- For nearly a week, the situation at the Fukushima Daiichi power complex has been slowly stabilizing. The three sets of reactor pressure vessel temperatures have been decreasing and their internal pressures have been stable and steady, with unit 2 & 3 approaching the 95 C temperature which IAEA defines as cold shutdown. Plant operators now seem to be using spent fuel cooling system piping to feed freshwater into the pools, rather than use of the water spraying. Spent fuel pools are being kept full in all reactor buildings and their temperatures have stayed below the 50 C level, except for Unit #4 which has risen sharply and water spraying has increased to counter it. While none of the processes used to maintain water levels and temperatures can be called routine, these make-shift methods have stopped the further degradation of plant conditions which marked the first 20 days at Fukushima. Until the slow process of draining the waters from each of the turbine building basements is completed, the equipment installed to provide emergency cooling water to the reactors and spent fuel pools cannot be operated. Once these systems are operating, all three reactors and all four spent fuel pools can be brought into cold shutdown.
- The same can be said for radiological conditions on land and at sea. Things are no longer deteriorating. To the contrary, airborne activity levels and sea water contamination concentrations have been steadily dropping for several days. In fact, seven of the ten 30 km. off-shore sampling points are below the 0.04 Bq/cc I-131 standard. Only the three sampling points due west of the power complex remain slightly above the health standard for I-131. Near shore contamination levels are currently at their lowest since March 15, with the concentrations at Daiichi being lower than those at Daini, 10 km. south. This does not mean Daini power complex has any seawater leaks. The shore currents tend to flow south in western Japan, so the numbers indicate that the leakage rate of I-131 to the sea at Daiichi is dropping. Part of this drop comes from Daiichi plant staff stopping leakage from the now-infamous power cabling pit crack, their on-going efforts to limit mixing of the port/dock waters inside their break-wall with the open sea, and the drop in I-131 levels due to it’s 8 day half life.Let’s look at the I-131 numbers. We can logically assume fuel damage in units 1, 2 & 3 reactor fuel cores did not get worse after March 18, the date when the fire trucks and their pumps arrived at the scene to boost replenishment water flows through the steam-driven pumps that were intermittently feeding the reactors. This has allowed the reactor operators to cover the fuel cells with at least 10 feet of water, stopping further decay heat damage. Thus, we have had a bit over 3 half-lives for the bulk of the I-131 released from the fuel prior to March 18 to decay, reducing the specific activity by a factor of 8.On the good news front, the Kariwa nuclear power station, 150 km. west of Fukushima, has done an airborne activity analysis for Cesium, and the levels are between a million and two million times lower than the health standard. The resulting annual whole body exposures are 3 million times lower than the 1 millisievert number the Japanese like to call normal.
- One interesting note to this writer, the background radiation levels of April 11, in the 25 cities monitored by MEXT and IAEA, have shown no appreciable decreases, while the radiation levels at the perimeter of the Fukushima Daiichi property are dropping. If this trend continues, could we be seeing the first-ever natural background radiation monitoring for these 25 cities? Up to this point, background radiation data around the world has focused on three population groups. The first is in the vicinity of all nuclear power stations, each of which is located away from urban areas. The second are those areas with high backgrounds, like the Kerala Plateau in India and the beaches of Brazil. The third comprises housing developments atop known Radon gas emitting rock formations. Except for these few areas of radiological interest, background radiation levels in cities and rural areas around the world are largely unknown. Hopefully the process of world-wide urban (as well as rural) natural background monitoring begins with Fukushima. Then we can let mother nature be our guide in setting safety and health standards that are realistic.
- No matter, things only seem to be getting better at Fukushima Daiichi. The problem is time and patience. The rate of stabilization is slow, but steady. There will be no rapid improvements for several days, at least, until the turbine basements are drained. The 700 operating staff and emergency workers at Fukushima Daiichi will tirelessly continue to do their jobs. For the rest of us, it appears we have reached a point where we can hunker down and practice our faculties of patience. On the other hand, the news media will not hunker down and wait. This goes for both the Japanese and the rest of the world. Now, they shift into what I call the “interim mode”, between the event-filled period of the emergency escalating and diminishing, and the eventual period of “coverage” I’ve previously called The War Against the Atom where the prophets of nuclear doom take stage. During this interim period, the Press is resorting to “human interest” and “flashback” stories.
- On the human interest front, we have an article from Asahi Shimbun (Tokyo’s largest newspaper) concerning the so-called “Fukushima 50”, popularized by western news media. The first paragraph takes a subtle stab at western Press by pointing out that there have been some 700 workers toiling at Fukushima from early-on in the emergency. Not 50. Later in the article, the western Press is further subtly chided by pointing out that the number of workers at the power complex never went below 70, at then only once when dark smoke began billowing out of the rubble heap atop Unit #3’s reactor building. That seems to have been the only true “evacuation” of the site by non-essential personnel. The other “evacuations” were actually when workers outside the damaged buildings were told to move away to a safer distance for a while, only as a precaution to prevent unexpected increases in whole body exposure. They’re not getting huge pay raises to coerce people to work there either. Check it out… http://www.asahi.com/english/TKY201104110137.html
On the “flashback” angle, we have another Asahi Shimbun article entitled, “WHAT WENT WRONG: Fukushima flashback a month after crisis started”. One interesting note concerning on of my pet peeves; emergency actions should be the sole domain of the plant’s highly trained operators, and what they do should not be interfered with by politicians. Let the experts on site make the decisions and keep the politicians as far away as possible because they can do nothing but make matters worse. I learned this with TMI when all the data from plant instruments strongly indicated that a severe level of fuel melting had probably occurred, but president Carter literally ordered the NRC to call the accident a “near meltdown” which left the door open for wild “what if” scenarios to proliferate for years.
It seems powerful political interference was the case early-on in the Fukushima emergency. Early in the morning of March 12, Prime Minister Naoto Kan became frustrated with the information he was getting from TEPCO, so he helicoptered to the emergency facility 5 km. from the scene of the emergency and put himself in charge. He wanted the venting of pressure from reactor no. 1 to begin immediately, and this was not happening. Of course, with a complete loss of power, the venting could not happen, but Kan didn’t understand because he has little or no knowledge of nuclear plants. Regardless, he arrived at the emergency center and demanded the venting start immediately. It took some time to explain to him that this was not immediately possible, and what would have to happen before a manual venting process could happen. He wanted it to happen ASAP, regardless. Kan left an hour before the venting began. Five hours later, the hydrogen that accumulated in the upper refueling deck area because of the venting, exploded. This may have happened anyway, but Kan’s nuclear-ignorant orders certainly did nothing to improve the situation, and may well have accelerated the time-table for the first hydrogen explosion. But, Kan’s exacerbating interference did not stop there. Back in Tokyo, after finding out that fuel damage of a severe nature had occurred in one or more of the reactor fuel cells, Kan and his staff descended on TEPCO head quarters and put themselves in charge of information flow. One Ministry official reported they were placed in the unwieldy position of “not releasing any information before it was first submitted to the Prime Minister’s Official Residence.” WHAT??? This is the blind leading those with vision! Why were TEPCO and other government agencies so slow with their release of information? The guilty finger can only be pointed at Prime Minister Kan. Read about it for yourself… http://www.asahi.com/english/TKY201104120153.html