Nuclear Energy

Nuclear Waste

The majority of high level radioactive waste produced comes from the fuel in the core of nuclear power reactors. Irradiated fuel is the most radioactive fuel on the planet and accounts for some 95% of radioactivity generated in the last 50 years from all sources, including nuclear weapons production. Once removed from the core, irradiated fuel is stored in cooling pools on the nuclear reactor site. Each 1000 megawatt nuclear power plant produces about 500 pounds of plutonium a year and about 30 metric tons of high-level radioactive waste.

Environmental Costs

While electricity generated from nuclear power does not directly emit carbon dioxide (CO2), the nuclear fuel cycle does release CO2 during mining, fuel enrichment and plant construction. Uranium mining is one of the most CO2 intensive industrial operations and as demand for uranium grows because of new electricity generation and new plant construction, CO2 levels will also rise.

In a case study in Germany, the Oko-Institute determined that 34 grams of CO2 are emitted per generated kilowatt (kWh). Other international research studies show much higher figures (up to 60 grams of CO2 per kWh). In comparison to renewable energy, energy generated from nuclear power releases 4-5 times more CO2 per unit of energy produced, taking into account the entire nuclear fuel cycle.

US government regulations allow radioactive water to be released into the environment at "permissible" levels. Accurate accounting of all radioactive wastes released into the air, water and soil from the nuclear fuel cycle is simply not available. The Nuclear Regulatory Commission relies on self-reporting and computer modeling from reactor operators to track radioactive releases and project dispersions.

Health

It has been scientifically established that low-level radiation damages tissues, cells, DNA and other vital molecules. Effects of low-level radiation doses cause cell death, genetic mutations, cancers, leukemia, birth defects, and reproductive, immune and endocrine system disorders.

Radioactivity is measured in "curies." An average operating nuclear power reactor core has about 16 billion curies at its core, which is equivalent to the long-lived radioactivity of at least 1,000 Hiroshima bombs. In comparison, a large-sized medical center with as many as 1000 laboratories in which radioactive materials are used, has a combined inventory of about 2 curies.

Nuclear Safety

There have been repetitive problems with security, safety and environment impact in the nuclear industry. Radioactive contamination does not discriminate between national borders and nuclear power plants threaten the health and well-being of all surrounding environments.

Nuclear Sustainability

Nuclear power plants produce extremely toxic radioactive wastes that are long-lived and have no safe means of disposal. Disposal is neither scientifically credible nor is there any sustainable options for interim storage. Producing long-lived radioactive wastes with no solution for its disposal will leave serious and irreversible environmental damage and degradation for generations to come, which is contrary to the principles of sustainability.

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Radiation Safety Logo

The radioactive sources used in the experiments on these pages are very low level isotopes referred to as "license free" sources. This does not mean, however, that these materials represent no hazard to students. The Nucleus, PO Box T, Oak Ridge, Tennessee, 37830, has provided the following guidelines for use of low-level radioactive materials in classroom environments.

Eating, drinking, and application of cosmetics in the laboratory is not permitted.

Pipetting by mouth is never permitted. Use suction devices such as pipette fillers.

Gloves and lab coats should be worn when working with all liquid radioisotopes.

Before leaving the lab, wash your hands thoroughly then check for possible contamination with a survey instrument.

Report ALL spills, wounds, or other emergencies to your teacher.

Keep exposure time to a minimum.

All radioactive liquids wastes are to be poured into the liquid waste container, NEVER a sink.

Maintain good housekeeping at all times in the lab.

Store radioactive materials only in designated storage areas. Do not remove sources from the lab.

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Efek Radiasi pada Tubuh Manusia

Kerusakan sel akan mempengaruhi fungsi jaringan atau organ bila jumlah sel yang mati/rusak dalam jaringan/organ tersebut cukup banyak. Semakin banyak sel yang rusak/mati, semakin parah gangguan fungsi organ yang dapat berakhir dengan hilangnya kemampuan untuk menjalankan fungsinya dengan baik. Perubahan fungsi sel atau kematian dari sejumlah sel menghasilkan suatu efek biologi dari radiasi yang bergantung antara lain pada jenis radiasi (LET), dosis, jenis sel dan lainnya.

Pada tubuh manusia, secara umum terdapat dua jenis sel yaitu sel genetik dan sel somatik. Sel genetik adalah sel ogonium (calon sel telur) pada perempuan dan sel spermatogonium (calon sel sperma) pada laki-laki. Sedangkan sel somatik adalah sel-sel lainnya yang ada dalam tubuh. Bila dilihat dari jenis sel, maka efek radiasi dapat dibedakan atas efek genetik dan efek somatik.

