Title: Inherently Safe Nuclear Reactors for Reducing Greenhouse Emissions
1Inherently Safe Nuclear Reactors for Reducing
Greenhouse Emissions
- Andrew Kenny
- Energy Research Centre (ERC)
- University of Cape Town
- South Africa
2Whenever We Discuss Measures and Technologies for
Reducing Greenhouse Emissions, There is an
Elephant in the Room
Wind Power
Carbon sequestration
Nuclear Power
Solar Power
Energy efficiency
Biofuels
Geothermal energy
Wave Power
Hydro power
3Advantages of Nuclear Power
- Safety.
- By far the best safety record of any large scale
source of electricity (full energy cycle cradle
to grave) - Waste.
- Waste is small, solid, stable and easy to store
so that it presents no danger to man or the
environment - Economics.
- Among the cheapest, if not the cheapest, source
of electricity in Europe, Japan and the USA - Sustainability.
- Enough uranium thorium in the crust sea to
provide the world with electricity until the sun
turns into a Red Giant
4Advantages of Nuclear Power (continued)
- Security of Fuel Supply.
- Stable fuel prices. Long term storage easy.
- Siting
- Can be sited wherever you want. (Fuel cheap
easy to transport). - Reliable Despatchable
- When you want the power, you can have it (unlike
wind solar) - High load factors
- Greenhouse Emissions
- Among the lowest, if not the lowest, greenhouse
emissions per unit of electricity of any source
of energy (full energy cycle cradle to grave
fuel preparation, construction, operation,
decommissioning etc)
5Number of Energy Accidents from 1969 to 1996
with at least 5 Fatalities(Paul Scherrer
Institut, "Severe Accidents in the Energy
Sector)
6The Worst Nuclear Accident at a Nuclear Power
Station in the West
- In over 45 years of operating nuclear power
station in the Western world, the worst nuclear
accident was at Three Mile Island (Harrisburg) in
the USA in 1979. It was a partial meltdown. - The consequences of the accident were these
- deaths 0
- injuries 0
- health aftermath 0
- (Pennsylvania Dept of Health Study)
7Some Recent Energy Accidents
- Natural Gas Well Burst China, Chongqing,
December 2003 - Toxic fumes of natural gas and sulphurated
hydrogen - At least 233 people died soon after
- About 42,000 people were evacuated
- A total of 10,175 people were either hospitalized
or treated and discharged - (Reuters News Service 30 Dec 2003)
- Natural Gas Plant Explosion, Algeria, Skikda, Jan
2004 - 20 people killed soon after
- 74 injured (IOL Website 20 Jan 2004)
- Russian mine blast, Tiazhina pit, Kemerovo
region, Siberia, Apr 04 - 47 miners died (BBC News, 13 April 04)
- Belgium gas blast, near Brussels, Jul 2004
- At least 14 dead, 200 injured (BBC, 30 Jul 2004)
- China coal mine blast, Daping Mine, city of
Xinmi, Henan province, Oct 2004 - 148 dead (BBC News, 21 Oct 2004)
- China coal mine blast, Chenjiashan mine, Shaanxi
province, central China, Dec 04 - 166 dead (BBC News, 1 Dec 2004)
- Texas oil refinery explosion, Mar 2005
- At least 14 people killed
8Greenhouse emissions for Full Energy Chain of
different Generation TechnologiesJ F van de
Vate. Elsevier. Energy Policy. Vol 25 No1 1997
9Nuclear Weapons Proliferation
- This is a very serious problem.
- But it is a political problem, which has little
to do with nuclear power. - Israel has nuclear weapons but no nuclear power
station. - Sweden, Finland, Japan, Switzerland etc have
nuclear power stations but no nuclear weapons. - The only solution to this problem is by honest
political commitment and by reforming the
Non-Proliferation Treaty. - For example, if all nations agreed to a strict
ban on uranium enrichment above 10, enforced by
inspection, this would greatly reduce the danger
of weapons proliferation. - You could have a similar ban on the production of
weapons grade plutonium.
10Disadvantages of Nuclear Power
- Poor public perceptions
- Contrary to evidence, many people believe nuclear
is dangerous and has a major waste problem - High capital costs
- To a large extent both of these can be blamed on
the existing designs of nuclear power reactors
11Existing Reactors Light Water Reactors (LWRs)
- They generate 87 of world nuclear power
- Advantages
- Reliable
- Excellent safety record
- Disadvantages
- High power density
- Complicated expensive
- Safety comes at the high cost of expensive,
ACTIVE safety systems - Essentially an big submarine propulsion unit
- Ideal for a submarine but not ideal for a power
station - The world is waiting for a better reactor
12The New Nuclear Generation Inherently Safe
reactors
- Various designs are being considered.
