Friday, June 3, Massachusetts Institute of Technology (MIT) posted their May faculty report on Fukushima. MIT identifies the key issues specific to Fukushima and possible corrective actions to be considered with respect to currently operating and future nuclear power plants. The report is brilliant. We at hiroshimasyndrome.com fully agree with almost everything contained in the report, with the exception of the unit #4 spent fuel pool fire issue. It is astonishing that we agree on so much, given the often conflicting informational flow relative to the nuclear emergency.
MIT correctly gives caution to the reader…the situation in Japan cannot be evaluated with a high degree of confidence, at this point, because the situation continues to evolve and new information on emergency actions taken in the days following March 11 continues to emerge. MIT concludes that corrective actions (improved safety) for nuclear plants should be addressed on a plant-specific basis…changes should occur only if they have site-specific relevance. For example, changes in safety regulations for U.S. plants that already have waterproof rooms and adequate flooding protection for emergency diesel generators and their related equipment would not be relevant.
We at hiroshimasyndrome.com highly recommend that everyone read the MIT posting, and pass the URL to all friends and family concerned about nuclear energy issues and the impact of Fukushima. It’s very, very good stuff.
http://mitnse.files.wordpress.com/2011/06/fukushima-lessons-learned-mit-nsp-025.pdf
And now, updates of this past weekend’s events in Japan…
- Japan’s Atomic Industrial Forum (JAIF) reports TEPCO has replaced one of the pressure sensing gauges for RPV #1 with a new one. The older gauge has steadily indicated about 6 atmospheres of pressure since March, and the readings did not change with conditions inside the RPV. Many informational sources, including this web site, have felt the pressure gauges on units 1, 2 & 3 were damaged during the early days of the emergency and have been giving a false readings. The new gauge shows a pressure at just above one atmosphere, which now conforms with the temperatures indicated inside the vessel. TEPCO has added the replacement of the pressure gauges for units #2 & 3 to their “as soon as possible” list of jobs to be done, in addition to recalibration of the two sets of water level instruments.
- JAIF also announced TEPCO has permission to transfer ~1,500 tons of contaminated water from turbine building basement #2 to the basement area of a waste treatment storage facility. Transfer started immediately upon getting the OK from the Nuclear and Industrial Safety Agency (NISA) on Saturday. It is calculated that this will add three more days of time before the buildup of waste waters will potentially reach a point of overflowing drainage trenches. TEPCO believes it’s new water purification system will be running by June 15, well before the potential for further sea contamination which might occur ~June 20. The current rate of build-up is ~500 tons a day, and once in operation the clean-up system will decontaminate ~1,200 tons per day. The decontaminated waters will be used as “make-up” for injection into the three RPVs, to keep the damaged fuels cooled. With no new water being added to the mix, this could avoid the on-going issue of overflowing into the sea.
- JAIF also says TEPCO has amassed 270 one-hundred-ton portable storage tanks, and will be shipping them to Fukushima Daiichi as soon as possible. These tanks will provide ~30,000 tons capacity for decontaminated waters, and become the source of RPV replenishment supplies from the purification system. This will effectively keep water replenishment of the three RPVs in a closed-loop arrangement, and effectively eliminate adding more water to the system.
- JAIF also states the successful cooling of unit #2 spent fuel pool has not reduced the reactor building’s excessive humidity. It must be coming from somewhere else inside the structure. TEPCO is now considering opening all doors to the building and letting natural circulation dissipate the moist air. However, TEPCO must analyze the internal atmosphere for airborne activity and weigh the pros and cons of possibly having further, albeit relatively small, releases to the outer environment.
- Radioactive Cesium concentrations in the sea water immediately adjacent to #3 intake structure, inside the multi-barrier port/quay, have dropped by a factor of 10,000 since May 11. (not a typo) Current concentrations are ~1.2 Bq/cc, which is about 20 times the regulatory limit. Cesium is not very soluble in water, and is relatively heavy, so it may well be precipitating out and dropping into the mud and sand on the intake’s sea floor. Sea water samples taken adjacent to #2 intake show Iodine concentrations have dropped considerably since May 11 too, now at ~60 times the legal standard.
- Current thermal conditions inside Unit #1 & 2 RPVs are essentially stable, as has been the case for nearly two weeks. However, temperatures in the #3 RPV have risen considerably over the past 5 days, and the inverse temperature gradient for #3 RPV, reported several times in past updates, has returned. The feed water nozzle is at 138 oC and the bottom head is at 170 oC.
