BACK END NUCLEAR FUEL CYCLE

"radioactive waste will last billion years and it is unfair to gain benefit from nuclear today and leave the next generation to deal with the nuclear waste"

>>The above issue may be unfair to present generation, but we future generation of Malaysia are ready to face any manner dealings in order to save the planet and secure upcoming generation. It also can be said as cycle of life where there is usage need to do replacement and backup the spent used material/fuel......

Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor (usually at a nuclear power plant) to the point where it is no longer useful in sustaining a nuclear reaction.

Long-lived radioactive waste from the back end of the fuel cycle is especially relevant when designing a complete waste management plan for SNF. When looking at long-term radioactive decay, the actinides in the SNF have a significant influence due to their characteristically long half-lives. Depending on what a nuclear reactor is fueled with, the actinide composition in the SNF will be different.

An example of this effect is the use of nuclear fuels with thorium. Th-232 is a fertile material that can undergo a neutron capture reaction and two beta minus decays, resulting in the production of fissile U-233. The SNF of a cycle with thorium will contain U-233, an isotope with a half-life of 160,000 years. Its radioactive decay will strongly influence the long-term activity curve of the SNF around 1,000,000 years. A comparison of the activity associated to U-233 for three different SNF types can be seen in the figure on the top right.

The burnt fuels are Thorium with Reactor-Grade Plutonium (RGPu), Thorium with Weapons-Grade Plutonium (WGPu) and Mixed Oxide fuel (MOX). For RGPu and WGPu, the initial amount of U-233 and its decay around 10E5 years can be seen. This has an effect in the total activity curve of the three fuel types. The absence of U-233 and its daughter products in the MOX fuel results in a lower activity in region 3 of the figure on the bottom right, whereas for RGPu and WGPu the curve is maintained higher due to the presence of U-233 that has not fully decayed.

The use of different fuels in nuclear reactors results in different SNF composition, with varying activity curves.

Nuclear reprocessing can separate spent fuel into various combinations of reprocessed uranium, plutonium, minor actinides, fission products, remnants of zirconium or steel cladding, activation products, and the reagents or solidifiers introduced in the reprocessing itself. In this case the volume that needs to be disposed of is greatly reduced.

Alternatively, the intact Spent Nuclear Fuel (SNF) can be disposed of as radioactive waste.

"WE ARE THE YOUNG GENERATION, WE ARE THE YOUNG MALAYSIANS,IT IS OUR FUTURE WE ARE TALKING ABOUT, AND WE WANT A SUSTAINABLE,GREEN,BEAUTIFUL, SECURE PLANET THAT WE CAN SHOW OUR OWN CHILDREN WITH OUR OWN EYES INSTEAD OF JUST THROUGH PICTURES IN HISTORY BOOKS-WE WANT FUTURE AND LET US MANAGE THE WASTE"

BONUS ASSIGNMENT( NUCLEAR SAFETY )

do u think it is safe to build a nuclear power plant in malaysia?????

>>>>>The answer for sure yes.
>>Because nuclear power plant equiped with the most advanced engineered safety system  that can support in any type of accident no matter minor or major problem. Due to that, it is completely safe to build a NPP power plant in MALAYSIA....
>>Present nuclear plant is designed with more safety system consideration after the 3 mile island & chernobyl accident. So in order to that, the goverment decided to consider and approve for the power plant placement somewhere near to seaside and far from housing area. Mostly accident happened so far is due to man made mistake in it clearly stated that chernobyl is due to some unauthorized experimental case causes major reactor unbalance and uncontrolable.
>>if the nuclear power plant cooling system uses sea as cooling medium, this will cause some effect to aquatic system where the sea temperature goes up and from normal to abnormal temperature can affect the marine lifes. The reactor building is designed with two compartment which each made of thick wall where it can protect from radiation release.
>>The building design is completely safe from any external plane crash and also internal reactor failure.
Nuclear power plant uses low enriched uranium fuel,so it is not ment to explode otherwise only can melt the core due to control rod failure or other causes.
>>Considering natural disasters, so far malaysia dont have any hurricane or earth quake disaster and it is completely safe to build in malaysia....
>>NUCLEAR POWER PLANT for MALAYSIA is extremely good solution to replace coal and hydro due to cost and other factors. MALAYSIA is approaching go green technology to transform entire nation to CO2 emission free....

Nuclear Safety

Do you think it is safe to build a nuclear power plant in Malaysia?


First of all, think about radiation. We were exposed to radiation regularly in our daily life.
Below is some information about common sources of radiation the we were exposed to.

So, nuclear suppose not a big deal since we are already exposed to great amount almost to 3 milisievert (msV) per year! Beside, the nuclear containment itself is already safe as it has the condition of being protected against any types or consequences of failure, damage,error, accident, harm or any other event which could be considered non-desirable. Even an airplane crash still couldn't leak the nuclear fuel from bursting out!

