Last operational nuclear reactor shut down in Japan
The last of the three reactors of the Tomari power plant in Hokkaido was shut down last afternoon, forcing Japan to rely on other forms of energy minus nuclear power after more than 40 years. This coincides with “Kodomono-hi” or “Boy’s day” in Japan (anti-nuclear protesters used carp-shaped banners symbolizing kodomono-hi). Now all 54 reactors in Japan have to demonstrate their resilience to earthquakes and tsunamis before consideration is given by local governments to reopen them. From now on, other energy sources have to fill the gap in supply due to the total nuclear shutdown. Nuclear power is accounted for nearly 30% of the energy supply in Japan.
Event lineup at the Fukushima NPP: first five days after the earthquake
In November last year, a special report on the Fukushima NPP was published in the IEEE Spectrum magazine on the first 24 hours at the plant after the earthquake and tsunami. Last Month, a more detailed report went to the Japanese press as published by the Nihon Keisai Shimbun on 27th December. The events brought to our notice by these reports sketch a text-book scenario of a nuclear disaster, which the world saw for the first time in its short nuclear history. Those events that lead to the triple-core meltdown as reported by the Keisai Shimbun are listed below.
| Date | Time | Event |
| March 11 | 14:46 | Earthquake |
| 14:47 | Reactors 1 -3 stopped (emergency stop) | |
| 14:50 | Cooling started manually at Reactor 2, then stopped until the 14th | |
| 14:52 | Emergency Isolation Condenser (IC) at Reactor 1 started | |
| 15:03 | IC at Reactor 1 manually stopped (subsequently started and stopped several times) | |
| 15:05 | Cooling system at Reactor 3 opened | |
| 15:25 | Cooling system at Reactor 3 automatically stopped | |
| 15:30 | ~13m Tsunami entered the small harbour | |
| 15:37 | Lost AC power (total blackout) | |
| 16:03 | Cooling at Reactor 3 manually started | |
| March 12 | 04:00 | Water pumped into Reactor 1 using a fire truck |
| 06:00 | Meltdown begins in Reactor 1 | |
| 10:17 | Pressure vessel valves opened at Reactor 1 | |
| 11:36 | Cooling automatically stopped at Reactor 3 | |
| 12:35 | High pressure pumping system automatically started at Reactor 3 | |
| 14:53 | Fresh water supply to Reactor 1 ran out | |
| 15:36 | Hydrogen explosion at Reactor 1 | |
| 19:04 | Started pumping sea water into Reactor 1 | |
| March 13 | 02:42 | High pressure pumping manually stopped at Reactor 3 |
| 08:41 | Vents at Reactor 3 opened to release pressure | |
| 09:25 | Started pumping fresh water into Reactor 3 | |
| 11:00 | Vents at Reactor 2 opened to release pressure | |
| 13:12 | Started pumping sea water into reactor 3 | |
| March 14 | 03:00 | Meltdown begins in Reactor 3 |
| 11:01 | Hydrogen explosion at Reactor 3 | |
| 13:25 | Cooling system at Reactor 3 stopped | |
| 19:57 | Started pumping sea water into Reactor 3 | |
| March 15 | 06:00 | Pressure inside Reactor 2 rapidly decreased (i.e. the reactor was leaking) |
| 20:00 | Meltdown at Reactor 2 |
Evidently, the above events have supplied plenty of food for thought in future NPP construction and operation. A full-scale analysis of the Fukushima accident may hopefully lead to safe plant design in the future. I won’t be surprised if we see a movie based on the above seemingly chaotic events in the near future.
Special thanks to Mr. Koji Masuda for his time spent on explaining and translating the Keisai Shimbun Article
Data Source: Nihon Keisai Shimbun
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You may contact the author at suntomoonblog@gmail.com
Heroes of Fukushima
More than nine months elapsed after the world’s worst nuclear accident since Chernobyl. We heard so much about the 9.0 earthquake, the tsunami, the crippled nuclear reactors, hydrogen explosions and the triple-core meltdown. We saw thousands of people taking refuge in evacuation centers and many others leaving Fukushima for safety concerns. Frequent radiation checks were conducted by local governments and individuals equipped with the right tools, not only in the vicinity of the plant, but also in places hundreds of miles away from Fukushima. Being one of those few countries in the world that has an indigenous philosophy of a safety-culture, the Japanese government was under immense pressure to live up to her people’s expectations. Even now, radiation checks are a mandatory requirement for food coming from affected areas to ensure safety and to build consumer confidence. However, after a long struggle, everything seems to be returning to normal now. Even the hourly aftershocks seems to be a thing of the past, adding some relief to an already shaken nation. The massive rebuilding effort is already underway with the government pouring in money to the affected region. Even the Tohoku expressway was made a free-zone to lure travelers to North-Eastern Japan.
