Month: March 2014

 

The Fukushima nuclear accident occurred at the Fukushima Nuclear Power Plant on March 11, 2011, comprising a series of incidents, such as explosions in the buildings housing the nuclear reactor, failures in refrigeration systems and release of radiation to the exterior, recorded as a result of the damage caused by the earthquake in eastern Japan.

-CAUSES:

 The Great East Japan Earthquake

Of magnitude 9.0 at 2.46 pm on Friday 11 March 2011 did considerable damage in the region, and the large tsunami it created caused very much more. The earthquake was centred 130 km offshore the city of Sendai in Miyagi prefecture on the eastern cost of Honshu Island (the main part of Japan), and was a rare and complex double quake giving a severe duration of about 3 minutes. Japan moved a few metres east and the local coastline subsided half a metre. The tsunami inundated about 560 sq km and resulted in a human death toll of over 19,000 and much damage to coastal ports and towns with over a million buildings destroyed or partly collapsed.

Eleven reactors at four nuclear power plants in the region were operating at the time and all shut down automatically when the quake hit. Subsequent inspection showed no significant damage of any form, from the earthquake. Fukushima Daiichi units 4, 5 & 6 were not operating at the time, but were affected. The main problem initially centred on Fukushima Daiichi units 1-3. Unit 4 became a problem on day five.

The Tsunami

-The Daiichi plant sit’s about 11 km apart from the coast, Daini to the south.

-550 Gal (0.56 g) was the maximum ground acceleration for Daiichi

-Daiichi units 2, 3 and 5 exceeded their maximum response acceleration design basis in E-W direction by about 20%. The recording was over 130-150 seconds. (All nuclear plants in Japan are built on rock – ground acceleration was around 2000 Gal a few kilometres north, on sediments).

-The original design basis tsunami height was 3.1 m for Daiichi based on assessment of the 1960 Chile tsunami and so the plant had been built about 10 metres above sea level with the seawater pumps 4 m above sea level.

-Tsunami heights coming ashore were about 15 metres, and the Daiichi turbine halls were under some 5 metres of seawater until levels subsided.

-The maximum amplitude of this tsunami was 23 metres at point of origin, about 180 km from Fukushima.

 

Sequence of Evacuation Orders Based on the Report by the Independent Investigation Commission on the Fukushima Nuclear Accident:

11 March 
14:46 JST The earthquake occurred.
15:42 TEPCO made the first emergency report to the government.
19:03 The government announced nuclear emergency.
20:50 The Fukushima Prefecture Office ordered 2km evacuation.
21:23 The government ordered 3km evacuation and to keep staying inside buildings in the area of 3-10km.

12 March
05:44 The government ordered 10km evacuation.
18:25 The government ordered 20km evacuation.

15 March
11:01 The government ordered to keep staying inside buildings in the area of 20-30km.

25 March
The government requested voluntary evacuation in the area of 20-30km.

21 April
The government set the 20km no-go area.

What Happened to The Plant:

Because the reactor pressure was higher than the capacity of the pumps in the fire extinguishing system, water could not be fed in properly from outside. While work for pressure reduction was repeatedly held up by power outages, the fuel rods in the reactor (Unit 1) became exposed, their temperature rose, and oxidation of the zirconium at fuel cladding tubes caused water reduction resulting in the generation of hydrogen. Radiation doses were also high, which further hampered work activity.

Hydrogen is noncondensable so the pressure within the containment vessels rose. To reduce the pressure in the containment vessels (and thereby prevent damage to them and maintain their containment function), gas was released from inside. As the pressure in the reactors and containment vessels fell, hydrogen collected in the top of the reactor buildings. On March 12 and 14 respectively, the hydrogen in Units 1 and 3 ignited explosively and the two reactor buildings were destroyed. The reactor pressure vessels and their containment vessels are housed within concrete 2 meters thick so they were not damaged. (The reactors did not explode. They shut down.) In Unit 2 there was an explosion in the bottom of the containment vessel, which damaged the reactor pressure vessel and the containment vessel.

