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Friday, March 11, 2011

Scientists move to allay fears

Scientists move to allay fears

Last updated 13:09 12/03/2011
Scientists are saying there is no link between Christchurch’s killer quake and Japan’s devastating one.

Reaction to calm fears has been swift from the scientific community globally.

''There is no relation to the Christchurch earthquake - these earthquakes were 'relatively' small and a long way away," says Dr John Elliott from the Department of Earth Sciences at the UK’s prestigious University of Oxford.

''Earthquakes happen regularly on active faults around the world, so it is not surprising to have a magnitude 6.3 earthquake in New Zealand followed several weeks later by a magnitude 8-9 earthquake somewhere else," says Dr Lisa McNeil, senior lecturer in geology at the University of Southampton.

''There is not likely to be any direct connection between today's earthquake and the recent Christchurch earthquake. They occurred many thousands of km apart, on different plate boundaries. There is, on average, one large (magnitude 8.0 or greater) earthquake in the world each year, and Japan has a long history of large earthquakes, so this is not unusual,'' says Dr Alex Densmore at the Department of Geography and Institute of Hazard, Risk and Resilience, at Durham University.

''It is likely to be, however, the largest recorded earthquake (in terms of magnitude) since historical records began with the 684 earthquake off Tokyo,” Densmore said.

Scientists are also moving to dampen fear about Japan’s nuclear reactors, which have been damaged in the quake.

In 2007 a 6.6 earthquake caused damage at the Kashiwazaki-Kariwa power plant. This relatively small earthquake caused numerous problems at the site - from radioactive water leaks to cracked cooling pipes.

Nuclear experts says Japan learned lessons from that.

And John Luxat, Professor and Industrial Research Chair in Nuclear Safety Analysis at McMaster University says: "This is very, very different from Chernobyl. It's not a comparable situation - they didn't have a containment unit, and the reactor didn't shutdown prior to damage occurring, as was the case here.''

"All Japanese reactors are designed to withstand substantial earthquakes since they are situated in a known earthquake zone. Instrumentation is provided for the early detection of tremors which would lead to a controlled shutdown of the reactor. These systems appear to have successfully shut down the affected reactors. Problems at Onagawa are attributed to the failure of mechanical/electrical systems used to provide cooling water'' said Paul Haigh, a Fellow of the Institution of Chemical Engineers  and an independent nuclear consultant.

"Several years ago a power reactor in Armenia was closed down as it was in an earthquake zone. After several years, with EU assistance, the reactor was upgraded, including substantial 'seismic proofing' and the reactor was returned to service. Modern western reactors, including those planned for the UK, are already designed to withstand significant seismic events. Tremors have been detected at UK power plant in the past.

"It is to be hoped that the Japanese reactors will not have suffered damage which precludes their return to service, but that is a matter for the Japanese utility and licensing authorities.''

Dame Sue Ion, nuclear engineer and Fellow of the Royal Academy of Engineering, said: "Japan has extremely tight standards when it comes to earthquake resistance of nuclear power plants and other facilities. Authorities and utilities and reactor vendors ensure that appropriate safety systems are incorporated at the design stage and implemented in construction and operation.

''Systems automatically shut down when trigger points are reached to allow for relevant safety inspections to take place before restart. Japan's nuclear power stations are being shown to be robust against the threat of earthquake:

Safety systems have operated as they should. Authorities have well developed precautionary evacuation procedures pending confirmation of ongoing safe operations.

"Although this earthquake is particularly severe, the devastation we are witnessing on our TV's is mainly associated with the subsequent Tsunami not the quake itself.''

The Fukushima nuclear plant is the focus of most worry.

- Stuff

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