Waktu yang dibutuhkan sampai terlihatnya gejala efek somatik sangat bervariasi sehingga dapat dibedakan atas efek segera dan efek tertunda. Efek segera adalah kerusakan yang secara klinik sudah dapat teramati pada individu terpapar dalam waktu singkat (harian sampai mingguan) setelah pemaparan, seperti epilasi (rontoknya rambut), eritema (memerahnya kulit), luka bakar dan penurunan jumlah sel darah. Sedangkan efek tertunda merupakan efek radiasi yang baru timbul setelah waktu yang lama (bulanan-tahunan) setelah terkena paparan radiasi, seperti katarak dan kanker. Bila ditinjau dari dosis radiasi (untuk kepentingan proteksi radiasi), efek radiasi dibedakan atas efek deterministik dan efek stokastik.

Bila sel yang mengalami perubahan ini adalah sel genetik maka sifat-sifat sel yang baru tersebut akan diwariskan kepada turunannya sehingga timbul efek genetik atau efek pewarisan. Apabila sel terubah ini adalah sel somatik maka sel-sel tersebut dalam jangka waktu yang relatif lama, ditambah dengan pengaruh dari bahan-bahan yang bersifat toksik lainnya, akan tumbuh dan berkembang menjadi jaringan ganas atau kanker.


1. Efek : Efek radiasi yang dapat dirasakan langsung oleh orang yang menerima radiasi (contoh: kanker, leukimia, luka bakar, katarak, kemandulan, kelainan kongenital)
2. Efek Genetik : Efek radiasi yang diterima oleh individu akan diwariskan kepada keturunannya (contoh: penyakit keturunan, kanker pada masa kanak-kanak)
3. Efek Teragonik: Efek pada embrio (contoh: kemunduran mental)
4. Efek Stokastik: Efek yang kebolehjadian timbulnya merupakan fungsi dosis radiasi dan diperkirakan tidak mengenal dosis ambang (contoh: leukimia, kanker, efek genetik)
5. Efek Deterministik: Efek yang kualitas keparahannya bervariasi menurut dosis dan hanya timbul bila dosis ambang dilampaui (contoh: katarak, anemia, penurunan IQ janin, pneunomitis, kemandulan, sindrom radiasi akut)

Sifat Efek Stokastik	Sifat Efek Deterministik
- Tidak mengenal dosis ambang - Timbul setelah melalui masa tenang yang lama - Tidak ada penyembuhan spontan - Keparahan tidak tergantung pada dosis radiasi	- Punya dosis ambang - Timbul beberapa saat setelah terkena radiasi - Ada penyembuhan spontan - Keparahan tergantung dosis radiasi

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ALFABET YUNANI

Kapital	Kecil	Latin	Ekuivalen	Indonesia
A	α	Alpha	a	Alfa
B	β	Beta	b	Beta
Γ	γ	Gamma	g	Gamma
Δ	δ	Delta	d	Delta
Ε	ε	Epsilon	e	Epsilon
Ζ	ζ	Zeta	z/dz	Zeta
Η	η	Eta	(e panjang)	Eta
Θ	θ	Theta	th	Theta
Ι	ι	Iota	i	Iota
Κ	κ	Kappa	k	Kappa
Λ	λ	Lambda	l	Lambda
Μ	μ	Mu	m	Mu
Ν	ν	Nu	n	Nu
Ξ	ξ	Xi	x, ks	Ksi
Ο	ο	Omicron	o	Omikron
Π	π	Pi	p	Pi
Ρ	ρ	Rho	r	Rho
Σ	σ	Sigma	s	Sigma
Τ	τ	Tau	t	Tau
Υ	υ	Upsilon	u	Upsilon
Φ	φ	Phi	f, ph	Phi
Χ	χ	Chi	kh	Khi
Ψ	ψ	Psi	ps	Psi
Ω	ω	Omega	(o panjang)	Omega

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Dosimetri

PERHITUNGAN DOSIS

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Dosis Ekuivalen
H =DQN

dengan  H = dosis ekuivalen (Sv)   
D = dosis serap (Gy)
Q = faktor kualitas
N = faktor modifikasi lainnya

Dosis Ekuivalen ICRP 60
H_T = W_R D_T.R

dengan  HT   = dosis ekuivalen pada jaringan T (Sv)
WR   = faktor bobot radiasi
DT.R  = dosis serap rata-rata pada jaringan T akibat radiasi R (Gy)

FAKTOR BOBOT RADIASI

Jenis Radiasi	WR
Foton, semua energi	1
Elektron dan muon, semua energi	1
Netron, dengan energi
<10 keV	5
<10 - 100 keV	10
100 keV - 2 MeV	20
2 - 2 MeV	10
>20 MeV	5
Foton, selain dari proton rekoil, energi >2 Mev	5
Partikel alfa, fragmen fisi, inti berat	20

• Semua harga tersebut berlaku untuk radiasi eksternal dan internal.
  