 

Accident Resolution: Cooling by Injecting Water:

Water has being injected into the reactors to cool them. The most important thing for cooling the fuel and preventing the release of radioactive materials is to keep the fuel covered in water. Although the cooling method of injecting water and condensing the resulting steam is unstable, the external power supply has been restored so there is only a low possibility of failure to the extent that there would be long-term fuel uncover.

Restoration of the pump and power supply in Unit 2 is taking a long time because of the high radiation level. The contaminated water injected into the reactor flows from the reactor building to the turbine building and has a high radiation dose, and the pump and power supply are positioned in these buildings. The water injected into the unit was flowing from the pit in through a crack caused by the earthquake and into the ocean. The flow from the pit in Unit 2 has been stopped. Leaking and cooling can be resolved by returning the leaking water to the reactor and connecting a heat exchanger along the way to achieve stable cooling.

(The path to accident resolution was shown by TEPCO on April 17. Simultaneous measures include stable cooling of the reactor and spent fuel pool, the containment, treatment, and storage of contaminated water and its reuse for cooling, and the control of radioactive material.)

 

Radioactive releases to air

Major releases of radionuclides including long-lived cesium occurred to air, mainly in mid-March. The population Within a 20km radius Had been evacuated three days earlier. Considerable work was done to reduce the amount of radioactive debris on site and to stabilize dust. The main source of radioactive releases was the apparent hydrogen blast in the suppression chamber of unit 2 on 15 March. A cover for unit 1 reactor building has-been built and commissioned to more substantial businesses one for unit 4 is under construction. Radioactive releases in mid-August 2011 had reduced to 5 GBq /hr and dose rate at the plant from These boundary was 1.7 mSv/yr  less than the natural background.

Farmland Contamination

Just a year after the nuclear disaster, Japanese farmers were allowed to return to their fields near the plant. This despite government estimates that it could take as long as 40 years to clean up the farmland around the Fukushima plant. Despite claims that the area has been cleaned up, the farmers themselves know that they’re simply growing food stuffs in contaminated soil. Although all farm produce must be checked for the cesium level prior to shipping (below 100 becquerel is considered “safe”), the farmers refuse to eat it themselves and are stricken with guilt over selling it to their countrymen.

Seafood Industry Threatened

Toward the end of last year, U.S. scientists and wildlife specialists officially became worried about Fukushima’s impact on the fishing industry. As I’ve mentioned before, it’s all one big ocean. If a massive amount of contamination is dumped into the ocean on one side of the world, rest assured it will eventually make it’s way to the other. We saw this with physical rubble from the Japanese earthquake and tsunami, and the same currents are bringing the invisible contaminants as well. Fish, especially salmon, must migrate through the radioactive plumes coming off Fukushima before being harvested on North American coasts. Some believe this represents an eventual health crisis, and that it’s no longer safe to eat fish from the Pacific Ocean.

Radiation in U.S. Snow and Beach Sand

If you live in a landlocked state, you might think you’re safe from toxic fish and Fukushima fallout, but that’s not necessarily the case. Just days ago, snow falling in Missouri was found to contain double the normal radiation amount. No snow where you live? You’re not out of the clear yet. Early in the New Year, Infowars reported on a YouTube video that showed background radiation at a Coastside beach reaching over 150 micro-REM per hour. Health officials in San Mateo County confirmed the spike but remain ‘befuddled’ as to its cause.

 

 DISCLAIMER:

SOURCES:

http://www.world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Fukushima-Accident/

http://www.world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Fukushima-Accident/

http://es.wikipedia.org/wiki/Accidente_nuclear_de_Fukushima_I

This week on our hands-on class activity, once again using the NXT Lego robot, we created a generator. In this week’s activity the set up changed once again, this time the set up consisted of the following: 1 generator which contained a magnet inside which moved back and forth inside a coil of wire, then we had a voltage probe which provides the voltage being created through friction,  one Nxt adaptor, and at last the main key by which everything evolves around in all our hands on activity or atleast for now, the Nxt robot.