Next is a the position of the building site that next to the ocean. Will it affect the fish?

The answer is yes, it will affect the fish because the water discharge from the cooling system is 25 ⁰C warmer and it will effect the ecosystem. But anyway, the was the past generation of Nuclear Power Plant(NPP) cooling system layout. 

The next generation of NPP cooling system layout is the Closed Cooling System. The closed cycle cooling system would reuse the same water over and over. Once the water is cycled through the cooling system, it would be sent to a cooling tower where it would cool off and be used again. Some water is lost through evaporation in the closed cooling system, so the cooling system would still have to intake some water. The closed cooling system would cut water usage by up to ninety-five percent (95%) and significantly reduce damage to the ecosystem.

1 of NPP illustration take from "The Simpson"

Then, this topic goes further to the exclusion area boundaries. Most of our people, or the issues being brought is the Not-In-My-Backyard (NIMBY) issues. As being told before, nuclear power is safe and green. It doesn't affect the nature with it's low level radiation, no CO2 emission, an alternative for the renewable, last long cycle and much more. So, why we need to worry? How about the factory that being build near to the housing area that they are suppose to be 10 km further from it? The factory itself is already emits too much of CO2 with its dark smoke and the people don't mind? Or because it was a food factory, so people doest need to worry? Here we want to remind again, nuclear power plant emits no CO2 or any other greenhouse gases! It doesn't matter wither its near to your house or not, it is totally GREEN. Beside, doesn't it looks cool when 1 of the nuclear reactor just near to your house since it is near to our country like we seen in "The Simpsons"? Haha.. 

This topic could go on further and further but i would like to end it for now because it will make this post too long and reader are lazy to read long post. We will make a new post to continues this topic if its get any hit. Here's is some word that being quoted that we think it is interesting:

"Existing nuclear plants are cash cows for utilities. Although fairly expensive to build, nuclear plants are much less expensive to operate than oil or gas plants and slightly less expensive to run than coal-burners. Also, they're non-polluting." said by Forrest J. Remick, Professor Emeritus of Nuclear Engineering.

The People Who Made Our Group Happen

One of The Safety Mechanism for a Nuclear Power Plant (Core Catcher)