• Untuk elektron tidak termasuk elektron Auger yang dipancarkan inti yang diikat DNA.
  
• Harga W_R berdasarkan ICRP 60 (1990)

Dosis Efektif ICRP 60

Jumlah dosis rata-rata dalam organ atau jaringan tubuh dengan memperhitungkan nilai bobot masing-masing.

E = W_TH_T

dengan E= dosis efektif individu
W_T= faktor bobot jaringan
H_T= dosis ekuivalen dalam jaringan T

Dosis Kolektif

Digunakan apabila terjadi paparan dalam sejumlah besar populasi (penduduk). Biasanya karena kecelakaan radiasi.

S_T = pH

S_T = pE

dengan S_T = dosis ekuivalen kolektif = dosis efektif kolektif (Sv-Man)
p = populasi
H = dosis ekuivalen (Sv)
E = dosis efektif (Sv)

Dosis Terikat

Dosis terhadap organ atau jaringan tubuh yang akan diterima selama 50 tahun yang disebabkan oleh asupan satu macam atau lebih radionuklida ke dalam organ atau jaringan yang bersangkutan.

ICRP 23 Reference Man
Air masuk harian = 2,2 l/hr
Nafas rata-rata = 2E4 ml/mnt
Permukaan kulit = 18.000 cm²

Kira-kira terdapat 10E13 sel di dalam tubuh manusia. Ada 140 gram Kalium, 125 nCi (4,625 kBq) adalah K⁴⁰ yang menghasilkan 0,25 mrem/minggu atau 13 mrem/th (2,5 μSv/minggu atau 0,13 mSv/th) untuk seluruh tubuh. Akan terjadi penambahan 15 mrem/th ketika mengkonsumsi senyawa garam lainnya.

DOSIMETRI INTERNAL

Kontaminasi Internal

ALI=BMT=L/h
dengan ALI = Anually Limited Intake (Bq)

BMT = Batas Masukan Tahunan (Bq)

L = batas dosis efektif tahunan atau NBD (Sv)

h = dosis efektif terikat per Bq intake (Sv/Bq)

Tingkat Dosis Efektif Terikat

D=(C:ALI)*L

dengan ALI = Anually Limited Intake (Bq)

L = batas dosis efektif tahunan atau NBD (Sv)

D = tingkat dosis efektif terikat (Bq)

C = nilai kontaminasi permukaan (Bq)

DOSIMETRI EKSTERNAL

Menghitung Lama Penyinaran

Penghitungan lama penyinaran secara khusus digunakan untuk menentukan berapa lama seseorang dapat berada di daerah radiasi yang tinggi sampai mencapai batas dosis.

Resolusi dari Sistem Spektroskopi Gamma
R = (FWHM : Peak Energy) x 100%
dengan R = Resolusi
FWHM = Full Width Half-Max peak height (lebar dari setengah tinggi maksimum) (keV)
Peak energy = energi puncak (keV)

Laju Dosis di Udara dari Sumber Beta Berbentuk Titik
D = 3,2291A / d2

dengan D= laju dosis serap (rad/jam)

A = aktivitas sumber (Ci)

d = jarak dari sumber (m)

Laju Fluks Foton dari Sumber Titik

Φ = AY/4πr²

dengan Φ = laju fluks foton (γ/cm².jam)

A = aktivitas sumber (peluruhan/jam)

Y = medan foton (γ/peluruhan)

d = jarak dari sumber titik (cm)

Laju Paparan dari Sumber Gamma Berbentuk Titik

X = ΓA/r²

dengan X = laju paparan (R/jam)

Γ = faktor gamma spesifik (R/jam pada 1 meter/Ci)

A = aktivitas sumber (Ci)

r = jarak dari sumber titik (m)

Hukum Kuadrat Terbalik

X₁ (d₁)² = X₂ (d₂)²

dengan X₁ = laju paparan terukur (Sv/jam)

X₂= laju paparan yang akan dihitung (Sv/jam)

d₁ = jarak dari sumber dengan paparan terukur (m)

d₂ = jarak dari sumber yang akan dihitung (m)

