Nuclear Safety Standards, Japan
Tokyo Electric Power Company had received warning from their own senior safety engineer about the vulnerability of the Fukushima Nuclear Power Station years ago. Those warnings were set aside. The warning, after all was that there was only a 10% chance that a tsunami could breach the defences of the power plant within a 50-year time span.And Japan's Nuclear & Industrial Safety Agency charged with nuclear safety, catalogued damage to plant vent systems from an earlier earthquake. But it made no requirement that they be protected in the possibility of future disasters. When the tsunami struck it overwhelmed the safety measures in position, and did so with ease, because they were wholly inadequate.
Japan, a country obsessed with its history as the only country of the world that had experienced the terror and the horror of two nuclear attacks, yet needing a reliable and practical energy source, became hugely dependent on nuclear energy. The country has 55 nuclear plants. Most of them placed in vulnerable, potentially dangerous coastal areas for the simple reason of ease of access to cooling water.
TEPCO's Fukushima Daichi plant, built 40 years ago, was placed on a known quake zone that had produced high magnitude earthquakes in the past 400 years - at 8 or higher on the Richter scale. It was felt that the structure could withstand a six-metre wall of water, and that was what it was designed to handle. Original plans were to decommission reactor No.1, but those plans were shelved.
The tsunami that resulted from the 9.0 quake was 14 metres in height.
Japan is highly dependent on the energy its 55 nuclear reactors provide, receiving half its total generation of electricity from them. Fourteen new nuclear plants were in the drawing board stage. And the Fukushima No.1 reactor had its dependable working life extended. The ageing plants were given upgraded maintenance and checked for flaws.
TEPCO gave assurances to the safety regulators that the reactor's component parts were not being worn down. Safety inspectors thought nothing of enquiring why backup generators were placed on low ground near the shore, at high risk for damage from tsunamis.
Chaos broke out with the quake rumbling through, and workers were desperate to run to higher ground before the tsunami struck. In the pandemonium that ensued, the workers took no notice when the diesel pumps at No.2 were out of fuel, and water levels fell leaving fuel exposed and overheating.
The workers did manage to escape to high ground and survived, all but two workers whose bodies were just recently found inside the reactor.
And then, soldiers and workers struggled to contain the radiation levels in the damaged reactors. It is always after the fact that solutions emerge, too late to do any practical good, because the solutions might have worked, but could not, because they weren't implemented. The vent systems that should have been 'hardened' to withstand pressure, hadn't been.
And when TEPCO began venting the No.1 reactor, the pressure in the reactor, twice its designed limited, resulted in the reactor exploding. And the same thing happened with reactor No.3; venting to relieve a build-up of pressure, and then the concrete and steel shell exploded there too. Japan, long respected in the global industry for its concerns for safety, failed the test.
It was well known that a major earthquake could damage the reactors. It was acknowledged the ground could sink as a result of an earthquake, and that underground pipes could break. No new standards were drawn up and put into place to protect against potential damage and danger. Complacency ruled the day.
That, and the belief that nothing untoward could possibly occur.
Labels: Japan, Natural Disasters, Technology
posted by Pieface @ Monday, April 04, 2011
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