Core Catching
One of the worst accidents in American nuclear history occurred in 1979 at Three Mile Island, located in Pennsylvania. As a result of a series of mechanical and human errors, the reactor core containing the nuclear fuel, which is normally covered in cooling water, was actually uncovered for an unspecified period of time. Before the flow of water could be restored, about half of the nuclear fuel had melted.
The diagram from the Nuclear Regulatory Commission’s website shows what the reactor core “theoretically” looked like immediately after the meltdown. Even though half of the nuclear fuel in the reactor vessel was reduced to a molten mass, none of it escaped the reactor vessel or the containment building, thus avoiding a much more serious disaster.
But what would have happened if the nuclear fuel actually did melt through the bottom of the reactor vessel? At least one report, titled “The President’s Commission on the Accident at TMI,” chaired by John G. Kemeny, theorizes that the nuclear fuel still would have been contained inside the containment building that surrounds the reactor vessel. This commission, also known as the Kemeny commission, was formed two weeks after the TMI accident (at the order of the President) and was tasked with investigating the events that unfolded at TMI. The report theorizes that if the molten core had melted through the reactor vessel, there is a high probability that the containment building and the hard rock on which the containment building was built would have been able to prevent the escape of a large amount of radioactivity.
Long before the TMI accident, nuclear plant designers were already placing systems below the reactor vessel in case of just such an emergency – the melting of the nuclear core. These systems are sometimes called core catchers, since they are designed to catch the flowing molten core that has melted through the metal reactor vessel. These systems continue to evolve and grow more complex as new materials are discovered and researched.
For example, U.S. Patent No. 4,036,688, issued on July 19, 1977, and owned by the United States government, describes a system where the melted core is funneled onto magnesia and graphite bricks layered below the reactor vessel.
As can be seen in the diagram from the patent, a molten reactor core melts through the bottom of the reactor vessel (10) and flows into a funnel (14) made of carbon steel. The funnel (14) directs the molten core to the core debris receptacle (16), whose primary purpose is to prevent the molten core from forming a geometry that would result in a critical mass, resulting in an unwanted fission chain reaction.
The core debris receptacle (16) includes a center dome (24), made of blocks of alumina, as well as tantalum rods (26). Both tantalum and alumina have high melting points and are highly neutron absorbent. The center dome (24) disperses the molten core so that it spreads out over a large surface area thus preventing the formation of a critical geometry. Although the blocks making up the core debris receptacle (16) will reduce nuclear fission reactions in the molten debris, they will eventually melt and combine with the molten debris as it flows into the bed (18) area. The bed (18) contains bricks of magnesia which are designed to melt and mix with the molten core in order to further dilute the amount of nuclear fuel in the molten debris.
The walls of the bed (18) are lined with a layer of heat-resistant graphite blocks (30), which have cooling pipes embedded in them (not shown in the diagram). As the molten debris eventually flows toward the graphite blocks (30), it solidifies as it is cooled by the fluid flowing through the pipes.
Another core catcher system is described in U.S. Patent No. 4,113, 560, issued on September 12, 1978, and assigned to Massachusetts Institute of Technology. As can be seen in the diagram from the patent, a bin (7) located beneath the reactor core (1) contains a bed of graphite particles (6). Since graphite dissipates heat rapidly, the molten core would initially be cooled as heat is transferred from the molten core to the graphite particles. As the molten core begins to cool, it begins to solidify and flows more slowly through the bed of graphite particles (6). The patent indicates that the molten material would flow through the graphite particles at a rate of about a foot per hour.
Without intervention, however, the molten material would eventually flow to the bottom of the bin (7) and melt right through it. For this reason, the system also includes an overhead spray (9) combined with a bottom drain (10) in order to circulate cooling water through the particle bed (6). The water could also contain boron, a neutron absorber, which impedes any fission chain reaction in the molten material as it cools and hardens.
Another core catcher design is described in U.S. Patent No. 4,464,333, issued on August 7, 1984, and assigned to Combustion Engineering, Inc.
The diagram from the patent shows the bottom of the reactor vessel (14) enclosed inside concrete walls (12) of the containment building (16). Below the reactor vessel (14) is an array of vertically oriented water-cooled tubes. Pressurized water flows into the array through the inlet tube (18), then flows through the vertical cooling tubes before exiting via the outlet tube (30). The exterior of the vertical tubes are coated with a heat-resistant material, such as a ceramic or graphite matrix to resist melting from the heat of the molten core.
The inside of the vertical tubes are coated with a neutron absorbent material in order to prevent the neutrons emitted from the molten fuel from being reabsorbed by the fuel, thus preventing a sustained fission chain reaction. The water flowing out of the array via the outlet tube (30) is directed to a heat exchanger (e.g., such as cooling towers) located outside of the reactor containment vessel (16).
Another core catcher design is described in U.S. Patent No. 4,643,870, issued on February 17, 1987, and assigned to the Department of Energy. The diagram from the patent depicts a core meltdown situation, where the core debris (46) has melted through a hole (44) in the bottom of the reactor vessel (34). The core debris (46) comes to rest on a 3 foot thick metal basemat (28) that extends 200 feet outwards from the wall of the reactor vessel (34).
The long length of the basemat (28) helps to dissipate heat transferred to it from the core debris (46). Underneath the basemat (28) are several layers of sand and gravel (32a-d). The top layer (32a) is a 1 foot layer of fine sand, followed by a 1 foot layer (32b) of course sand, followed by 4 foot layer (32c) of fine gravel, followed by a 6 foot layer (32d) of coarse gravel. Two sets of perforated pipes (50, 52) runs through the layers of sand and gravel. One of the pipes (52) carries cooling water to the heated area, which quickly turns the water to steam. The steam is then carried away by the other pipe (50), and is vented some distance from the reactor vessel. Metal pilings (30), extending downwardly and outwardly from the bottom of the reactor, supports the reactor vessel during a meltdown condition. The metal pilings (30) also absorb a substantial amount of heat which then travels down the length of the metal piling (30) away from the reactor vessel.
Another core catcher design is described in U.S. Patent No. 6,658,077, issued on December 2, 2003, and assigned to Areva NP GMBH. The diagram from the patent shows the bottom of the reactor vessel (8) with the core catching system below it. If the conditions for a core meltdown are present, pressurized water held in the storage tank (9) is immediately pumped though a coolant line (5) and is disbursed through multiple coolant lines (4). The water then fills a porous layer (3) made of porous concrete and/or ceramic, which may also contain particles of steel or iron. A sealing layer (7) made of plastic or metal encases the porous layer (3) so that the water remains pressurized once all the cavities of the porous layer (3) have been filled. A layer of concrete (6) having a low melting point sits on top of the sealing layer (7). The purpose of the layer of concrete (6) is to melt and mix into the molten core so that when the molten mixture subsequently melts through the sealing layer (7) and comes into contact with the water in the porous layer (3) the molten mixture is immediately solidified, fragmented and cooled.
A complex core catching system is described in U.S. Patent Publication No. 20090116607, issued on May 7, 2009, assigned to the Korea Atomic Energy Research Institute.The system includes a molten core retention tank (20) situated below the reactor vessel (10). A cooling water storage tank (40) and a compressed gas tank (30) is connected to the retention tank (20) through a section of piping called the mixer (50). In the event of a core meltdown, a valve (41) opens and water begins flowing by gravity from the water storage tank (40). At the same time, a valve (31) opens releasing the inert gas from the gas tank (30), which then mixes with the water in the mixer (50) portion of the piping. The water cools the molten material in the retention tank (20), while the inert gas prevents a possible steam explosion caused by the water suddenly coming into contact with the hot molten material.
Because all of the components shown in the diagram are enclosed in a reactor containment building, the steam produced from the water contacting the molten core (left-hand side of the diagram) will begin to condense on cooler surfaces. For example, water is likely to condense on the outer surface (1) enclosing the water storage tank (40) - as can be seen on the upper right-hand side of the diagram. As water condenses, it will flow through a filter (61) and into an intermediate storage tank (60). This tank (60) refills water depleted from the water storage tank (40) through piping (62) connecting the two tanks. This ensures an adequate supply of cooling water to remove heat from the molten core in the retention tank (20).
Fortunately, no core catching device has actually been utilized in an operating reactor plant. Most nuclear plants have layered protection systems in place that can quickly determine if a dangerous conditions is approaching and prevents it. The core catching mechanisms are meant to be the very last line of defense when these systems, for some reason, fail. However, the lack of actual physical testing of these core catchers caused concern in the report by the Kemeny commission.