In the backdrop of all this activity, TEPCO could finally stabilize the reactors last month. Obviously, it was no easy task bringing the reactors to a cold shutdown. In fact it would have been impossible without the untiring efforts made by a small group of brave men, who worked day and night to re-stabilize the plant. They had been risking their lives from the very moment the first shock waves rattled the ground beneath them. As the electricity supply to the plant was severed soon after the 14m+ tsunami breached the shorelines of Fukushima, they must have sincerely thought that the emergency generators would take over the cooling. However, optimism had no chance on that extraordinary day. Waves went nearly 5m above the tidal gauge, inundating the emergency generators and other vital equipment. A complete blackout is a nightmarish situation, yet those brave men never gave up. They had to get a glimpse of the current status inside the reactors. So, according to a recently released special report, they even went to the extent of gathering car batteries from the parking lot to revive the instrument panels. They could not just wait for the emergency power trucks coming from Tokyo. The trucks could not be airlifted due to their excessive weight, so they were taking the already congested roads to Fukushima. Throughout the night of 3/11, radiation levels in and around the NPP were rising. Those brave men worked hard to plug-in the batteries to the instrument panels and subsequently connect the cables of the power supply trucks arrived from Tokyo around midnight. They knew the danger they were running into. Due to rising radiation levels, the workers were prohibited entry into the reactor 1 building.
The arduous job of pumping water into the reactor building was also a Goliath task. Amidst rising radiation levels, the crew pumped water into the tanks of a fire truck, then drove it near the reactor building, pumped in the water and went back to fetch more water when the supply was running low. They had been doing this for many hours in a swamp left behind by the tsunami. Later on some crew members had succeeded in setting up a steady flow of water into the reactors. However, as fresh water supplies were running low, they resorted to sea water as a final desperate measure. While water pumping continued outside, people inside the central control room knew they had to open the vents. The pressure was building up inside the reactor building and an explosion was approaching. No remote operation of the venting valves were possible as there was no power to do so. So, someone must go inside! It was just like asking someone to commit suicide. But a team had volunteered to go in knowing the gravity of the problem at hand. For protection, they took some iodine tablets. And they wore protective suits. But isn’t that just like trying to disarm a bomb, wearing a bullet-proof jacket? But they took the risk for us. However, those brave men who entered the building to get a reading on radiation and to open the vents had to turn back. According to a report, they spotted a ghostly white cloud reaching out its ghastly arms to embrace them and had to temporarily give up the intended job. The ghostly cloud was an indication of the imminent meltdown. After this failed attempt, the government decided to evacuate the residents living in a 10km radius from the plant. As soon as the last resident boarded the last bus leaving the area, our brave group of men entered the building again, risking their lives once more to save the lives of millions. They had only flash lights to show them the way inside a dark wreck. They kept on walking, possibly praying for their loved ones and also for success in opening the vents. Sometime later, the dosimeters ordered them to stop. They were exceeding the 100 mSv/year dose (a nuclear plant employee’s annual dosage limit is 50 mSv and in emergencies it is 100 mSv). They had to turn back and return to the control room! Later on, they were able to open the venting valve with a portable air compressor hauled by a crane. However, it was too late. The reactor building was destined to explode.
The first hydrogen explosion at reactor 1 was reported in the late hours of 12th of March. Reactor 3 met its destiny with another hydrogen explosion on March 14th. Reactor 2, underwent meltdown on the 15th. That was the last of the triple meltdown after reactor 1 and 3.
Three brave men who worked at Fukushima NPP died in various accidents at the plant after 3/11. Some more had reportedly exposed themselves to high levels of radiation above the safe limit. Many more risked their lives. They are truly the finest modern day Samurai worriers of Japan. This is a tribute to those heroes!
The author wishes to credit the following sources for some information contained in this write up.
Special report on Fukushima, Asahi Shimbun 11/12
Special report on Fukushima, IEEE Spectrum 11/11
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You may contact the author at suntomoonblog@gmail.com
Himawari, the sunflower light
There’s no light that can beat sunlight. The amount of sunlight we receive in our homes has a direct relationship with the occupants’ mental health. Yes, the lack of sunlight can indeed stress your mind. In countries having a winter season where dusk can appear over the horizon quite earlier than in tropical countries, tenants prefer to bask in warm rays of the sun as long as possible in a day. Irrespective of the season, people living in lower floors of multi-storey apartments in bustling cities like Tokyo may have an additional worry that cuts off most of the sunlight they are entitled to; nearby buildings! One important factor that decides the price of real estate here in Japan is the amount of sunlight received in the apartment. Tenants may also run the risk of losing their fair share of sunlight whenever a new highrise building is erected near the house. Daytime use of electricity for lighting a house can lead to undesirable electricity bills due to the peak-time pricing methods employed here. So, how do we get the maximum out of freely available sunlight during daytime?
