Advantages of isotope tailored tungsten
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008
Ir. B.P. [email protected]
+31 224568028
G.Dowling,Urenco
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Contents
• Introduction
• Possible Candidates
• Tailoring of Tungsten
• Possible Application Areas
• Isotope tailored molybdenum
• Status
• Questions/Discussion
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008
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Introduction
Aim
• Inform you about the possibilities of isotope tailoring of materials
• Show the possible advantages
• Check your ideas about the topic
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008
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Introduction
Isotope tailoring• Remove specific isotopes of materials
- Reduce short term or long term activation- Possible for virtually all metals, f.e. Zn, W, Mo,
• Mechanical behaviour unaffected, only chemical composition tailored
• Various applications known- “depleted zinc” in nuclear power plants. Add depleted
zinc in primary cooling water circuit to reduce dose rate of the personnel by a factor two
- Enriched iridium sources, made for Medical Treatment (brachy therapy)
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008
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Possible Candidates
Enrichment or Depletion technology is possiblefor almost every material. Candidates are :
•Cadmium •Iridium •Nickel •Silicon •Tungsten
•Chromium •Iron •Osmium •Tellurium •Zinc
•Germanium •Lead •Rutetium •Tin •Zirconium
•Indium•Molybdenum
•Selenium•Titanium
Tungsten
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008
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Tailoring of Tungsten
Natural isotopes
• 180W (0.12 %) 182W (26.50 %) 184W (14.31%) 185W (30.64 %) 186W (28.43 %)
• Under influence of irradiation, about 30 different isotopes can occur
• Removing the isotope tungsten 186, the production of the radioactive tungsten 187 is limited. As a result, the radiation dose rates will be reduce. Tungsten 187 is main source of activity
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008
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Possible Application Areas
• Tungsten divertor parts. Especially in case of ELM. Highly active W-dust probably not favoured because of radioactive waste after cleaning
• Coating of plasma facing components to extend lifetime
• Mirrors
Advantages
• Reduce activation
• No compromise on thermo-mechanical properties
• Possibly reduced He production
Disadvantages
• (Much) more expensive than regular W
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008
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Possible Candidates
Enrichment or Depletion technology is possiblefor almost every material. Candidates are :
•Cadmium •Iridium •Nickel •Silicon •Tungsten
•Chromium •Iron •Osmium •Tellurium •Zinc
•Germanium •Lead •Rutetium •Tin •Zirconium
•Indium•Molybdenum
•Selenium•Titanium
Molybdenum
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008
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Isotope tailored Molybdenum
Possibilities for Molybdenum in mirrors
• Currently about 40 Mo mirrors planned. Lifetime of mirrors close to plasma limited due to irradiation consequences
• Eliminate 95Mo and 98Mo isotopes drastically reduces cross section.
• Reduced activation could extend mirror lifetime by a factor 2 to 10!
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008
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Status
Status now
• Currently the first steps are taken to investigate the activation behaviour of the different isotopes, i.e. determine effect of individual isotopes and neutron energy influence
• Investigation of possibilities for isotope tailored materials in ITER
Next steps
• Analyse tailored isotopes to prove characteristics
• Optimise isotope ratios for activation behaviour
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008
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Questions/ Discussion
Is aim achieved?
• Inform you about the possibilities of isotope tailoring of
materials
• Show the possible advantages
• Check your ideas about the topic
Questions?
What advantages do you see?
7th annual meeting of the EU-PWI Task Force, Frascati, 27-29. October 2008