nuclear safety (summary)

NUCLEAR SAFETY

it is says that the nuclear reactor will have the following secured layer.,

1st layer of defense is the inert, ceramic quality of the uranium oxide itself.
2nd layer is the air tight zirconium alloy of the fuel rod.
3rd layer is the reactor pressure vessel made of steel more than a dozen centimeters thick.
4th layer is the pressure resistant, air tight containment building.
5th layer is the reactor building or in newer powerplants a second outer containment building.

safety system are take into consideration very-very seriously so the nuclear power plant accident shouldnt happen again. if any on eof the country lead to nuclear reactor blow up, melting core, with immediate effect entire nations NPP will  be terminated. so as a engineer, technician and others are very concerned about safety system.

Nuclear4malaysia video blog project ( latest updated )

The video blog project edited by harii and nuclear4malaysia team and uploaded on youtube with the
following URL :

http://www.youtube.com/watch?v=AtBBb0ctSgo

Recap of Class 19 /10/2010

- Of the composition of spent fuel 95% is Uranium and only 1% is plutonium
- There are 350 nuclides identified as fission products, which are all Beta
and gamma emitters.
- Half life of fission materials vary from seconds to 100’s of years
- After usage the nuclear reactors produce waste known as spent fuel which if processed using the rights methods could be recycled and use again.
- Some of the methods of Irradiation Phenomena :
• Full Swelling
• Densification
• Formation of Hydrides
• Pellet and Cladding Iteration (PCI)
- The fuel pellets are pressurized with Helium so that if there is a breach in the form of a crack on the cladding body, the coolant can get into the fuel pellet storage and wash away radioactive material into the open loop, this are some of the safety precautions taken.
- Waste storage at a nuclear power plant can either be in the form of a wet pond or a dry pond.
- Also known as cooling ponds there are filled with water which also contain boron and cadmium, known as neutron poison.
- Reactor fuel is made from uranium and recycled plutonium
- This reactor fuel is a mixture of UO2 and PuO2, which is a mixed oxide fuel known as MOX
- Depleted or natural Uranium is use to dilute Plutonium so that it can be used again showing that there is a least of waste product produces.
- Reprocessing Uranium saves up to 84 tonnes.
- There has never been any significant accident in transporting fuel throughout the 40 years of nuclear power history.
- A Generic Flask- LWR Fuel is used to transport fuel, and its built to withstand the highest safety standards with exceptional durability, you can Google generic flask to find out furthermore.
- Type of packages chosen depends on the transported material (solid or liquid)
- These are some of the packages used to transport material
• Excepted packages (no significant hazard)
• Industrial packages
• Type A (design to withstand major accidents)
• Type B ( design to withstand severe accidents/ attack)
• Type C (as above)

People's Perception About Nuclear Power

As be assigned to us, we need to conduct a video of people's perception about Nuclear. Below is the video, enjoy:

ENRICHMENT METHOD

Enrichment methods

Isotope separation is difficult because two isotopes of the same elements have very nearly identical chemical properties, and can only be separated gradually using small mass differences. (235U is only 1.26% lighter than 238U.) This problem is compounded by the fact that uranium is rarely separated in its atomic form, but instead as a compound (235UF6 is only 0.852% lighter than 238UF6.) A cascade of identical stages produces successively higher concentrations of 235U. Each stage passes a slightly more concentrated product to the next stage and returns a slightly less concentrated residue to the previous stage.

highly enriched uranium

yellow cake

There are currently two generic commercial methods employed internationally for enrichment: gaseous diffusion (referred to as first generation) and gas centrifuge (second generation) which consumes only 6% as much energy as gaseous diffusion. Later generation methods will become established because they will be more efficient in terms of the energy input for the same degree of enrichment and the next method of enrichment to be commercialized will be referred to as third generation. Some work is being done that would use nuclear resonance; however there is no reliable evidence that any nuclear resonance processes have been scaled up to production.