Bit different from the past couple of week’s, this time the procedure was different, in this lab we where the ones who had to shake the generator, a tube which had a magnet inside and that by traveling back and forth through  the coil wires we would create changes in the magnetic flux, and by soo, creating energy.

 

 

Now the instructions where the next :

-Shake the tube at a particular rate.

-Count the number of shakes in the data collecting interval (set to 30 seconds)

-Calculate in Excel the sum of the squares of the voltages (SSV’s) (the voltage is logged after each second)

-Plot the SSQV’s as a function of # of shakes and fit the result to a linear curve

At first me and my team-mate where more than frustated hahah, we had to figth around with our computer for 20 or so minutes hahahah, until we finally where able to open the virtual lab, once we had all the tecnical stuff down we started with our 1st run, without shaking it we let the computer and robot record the energy being created without us creating any friction by shaking the generator. From then on we just kept escalating from a lower range of shakes in the 30 seconds we had, to the hisghest range of shakes in our last run. (here is the data we recolected)

               shakes     Sum of squares
run 1            0           0.405376545
run 2          40          102.0386884
run 3          70          209.9912604
run 4         120        298.7808609
run 5         145         370.2757052

 

By looking at the table above, we can notice how by raising the number of shakes in 30 seconds (shaking it faster), the sum of the squares was raised too. For thouse of you who migth not know what the sum of squares is, its nothing complicated, its just the addition of all the waves and different voltages created by shaking the generator in that 30 second time period.

Overall, this experiment  testing Faradays Law was pretty interesting and fun. It’s main objective was to understand that changes in the magnetic environment of a coil of wire will cause voltage to be induced in the coil,  which was more than proved since we could notice that  the greater the change in the magnetic flux due to the shakening of the generator,  the greater the currents and voltages been generated where, and that either small or large there was always something produced by the movement.

STIRLING MOTOR

HISTORY & DEVELOPMENT

The Scottish religious Robert Stirling (1790-1878), invented this engine in 1816. Another important contribution in the development of the automotive machine handed the French genius Sadi Carnot (1796-1832), who was the first scientist to make a theoretical interpretation of the operation of heat engines, establishing the physical principles involved in their movement. This theory allowed us to understand more clearly the phenomenon that allows the Stirling produce motive force.

Originally conceived in 1816, was created by Robert Stirling as the first engine designed to rival the steam engine, due to high efficiency, if it is compared with steam engines, besides its easy to be applied to any source heat. That’s until the electric and internal combustion engines replaced Both at the turn of the 20th century. Stirling engines have only been used in very Specialized applications ever since, for example, in the 1960’s a tiny Stirling engine was developed to power an artificial heart and today They are Commonly used To provide the cooling for infrared guidance systems in missiles. However, With the Increased focus on Environmental Concerns and our quest for cleaner, more efficient power sources, the Stirling engine is back in the spotlight as a feasible power source for wide-scale use.

HOW IT WORK’S

The hot air Stirling engine uses a fixed heat source for heating air in your cylinder. It can be considered external combustion, as it requires no burn fuel therein and to operate, does not transfer heat to the environment. It’s movement is due to differences in air pressure between the warmer and cooler portion. The central mechanism of a Stirling consists of two pistons / cylinders, one for dissipating heat and displace warm air into the cold section (vice versa). In practice this cylinder functions as heat exchanger and is called regenerator. The other piston delivers power to apply torque to the crankshaft.

Every Stirling engine has a sealed cylinder with one part hot and the other cold. The working gas inside the engine (which is often air, helium, or hydrogen) is moved by a mechanism from the hot side to the cold side. When the gas is on the hot side it expands and pushes up on a piston. When it moves back to the cold side it contracts. The two piston type Stirling engine has two power pistons. The displacer type Stirling engine has one power piston and a displacer piston.

Displacer Type:
The displacer type Stirling engine is shown here. The space below the displacer piston is continuously heated by a heat source. The space above the displacer piston is continuously cooled. The displacer piston moves the air (displaces the air) from the hot side to the cold side. When the engine pressure reaches its maximum because of the motion of the
displacer, a power piston is pushed by the expanding gas adding energy to the crankshaft.

