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Can someone provide background information on the type of reactor at Fukusima, it's age, and it's failsafe mechanism. I was under the impression that no modern

by brg 16y ago

Can someone provide background information on the type of reactor at Fukusima, it's age, and it's failsafe mechanism. I was under the impression that no modern reactor would sustain criticality in the event of a failure.

hartror 16y ago
From wikipedia: "Fukushima I – 1 BWR First criticality: March 26, 1971". So it isn't a "modern" reactor, not sure what the fail safes are but I have read from some sources all the fail safes are older generations which require power.
- brg 16y ago
  Thanks, wiki continues to provide detailed information in the deep links on the page. It seems we are witnessing a case of failure upon failure. Truly a horrific tragedy for the country and the world.
- cosmicray 16y ago
  The Three Mile Island accident occurred on Wednesday, March 28, 1979. TMI Unit 2 received its operating license on February 8, 1978. So the Fukushima I appears to be slightly older than TMI.
brg 16y ago
To answer my own question, Fukushima is a first generation bwr: http://en.wikipedia.org/wiki/Boiling_Water_Reactor http://en.wikipedia.org/wiki/Boiling_Water_Reactor It lacks the safety mechanisms of an abwr. Namely even after the control rods are deployed, heat can continue to build up. Hence the plant requires forced cooling, in this case provided by diesel and electric pumps. After the earthquake the diesel pumps failed and cooling was effected by battery power. While the government rushed in new diesel generators, they were not installed in time to prevent the build up of pressure resulting in this explosion.
- gregholmberg 16y ago
  Japanese officials believe that the tops of the fuel rods are exposed. Agency officials said a team of National Institute of Radiological Sciences detected cesium, a radioactive substance contained in nuclear fuel rods, near the No. 1 reactor of the No. 1 nuclear plant, leading them to suspect nuclear fuel rods in the reactor began melting amid the high temperatures. The nuclear safety agency said in the afternoon that the level of cooling water in the No. 1 reactor likely had dropped to 1.7 meters below the top of nuclear fuel rods, leading officials to suspect that about half of the rods' length had been exposed. Reactor meltdown feared / Quake disabled Fukushima N-plants' cooling systems http://www.yomiuri.co.jp/dy/national/20110312dy01.htm http://www.yomiuri.co.jp/dy/national/20110312dy01.htm
  - uvdiv 16y ago
    This was confirmed by Tokyo Electric Power (the operator): "A portion of the reactor's fuel rods, which create heat through a nuclear reaction, had become exposed due to the cooling-system failure. The spokesman for Tepco said 1.5 meters of the 4.5 meter long fuel rods were exposed. It was unclear Saturday afternoon whether the water added by workers had re-covered the rods." http://online.wsj.com/article/SB10001424052748703555404576195700301455480.html http://online.wsj.com/article/SB1000142405274870355540457619...
- neutronicus 16y ago
  Read my comment here: http://news.ycombinator.org/item?id=2316851 http://news.ycombinator.org/item?id=2316851 It's going to take a couple days for any nuclear reactor to burn off decay heat.

by brg 16y ago

hartror 16y ago

From wikipedia: "Fukushima I – 1 BWR First criticality: March 26, 1971". So it isn't a "modern" reactor, not sure what the fail safes are but I have read from some sources all the fail safes are older generations which require power.

brg 16y ago
Thanks, wiki continues to provide detailed information in the deep links on the page. It seems we are witnessing a case of failure upon failure. Truly a horrific tragedy for the country and the world.
cosmicray 16y ago
The Three Mile Island accident occurred on Wednesday, March 28, 1979. TMI Unit 2 received its operating license on February 8, 1978. So the Fukushima I appears to be slightly older than TMI.

brg 16y ago

To answer my own question, Fukushima is a first generation bwr: http://en.wikipedia.org/wiki/Boiling_Water_Reactor http://en.wikipedia.org/wiki/Boiling_Water_Reactor It lacks the safety mechanisms of an abwr. Namely even after the control rods are deployed, heat can continue to build up. Hence the plant requires forced cooling, in this case provided by diesel and electric pumps. After the earthquake the diesel pumps failed and cooling was effected by battery power. While the government rushed in new diesel generators, they were not installed in time to prevent the build up of pressure resulting in this explosion.

gregholmberg 16y ago
Japanese officials believe that the tops of the fuel rods are exposed. Agency officials said a team of National Institute of Radiological Sciences detected cesium, a radioactive substance contained in nuclear fuel rods, near the No. 1 reactor of the No. 1 nuclear plant, leading them to suspect nuclear fuel rods in the reactor began melting amid the high temperatures. The nuclear safety agency said in the afternoon that the level of cooling water in the No. 1 reactor likely had dropped to 1.7 meters below the top of nuclear fuel rods, leading officials to suspect that about half of the rods' length had been exposed. Reactor meltdown feared / Quake disabled Fukushima N-plants' cooling systems http://www.yomiuri.co.jp/dy/national/20110312dy01.htm http://www.yomiuri.co.jp/dy/national/20110312dy01.htm
- uvdiv 16y ago
  This was confirmed by Tokyo Electric Power (the operator): "A portion of the reactor's fuel rods, which create heat through a nuclear reaction, had become exposed due to the cooling-system failure. The spokesman for Tepco said 1.5 meters of the 4.5 meter long fuel rods were exposed. It was unclear Saturday afternoon whether the water added by workers had re-covered the rods." http://online.wsj.com/article/SB10001424052748703555404576195700301455480.html http://online.wsj.com/article/SB1000142405274870355540457619...
neutronicus 16y ago
Read my comment here: http://news.ycombinator.org/item?id=2316851 http://news.ycombinator.org/item?id=2316851 It's going to take a couple days for any nuclear reactor to burn off decay heat.