Gaseous diffusion is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride (hex) through semi-permeable membranes. This produces a slight separation between the molecules containing 235U and 238U. Throughout the Cold War, gaseous diffusion played a major role as a uranium enrichment technique, and continues to account for about 33% of enriched production but is now an obsolete technology that is steadily being replaced by the later generations of technology as the diffusion plants reach their ends-of-life.



Thermal diffusion utilizes the transfer of heat across a thin liquid or gas to accomplish isotope separation. The process exploits the fact that the lighter 235U gas molecules will diffuse toward a hot surface, and the heavier 238U gas molecules will diffuse toward a cold surface. The S-50 plant at Oak Ridge, Tennessee was used during World War II to prepare feed material for the EMIS process. It was abandoned in favor of gaseous diffusion.

A cascade of gas centrifuges at a U.S. enrichment plantThe gas centrifuge process uses a large number of rotating cylinders in series and parallel formations. Each cylinder's rotation creates a strong centrifugal force so that the heavier gas molecules containing 238U move toward the outside of the cylinder and the lighter gas molecules rich in 235U collect closer to the center. It requires much less energy to achieve the same separation than the older gaseous diffusion process, which it has largely replaced and so is the current method of choice and is termed second generation. It has a separation factor per stage of 1.3 relative to gaseous diffusion of 1.005,[8] which translates to about one-fiftieth of the energy requirements. Gas centrifuge techniques produce about 54% of the world's enriched uranium.

Diagram of the principles of a Zippe-type gas centrifuge with U-238 represented in dark blue and U-235 represented in light blueThe Zippe centrifuge is an improvement on the standard gas centrifuge, the primary difference being the use of heat. The bottom of the rotating cylinder is heated, producing convection currents that move the 235U up the cylinder, where it can be collected by scoops. This improved centrifuge design is used commercially by Urenco to produce nuclear fuel and was used by Pakistan in their nuclear weapons program.



Laser processes promise lower energy inputs, lower capital costs and lower tails assays, hence significant economic advantages. Several laser processes have been investigated or are under development.


None of the laser processes below are yet ready for commercial use, though SILEX is well advanced and expected to begin commercial production in 2012.(see here: 30 April 2008) and May 2010 Investor Presentation

Atomic vapor laser isotope separation (AVLIS)

Atomic vapor laser isotope separation employs specially tuned lasers to separate isotopes of uranium using selective ionization of hyperfine transitions. The technique uses lasers which are tuned to frequencies that ionize 235U atoms and no others. The positively charged 235U ions are then attracted to a negatively charged plate and collected.

Molecular laser isotope separation (MLIS)

Molecular laser isotope separation uses an infrared laser directed at UF6, exciting molecules that contain a 235U atom. A second laser frees a fluorine atom, leaving uranium pentafluoride which then precipitates out of the gas.


Separation of Isotopes by Laser Excitation (SILEX)

Separation of isotopes by laser excitation is an Australian development that also uses UF6. After a protracted development process involving U.S. enrichment company USEC acquiring and then relinquishing commercialization rights to the technology, GE Hitachi Nuclear Energy (GEH) signed a commercialization agreement with Silex Systems in 2006 (see here). GEH has since begun construction of a demonstration test loop and announced plans to build an initial commercial facility. (see here: 30 April 2008). Details of the process are restricted by intergovernmental agreements between USA and Australia and the commercial entities. SILEX has been indicated to be an order of magnitude more efficient than existing production techniques but again, the exact figure is classified.

Schematic diagram of an aerodynamic nozzle. Many thousands of these small foils would be combined in an enrichment unit.Aerodynamic enrichment processes include the Becker jet nozzle techniques developed by E. W. Becker and associates using the LIGA process and the vortex tube separation process. These aerodynamic separation processes depend upon diffusion driven by pressure gradients, as does the gas centrifuge. In effect, aerodynamic processes can be considered as non-rotating centrifuges. Enhancement of the centrifugal forces is achieved by dilution of UF6 with hydrogen or helium as a carrier gas achieving a much higher flow velocity for the gas than could be obtained using pure uranium hexafluoride. The Uranium Enrichment Corporation of South Africa (UCOR) developed and deployed the Helikon vortex separation process based on the vortex tube and a demonstration plant was built in Brazil by NUCLEI, a consortium led by Industrias Nucleares do Brasil that used the separation nozzle process. However both methods have high energy consumption and substantial requirements for removal of waste heat; neither is currently in use.


