" concepts, developed years ago by CEA's Reactor Studies Department, has also been renewed. "The ultimate safety challenge in a reactor," says Mazière, "is the evacuation of residual power when all cooling systems fail. Ideally, in a 'passive system,' heat evacuation occurs naturally. We are assigning new teams to pursue the development of such systems."

Thirty-six years after he first passed the gates of Cadarache as a young intern from École Centrale in Paris, Maurice Mazière has to steer CEA's largest nuclear research centre in the post-Fukushima world. "I see Fukushima as the starting point for a deep reflection process. We have to ask ourselves the right questions, dig into the tiniest details and devise rescue systems able to withstand 'unthinkable' events or situations. Whatever political decision might be taken in the future, we will continue, in the meantime, to stick to the course we've set."


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