Environmental aspects of Uranium Enrichment - Etusivu · Environmental aspects of Uranium...
Transcript of Environmental aspects of Uranium Enrichment - Etusivu · Environmental aspects of Uranium...
Environmental aspects of Uranium Enrichment
Presentation for Finnish Young Generation
Helsinki, 3 November 2006
Pieter Kleerebezem
Chair Dutch Young Generation
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Content
• Introduction
• The Urenco Group
• Nuclear energy cycle
• Environmental aspects
• Safety aspects
• Summary / Conclusion
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The Urenco Group
Urenco Enrichment
Company Ltd
Urenco Inc.
Urenco Investments Inc.
100 % 100 %
50 %50 %
Enrichment Technology
Company Ltd
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Conversion factories:
• Comurhex (France)• ConverDyn (USA)• Cameco (Canada)• BNFL (UK)• Minatom (Russia)
Fuel cycle, conversion
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Enrichment with Gas centrifuges or Gas diffusion,
Laser is not (yet) feasable
Fuel cycle, enrichment
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Environmental aspects
• Containment, normal operation
• Lack of containment
- What can happen
- How serious can it be
- We talk about a safety issue
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Environmental aspects, the cascade
Cooling
Cooling
Hot box with UF6 transport
container
Separation in Centrifuge Cascades
Compressor
Depleted UF6
Cooling box with transport container with enriched UF6
Compressor
Enriched UF6
UF6
Sub-atmospheric Pressure
Heating
Cooling box with transport container with depleted UF6
2.000 kg
10.000 kg
10.000 kg
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Enviromental aspects, the cascade
Cooling
Cooling
Hot box with UF6transport container
Separation in Centrifuge Cascades
Compressor
Depleted UF6
Cooling box with transport container with enriched UF6
Compressor
Enriched UF6
UF6
Sub-atmospheric Pressure
Heating
Cooling box with transport container with depleted UF6
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Environmental aspects, emissions of the cascade
UF6 (Feed)
Electricity
Water
GasTails (depleted UF6)
Radiation
Cooling
Cooling
Hot box with UF6transport container
Separation in Centrifuge Cascades
Compressor
Depleted UF6
Cooling box with transport container with enriched UF6
Compressor
Enriched UF6
UF6
Sub-atmospheric Pressure
Heating
Cooling box with transport container with depleted UF6
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Environmental aspects, enrichment
• Input
- UF6, Electricity
• Output
- Tails, Product
- Radiation
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Environmental aspects
• Enrichment of uranium has minimal influence on the environment in normal operation because there is a “containment” (closed loop system)
• What if “lack of containment”, then a safety issue
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Safety aspects
• Criticality
• Lack of containment
• Prevention
• Radiation of UF6 is minimal, it’s chemic toxic!
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Safety aspects, criticality
• A system with fissionable material is critical ifselfsustaining fission occurs
• Prevent criticality by design/process or doublecontingency
Double contingency: at least a combination of twounlikely and independend events must take place before safety limits can be exceeded
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Safety aspects, criticality prevention
• Safe geometry / Process- D˜ 200mm or H˜ 100mm or Volume˜ 20liter,
if not exceeded the critical mass can not be reached
• Double contingency- Enrichment < 1%, no reaction can occur
- Container and < 12 liter water
- Water and < 15 kg uranium
Remark: all values depend on percentage of enrichment
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Safety aspects, lack of containment
• Content UF6 in a cascade, 10 kg
• Airplane crash
• Consequenses
- Detectable on area of Urenco, or outside
- Effect on people
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Safety aspects, lack of containment
Cascade content, airplane crash
• Reaction of UF6 with air/water
• 4HF is gasseous, hydrogen fluoride and is a poissonous gas forhumans.
• UF6 starts to smoke if it reacts with atmosphere
• UF6 cannot explode if it reacts with atmosphere
HFFUOOHUF 426 222 +⇒+
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Safety aspects, containers
• The Feed, Tails and Product containers are testedaccording to international standards.
- Fire test
- Drop test
- Pin test
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Summary / Conclusion
• Environmental impact of enrichment is minimal (containment)
• Safety measures are high in enrichment proces
• Airplane crash, local impact but severe
• UF6 reacts with H2O => chemic toxic gas, not explosive