Archive | September, 2010

How much waste is produced from a Nuclear Power Plant??????

30 Sep

As already noted, the volume of nuclear waste produced by the nuclear industry is very small compared with other wastes generated. Each year, nuclear power generation facilities worldwide produce about 200,000 m3 of low- and intermediate-level radioactive waste, and about 10,000 m3 of high-level waste including used fuel designated as waste.

In the OECD countries, some 300 million tonnes of toxic wastes are produced each year, but conditioned radioactive wastes amount to only 81,000 m3 per year. In the UK for example, around 120,000,000 m3 of waste is generated per year – the equivalent of just over 20 dustbins full for every man, woman and child. The amount of nuclear waste produced per member of the UK populations is 840 cm3 (i.e. a volume of under one liter). Of this waste, 90% of the volume is only slightly radioactive and is categorized as low-level waste (with only 1% of the total radioactivity of all radioactive wastes). Intermediate-level waste makes up 7% of the volume and has 4% of the radioactivity. The most radioactive form of waste is categorized as high-level waste and whilst accounting for only 3% of the volume of all the radioactive waste produced (equating to around 25 cm3 per UK citizen per year), it contains 95% of the radioactivity.

A typical 1000 MWe light water reactor will generate (directly and indirectly) 200-350 m3 low- and intermediate-level waste per year. It will also discharge about 20 m3 (27 tonnes) of used fuel per year, which corresponds to a 75 m3 disposal volume following encapsulation if it is treated as waste. Where that used fuel is reprocessed, only 3 m3 of vitrified waste (glass) is produced, which is equivalent to a 28 m3 disposal volume following placement in a disposal canister.

This compares with an average 400,000 tonnes of ash produced from a coal-fired plant of the same power capacity. Today, volume reduction techniques and abatement technologies as well as continuing good practice within the work force all contribute to continuing minimization of waste produced, a key principle of waste management policy in the nuclear industry. Whilst the volumes of nuclear wastes produced are very small, the most important issue for the nuclear industry is managing their toxic nature in a way that is environmentally sound and presents no hazard to both workers and the general public.

Reactor completion the preferred choice

29 Sep

The Advanced Boiling Water Reactor (ABWR) is a Generation III boiling water reactor. The ABWR was designed by General Electric and is currently offered by the alliance of General Electric and Hitachi. The ABWR generates electrical power by using steam to power a turbine connected to a generator, the steam is boiled from water using heat generated by fission reactions within nuclear fuel. The Gen III design is available today to meet power generation needs ranging from 1350 to 1460 MW net. It delivers proven advanced technology and competitive economics.

ABWR have a benefits and features which is, Improved safety, reliability, operability, and maintainability, demonstrated reduction in capital and O & M costs, proven advanced reactor technology and performance enhancements, shorter construction time of approximately 39 months from first concrete to first fuel load proven in Japan. ABWR also have no Steam generators US NRC, receive one-step license (1997) and have pre-fabricated modules for proven short construction time. This reactor is very good in overall economics.

There are also Technology Enhancements that Improve Performance of ABWR :

• Reactor internal pumps – improved safety and performance

by eliminating external recirculation systems

• Integrated containment and reactor building – improved seismic response, compact, and easier to construct

• Compact reactor building – less construction material and shorter construction times

• Optimized modularization – module designs refined and proven in real installations

• Sophisticated control systems – fully digital, providing reliable and accurate plant monitoring, control, and

diagnostics

• High integrity fuel, improved water

chemistry,  and radiation source elimination – reduced radwaste and occupational exposure

Positive & Negative Reactivity

28 Sep

The reactivity is a measure of changes in the chain reaction in the reactor’s core.. In  this particular   chain reaction, the neutrons produced by the fission of heavy nuclei, slowed by the nuclear moderator.The water under pressure of the primary circuit and absorbed to a greater or lesser extent by the nuclear reactor  control rods and the dissolved boron, come in their turn to produce further fissionA parameter called reactivity  positive when a reactor is supercritical, zero at criticality, and negative when the reactor is subcritical. Reactivity can be controlled in various ways which are:

1.By adding or removing fuel.

2.Changing  of  the fraction of neutrons that leaks from the system;

3.Changing the amount of an absorber that competes with the fuel for 

 neutrons. Control is generally accomplished by varying absorbers, which are commonly in the form of movable elements control rods. 

4. Changing the concentration of the absorber in a reactor coolant. Leakage

     changes are usually automatic.

Reactor control is facilitated by the presence of delayed neutrons. These neutrons are emitted by fission products some time after fission has occurred. The fraction of delayed neutrons is small, but there is a sufficient number of such neutrons for the types of changes needed to regulate an operating reactor, and so the chain reaction must “wait” for them before it can respond. This eases operation considerably.

The Story of Hiroshima- Nuclear Reactivity

28 Sep

Designs of Two Bombs

The Manhattan Project produced two different types of atomic bombs, code-named Fat Man and Little Boy. Fat Man, which was dropped on Nagasaki, was the more complex of the two. A bulbous, 10-ft. bomb containing a sphere of the metal plutonium 239, it was surrounded by blocks of high explosives that were designed to produce a highly accurate and symmetrical implosion. This would compress the plutonium sphere to a critical density and set off a nuclear chain-reaction. Scientists at Los Alamos were not entirely confident in the in the plutonium bomb design, so they scheduled the Trinity test.

The Little Boy type of bomb, which was dropped on Hiroshima, had a much simpler design than the Fat Man model that had been tested at Trinity. Little Boy triggered a nuclear explosion, rather than implosion, by firing one piece of uranium 235 into another. When enough U235 is brought together, the resulting fission chain reaction can produce a nuclear explosion. But the critical mass must be assembled very rapidly; otherwise, the heat released at the start of the reaction will blow the fuel apart before most of it is consumed. To prevent this inefficient pre-detonation, the uranium bomb uses a gun to fire one piece of U235 down the barrel into another. The bomb’s gun-barrel shape was believed to be unquestionably reliable and had never been tested. In fact, testing was out of the question since producing Little Boy had used all of the purified U235 produced to date; therefore, no other bomb like it has ever been built.

Detonated by a mechanism that resembled a cannon, Little Boy had a muzzle or target that was a hollowed-out subcritical mass of uranium. The cannon ball was another subcritical mass of uranium, which fit perfectly into the hollow of the target as a plug. The plug was propelled down the cannon barrel by several thousand pounds of high explosive. When it hit, the combination of compression and increased mass pushed the uranium to the supercritical level and the bomb went off.

Little Boy Nuclear Bomb

Viewers who do have question please do not hesitate to leave comments…………………thank you

HIE TO ALL MALAYSIAN’S

28 Sep

Welcome to Nuclear powering Vision 2020 blog.Before we go in futher details lets get introduced to the nuclear ambasadors from University Tenaga Nasional.From Left Shu Raj Subhamaniam, middle M.Thevindran A/L Marhalingam and right Mohd Shahmi.The main purpose of this blog is to get the public exposed about the usage of nuclear energy as an alternative source to replace fossil as the source for power generation in Malaysia.Until then Please do enjoy this blog as we will update it almost everyday.

Putrajaya to sell Bakun dam to S’wak; no power transmission to peninsula

24 Sep

Putrajaya to sell Bakun dam to S’wak; no power transmission to peninsula.

Tenaga ‘ready’ for nuclear power

24 Sep

Tenaga ‘ready’ for nuclear power.

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