Two Piston Type:
The two piston type Stirling engine is shown here. The space above the hot piston is continuously heated by a heat source. The space above the cold piston is continuously cooled. But its during the expansion part of the cycle where the engine gets its power.

 

MODERN DAY USES

Military uses:
A Swedish army submarine is Equipped with Stirling engines for its auxiliary electrical production in order to Provide the vital functions in the event of unavailability of the main source. Its silence of operation is a major asset In this application. In the same context, the Australian navy ADOPTED Also have it for a 3000 tons displacement submarine.

Spatial domain:
Some satellites get energy through a Stirling engine. The efficiency is high Particularly Considering the great Differences in temperature. The hot source Consists of radioactive isotopes. The use of radioactive elements is not very ecological, it presents Risks at the time of the take-off of the rocket. The justification comes owe owing to the fact That solar panels can be dirtied or be destroyed in Un certain zones of space, as near Mars.

Domestic uses:
Small installations were developed in order to function in cogeneration: electricity supply and dwelling heating. One chooses fuel (oil, wood, wood pellets…) to make electricity and to heat a house. During certain periods, it is possible to sell excess electricity if one is connected to the grid.
Some pleasure boats are equipped like that.

Generators :
After the second world war, Philips developed and marketed the generator which group had a power of approximately 150 Watts.

Cryogénic domain :

The reversibility of the Stirling engine is used in order to produce cold in an industrial way. Its efficiency is then excellent. In this type of operation, described on this site in the page “Stirling coolers”, we provide mechanical energy to the engine. In fact, we transfer calories from the cold source the hot source, like in a domestic refrigerator. This mode of operation is so efficient that we use this type of installation to liquefy certain gas.

-Paradox : use sun for generating electricity by a Stirling engine, then this electricity drives a Stirling engine for making cold. How to make ice under a blazing sun, and all thanks to him!!

-At last i would like to show you this 10 top modern uses of a stearling motor as a curiosity, which i found to be pretty interesting:

Picture gotten from —>   http://www.discoverthis.com/article-stirling-engine-top10.html

 

WHAT’S FOR THE FUTURE?

A very promising use of Stirling engines is cogeneration, where they produce both heat and electricity for homes.  If the excess heat produced by Stirling engines was directly used to replace furnaces and water heaters in homes, this would yield a dramatic increase in energy efficiency.  This is especially useful for “off-grid” applications where people are too far from power plants to get electricity over cables.  Many companies are currently looking into using Stirling engines to replace the current systems in refrigerators.  Driven in reverse, Stirling machine pistons manipulate the contained gas to affect temperatures outside the machine. Stirling engines would use as much as 50% less electricity and even more importantly, they do not require CFCs for cooling.  One company, Global Cooling, has developed a solar-powered Stirling refrigerator that could be used in the developing world for keeping food and medicine cool.

Researchers at Los Alamos are currently working to design a Stirling engine that would cool the gas so that it becomes a liquid, which would make it much easier to transport in conventional pipelines.Their new engine uses intense acoustic energy instead of pistons for the heat transfer.  Constructed of welded pipes, the engine is remarkably simple, efficient, and inexpensive.

Perhaps the greatest challenge facing Stirling engines is the popularity of internal combustion engines.  Designers of Stirling engines will need to offer incredible advantages to be able to attract manufacturers aways from gasoline engines. In addition, new materials need to be developed for the hot parts of the engine; this is the part that is most likely to wear out. Once they are mass produced, the cost of Stirling engines will come down greatly and their popularity should increase.

 

 

PELTIER DEVICE

PELTIER HISTORY

Early 19th century scientists, Thomas Seebeck and Jean Peltier, first discovered the phenomena that are the basis for today’s  thermoelectric industry :

-Seebeck found that if you placed a temperature gradient across the junctions of two dissimilar conductors, electrical current would flow.
-Peltier, on the other hand, learned that passing current through two dissimilar electrical conductors, caused heat to be either emitted or absorbed at the junction of the materials.