Laju Dosis Ekuivalen

H = AE / 6r²

dengan H = laju dosis ekuivalen (μSv/jam)

A = aktivitas (MBq)

E = energi (MeV)

r = jarak (m)

Laju Dosis Serap Sumber β dan γ Berdimensi Besar

D = 1,07 SE

dengan D = laju dosis serap (rad/jam)

S = aktivitas jenis sumber (μCi/gram)

E = energi rerata perdisintegrasi (MeV)

untuk β,

energinya (E) adalah 1/3 dari energi maksimum spektrum β

Konstanta Peluruhan

λ_eff = λ_r + λ_b

dengan λ_eff = konstanta peluruhan efektif (dt^-1)

λ_r = konstanta peluruhan radioaktif (dt^-1)

λ_b = konstanta peluruhan biologi (dt^-1)

Oleh karena

λ = 0,693 / T

dengan T = waktu paruh (dt)

maka, 1/Teff = 1/Tr + 1/Tb

dengan T_eff = waktu paruh efektif (dt)

T_r = waktu paruh radioaktif (dt)

T_b = waktu paruh biologi (dt)

Radioisotop Pemancar Gamma Berbentuk Bola

Diasumsikan radioisotop yang terdeposit dalam organ berbentuk bola

D = C Γ g

dengan C = konsentrasi radioisotop (aktivitas per satuan volume) (Ci/l)

Γ = faktor gamma (R.m²/Ci.jam)

g = faktor geometri, diberikan harga g rata-rata

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Cosmic Rays

High energy electrons, protons, and complex nuclei can be produced in a number of astronomical environments. Such particles travel throughout the universe and are called cosmic rays. Some of these particles reach our Earth. As these objects hit our atmosphere, other particles called pions and muons are produced. These particles then slow down or crash into other atoms in the atmosphere. Since the atmosphere slows down these particles, the higher we travel, the more cosmic radiation we see. When you visit the mountains or take an airplane ride, you will encounter more cosmic radiation than if you stayed at sea level.

Most cosmic radiation is very energetic. It can easily pass through an inch of lead. Since cosmic radiation can cause genetic changes, some scientists believe that this radiation has been important in driving the evolution of life on our planet. While cosmic radiation can cause some damage to individuals, it also has played an important role in creating humans. Our atmosphere is naturally shielding us from harmful effects. However, if we were to leave the earth and travel to some planet, we could be subjected to very high levels of radiation. Future space travelers will have to find some way to minimize exposure to cosmic rays.

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Konversi Satuan

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1. Satuan Radiasi
   Rad, Roentgen, Sievert, Rem, Curie, Gray, J/Kg, C/Kg dan lain-lain
   
2. Satuan Panjang
   meter, mil, yard, kaki, amstrong, inchi, dan lain-lain
   
3. Satuan Luas
   are, barn, meter kuadrat, kaki kuadrat, mil kuadrat, inchi kuadrat, dan lain-lain
   

1. Satuan Massa
   gram, kilogram, pound, ton, ons, kwintal, dan lain-lain
   
2. Satuan Volume
   kaki are, kaki kubik, liter, galon, yard kubik, inchi kubik, fl oz, fluid ons, cc, kuart, dan lain-lain
   
3. Satuan Kecepatan
   mil/jam, m/s, ft/s, km/jam, dan lain-lain
   
4. Satuan Kerapatan
   gram/cm, pound/kaki kubik, pound/galon, dan lain-lain
   
5. Satuan Panas
   BTU/lb, kJ/kgC, dan lain-lain
   
6. Satuan Gaya
   kip, lbf, N, dan lain-lain
   
7. Satuan Tekanan
   atm, bar, Pascal, mmHg, dan lain-lain
   
8. Satuan Energi
   kWh, kal, BTU, erg, joule, dan lain-lain
   
9. Satuan Waktu
   jam, menit, detik, hari, tahun, dan lain-lain
   
10. Satuan Konsentrasi
    Ci/lt, Bq/m3, dpm/m3
    
    

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Fusion and Fissian Reaction

Reactions

If nuclei come close enough together, they can interact with one another through the strong nuclear force, and reactions between the nuclei can occur. As in chemical reactions, nuclear reactions can either be exothermic (i.e. release energy) or endothermic (i.e. require energy input). Two major classes of nuclear reactions are of importance: fusion and fission.