Electromagnetic isotope separation

Schematic diagram of uranium isotope separation in a calutron shows how a strong magnetic field is used to redirect a stream of uranium ions to a target, resulting in a higher concentration of uranium-235 (represented here in dark blue) in the inner fringes of the stream. In the electromagnetic isotope separation process (EMIS), metallic uranium is first vaporized, and then ionized to positively charged ions. The cations are then accelerated and subsequently deflected by magnetic fields onto their respective collection targets. A production-scale mass spectrometer named the Calutron was developed during World War II that provided some of the 235U used for the Little Boy nuclear bomb, which was dropped over Hiroshima in 1945. Properly the term 'Calutron' applies to a multistage device arranged in a large oval around a powerful electromagnet. Electromagnetic isotope separation has been largely abandoned in favour of more effective methods.


Chemical methods

One chemical process has been demonstrated to pilot plant stage but not used. The French CHEMEX process exploited a very slight difference in the two isotopes' propensity to change valency in oxidation/reduction, utilising immiscible aqueous and organic phases.


An ion-exchange process was developed by the Asahi Chemical Company in Japan which applies similar chemistry but effects separation on a proprietary resin ion-exchange column.


Plasma separation

Plasma separation process (PSP) describes a technique that makes use of superconducting magnets and plasma physics. In this process, the principle of ion cyclotron resonance is used to selectively energize the 235U isotope in a plasma containing a mix of ions. The French developed their own version of PSP, which they called RCI. Funding for RCI was drastically reduced in 1986, and the program was suspended around 1990, although RCI is still used for stable isotope separation.

URANIUM MINING

URANIUM MINING

Uranium mining is the process of extraction of uranium ore from the ground. As uranium ore is mostly present at relatively low concentrations, most uranium mining is very volume-intensive, and thus tends to be undertaken as open-pit mining. It is also undertaken in only a small number of countries of the world, partly because sufficiently high uranium concentrations to motivate mining at current prices are rare.

The worldwide production of uranium in 2009 amounted to 50,572 tonnes, of which 27% was mined in Kazakhstan. Kazakhstan, Canada, and Australia are the top three producers and together account for 63% of world uranium production. Other important uranium producing countries in excess of 1000 tonnes per year are Namibia, Russia, Niger, Uzbekistan, and the United States.

A prominent use of uranium from mining is as fuel for nuclear power plants. As of 2008, known uranium ore resources that can be mined at about current costs are estimated to be sufficient to produce fuel for about a century, based on current consumption rates.

After mining uranium ores, they are normally processed by grinding the ore materials to a uniform particle size and then treating the ore to extract the uranium by chemical leaching. The milling process commonly yields dry powder-form material consisting of natural uranium, "yellowcake," which is sold on the uranium market as U3O8.

We were told to give our comments on the TEST......first thing a big thank you to the lecturers by supplying with substantial tips..yahoo,then here comes the best part...we were given the life line of a cheat sheet.....which i don't think I utilised wisely.Any way, I found the paper to be moderate, even though i get tis gut feeling that the outcome wont be impressive..as in the results..god save me...its kinda like a discomfort in the stomach,hhaa..i know like a spotenous nuclear explosion in your tummy

Good Luck for the test!!

For those people who currently taking MEHB513, we wish you good luck! (including ourself!)
May the force be with you.....

Can a car run on nuclear power?

It just an article that found when googling around about nuclear. Maybe its a myth, maybe it still in concept or prototype. But in late 50's, Ford as a well known car company these already done a research about it. Ford Nucleon the car was named. 


According to Ford, based on the assumption that future nuclear reactors would be smaller, safer, lighter and more portable. The design called for a power capsule located in the rear of the car, charging stations replacing gas stations and 5,000 miles of driving before recharging or replacing the fuel. As is the case with manyconcept cars, Ford never built the Nucleon -- only a model car half the size of a normal car.


Here is some picture of the Ford Nucleon :

It's look like the car was inspired from a science-fiction movie, but its theoretically logical and can be produced. Nuclear is safe to anyone if it being handled properly. Beside, a nuclear submarine is already and widely used in military, why not car?

One such possibility is nuclear-fueled hydrogen, by using nuclear energy to create clean, safe, affordable hydrogen fuel. Nuclear reactors could also power stations where motorists charge highly efficient batteries. Finally, scientists could create a miniature nuclear power plant and stick it in a car.

Futher info about the nuclear powered car, click here!

5 Myths About Nuclear Power Plants

5 myths about nuclear power plants….

Myth 1 : It's A Nuclear Bomb Waiting To Happen


First it’s a big NOOOOOOOO!!! with today’s safety standards there is a higher chance of one dying with your television exploding. Nuclear power plants are built to control nuclear scattering using control rods and unlike a bombs intention were extensive neutron scattering is desired.
A nuclear plant is designed is explicitly designed NOT to be a bomb.
Anti nuclear activist throughout times have generated negative remarks and speculations regarding nuclear power this could be maybe due to ignorance in some way. They have generated a lot of hysteria by comparing nuclear power plant s to nuclear weapons.
Many don’t realize that the fuel burned in a natural gas power plant in a year if were made into a fuel-air explosive could be as detrimental but there is no stereotype surrounding gas plants. Thus no- one’s scared of natural plants blowing up, and significantly less effort has been put into designing them to be safe
Even in the utterly worst case scenario, if every one of the technicians at the least safe nuclear power plant in production conspired to make it fail in the most spectacular possible way - it still wouldn't blow up like a nuclear bomb. At absolute worst, it would melt down.