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- Himawari with twelve lenses
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- Optical fiber connections
About fifteen years ago, one Japanese company found a solution to the above problem through what is called a sunflower (Himawari in Japanese) light. A device with multiple lenses which is mounted on the roof-top of a building is made to track the direction of the sun and transmit the incident sunlight through an optical fiber. This transmitted light, free of harmful UV and IR rays is sent to indoor lighting appliances in rooms that receive limited or no sunlight. Himawari can save electricity while supplying natural light to otherwise dark interiors. Couple of days ago, I came across a Himawari installation at a friend’s apartment in Kyodo, which is shown in the pictures.
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You may contact the author at suntomoonblog@gmail.com
Tokyo’s Hi-Tech Parking
I stop at the entrance to the car park to pick up a ticket, the barrier opens as I take out the ticket from the dispensing machine. I park the car and go into the arrivals lounge at the Haneda airport for a pick up. Sounds like a typical, uninteresting parking experience? Read on and you will see why it’s not. Plane arrives, we meet and then head back to the parking lot. On the way I see a payment machine for parking inside the arrivals lounge with the notice, “Pay here and leave within 20 minutes”. Because it’s cumbersome to pay at the gate by lowering the glass and trying to find the slot to enter the money (and collecting the balance), I decide to pay here. Then we get in the car and drive towards the gate. I stop and start lowering the glass to insert the ticket. Voila! the gate opens. I still didn’t insert the ticket!! But I know I made the payment. How does the gate know that I payed inside the building? Is there something wrong with the gate? Should I drive through? Will the barrier pole come down thumping the car on the head? Should I call for assistance? Oh! then I start to imagine things. There must be a smart chip embedded in the card.The device at the gate must have sensed it’s ID and opened the gate for me. I turn on the light and start looking for a chip. No chip? No chip what so ever. It’s a plain card, like the one you use at the shopping mall. It’s not even plastic! I decide to take the risk and drive through as I see some head lights in the rear-view mirror. Thumpppp!! No, just kidding. The barrier pole stays fully raised and close as soon as I clear the entrance. Wow! how did that happen?
Then we decide to investigate by calling the airport parking assistance. Well, they tell us the simple technology behind it. It’s like this.
1. When entering the car park, a simple system registers the license plate and extracts the registration number using a camera. (This number is recorded in the ticket as well)
2. When paying at the machine in the building, the system notifies the device at the gate that a payment has been made for our license plate number
3. When exiting the car park, it checks the registration number on the license plate again. Ascertains the payment and opens the gate. No need to waste time at the gate!
Simple, isn’t it? Not rocket science, but a combination of available technologies. This is just one example of how the people in Japan think and make continuous, sharp improvements to existing systems in order to make our lives easy and fun.
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You may contact the author at suntomoonblog@gmail.com
International Robotics Exhibition 2011
A couple of days ago I wrote about the Tokyo Motor Show. Today I want to share with you a similar event that took place last month in Tokyo, the international robotics exhibition. I was looking forward to this event since August, mainly because I have a special interest in robotics and also because I am doing research in the field of evolutionary robotics. The exhibition was kind of a one horse race with almost 99% of the companies taking part being home-bred Japanese firms. No wonder Japan dominates the global robotics arena with so many big companies! Few foreign companies were present. Here and there we could see one Korean company and one or two European and American companies displaying their latest products. Many industrial robots of different sizes and functions were seen among other types of robots. To my disappointment, I saw only two humanoids in action, one surrogate from Yaskawa (smartpal) and another from a European company (Robosapien, the emotional bot). Oh! almost forgot to mention the miniature humanoid Kondo. There were many service robots from several companies, while parts suppliers and university laboratories also presented their latest products and research activities to the public. A notable absence? Honda! Although I wanted to see the Gen3 Asimo in action, Honda did not put up a show. There was also a stall by CyberDyne from Tsukuba to display their robotic suits (HAL and newer versions of it). Some pictures from the exhibition are posted below. I will upload some interesting videos (pictures don’t say much about the operation of these sophisticated creatures) to my homepage soon and post the link here.