Fusion

Fusion is a nuclear process in which two light nuclei combine to form a single heavier nucleus. An example of a fusion reaction important in thermonuclear weapons and in future nuclear reactors is the reaction between two different hydrogen isotopes to form an isotope of helium:

2H + 3H ----> 4He + n

This reaction liberates an amount of energy more than a million times greater than one gets from a typical chemical reaction. Such a large amount of energy is released in fusion reactions because when two light nuclei fuse, the sum of the masses of the product nuclei is less than the sum of the masses of the initial fusing nuclei. Once again, Einstein's equation, E=mc², explains that the mass that is lost it converted into energy carried away by the fusion products.
Even though fusion n is an energetically favorable reaction for light nuclei, it does not occur under standard conditions here on Earth because of the large energy investment that is required. Because the reacting nuclei are both positively charged, there is a large electrostatic repulsion between them as they come together. Only when they are squeezed very close to one another do they feel the strong nuclear force, which can overcome the electrostatic repulsion and cause them to fuse.
Fusion reactions have been going on for billions of years in our universe. In fact, nuclear fusion reactions are responsible for the energy output of most stars, including our own Sun. Scientists on Earth have been able to produce fusion reactions for only about the last sixty years. At first, there were small scale studies in which only a few fusion reactions actually occurred. However, these first experiments later lead to the development of thermonuclear fusion weapons (hydrogen bombs).
Fusion is the process that takes place in stars like our Sun. Whenever we feel the warmth of the Sun and see by its light, we are observing the products of fusion. We know that all life on Earth exists because the light generated by the Sun produces food and warms our planet. Therefore, we can say that fusion is the basis for our life.

When a star is formed, it initially consists of hydrogen and helium created in the Big Bang, the process that created our universe. Hydrogen isotopes collide in a star and fuse forming a helium nucleus. Later, the helium nuclei collide and form heavier elements. Fusion is a nuclear reaction in which nuclei combine to form a heavier nucleus. It is the basic reaction which drives the Sun. Lighter elements fuse and form heavier elements. These reactions continue until the nuclei reach iron (around mass sixty), the nucleus with the most binding energy. When a nucleus reaches mass sixty, no more fusion occurs in a star because it is energetically unfavorable to produce higher masses. Once a star has converted a large fraction of its core's mass to iron, it has almost reached the end of its life.

The fusion chain cannot continue so its fuel is reduced. Some stars keep shrinking until they become a cooling ember made up of iron. However, if a star is sufficiently massive, a tremendous, violent, brilliant explosion can happen. A star will suddenly expand and produce, in a very short time, more energy than our Sun will produce in a lifetime. When this happens, we say that a star has become a supernova.
While a star is in the supernova phase, many important reactions occur. The nuclei are accelerated to much higher velocities than can occur in a fusing star. With the added energy caused by their speed, nuclei can fuse and produce elements higher in mass than iron. The extra energy in the explosion is necessary to over come the energy barrier of a higher mass element. Elements such as lead, gold, and silver found on Earth were once the debris of a supernova explosion. The element iron that we find all through the Earth and in its center is directly derived from both super novae and dead stars.
More peaceful uses of fusion are being researched today with the hope that soon we will be able to control fusion reactions to generate clean, inexpensive power.

Fission

Fission is a nuclear process in which a heavy nucleus splits into two smaller nuclei. An example of a fission reaction that was used in the first atomic bomb and is still used in nuclear reactors is

235U + n ----> 134Xe + 100Sr + 2n

The products shown in the above equation are only one set of many possible product nuclei. Fission reactions can produce any combination of lighter nuclei so long as the number of protons and neutrons in the products sum up to those in the initial fissioning nucleus. As with fusion, a great amount of energy can be released in fission because for heavy nuclei, the summed masses of the lighter product nuclei is less than the mass of the fissioning nucleus.
Fission occurs because of the electrostatic repulsion created by the large number of positively charged protons contained in a heavy nucleus. Two smaller nuclei have less internal electrostatic repulsion than one larger nucleus. So, once the larger nucleus can overcome the strong nuclear force which holds it together, it can fission. Fission can be seen as a "tug-of-war" between the strong attractive nuclear force and the repulsive electrostatic force. In fission reactions, electrostatic repulsion wins.
Fission is a process that has been occurring in the universe for billions of years. As mentioned above, we have not only used fission to produce energy for nuclear bombs, but we also use fission peacefully everyday to produce energy in nuclear power plants. Interestingly, although the first man-made nuclear reactor was produced only about fifty years ago, the Earth operated a natural fission reactor in a uranium deposit in West Africa about two billion years ago!

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