Minggu, 11 September 2011

Safer Nuclear Reactors For The Future?


Areva's Taishan 1 EPR Facility Under Construction in China.

At this time last week, the Nuclear Renaissance was in full swing. Plans were moving forward to use the $36 billion in loan guarantees for new reactors in President Obama's 2012 budget. 

China was approving reactor stations at a steady pace, and nations across Europe were considering new nuclear sites of their own. Seven days later, the push toward more and better nuclear power has come to a full stop, as the crisis at Japan’s crippled Fukushima Daiichi power station threatens to unravel into the worst nuclear disaster in history.
 
But amid a strong, worldwide nuclear backlash, it's important to remember that the next generation of nuclear reactors are designed to prevent exactly what went wrong at the 40-year-old Fukushima Daiichi plant. Which is good, because according to the experts, a future weaned from fossil fuels will include nuclear power whether we like it or not. Here's what that future may look like. 

In the days since the 9.0-magnitude quake and resulting tsunami heaped human tragedy and potential atomic disaster on Japan, things have gone from bad to worse at Fukushima Daiichi, sparking a flood of conjecture about the future of nuclear energy worldwide. Switzerland quickly suspended the approval process for three new plants, Germany's Chancellor announced that country would undertake a "measured" exit from nuclear power, and even China--the vanguard of the global nuclear energy charge--showed apprehension, freezing all new approvals for new nuclear power plants.

It’s too early to begin tallying the lessons learned in Japan, but technically speaking most of what’s gone wrong with Fukushima Daiichi's 1970s-era reactors has already been learned and accounted for in the latest nuclear power plant technology. 

Keeping a nuclear plant safe means keeping it cool in any circumstances, including those in which man-made or natural disaster knocks out the usual cooling methods. This highlights the importance of safety features built into so-called Generation III-plus nuclear plant models, the latest feasible plant designs. These redundant and passive safety systems work without the help of an operator, or even electricity, during times of duress, be it man-made or natural.

Generation III-plus includes a handful of high-tech plant designs, many of which still await regulatory approval. Others, like France-based Areva’s Evolutionary Power Reactor (EPR) and Westinghouse’s AP1000 (both are pressurized water reactors) are already under construction, and they are designed to withstand exactly the crisis the 40-year-old Japanese reactors are failing to deal with, whether operators are around to trigger emergency countermeasures or not.

“The new reactors really have a lot of features that were not available thirty, forty years ago,” says Michael Podowski, a visiting professor in MIT’s department of nuclear engineering and an expert on nuclear plant safety systems. “These new advanced reactors will employ more passive safety systems that will make them safe without any external intervention.”

Areva is currently building four EPR reactors, two in China and two in Europe. The design includes four independent redundant cooling systems, two of which are engineered to survive an airplane crash.
Westinghouse’s AP1000 packs a battery of passive systems that use natural air flow, gravity, and other natural phenomena to remove pumps and valves from the equation; if the plant begins to overheat these measures will automatically cool the core for up to three days with no external intervention whatsoever.

 by "environment clean generations"

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