- The one discussed here is the South African
Pebble Bed Modular Reactor (PBMR)
13Fundamental Design Philosophy of PBMR
- The fundamental design philosophy is inherent
safety. - No human error or equipment failure can cause an
accident that endangers the public. This
includes total loss of cooling at 100 power. - There are no safety systems. Safety is built in.
- The control rods and small absorber spheres can
shut the reactor down quickly but are not
necessary for safety. They are operating
systems. - Simple, small, cheap design. Low capital costs.
Quick construction time.
14Aims of PBMR Project
- Capital costs
- 1000 / kW
- Construction Time
- 24 months per unit
- Emergency Planning Zone
- 400 metres
- No LWR can come close to matching this
15Features of PBMR (power unit)
- Coolant helium (inert chemically and
radiologically) - Moderator graphite
- Fuel enriched uranium (about 9.5)
- Configuration Fuel pellets embedded in graphite
spheres (pebbles) - Power cycle Brayton (heated helium drives gas
turbine) - Power density about 6 kW/l (PWR 50 kW/l )
- Unit Size about 180 MWe (440 MWt)
- size limited so that surface area/mass always
sufficient to ensure enough loss of radiant heat
to prevent dangerous temperatures - Highest coolant temperature about 900C
- Highest coolant pressure about 90 bar
- Efficiency 42
16 PBMR Main Power System
17Thermo Hydraulic Layout
5
7
6
3
2
T
PT
LPC
HPC
4
1
7
S
8
18PBMR Module
19Pebble Fuel
20Fuel Design, Handling Disposal
- Extremely stable fuel, even up to high
temperatures - Heat is generated throughout each Pebble
- flat temperature profile no hot spots
- Pebbles are constantly removed and sampled (by
machine) - if useful energy remains, put back into reactor
- if spent, put into storage tank, where it remains
for the life of the plant - Multiple barriers around each fuel pellet and
encasement in graphite - makes it extremely difficult to use waste fuel
for weapons - makes waste disposal very easy (each Pebble is
its own containment)
21Control
- Reactor runs at steady temperature of about
1100C. Doppler effect (passive) - Control rods small absorber spheres can shut
the reactor down. - Power control comes from adjusting the mass
(pressure) of helium in the circuit - tanks putting helium into circuit
- or tanks receiving helium from circuit
- Additional control from turbine by-pass valve
- The PBMR is load following
22Reactor Unit
23Why Dangerous Nuclear Accidents are Impossible
for the PBMR
- 1. Uncontrolled Reactivity (Chernobyl)
- Impossible because good physics ensures that the
reactor is always under control at all power
ranges and for all transients. - 2. Fuel Damage by Overheating (Three Mile Island)
- Impossible because the small design ensures even
in the worst accident (total loss of coolant at
100 power) sufficient heat will be naturally
dissipated to keep fuel temperatures below the
level at which they begin to sustain damage. - Normal fuel temperature 1100ºC
- Worst accident temperature 1400ºC
- Fuel damage begins slowly at 1600ºC
24(No Transcript)
25Turbo Generator System
26Additional Advantages of PBMR
- Units can be grouped together in modules of
eight, sharing facilities - 8 x 180 MW 1440 MW
- Small unit size and quick construction times
gives planning flexibility to power utilities
27Additional Uses of PBMR
- Hydrogen Production
- thermo-chemical
- Desalination
28History Future of PBMR
- 1967 to 1989. Germany runs 15 MWe AVR Pebble
Bed reactor. Highly successful. - 1985 to 1989. Germany builds 330 MWe THTR
reactor. Too big. Loses inherent advantages of
AVR. Teething problems. Political problems.
Shut down. - (Klaus Töpfer, Germanys Minister of Nuclear
Power and Environment when the original pebble
bed programme in Germany closed down, stated in
Davos, Jan 2003 Germany had made a mistake in
halting the High Temperature Reactor programme.) - 1993. Eskom looks for future economic
generating technologies, including nuclear. IST
shows it the Pebble Bed concept. Eskom adopts it
for study. - 1995 to 1999. Feasibility study, concept
design, costing. - Cabinet support. Commercial partners. Licence
EIA application. - 2002. Business case completed. (McKinsey)
- 2003. Favourable Record of Decision on EIA by
DEAT - 2004. South African Government designates PBMR as
a national strategic project. - 2005. Successful appeal by anti-nuclear group
against procedures of EIA. - Future, if necessary approvals are granted
- 2007 Construction begins on Koeberg site 2007.
- 2011 Unit comes on stream.
-
29PBMR Site
30Conclusion
- If the pilot plant proves successful,
- the PBMR will be able to provide South Africa
with safe, clean, sustainable, economic
electricity - and it will be able to offer the same to the rest
of the world - including the countries gathered here.
31The EndThank You
32Acknowledgements
- Technical slides and drawings from
- PBMR Company, South Africa
- IST, South Africa
- Please do not publish any of them without
permission from the PBMR Company as some of the
information shown might now be out of date