NuclearPowersem atomic energy commission.ppt

Nuclear Safeguard

1. NuclearPower
In the US, 20% of our
electricity is produced by
nuclear power. There are 103
US nuclear power plants.
Dennis Silverman, U C Irvine

2. California related reactors
Diablo Canyon, two reactors
San Onofre, two reactors
⅓ of Palo Verde 1, 2, & 3 in
Arizona

3. California Nuclear energy
Each of the five reactors produces about 1,100
million watts (megawatts) of electricity
This is enough to power one million homes per
reactor
Each reactor’s production is equivalent to 15 million
barrels of oil or 3.5 million tons of coal a year.
The total 5,500 reactor produced megawatts is out
of a peak state electrical power of 30,000 –40,000
megawatts.

4. Worldwide Nuclear Power
Reactors
There are 440 nuclear power reactors in 31
countries.
30 more are under construction.
They account for 16% of the world’s
electricity.
They produce a total of 351 gigawatts (billion
watts) of electricity.

5. World Nuclear Power Plants

6. Nuclear Electricity Production by Countries
and Regions in Gigawatts (World Total 350
Gigawatts) and percent of electricity
US 97 Trend: declining
North America Region109
France 63 Increasing
Germany 21 Being phased out
U. K. 12
Western Europe Region126
Japan 44 Increasing
Asia Region 66 Increasing
Eastern Europe Region11
Former Soviet U. Region34

7. How a Nuclear Reactor works

235
U fissions by absorbing a neutron and producing 2 to 3 neutrons,
which initiate on average one more fission to make a controlled
chain reaction
Normal water is used as a moderator to slow the neutrons since
slow neutrons take longer to pass by a U nucleus and have more
time to be absorbed
The protons in the hydrogen in the water have the same mass as
the neutron and stop them by a billiard ball effect
The extra neutrons are taken up by protons to form deuterons

235
U is enriched from its 0.7% in nature to about 3% to produce the
reaction, and is contained in rods in the water
Boron control rods are inserted to absorb neutrons when it is time to
shut down the reactor
The hot water is boiled or sent through a heat exchanger to produce
steam. The steam then powers turbines.

8. Nucleons more tightly bound in Fission
Product Nuclei –Gives 200 Mev Energy per
Fission

9. Nuclear Fission from Slow Neutrons
and Water Moderator

10. Inside a Nuclear
Reactor
Steam outlet 
Fuel Rods 
Control Rods 

11. Energy Taken out by Steam Turbine

12. Production of Plutonium (Pu) in
Nuclear Reactors

239
Pu is produced in nuclear reactors by the
absorption of a neutron on
238
U, followed by two
beta decays

239
Pu also fissions by absorbing a thermal neutron,
and on average produces 1/3 of the energy in a fuel
cycle.

239
Pu is relatively stable, with a half life of 24
thousand years.
It is used in nuclear weapons
It can be bred for nuclear reactors

13. Nuclear Weapons to Reactor
Fuel
We are buying highly enriched uranium (20%
235
U) from the former Soviet Union’s nuclear
weapons for 20 years from 1993--2013
Converting it to low enriched uranium (3%
235
U) for reactor fuel
It will satisfy 9 years of US reactor fuel
demand
It comes from 6,855 Soviet nuclear warheads
so far

14. Nuclear Plant Future
The countries of the world are each planning their own
course of nuclear plant development or decline
Nuclear power is competitive with natural gas
It is non-polluting
It does not contribute to global warming
Obtaining the fuel only takes 5% of the energy output
Plant licenses have been extended from 20 years to an
additional 20 years

15. Nuclear Plant Future
Newer designs are being sought to make them more
economical and safer
Preapproval of a few designs will hasten development
Disposal of high level radioactive waste still being
studied, but scientists believe deep burial would work
Because they are have large electrical output, their cost
at $2 billion is hard to obtain and guarantee with banks
Replacing plants may be cheaper using the same sites
and containment vessels

16. Nuclear Problems and Solutions
Three Mile Island 1979
50% core meltdown, stuck valve with no indicator released
water, but containment vessel held
More sensors added, better communication to experts in
Washington, don’t turn off emergency cooling
28 year US safety record since accident
Chernobyl 1986
Human stupidity turned off cooling system
Poor steam cooling reactor design allowed unstable steam
pocket to explode
Graphite caught fire
Design not used in other countries

17. Yucca Mountain Project: Nuclear Fuel
and High Level Waste Repository
Much more secure repository than leaving high level waste at 60
reactor sites around the country.
On old atomic bomb testing base, inside a mountain.
The storage is above the water table.
The Yucca Mountain site would be 60% filled by present waste.
US has legal commitment to the reactor industry.
Site has been studied extensively by scientists for over 20 years.
Will store waste during its 10,000 year decay time.
Questions of how to deflect dripping water around and under the
storage vessels.
Questions of radioactive decay weakening storage containers.
A solution would be to build containers that can be opened and
reincased, or to which surrounded casings could be added.

19. Liquid Metal Fast Breeder Reactor
Uses the fast neutrons from
235
U fission on
surrounding
238
U to produce
239
Pu
In 10-20 years, enough Pu is produced to power
another reactor
No moderators are allowed
No water, must use liquid sodium coolant
U must be at 15%-30% enrichment to generate
power with fast neutrons while breeding Pu
This is at weapons grade enrichment, however
Super-Phenix in France has operated for 20 years

20. Nuclear Power Proposed
Solution?
Richard Garwin, MITand industry propose:
If 50 years from now the world uses twice as much energy, and half
comes from nuclear power
Need 4,000 nuclear reactors, using about a million tons of Uranium a
year
With higher cost terrestrial ore, would last for 300 years
Breeder reactors creating Plutonium could extend the supply to 200,000
years
Nonpolluting, non-CO2 producing source
Need more trained nuclear engineers and sites
Study fuel reprocessing, waste disposal, and safer designs.
While nuclear reactors have to be on all day and night, and power use
is less at night, they could be used to charge up electric cars.
Until electric cars or a hydrogen generation economy, they might only
be used for the 40% of generation used at night, up from the present
20% that they generate.

21. Fusion Reactors
Fusion easiest for Deuteron (D) + Tritium(T):
D(p,n) + T(p,nn) →
4
He(pp,nn) + n
in a high temperature plasma.
Replacement T created from Li blanket around reactor
n +
6
Li →
4
He + T
Fusion reactors
International ITER in 2012 for research for a decade, costing $5
billion
Current stalemate over siting in France or Japan
Followed by DEMO for a functioning plant, taking another 10
years.
Design and completion of a commercial plant not until 2050.
US Lithium supply would last a few hundred years.
Still would be a radioactive waste disposal problem.

22. International Thermonuclear
Experimental Reactor (ITER)