It was only after mid-20th Century advancements in semiconductor technology, however, that practical applications for thermoelectric devices became feasible. With modern techniques, we can now produce thermoelectric “modules” that deliver efficient solid state heat-pumping for both cooling and heating; many of these units can also be used to generate DC power at reduced efficiency. New and often elegant uses for thermoelectrics continue to be developed each day.

PELTIER STRUCTURE

Looking at the figure, we can see that practically two semiconductor materials, include one with and one with N channel P channel, linked together by a copper foil.
If in the N side of the material feeding the positive polarity on the side of the material P the negative polarity is applied, the copper plate cools the top while the bottom heat.
If in the same cell, the power supply polarity is reversed, that is, applied on the side of the material N negative polarity and on the side of P positive material function heating / cooling is reversed top heated and the lower cooling. It is, therefore, static heat pump that requires neither gas nor moving parts. Physically a Peltier element module 1 mm cubic blocks are connected electrically in series and thermally in parallel.Today, they are solidly constructed and have the size of a quater. Semiconductors are made ​​for Tellurium and Bismuth type P or N (good conductors of electricity and heat) which facilitate the transfer of heat from cold to hot by the effect of a direct current side.

PELTIER THEORY

When DC voltage is applied to the module, the positive and negative charge carriers in the pellet array absorb heat energy from one substrate surface and release it to the substrate at the opposite side. The surface where heat energy is absorbed becomes cold; the opposite surface where heat energy is released, becomes hot. Reversing the polarity will result in reversed hot and cold sides.

 

CURRENT DAY USES OF THE PEILTER DEVICE 

-Currently, one of its most common uses is as part of the CPU cooling computers.

-Board control Refrigerator: the Peltier module for cooling booths telecommunications network and dashboards within the factories are used.

–Small sump constant temperature: In the experiments of culturing microorganisms is required to control the temperature near the body temperature and the ambient temperature. The precise temperature control near ambient temperature with cold hampers or heating facilities, the best thing is the Peltier module.

-Milk cooling: Recently established machines coffee and soft drinks are, with increasing free sites beverage services in different types of restaurants. This machine coffee service has put a milk cooler wearing a Peltier module. It may take 2-4 packs of 1 liter milk and keep it cold.

-In the field of air conditioning there are air conditioning equipment that control temperature and humidity equipped with compression refrigerators which use refrigerant fluids based on compounds of fluorine and chlorine in greater or lesser extent that attack the ozone layer.

-They have also developed air dehumidification equipment employing chemical absorbers and compression equipment generally of large dehumidifier power.The presented technology involves passing aire from a room , residence, etc.., Drawn by a fan through some cold packs, which are cooled by Peltier effect, collecting the condensed water in the system at a lower tray. It is very suitable for controlling moisture in humid climates, which eliminate noise and vibration, avoiding the moving parts of the compressor that carry current dehumidifiers and refrigerants, as potential environmental contamination compact

 

Problems related to Peltier cooling

-The power usage and high power dissipation are the biggest problems related to peltier cooling. In the days of first-generation Pentium CPUs, readymade peltier/heatsink combinations were widely available, which could be installed and used just like a regular heatsink. For today’s CPUs having a power dissipation of over 100W, building a Peltier CPU cooler using just a peltier element and a heatsink is quite a challenge, and ready-made peltier coolers are scarce and expensive. With such coolers, over 200W of heat may be dissipated inside the case. The resulting cooling system will be expensive to run, due to its high power usage, and not very eco-friendly. The large power dissipation will require powerful (and thus loud) fans.

-Also, keep in mind that if the cooling of the peltier element fails (e.g. fan failure or pump failure in case of watercooling), the results will be more disasterous that if a conventional cooling system fails. Even if your CPU has a thermal protection that will cause it to shut down if the temperature gets too high, the peltier element may still kill it by continueing to heat it up long after it has shut itself down.

