1. Effect Short term effects on rivers and groundwater
4 square KM of pine forest in the vicinity of the reactor died
Some animals died or stopped reproducing
Since the abandonment by humans, many wildlife species have returned to the area, with reports of higher incidences of deformities etc compared to non contaminated areas
A black melanin rich fungi is growing on the reactors walls
It is difficult to assess the human impact

2. Extent of the radioactive cloud

3. Fukushima Nuclear plant accident
11 March 2011 –9.0 magnitude undersea Earthquake and Tsunami hit northern Japan
Plant contains 6 boiling water reactors, 3 of which were offline at the time of the earthquake(4,5,6).
Reactors 1,2,3 were shut down after the earthquake, but the tsunami flooding caused electrical failure which knocked out the emergency pumps needed to cool and control water flowing into the reactors.
Initial concern is over the damaged storage pool for spent fuel from reactor 2
Pressure is seen to rise in Unit 1, as cooling system fails

4. Fukushima 2011

5. Fukashima Timeline March 12 March 14
Battery power for reactor 3 cooling system runs out and its fuel rods are exposed.
Unit 1 and 2 vent radioactive steam to relieve the pressure building up
H explosion occurs in Unit 1
March 14
H explosion at Unit 3
Unit 2 fuel rods are fully exposed to air, and seawater is pumped in to cool them

6. Fukushima Timeline March 15 Fire breaks out in Unit 4
Unit 2 experiences another explosion. Fuel rods may be melting
Explosion occurs at Unit 4
Fire in the spent fuel pond at Unit 4 is releasing radioactivity into the air and water may be boiling off in the pond
Unit 5 water level is falling
Unit 3 spent fuel pond has decreasing water levels

7. Fukushima Timeline March 17
Radiation levels are rising in cities within 75KM of the plant
March 19
Power becomes available to Unit 5 and 6.Cooling of Unit 5 spent fuel pond begins.
Milk and spinach in areas near the power station are found to have increased levels of radioactivity.
Unit 6 spent fuel pond begins to be cooled
March 21
Full cooling to reactor 5 is resumed

8. Fukushima Timeline March 22
Seawater near the plant shows elevated levels of radioactivity
March 23
Power restored to Unit 3
March 24
3 workers exposed to radiation in Unit 3 turbine building. 2 received radiation burns after standing in contaminated water for2 hours without protective boots.

9. Fukushima Timeline March 25
Possible breaches in the containment buildings of Units 1,2,3 reported.
March 26
Radiation levels of 10 million times normal in the Unit 2 turbine room were reported, but later found to be inaccurate. It was only 100,000 times higher than normal.
Damage is now known to be:
Roof of reactor 2 damaged but intact
Reactor 3 roof is blown away
Walls of reactor 4 building have collapsed
Steam is emanating from reactors 2,3,4

10. Fukushima Timeline March 28 March 29
Radioactive water found in tunnels that house electrical wires from the turbines, and within meters over overflowing which would send this water into the sea.
March 29
Radiation reported to have reached the UK and US, though not at unsafe levels.

11. 3 minutes after second explosion at Unit 3

15. Other accidents-1980s
March 13, 1980 –- Orléans, France - Nuclear materials leak
A brief power excursion in Reactor A2 led to a rupture of fuel bundles and a minor release (8 x 1010 Bq) of nuclear materials at the Saint-Laurent Nuclear Power Plant. The reactor was repaired and continued operation until its decommissioning in 1992.
March, Tsuruga, Japan – Overexposure of workers
Overexposure of workers More than 100 workers were exposed to doses of up to 155 millirem per day radiation during repairs of a nuclear power plant, violating the company's limit of 100 millirems (1 mSv) per day.
September 23, Buenos Aires, Argentina - Accidental criticality
An operator error during a fuel plate reconfiguration in an experimental test reactor led to an excursion of 3×1017 fissions at the RA-2 facility. The operator absorbed 2000 rad (20 Gy) of gamma and 1700 rad (17 Gy) of neutron radiation which killed him two days later. Another 17 people outside of the reactor room absorbed doses ranging from 35 rad (0.35 Gy) to less than 1 rad (0.01 Gy).
April 26, 1986 — Prypiat, Ukraine (then USSR) - Power excursion, explosion, complete meltdown
A mishandled reactor safety test led to an uncontrolled power excursion, causing a severe steam explosion, meltdown and release of radioactive material at the Chernobyl nuclear power plant located approximately 100 kilometers north-northwest of Kiev.
May 4, 1986 – Hamm-Uentrop, Germany (then West Germany) - Fuel damage
A spherical fuel pebble became lodged in the pipe used to deliver fuel elements to the reactor at an experimental 300-megawatt THTR-300 HTGR. Attempts by an operator to dislodge the fuel pebble damaged its cladding, releasing radiation detectable up to two kilometers from the reactor.
November 24, 1989 — Greifswald, Germany (then East Germany) - Fuel damaged
Operators disabled three of six cooling pumps to test emergency shutoffs. Instead of the expected automatic shutdown a fourth pump failed causing excessive heating which damaged ten fuel rods. The accident was attributed to sticky relay contacts.

