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THE DISCOVERY OF NUCLEAR FISSION

Elements were not expected to break up this way.

THE HISTORY & FUTURE OF NUCLEAR FISSION

Zero emissions Nuclear power could run the planet for thousands of years. This is a long term goal well beyond the fumbling of western politicians to start building the next round of reactors. This long view influences the total design of all nuclear sites, though open discussion of this is absent so far.

We have gathered sufficient information on all aspects of nuclear energy to supply the framework on which to build. Proceed to the Primers on Fuels, Reactors, Safety, Thorium, or Wastes to see the current state of play.
The full scope of our nuclear offerings can be seen on the Nuclear picLinks page.

It is always fascinating for any technology to look at it's history when nothing at all was known about it. Our Fission history is given below. If aIf you need the basics of nuclear processes the discovery of atoms, nuclei, protons and neutrons is revealed in the
Fusion primer.
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NASA pictures recent Supernova. Uranium and Thorium are only made here.
1. Supernovae make Uranium
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Rutherford type tube using Radium sample .
2. Rutherford tube.
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Penetration by new 'rays'
3. Radiation types
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Splitting by electric and magnetic fields
4. Separation with electric & magnetic fields
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Modern Radium-Beryllium alpha emitter.
5. Radium-Beryllium neutron source.
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Hahn & Meitner, Berlin
6. Hahn & Meitner
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Museum reconstruction of Hahn-Meitner Lab. Alpha source & Uranium target in paraffin cylinder on right. Electronics counts events.
7. Hahn Meitner experiments
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Lise Meitner: Austrian accolade for great nuclear career.
8. Austrian Meitner stamp.
Radium-Beryllium neutron source.
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Fermi's Atomic Pile
9. Atomic Pile: the 1st reactor.
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Enrico Fermi lectures on Quantum Mechanics.
10. Enrico Fermi


HOW NUCLEAR FISSION WAS DISCOVERED

URANIUM
1. We now know that Uranium is created in Supernova explosions where conditions are hot enough to build the heavy elements beyond Iron. Collisions of binary neutron stars have recently been suggested as another source.

Only its very long half life of 4Bn years allows there to be any left on earth. Higher elements like Plutonium have essentially vanished in nature.

Uranium atoms occasionally disintegrate into other smaller atoms, releasing very hot Helium nuclei, very hot electrons and powerful electromagnetic pulses. The heaviest Uranium-238 isotope decays by half in 4.46 billion years. Most of the Uranium on earth fell into the core which is kept molten by this radioactive decay. The whole planet is nuclear powered.


SPONTANEOUS FISSION

The penetrating emissions from Uranium samples were first noticed by Becquerel when photographic plates stored nearby were fogged up. This was an entirely new phenomenon and the beginning of nuclear physics, though nuclei had not yet been identified.

Ernest Rutherford, working in Montreal, discovered that some of the Uranium was actually changing into lighter elements like Barium. Never before had any element been seen to lose its identity this way. Chemists everywhere were excited by this. Rutherford got a Nobel Prize for discovering the spontaneous fission of Uranium.

2. RADIOACTIVITY
Later, In Manchester Rutherford examined the radiations from Uranium and the more active Radium. He placed samples in an evacuated glass tube , screened in Lead to select a beam emitting through a slit. A pair of electrodes put an electric field across the beam. This split the beam in two, as seen on phosphorescent screens, showing that there were two sets of charged particles.

3. ALPHA, BETA, AND GAMMA RADIATION
The positive beam could be stopped by a sheet of paper. He called these Alpha rays. The negative beam he called Beta rays and could be stopped by a sheet of Aluminium. Later, undeflected rays were spotted hitting a phosphor across the laboratory. These he called Gamma rays. These are more dangerous than X-rays because of their million volt energies and deep penetration.

4. By placing a strong magnetic field across the beams, the charged particles turned in circles, allowing the relative mass of the particles to be measured. They were clearly electrons and particles 4 times the mass of Hydrogen and double the charge - they were Helium nuclei.

As you can see from the light-box of pictures on the left, the apparatus was very simple but used with skiil and imagination to pull out these details.

5. A SIMPLE NEUTRON SOURCE
Having discovered these emissions, the next step was to fire them back into matter, any matter, to see what would happen. Solid mixtures of Radium and the 4th element, Beryllium, did something very strange. The gamma emissions from Radium can hit a Beryllium-9 nucleus and excite it so much it shatters into three pieces, a neutron and two alpha particles. This is still an important and very convenient small neutron generator system.

6. URANIUM FISSION BY NEUTRONS

Otto Hahn, who had worked with Rutherford in Montreal, used a beam of these neutrons to irradiate Uranium. In Berlin, 1938, he and his Jewish colleague Lise Meitner, found that neutrons absorbed by Uranium could trigger fission without waiting 4 billion years.He got the Nobel Prize for this.

7. Their experimental equipment is preserved as a museum display. It is very simple by modern standards.

8. Meitner was fired and lucky enough to move to Sweden. But that is another story. She became a famous woman scientist, honoured by her own stamp.

Everyone in the nuclear game at this time knew what was implied, and Hahn was aware that a weapon of enormous power might be derived from this.

FISSION PRODUCTS

So, Uranium fission produces copious amounts of alpha, beta, and gammas, several more neutrons, and splits in many ways into two lighter elements to produce about thirty different elements in several isotopic forms. This is like dropping a crystal wine glass which shatters.

Managing all these processes and their consequences is what Nuclear Power technology is all about. There was a great deal more to find out.

9. THE ATOMIC PILE
The world's first controlled nuclear reactor, the Atomic Pile, was built by Enrico Fermi (10) in Chicago in 1942. It used natural Uranium in a matrix of Graphite blocks to cool the neutrons, increasing the ease of absorption and fission by about 500 times. A great leap from samples in glass tubes.

NUCLEAR WEAPONS
In a race with only one runner, the Manhattan Project needed industrial strength reactors built at Oak Ridge Nuclear Laboratory. which led to the Atomic Bomb. Only two have ever been used but the threat of their existence by the thousand has been a fine political tool. Further discussion of the political failure to control the spread of nuclear weapons is relegated to the Politics Avenue.
The Politics of civilian nuclear power is equally convoluted in rested ways.

NUCLEAR OVERVIEWS
Kaziwazaki Kariwa plant, China
Kaziwazaki-Kariwa plant.
Overview Reports
US Regulatory Commission
US Nuc. Reg. Commission
Key Nuclear Lectures
PRIMERS
quinshan fuel loader
Loading Quinshan
FUELS
UK Fast Reactor
Dounreay Fast Reactor
REACTORS
EPR last stop.
EPR Core Catcher
SAFETY
Thorium 2 fluid
2-Fluid Molten Salt Thorium
THORIUM
THORP Reprocessing
THORP Reprocessing, UK
WASTE & RECYCLING
NUCLEAR LIBRARY
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Trinity College Library