-Another problem related to peltier cooling is condensation. Since it is possible to cool components below ambient temperature using peltier elements, condensation may occur, which is something you’ll definitely want to avoid – water and electronics don’t mix well. The exact temperature at which condensation occurs depends on ambient temperature and on air humidity

 

Advantages of Peltier elements

-After having focused on problems related to Peltier cooling, let’s not forget about their biggest advantage: They allow cooling below ambient temperature, but unlike other cooling systems that allow this (vapor phase refrigeration), they are less expensive and more compact.Peltier elements are solid-state devices with no moving parts; they are extremely reliable and do not require any maintainance.

 

—-SOURCES—

www.stirlingengine.com

en.wikipedia.org

www.stirlingshop.com

www.heatsink-guide.com

Geothermal energy

Energy that can be obtained by utilizing the heat from inside the Earth.
The term “geothermal” comes from the Greek geo (‘Earth’) and thermos (‘heat’), literally ‘heat of the Earth’.
This internal heat warms up the deeper water layers: at the rise, of the hot water or steam  produce manifestations such as geysers or hot springs,
used for heating since the time of the Romans. Today, advances in drilling and pumping methods allow to exploit geothermal energy in many parts of the world.

It can be considered that there are two types of geothermal reservoirs, which could be called:
-Hot water
-Dry

 

Hot Water Reservoir

The forming fountains, have been take advantage of since ancient times as hot springs. Initially they could be used to cool the water before use, but they often have relatively low flow rates.
As for the one’s underground, reservoirs of very hot thermal waters anywhere from little to average depth, serve to capture the heat from inside the earth. The hot water or steam  can flow naturally pumped or pulsed flow of water and steam.In most cases the operation must be made with two wells (or a pair number of wells), so that one obtains the hot water and the other is re-injected into the aquifer, having cooled the flow obtained.

Dry Deposits

In this case, there is an area underground, not too deep, with dry, hot materials or stones . Water is injected by a perforation and recovered, on the other hot, the heat is used, by means of a heat exchanger and is re-injected as previously mentioned.

 

-ICELAND-

Is a country located in the northeast corner of Europe.Its population is estimated at 320,000. The great grace of Iceland is that given the wide range of natural resources, an about 94% of its energy comes from renewable sources (mainly hydro and geothermal).

Iceland sits on one of the world’s greatest geothermal hot spots and a recent discovery of underground Lava has Increased the amount of geothermal energy harnessing the country could be. Iceland gets 94 percent already of its electricity from the renewable resource, and expects to be fully powered by renewable energy by 2050.

In 1940, 85% of Iceland’s energy came from coal and oil. Now 85% of the energy comes from underground volcanic water (geothermal source). Iceland currently has the largest geothermal heating system in the world, and other countries are interested. With most of its energy needs met, and having it been a success on the generation of clean energy, Iceland has made countries like the UK interested in buying this type of energy from them.

A few months ago both negotiated the construction of an underwater cable that would pump through almost 1500 kilometers geothermal energy from Iceland to the UK. Such a cord will not be cheap to build, but in the long run, Iceland would have a really nice source of revenue and Europe would not have an abundant source of clean energy.

The giant undersea cable is being proposed by Landsvirkjun, Iceland’s biggest energy company. If built, the cable would be between 1000 and 1600 kilometers long and export 5.000.000.000 de kWh of power each year. That’s between $350 million and $448 million worth of energy–enough to cover the consumption of 1.25 million homes, according to the AFP. Currently, Iceland’s economy is largely dependent on fishing. But if it is completed, the undersea cable could trigger the growth of a major new economic sector in Iceland: exported energy. With a growing demand for clean power across Europe and the rest of the world, that could make Iceland’s resources a hot commodity.

 

Iceland’s Biggest Plant-

It’s the Hellisheidi geothermal plant, the newest built in Iceland which has an installed capacity of 303 MWe (electrical) and 130 MWt (thermal) capacity. Iceland has an installed capacity of 665 MW – geothermal energy – so only this plant, accounts for almost half of total installed capacity. Here you may see a wonderful diagram, with the operations of each of the constituent elements, or by accessing the following link, you’ll be able to see and interactive as well as descriptive virtual tour of all its components

www.or.is/vinnsluras/

 

SOURCES-

www.sciencedaily.com

www.ecogeek.org

www.fastcompany.com