7 nuclear fission

The Fires of Nuclear Fission
이영식
2004 . 11.

Seabrook Saga
Seabrook, New Hampshire coast
was settled as early as 1638 and granted on June 3, 1768.
Its name was suggested by the fact that so many rivers and streams run through it
The town historically was a small rural community with a beautiful harbor, beach, and dunes
Seabrook, NH ? close to Boston
History of Seabrook NPR Plant
Proposal of twin nuclear power reactors
By Public Service Company (1972)
$973 million by 1979
Site selection
Atlantic ocean ? easy access
Ocean provides cooling water
Solid and stable rock
Close to Boston

Opposition groups (1974)
Clamshell Alliance
Commonwealth of Massachusetts
Construction
Began in July 1976
Protests in 1977
In 1984, canceled the second unit
First unit finished in 1986
First Test in 1989 ($6.45 billion)

Elements of Nuclei
원자핵의 구성
양성자 (Z)
중성자 (N)
질량(A=Z+N)
양성자의 숫자, 원자번호(Z)
23892U
동위원소, Isotopes
same element (Z) with different number of neutrons(N)

Chemical vs. Nuclear Energy
Elements do not change
Electron are involved in bonding
Reaction occur with small changes in energy
Rates are influenced by temperature, concentration or catalyst
Elements change

Nucleus in not involved in bonding
Changes occur with huge amounts of energy
Rates are dependent on the nucleus and number of nuclei

Finding of nuclear fission
1910년, 아인시타인의 질량과 물질 상관 관계 발표
1938년, 독일 오토 한과 Strassmann, 우라늄 235의 연쇄 반응 실험실 성공
Lise Meitner 는 우라늄의 핵 “분열”로 설명

Albert Einstein
The Nobel Prize in Physics 1921
"for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect“
Germany and Switzerland
Kaiser-Wilhelm-Institut (now Max-Planck-Institut) fur Physik
Berlin, Germany
b. 1879 (in Ulm, Germany) d. 1955

Otto Hahn
The Nobel Prize in Chemistry 1944
"for his discovery of the fission of heavy nuclei"
Germany Kaiser-Wilhelm-Institut (now Max-Planck Institut) fur Chemie
Berlin-Dahlem, Germany
b. 1879 d. 1968

Lise Meitner
Born: Vienna, Austria, November 7, 1878
Died: Cambridge, England, October 27, 1968
A Battle for Ultimate Truth
The Nobel "mistake," never acknowledged, was partly rectified in 1966, when Hahn, Meitner, and Strassmann were awarded the U.S. Fermi Prize.
Otto Hahn and Lise Meitner

Nuclear Fission
핵분열 Fission
무겁고, 에너지가 크고, 불안정한 핵이 가볍고 더 안정한 핵으로 쪼개지는 것

Nuclear Bomb

Nuclear Power

States of nuclear fission
Three states of nuclear fission reaction
부임계 상태 subcritical
not enough neutron to maintain fission
임계 상태 critical
just enough neutrons to maintain a fission reaction
초임계 상태 supercritical
too many neutrons and the fission reaction is uncontrollable
임계 질량

Nuclear Reactor
Principles
Heated water turns turbine & generator
Heating by fission of nuclear fuel
Thermodynamic efficiency = 55-65%
Power plant = Nuclear reactor +Turbine and generator

Nuclear Power
Countries that use nuclear power
France72.7%
Belgium59.3%
Sweden51.6%
Germany27.6%
United States21.7%
United Kingdom20.6%
U.S.S.R12.6%

우리나라 발전량의 구성

Fuel assembly
Pellet
Fuel Rod
Fuel Assembly

Nuclear Fuel Cycle

Nuclear Power
Waste generated by an Nuclear Power plant
70 cubic feet of nuclear waste

Waste generated by Coal-Fired plant
3.5 million cubic feet of ash
35,000 tons of SO2
4.5 million tons of CO2

NPR Safety
China syndrome
nuclear power reactor melt down
Chernobyl (1986)

90 children without left forearm
Universe of pollution
100 children with alopecia

Loading the Nuclear Fuel

Three mile island, PA (1979)
사고
냉각수 상실과 부분 meltdown
치명적 인명피해 없음
방사능 누출 없음
반응로 벽은 8인치 두께 탄소강
Breeding Reactor at Monju, Japan (1995)