Myth 2: Nuclear Power Plants Can Dangerously Melt Down


Theoretically a in an certain obsolete nuclear power plant designs a meltdown would only happen if control of nuclear reaction or neutron scattering was lost completely. The inside of the power plant would melt and there would be just a radioactive mess to clean up.
Some of these obsolete plants are still in commission in the United States. Even though a meltdown is extremely unlikely, more extensively in today’s modern Generation 3 power plants, the radiation would be simply contained in the event of a meltdown.
In Reasonably modern nuclear power plant designs this simply can't happen. If control stops, or coolant is cut off, or any other drastic failure occurs, a modern nuclear power plant will simply shut itself off.
In the testing of the Integral Fast Reactor, a test reactor that is representative of next-generation reactor designs; two drastic coolant failures were simulated in the same day. They unplugged the coolant pumps. They disconnected the turbines so the power couldn't be turned into electricity. In both cases, the reactor just safely stopped, ready to be turned back on when the problem was fixed. Thus, in whatever worst case scenario nothing drastic like an atomic explosion is going to happen in your backyard even though you have Homer Simpson at the control room…..

Myth 3: Uranium Is Running Out


According to Greenpeace, uranium reserves are relatively limited. Besides that, other activist groups claimed that the significant increase in nuclear generation would reduce realible supples from 50 to 12 years
But on the contrary to those facts , there are 600 times more uranium in the ground than gold and there is as much uranium as tin. There has been no major new uranium exploration for 20 years, but at current consumption levels, known uranium reserves are predicted to last for 85 years.
Geological estimates from the International Atomic Energy Agency (IAEA) and the Organisation for Economic Cooperation and Development (OECD) show that at least six times more uranium is extractable – enough for 500 years’ supply at current demand . Modern day reactors can use thorium as a fuel and convert it into uranium – and there is three times more thorium in the ground than uranium. So how about that for a being piece of mind.
Uranium is just not like any other fuel, it generated more fuel when burnt. Even existing warheads can be converted to usable fuel as a pledge to peace. Also uranium and plutonium in radioactive waste can be reprocessed into new fuel, which for instance former UK chief scientist Sir David King estimates could supply 60 per cent of Britain’s electricity to 2060, Nuclear is truly renewable in my opinion.

Myth 4 : Leukemia Rates Are Higher Near Reactors


Childhood leukemia rates are no higher near nuclear power plants than they are near organic farms. ‘Leukemia clusters’ are geographic areas where the rates of childhood leukemia appear to be higher than normal, but the definition is controversial because it ignores the fact that leukemia is actually several very different (and unrelated) diseases with different causes.
The major increase in UK childhood leukemia rates occurred before the Second World War. The very small (one per cent) annual increase seen now is probably due to better diagnosis. Moreover leukemia is also diagnose to be caused by a viral infections too.
A continues pool of infections at a certain geographic scattering could possibly be due to recent influx of immigrants - which hints of a virus. Thus the margin of one getting leukemia are divided evenly everywhere any anywhere. It is purely by chance that a leukemia ‘cluster’ will occur near a nuclear installation, a national park or a rollercoaster ride.

Myth 5 : Nuclear Power Is Expensive


With any power generation technology, the cost of electricity depends upon the investment in construction (including interest on capital loans), fuel, management and operation. Like wind, solar and hydroelectric dams, the principal costs of nuclear lie in construction.
Acquisition of uranium accounts for only about 10 per cent of the price of total costs, so nuclear power is not as vulnerable to fluctuations in the price of fuel as gas and oil generation.
The nuclear power plant for Malaysia with its new designs will be pre-approved for operational safety, modular to lower construction costs, produce 90 per cent less volume of waste and incorporate decommissioning and waste management costs.

The coal industry will never tell you the truth about this.

Here’s a brilliant concept to remember - The ONLY time coal can be considered clean coal is when its left in the ground untouched, because it’s full of carbon that’s being kept out of the air.


Coal in the ground is its only proven form of carbon sequestration. It has worked for thousands of years. The minute you start to mine it, move it and especially burn it in any way it becomes dirty, polluting and a global warming enemy

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Thought Of The Day 4.0

Xenon


A major contribution to the sequence of events leading to the Chernobyl nuclear disaster was the failure to anticipate the effect of "xenon poisoning" on the rate of the nuclear fission reaction in the Chernobyl nuclear reactor. 