- Japan Times and Asahi Shimbun say that the venting of unit #1, which began about five hours before it’s refueling deck hydrogen explosion, may have led to the explosive hydrogen build-up. There are two venting pathways out of the primary containment, one through a particulate filtering assembly which would remove nearly all fission products except for inert gasses, and the other up the tall external chimney next to unit #1. The two pathways have a common point of cross-connection between them, separated by an electric-operated isolation valve. When all power was lost, it is believed the cross-connection valve opened (the electricity held it shut). This is not a “fail-safe” condition. The valve ought to have automatically shut upon de-energizing. After manual venting began, some of the gasses intended to be directed up the outer chimney, were instead by-passing into the outer containment structure and eventually migrated onto the refueling deck.While the stuck-open cross-connecting valve may have contributed to the unit #1 hydrogen gas build-up, the fact remains that the operators could not (or were not allowed to) begin manual venting until the pressure-suppressing torus was more than two times it’s maximum design pressure. As stated last week in this page, the severe over-pressure condition probably caused leaks through the suppression pool’s weak points, initiating the gas build-up many hours before the venting began. TEPCO seems to be blaming the H2 build-up on a design flaw with the cross-connect valve. However, unit #3 had a type of cross-connect valve that automatically closed upon loss of power, effectively eliminating the unit’s interconnected pathways as a possible source for its H2 explosion. What will they blame the source of unit 3 & 4 H2 on?
- NHK World News reports that some of the roadside drainage ditches in and around Fukushima City have radiation levels of 3-4 microsieverts at one meter above the top of the leaves and other run-off debris. The readings at just above the surface are about 100 microsieverts. General background readings across the City are believed to be between one and two microsieverts. The readings were taken by Nuclear Safety Commission (NSC) staff. Contamination is believed to have been washed from surrounding buildings caused by rain, and concentrated in the ditches. NSC recommends that crews who clean out the ditches wear masks and other protective clothing to prevent contamination. The debris will be buried outside the City. NSC also says people walking near the ditches in the course of their daily activities can wear masks to prevent any possibility of inhaling radioactive dust.
- Japan’s Science Ministry is initiating a comprehensive soil sampling project covering all of Fukushima Prefecture. In addition to their own staff, some 80 experts from 35 universities across Japan are taking part. Up to this point, estimates of soil contamination have been made using theoretical modeling deduced from airplane and helicopter gamma radiation measurements. This will be the first direct soil sampling aimed at verifying (or refuting) the prior estimates. Samples will be taken according to a grid of 4-square-kilometer locations covering all of the land within 80 km of Fukushima Daiichi, and every 100-square-kilometers beyond the 80 km radius. There will be more than 2,200 locations sampled.
- Japan’s Environmental Ministry has approved burial and incineration of all debris (garbage) for 10 communities outside the 20km no-entry zone surrounding Fukushima Daiichi. Many municipalities have stopped their usual disposal methods for fear of radiation. The Ministry has quietly been checking municipal wastes for contamination and have found that these ten communities have no cause for concern. The testing of other community’s wastes is on-going.
- University researchers detected trace amounts of Plutonium in samples taken about a mile from the Fukushima power complex main gate on April 21, before the 20km no-entry zone was declared. They took the samples for NHK World News. The samples showed a trace level of reactor-based Plutonium, but much less than that of bomb-based Plutonium which fell on Japan from atmospheric weapons tests in the South Pacific. NHK reported the detection of Plutonium in April, but failed to tell us the levels were way too low to be of any rational health concern. Regardless, the professors who did the analysis say a close examination of the deposition of isotopes from the immediate vicinity of the power complex should be performed in order to gain real-world data on the spread of reactor-based contamination. We totally concur.
- NHK World also reports that Germany is on the verge of ending their nuclear option. Chancellor Angela Merkel signed a new energy bill that will eliminate all nuclear power generation by 2022. The eight nuclear plants currently shut down for refueling and/or maintenance will not be re-started. The nine currently-operating plants will be phased out over the next 11 years. The Chancellor says the lost electricity generation will be replaced with coal and gas! Let this be a lesson to prophets of nuclear energy doom around the world…”No-Nukes” means increased global warming. It’s unavoidable!
One final item…the MIT report (above) mentions an irrigation dam collapse near Sukagawa City, Fukushima Prefecture, caused by the earthquake on March 11. Our subsequent web search revealed the dam was 57 feet tall and nearly 500 feet long. It’s collapse washed away many homes downstream. On March 12, the Sankei Shimbun newspaper reported a number of homes were “washed away”, but the number of casualties was unknown. Why was there no wide-spread media coverage of this earthquake catastrophe? What emergency actions occurred? Are there survivors? What has happened since?
Oh…wait…that’s right! It wasn’t nuclear…