A-bomb
1939년 8월, 질라드와 위그너 (Szilard, Wigner) 아인시타인으로 하여금 루즈벨트 대통령에게 원자폭탄의 가능성에 대한 편지를 쓰도록 권유
1939년 10월, 미국 우라늄 위원회 결성
1940년, 독일 피어스가 영국에서 임계질량 이론적으로 계산
1940년, 영국 MAUD committee 결성. 우수한 성과에도 불구하고 독일의 공습으로 공장 건설을 불가능하다고 판단됨. 모든 연구 결과와 자료는 미국으로 보내짐.
1942년 9월, 미국 맨하탄 프로젝트 시작 (37000명, 22억달러 예산)
1943년, 미국 시카고 대학에서 페르미와 프랭크, 질라드와 비그너 연쇄반응 성공
1944년 10월, 당시 세계적인 물리학자였던 닐스 보어가 처칠과 루즈벨트에게 핵폭탄 개발 반대 편지 발송
1945년 5월 3일, 완성된 폭탄 투하에 대한 최종 토의. 찬성 - 오펜하이머와 페르미. 반대 - 컴프턴과 로렌스
1945년 8월 6일, 히로시마에는 우라늄 235 사용 Little boy 라는 별명의 13 kton 폭탄
8월 9일, 나가사키에는 플루토늄 239를 사용하는 Fat man 이라는 별명의 22 kton 폭탄
20 kt Atomic Bomb

Atomic Bomb
Stable Nuclei

Unstable Nuclei
Some Nuclei are unstable
spontaneously undergo a change that releases energy and/or particles

방사선 Radiation
energy and/or particles release from nucleus

Nuclear Stability
Unstable Nuclei spontaneously change through radiation

Type of radiation
alpha particle
beta particle
gamma rays
other types

Unstable Nuclei
Lighter Element (H through Ca)
ratio of one proton to one neutron is stable
Carbon-12
6 protons and 6 neutrons
Carbon-14
6 protons and 8 neutrons (Radioactive)

Heavier Element require more neutrons for stability

Alpha particle
emission of Helium nucleus from the nucleus
2 protons and 2 neutrons (Z=2, N=2, A=4)
The sum of the subscripts constant

Beta particle
emission of electron from the nucleus
electron (Z=-1, A=0, N=0)
중성자 하나가 양성자와 전자로 변환

Gamma Rays
Nuclei can lose energy without changing or losing particles - gamma ray
gamma ray - high energy, but no mass
nucleus - no change

Other Type of Decay
양전자 방출
전자포획
자발적 붕괴
유도된 붕괴

Other Type of Decay
양전자 방출 Positron emission
the change of a proton to a neutron and release a positron (positive electron)
nucleus loses 1 proton and gains 1 neutron

Other Type of Decay
전자 포획 Electron capture
capture of an electron by a proton to make a neutron
electron from the inner shell
nucleus loses 1 proton and gains 1 neutron
Other Type of Decay
자발적 붕괴 Spontaneous Fission
nucleus split into two smaller nuclei
유도된 붕괴 Induced Fission
nucleus split into two smaller nuclei, but is caused by the collision with another particle

Half-life
반감기
지금 농도의 반이 될 때 까지의 시간
반응물의 농도가 지수함수로 감소할 경우 반감기는 일정하다
N(t) = N(t=0)exp(-kt)
t1/2 = ln2 / k

Application of Radioactivity
How is radioactivity useful?

Industrial Uses
감마선 사진 Gamma-ray photography
연기 감지기 Smoke Detectors
종이 두께 조절 Paper Thickness
Medical Uses
Imaging internal organs
brain, liver and thyroid

References
Richard Rhodes, The Making of the Atomic Bomb, (1995)
원자폭탄 만들기, 문 신행 옮김, 민음사
Why America dropped the Bomb,
Newsweek, July 24 (1995)
김 명자, 현대 사회와 과학
동아 출판사 (1992) 제 1 장, 원자탄의 개발
이갑진, 서만석, 박 명순, 현대 과학의 두 얼굴, 아침 (1994)
References
MBC TV 시사다큐 이제는 말할 수 있다
제 8회 박정희와 한반도 핵
Fat Man and Little Boy (영화, 1989)
감독 Roland Joffe
출연 Paul Newman, John Cusack, Dwight Schultz, Bonnie Bedelia, Laura Dem, Nastasha Richardson, John C. McGineley, Ron Frazier
References
http://library.thinkquest.org/3426/data/disaster/graph/index.html
References
http://www.seabrooknh.org/
Seabrook, NH homepage
www.uic.com.au/nfc.htm
Nuclear fuel cycle

참고 - 어느 전문가의 원자폭탄 이야기