This last week or so there were a number of lectures on nuclear power and Fukushima and proliferation and Hiroshima, at both MIT and Harvard (http://www.dailykos.com/...). These were the two I decided to attend.
One was from a civil engineering perspective and the other was from the nuclear engineering viewpoint. Both events were packed. The first happened in the Civil Engineering lecture room and the second was part of a regular theoretical physics seminar over in the Physics building about a block away. I may have been the only person to attend both.
These are my notes. I try to be a fair witness but apologize for any mistakes, especially to Drs Kausel and Buongiorno if I've misrepresented them.
Disaster at Fukushima Dai-Ichi: Don't Blame the Quake
9/27/11
Dr Eduardo Kausel, civil engineer
Nuclear Energy After Fukushima: lessons learned and future prospects
10/3/11
Dr Jacopo Buongiorno, nuclear engineer
Disaster at Fukushima Dai-Ichi: Don't Blame the Quake
9/27/11
MIT
Eduardo Kausel, MIT, an experienced civil engineer prefaced his talk by saying he is for nuclear power and has great admiration for Japanese technology, science, and engineering.
He then explained that Japan is near four different tectonic plates: Pacific, North American, Philippine, and Eurasian plates, that the length of the Ring of Fire is about 40,000 km and, since large thrust earthquakes (8.8 - 9.5 Richter) happen every ten to twenty years somewhere around the world, the very rough estimate of risk for any segment along the fault line is about once every 1000 years, a 1000 year event. For Fukushima and other nuclear power plants the design standard for Safe Shutdown Earthquake (SSE) is a once every 2-3 thousand year event.
Fukushima was designed for a peak ground acceleration (PGA) which was exceeded by the earthquake but caused no structural damage to the 6 nuclear power plants at Fukushima Dai-Ichi.
However, going back in history, there is evidence for the Jougan Sanriku earthquake around Sendai, the same region, in 869 CE, estimated at 8.6 R [Fukushima Dai-Ichi was rated for 8.4 R ]. Near Fukushima, large earthquakes and tsunamis in excess of 5 meters happened in 1611, 1896, 1933, as well as 869.
There was a 5.7 meter sea wall but the actual tsunami height was 17 meters. [PBS' Nova reported that as a result of the earthquake, the ground in the region was lowered by about 2 meters as well. As Dr Kausel wrote in a Technology Review article on rebuilding Japan, "We know now that you can't tsunami-proof a town or building; all you can do is move it out of the way." (http://www.technologyreview.com/...) ]
The height of the tsunami is determined by the topography of the area and the Fukushima nuclear power plants are on a low platform in front of a wide bay of shallow depth. That shallowness may have let the tsunami wave build. The Onigawa nuclear plants were closer to the quake epicenter and suffered less damage as they were on a higher platform with a much smaller bay with a shorter expanse of shallow water. Fukushima was not adequately designed or retrofitted for tsunami effects. Dr Kausel believes tsunamis were not adequately considered in the planning and that the clear evidence of recent tall tsunami waves should have been taken into account by TEPCO.
There were a number of older professors there. Many who seemed to have nuclear power experience but were now in other fields. Out in the corridor, one such professor agreed that the present fleet of nuclear power plants is flawed and said that the money that went into most fusion research should have gone into developing better and safer fission plants instead.
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Nuclear Energy After Fukushima: lessons learned and future prospects
10/3/11
MIT
Jacopo Buongiorno, a nuclear engineer, began with an overview of nuclear power production. In the US there are 104 reactors, 13% of installed capacity, 20% of electricity. US plants ran at 91.2% capacity in 2010. About 2/3 of US reactors are pressurized water reactors (PWR) and about 1/3 boiling water reactors (BWR), like Units 1-6 at Fukushima. 71 reactors have extended their operating licenses another 10 to 20 years beyond their original operational lifetimes with 13 more in process. Production costs for an operating nuclear power plant are 1.7-2.5 cents per kWh, but this does not included the investment in the plant itself. Worldwide there are 440 reactors in 30 countries producing 14% of all global electricity.
60 new reactors are currently under construction with 3 projects in US, one each in GA, SC, and TN.
Nuclear fuel retains decay heat for a long time and heat must be removed from nuclear at all times. Up to two years of operation on one set of fuel rods and spent fuel rods stored on site in pools of water. Contrary to initial reports, the water in the spent fuel pools at Fukushima did not boil away or evaporate, exposing the spent fuel rods to the atmosphere. Spent fuel pools can last eight days without circulation before risking exposure of the fuel rods to the air. The confusion was a result of a lack of proper instrumentation and can be corrected.
The earthquake did exceed the design specifications but did not do structural damage. [I found it interesting that Drs Buongiorno and Kausel differed on the details of the height of the tsunami: 14 meters for Buongiorno and 17 for Kausel.] Grid, diesel, and battery power were knocked out by the tsunami and earthquake. There were hydrogen explosions at Units 1-4. Unit 5 and 6 had diesel generators that survived and suffered less damage.
Radiation released was 10 to the 16 th becquerels of cesium 137 and 10 to the 17 bq of iodine 131. The amount of radiation released is one tenth that of Chernobyl and is mostly shorter lived radionuclides. 200,000 people were evacuated from a zone based on 20 milliSievert/year dosage rate, a dosage rate that Dr Buongiorno thinks is not very dangerous. [Here is a Japanese Ministry of Education map of strontium and plutonium dispersal in the area released on 9/30/11: http://ex-skf.blogspot.com/... and here is the ongoing citizens' radiation monitoring project at Safecast: http://blog.safecast.org/ ]
Clean up of the nuclear power plants will take a decade with over $10 billion costs.
US "coping time" is now 4-8 hours of batteries after loss of grid power in our nuclear power plants. This should be extended and back-up power should be in waterproof rooms, as it is, mostly, in the US.
I asked directly about the US BWRs that have spent fuel pools outside of containment and Dr Buongiorno thought containing them is not a pressing issue.
Learning the lessons of Fukushima (http://web.mit.edu/...) is a paper by Dr Buongiorno and a group of co-authors with more information and recommendations.
Previous related diaries:
Japan Aftermath
http://www.dailykos.com/...
Fukushima: Prayers and Petitions http://www.dailykos.com/...
Citizens' Radiation Monitoring Networks http://www.dailykos.com/...
Harvard Workshop on the 25th Anniversary of Chernobyl http://www.dailykos.com/...
