Sabtu, 9 April 2011

Apa Itu Tenaga Nuklear? (Mari Belajar Bersama-sama)

Sertai Kami di Taman Melati :: Klik Disini ::

Selain menghabiskan masa kita dengan mengikuti perkembangan artis-artis & hiburan tanah air yang amat sedikit manfaatnya, adalah lebih baik untuk kite mengetahui tenaga nuklear & apa kepentingannya untuk menambahkan pengetahuan.

Apo bondo nuklear ni?

" Apa itu nuklear? istilah 'nuklear' merujuk kepada inti atau nukleus atom dan tenaga nuklear adalah tenaga yang dijana daripada tindak balas dalam nukleus atom.
Ada dua jenis tindak balas nuklear yang boleh digunakan untuk menjana tenaga, iaitu tindak balas pembelahan nukleus (nuclear fission) dan tindak balas pelakuran nukleus (nuclear fusion).
Loji-loji janakuasa nuklear yang terdapat di dunia adalah berasaskan tindak balas pembelahan nukleus, sedang loji nuklear berasaskan pelakuran nukleus kini masih dalam proses penyelidikan dan pembangunan dan dijangka tidak akan dapat digunakan dalam tempoh setengah abad akan datang kerana kesukaran teknologinya.
Proses penjanaan tenaga elektrik menggunakan tenaga nuklear melibatkan kitaran bahan api yang dimulai dengan perlombongan uranium, yang merupakan sumber utama untuk menyediakan tenaga nuklear.
Selepas itu, ia akan menjalani proses penukaran uranium, pengayaan uranium, penukaran semua uranium, fabrikasi bahan api dan diikuti dengan penggunaan dalam loji janakuasa nuklear.
Kemudian diikuti dengan penyimpanan sementara bahan api nuklear terpakai, sebelum diproses menjadi bahan api nuklear terpakai dan akhir sekali rawatan dan pelupusan akhir sisa nuklear aras tinggi.
Uranium biasanya diperolehi daripada negara-negara seperti Australia, Kazakhstan, Kanada dan Amerika Syarikat (AS).
Menurut sumber Agensi Nuklear Malaysia (ANK), penjanaan elektrik melalui loji janakuasa nuklear mampu menjamin keselamatan perbekalan tenaga negara." Utusan

Walaupun tenaga nuklear adalah lebih baik dari satu aspek iaitu membekalkan tenaga yang tetap, tetapi ia juga mempunyai kekurangan dari segi jaminan keselamatan dan beberapa perkara lain. Berikut adalah penerangan kenapa tenaga nuklear ini mempunyai risiko yang tinggi:

" 2. How It Doesn’t Work – Risks and Dangers of Nuclear Energy

  • Proliferation Risks
    • Plutonium is a man-made waste product of nuclear fission, which can be used either for fuel in nuclear power plants or for bombs.
    • In the year 2000, an estimated 310 tons (620,000 pounds) of civilian, weapons-usable plutonium had been produced.
    • Less than 8 kilograms (about 18 pounds) of plutonium is enough for one Nagasaki-type bomb. Thus, in the year 2000 alone, enough plutonium was created to make more than 34,000 nuclear weapons.
    • The technology for producing nuclear energy that is shared among nations, particularly the process that turns raw uranium into lowly-enriched uranium, can also be used to produce highly-enriched, weapons-grade uranium.
    • The International Atomic Energy Agency (IAEA) is responsible for monitoring the world’s nuclear facilities and for preventing weapons proliferation, but their safeguards have serious shortcomings. Though the IAEA is promoting additional safeguards agreements to increase the effectiveness of their inspections, the agency acknowledges that, due to measurement uncertainties, it cannot detect all possible diversions of nuclear material. (Nuclear Control Institute)
  • Risk of Accident
    • On April 26, 1986 the No. 4 reactor at the Chernobyl power plant (in the former U.S.S.R., present-day Ukraine) exploded, causing the worst nuclear accident ever.
      • 30 people were killed instantly, including 28 from radiation exposure, and a further 209 on site were treated for acute radiation poisoning.
      • The World Health Organization found that the fallout from the explosion was incredibly far-reaching. For a time, radiation levels in Scotland, over 1400 miles (about 2300 km) away, were 10,000 times the norm.
      • Thousands of cancer deaths were a direct result of the accident.
      • The accident cost the former Soviet Union more than three times the economical benefits accrued from the operation of every other Soviet nuclear power plant operated between 1954 and 1990.
    • In March of 1979 equipment failures and human error contributed to an accident at the Three Mile Island nuclear reactor at Harrisburg, Pennsylvania, the worst such accident in U.S. history. Consequences of the incident include radiation contamination of surrounding areas, increased cases of thyroid cancer, and plant mutations.
    • According to the US House of Representatives, Subcommittee on Oversight & Investigations, "Calculation of Reactor Accident Consequences (CRAC2) for US Nuclear Power Plants” (1982, 1997), an accident at a US nuclear power plant could kill more people than were killed by the atomic bomb dropped on Nagasaki.
  • Environmental Degradation
    • All the steps in the complex process of creating nuclear energy entail environmental hazards.
    • The mining of uranium, as well as its refining and enrichment, and the production of plutonium produce radioactive isotopes that contaminate the surrounding area, including the groundwater, air, land, plants, and equipment. As a result, humans and the entire ecosystem are adversely and profoundly affected.
    • Some of these radioactive isotopes are extraordinarily long-lived, remaining toxic for hundreds of thousands of years. Presently, we are only beginning to observe and experience the consequences of producing nuclear energy
  • Nuclear Waste
    • Nuclear waste is produced in many different ways. There are wastes produced in the reactor core, wastes created as a result of radioactive contamination, and wastes produced as a byproduct of uranium mining, refining, and enrichment. The vast majority of radiation in nuclear waste is given off from spent fuel rods.
    • A typical reactor will generate 20 to 30 tons of high-level nuclear waste annually. There is no known way to safely dispose of this waste, which remains dangerously radioactive until it naturally decays.
    • The rate of decay of a radioactive isotope is called its half-life, the time in which half the initial amount of atoms present takes to decay. The half-life of Plutonium-239, one particularly lethal component of nuclear waste, is 24,000 years.
    • The hazardous life of a radioactive element (the length of time that must elapse before the material is considered safe) is at least 10 half-lives. Therefore, Plutonium-239 will remain hazardous for at least 240,000 years.
    • There is a current proposal to dump nuclear waste at Yucca Mountain, Nevada.
      • The plan is for Yucca Mountain to hold all of the high level nuclear waste ever produced from every nuclear power plant in the US. However, that would completely fill up the site and not account for future waste.
      • Transporting the wastes by truck and rail would be extremely dangerous.
      • For a more detailed analysis of the problems of and risks incurred by the plan, see Top Ten Reasons to Oppose the DoE’s Yucca Mountain Plan
    • Repository sites in Australia, Argentina, China, southern Africa, and Russia have also been considered.
    • Though some countries reprocess nuclear waste (in essence, preparing it to send through the cycle again to create more energy), this process is banned in the U.S. due to increased proliferation risks, as the reprocessed materials can also be used for making bombs. Reprocessing is also not a solution because it just creates additional nuclear waste.
    • The best action would be to cease producing nuclear energy (and waste), to leave the existing waste where it is, and to immobilize it. There are a few different methods of waste immobilization. In the vitrification process, waste is combined with glass-forming materials and melted. Once the materials solidify, the waste is trapped inside and can't easily be released. "
    Sumber - Nuclear Age Peace  Foundation


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