16. Other Accidents 1990s April 6, 1993 — Tomsk, Russia – Explosion
A pressure buildup led to an explosive mechanical failure in a 34 cubic meter stainless steel reaction vessel buried in a concrete bunker under building 201 of the radiochemical works at the Tomsk-7 Siberian Chemical Enterprise plutonium reprocessing facility. The vessel contained a mixture of concentrated nitric acid, uranium (8757 kg), plutonium (449 g) along with a mixture of radioactive and organic waste from a prior extraction cycle. The explosion dislodged the concrete lid of the bunker and blew a large hole in the roof of the building, releasing approximately 6 GBq of Pu 239 and 30 TBq of various other radionuclides into the environment. The contamination plume extended 28 km NE of building 201, 20 km beyond the facility property. The small village of Georgievka (pop. 200) was at the end of the fallout plume, but no fatalities, illnesses or injuries were reported. The accident exposed 160 on-site workers and almost two thousand cleanup workers to total doses of up to 50 mSv (the threshold limit for radiation workers is 100 mSv per 5 years)
June, Ishikawa Prefecture, Japan - Control rod malfunction
Operators attempting to insert one control rod during an inspection neglected procedure and instead withdrew three causing a 15 minute uncontrolled sustained reaction at the number 1 reactor of Shika Nuclear Power Plant. The Hokuriku Electric Company who owned the reactor did not report this incident and falsified records, covering it up until March, 2007.
September 30, 1999 — INES Level 4 - Ibaraki Prefecture, Japan - Accidental criticality
Workers put uranyl nitrate solution containing about 16.6 kg of uranium, which exceeded the critical mass, into a precipitation tank at a uranium reprocessing facility in Tokai-mura northeast of Tokyo, Japan. The tank was not designed to dissolve this type of solution and was not configured to prevent eventual criticality. Three workers were exposed to (neutron) radiation doses in excess of allowable limits. Two of these workers died. 116 other workers received lesser doses of 1 mSv or greater though not in excess of the allowable limit.

17. Other accidents -2000s April 10, 2003 - Paks, Hungary - Fuel damaged
Partially spent fuel rods undergoing cleaning in a tank of heavy water ruptured and spilled fuel pellets at Paks Nuclear Power Plant. It is suspected that inadequate cooling of the rods during the cleaning process combined with a sudden influx of cold water thermally shocked fuel rods causing them to split. Boric acid was added to the tank to prevent the loose fuel pellets from achieving criticality. Ammonia and hydrazine were also added to absorb iodine-131.
April 19, 2005 — Sellafield, England, United Kingdom - Nuclear material leak
Twenty metric tons of uranium and 160 kilograms of plutonium dissolved in 83,000 literes of nitric acid leaked over several months from a cracked pipe into a stainless steel sump chamber at the Thorp nuclear fuel reprocessing plant. The partially processed spent fuel was drained into holding tanks outside the plant.
November 2005 — Braidwood, Illinois, United States - Nuclear material leak
Tritium contamination of groundwater was discovered at Exelon's Braidwood station. Groundwater off site remains within safe drinking standards though the NRC is requiring the plant to correct any problems related to the release.
March 6, 2006 — Erwin, Tennessee, United States - Nuclear material leak
Thirty-five liters of a highly enriched uranium solution leaked during transfer into a lab at Nuclear Fuel Services Erwin Plant. The incident caused a seven-month shutdown and a required public hearing on the licensing of the plant.

18. Fusion
Powers the sun
In fusion, we combine two atoms and release energy
Easiest to do this with H or its isotopes
We already talked about the proton-proton chain in the sun
D-T reaction-takes deuterium and tritium and creates He

19. Fusion
In order for these reactions to occur, one needs the deuterium and tritium at high temperatures
For the DT reaction, T = 40 x 106 K
For DD reaction, T = 100 x 106 K
DT is good for bombs, not so good for long term power, and tritium has a half life of 12 years

20. Thermonuclear devices
Also called H bombs, these are fusion bombs
Require fission to compress and heat the fusion fuel.
The fusion releases enormous amounts of high speed neutrons which are then often used to induce fission in matter that it is normally difficult to induce fission in (such as depleted Uranium, Uranium composed mostly of 238U).
This adds to the radioactive fallout of the bomb

21. Fusion reactors
Main problem is maintaining the fusion material at high enough T so that fusion produces the bulk of the energy (break even)
Confined plasma via a magnetic field so it does not contact the container walls (which would cool it and quench the reaction)
Not nearly as hazardous as fission reactors, most studies show severe failures to be contained within the plants themselves.

22. Barriers to fusion power
Scientific feasibility of the reactions
Economics
Damage to reactor components due to large flux of high energy neutrons
Availability of materials to build the reactors
Maybe in 50 years -but we have been saying that for 50 years!