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- A bird-like adaptive Denso robot sorting objects
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- Yaskawa’s surrogate Smartpal being remotely controlled by a human
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- Panasonic’s service robot coming to greet us
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- Nedo project’s service robot lineup (one Fujitsu Enon and one Yaskawa Smartpal visible)
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- Miniature humanoid Kondo
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- Human limb assistive suit by CyberDyne
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- Yamanashi University’s human limb assistive suit line-up
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- High precision pressure sensor by Fanuc
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- A Fanuc robot powered by IR-vision disassembling a small engine
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- A super-fast, high precision Fanuc robot picking nails
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- A Fanuc robot detecting faulty circuits using IR-vision
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- Two Kawasaki robots collaborating to move rice packs
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- A huge Fanuc robot moving train wheels
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- An adaptive Nachi robot sorting objects
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- More Nachi robots
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- A coil winding robot
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- More coil winding robots
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- A state-of-the-art automated assembly line from SUS (Standard Unit Supply)
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- A Mitsubishi robot and a Denso robot collaborating in object sorting
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- Not a robot, a highly detailed replica worth nearly one million JPY
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- Gundam had also found some time to pay a visit
Copyright (c) All Rights Reserved – dshwriter@suntomoon
You may contact the author at suntomoonblog@gmail.com
Tokyo motor show 2011
A much awaited event in the calendar of automobile enthusiasts here in Japan and elsewhere is the Tokyo motor show. This year, the show was held at Tokyo big sight from 2nd to 11th December, drawing large crowds who defied even the single digit temperatures and frequent showers. We could see many automobile manufacturers showcasing their new products as well as concept models under a common theme called “smart mobility city”. The focus was mainly green technologies, electric and fuel cell vehicles as well as the dream for a smart city enabled by the smart grid technology. Toyota was dominating the scene with their diverse product range, while many other Japanese and foreign manufacturers showcased equally competitive products. It was surprising to see the absence of Volkswagen and Suzuki, especially after their dispute over the stock holdings. Volkswagen owns 19% of Suzuki shares, which Suzuki wants Volkswagen to return after the alleged breach of the collaboration agreement by Volkswagen. Maybe the two partners could not see eye to eye in a global arena just after things fell out between them. Honda too didn’t put up a show to everyone’s surprise. Talking about no show companies, not even a single American automobile manufacturer were to be seen at the event. Foreign makers like Hyundai, Jaguar and Peugeot had also displayed their products. I am posting some pictures from the motor show below.
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- Future Delivery Van by Hino
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- Kobot’s in-house mobility
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- Daihatsu Box-like Van
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- Keio University’s Eight-Wheeled Car
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- Wireless Parking Charge
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- BMW Alpina
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- BMW i8 Concept
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- Mercedez Concept
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- Lexus LFA
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- Toyota Hybrid Sports II – GRMN
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- Hyundai Universe
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- NIssan GTR
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- Nissan Concept
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- Charging a Nissan Leaf
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- Nissan Leaf Nismo
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- Subaru Boxer
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- Subaru BRZ
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You may contact the author at suntomoonblog@gmail.com
Sporadic reports on radiation hotspots
More than seven months after the Fukushima disaster that ended up in a triple-core meltdown for the first time in our history, sporadic reports have begun to appear in the Japanese media about radiation hotspots in some parts of Tokyo. I saw the first such report about couple of weeks ago and got somewhat alarmed like everybody else. These radiation hotspots are not located close to each other, and they are sometimes as far apart as 60 km. Interestingly, most of these locations with high radiation levels are not so big in terms of land area. Few such places were reported in the Setagaya ward and alarmed residents had pressed the city officials to investigate the situation to find the reason for higher readings. One of the hotspots was found at an old house in Tsurumaki in the Setagaya Ward. Although everybody thought the radiation was from the crippled nuclear plant in Fukushima, which is more than 250 km away, the real reason was something else. Investigators found a stockpile of radium bottles believed to be nearly 50 years old, in the basement of the house. The previous landlord apparently supplied radium to wrist watch makers long ago and those leftovers were wreaking havoc with the Geiger counters in Tsurumaki (almost 3.5 mSv/h). All this time, this place was highly radioactive, but no one knew it was, until now. With the current nuclear crisis, many families had bought Geiger counters and scintillators, so these radiation hotspots that were not known before, are now getting the attention of the public. Another case similar to this was reported near a car park of a supermarket in Hachimanyama, just few kilometers from the old house in Tsurumaki. The officials dug the car park to find the culprit that was behind the 100 µSv/h reading and after digging for about 1 foot, they had found traces of Bismuth and Lead according to the Asahi Shimbun report on the incident. Bismuth and Lead are decay products of Radium-226. Further digging had led to the finding of another bottle suspected of having radium in it. Radium (half-life = 1600 years) was used as a self-luminous paint in the good old days (it’s still used in specialized areas like diving watch dials, medical treatment etc). However, many residents were relieved to know the absence of radioactive Cesium on both sites, a rough indication that the fallout from Fukushima did not reach those parts. The wind map after the 3/11 disaster (in fact after March 14th) suggests that the radioactive particles took a u-turn over Tokyo or just prior to entering Tokyo and the southern regions of Honshu.
Did the radioactive particles take a u-turn?
However, some parts of Tokyo and nearby prefectures had experienced the fallout up to some extent, as evidenced by the hotspots found in Kashiwa, just 60 km from Tokyo and the contaminated tea leaves in Shizuoka, about 170 kilometers south-west of Tokyo.
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You may contact the author at suntomoonblog@gmail.com
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