These neutron are absorbed to control the rate of nuclear fission in a reactor in  this case -²³⁵U absorbs thermal neutrons in order to fission, and produces other neutrons in the process to trigger other fissions in the chain reaction. In controlling this chain reaction , neutrons are absorbed by the control rods to  slow down reaction rates while the moderator slows down fast neutrons to sustain the reaction.

            In this fission reaction iodine-135 is produces as a fission product as its next phase of decay, that is into xenon-135. Iodine-135 is a common fission product but has a small probability in absorbing neutrons thus does not significantly affect the reaction. Having a half  life of 6.7 hours it decays into xenon-135( having a half life of 9.2hours). Xenon -135 has a very large neutron cross section for absorption, that is approximately 3 million barns comparing to 400 to 600 barns during the uranium fission event.

            Under normal operating conditions, the presence of  Xenon-135 is controlled by balancing reaction rates. In the sequence to the process, initially Iodine-135 is produced by subsequent decay of Xenon-135 which absorbs neutron and thereby ‘ burned away’ in the established balanced of operating conditions.

            Now we come to how all of these influence the subsequent events to the Chernobyl disaster. In a balance operating condition, there is an equilibrium concentration of both iodine-135 and xenon-135 but when the power level was drastically reduced in the Chernobyl reactor, xenon-135.

            The person handling the reactor at that point of time tried to increase the power during the time of testing but there was no obvious power increase. He certainly didn’t have a clear understanding that the failure to increase power was due to extensive neutron absorption by the xenon, the apparent thing to do was to remove the control rods to increase reaction and thus power. The increased power then burned away the xenon and also caused voids in the cooling water, both of which rapidly increased the reaction rate, driving it out of control.

            This case of ‘xenon poisoning’ of the reaction had been known based on our experience with plutonium producing reactors at Hanford, Washington. In was found the fuel concentration had So the phenomenon had been dealt with from the earliest days of our experience with nuclear fission, and should have been known by anyone who was in control of a nuclear reactor but sadly not in the case of the Chernobyl nuclear disaster.

Core Detail of RBMK-1000 Reactor

Here are some interesting facts on the world‘s worst nuclear power plant disaster and let’s  hopefully  the last!

Chronology of the Day of Disaster

1.         The reactor was powered down for a test sequence to determine if one of the turbo generators could supply power to feed water  pumps until standby diesel generators came on line in the case of a local power failure. The test sequence involved the following dangerous steps


a. Instead of the design based 22-32% full power, the power was inadvertently lowered to 1% of full power, an extremely unstable situation because of the positive void coefficient. Edwards reports that the operator failed to reprogram the computer to maintain power at 700-1000 MW(t).
b. Essentially all the control rods were pulled out of the core, to the point where they could not shut down the reactor rapidly if needed. This step was taken to get the power back up, but it only reached 7%, still well below the design parameters for the test. The reason the power could not be brought back up was the "xenon trapping" or "xenon poisoning" effect. Xenon is a decay product of I-135 and is a strong neutron absorber which "poisons" the fission reaction. It reaches equilibrium at normal operating power levels by being "burned away" by neutron absorption and further decay. When the power level was decreased from the 1600 MW level, you had lots of I-135 to decay into xenon, but a small neutron flux with which to burn it away, so it built up rapidly. c. In order to keep the reactor from automatically shutting down under these conditions, they had to disconnect the emergency core cooling system and several of the automatic scram circuits.
d. All eight cooling water pumps were running at the low power, compared to a normal six even at full power, so there was nearly solid water with almost no void fraction, which increased the vulnerability to any power excursion which produced boiling.


2.         The turbo generator was tripped to initiate the test, which caused the switching off of four of the eight recirculation pumps. (This would have scrammed the reactor if the automatic scram circuit had not been disconnected.)


3.         Reduced coolant flow caused voids to form rapidly in the pressure tubes, increasing reactivity because of the positive void coefficient.


4.         Within seconds, with rapidly rising power, an emergency manual scram was ordered, but the almost fully withdrawn rods could not insert negative reactivity fast enough because of their slow speed. Also, an unexpected displacement of water from the control rod tubes occurred, further adding to the positive reactivity.


5.         The core went to prompt criticality, overheating and shattering fuel rods and flashing the coolant into steam. Fuel channels were ruptured.


6.         Steam pressure blew the 1000-ton steel- and cement-filled biologic shield off the top of the reactor, severing all pressure tubes(some 1600 of them) and exposing the hot core to the atmosphere. Edwards says power reached 100 times operating maximum and the explosive force was about 1 ton of TNT.
Soviet scientist Legasov said of the violations of the safety restrictions "It was like airplane pilots experimenting with the engines in flight." The ORNL review says that if the operators had failed to complete the test they could not have repeated it for a year. This probably influenced them to take more risks than normal.