1. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Tritium inventory: Joint international scaling for ITER WP09-PWI-01-01/IPP/PS Status by end of 2008 New data with emphasis on retention in W -reduced uncertainty and confirmation of saturation -simultaneous He irradiation -influence of n-irradiation damage Conclusion at ITPA meeting Amsterdam, May 2009 Further research priorities

2. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Status by end of 2008 all-C materials initial ITER mix Be wall + W divertor all-W materials C vessel wall Be vessel wall all-W materials 150W/mK 50W/mK high flux low wall flux Be wall with CFC divertor - In a W wall, in saturation, 3·10 27 traps available (equivalent to 15 kg of tritium if all filled) - Modelling of trap creation and subsequent filling beyond m range are in progress

3. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Reduced uncertainty and confirmation of saturation V. Alimov, J. Roth, ITPA 09 Confirmation of saturation of retention with maximum around 500 K New low energy data from UoT narrow the data cloud J.W. Davis, A.A. Haasz, ITPA 09

4. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Influence of n-irradiation damage Pure W Diffusion up to at least 6 m, low concentration at the surface W W Deuterium behavior in self-implanted W is like in pure W diffuses up to 6 m High D concentration at the surface D fills the radiation defects C W In the presence of carbon, the deuterium diffusion decreases strongly B. Tyburska, IBMM Dresden, 2008

5. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Influence of n-irradiation damage 12 MeV Si ion irradiation, subsequent D plasma in PISCES (100 eV, 1e26 D/m 2 ) Number of traps produced from ITER lifetime neutron fluence ~0.005 /W at 200ºC, ~0.0001/W at 500ºC. Observed uptake rate is three orders of magnitude smaller than predicted by frequently used model based on diffusion and surface recombination. At 200ºC trapped D is limited by slow kinetics, ie. permeation. Trapping at 40ºC is smaller due to slower kinetics. Trapping at 500ºC is smaller due to annealing of damage. Tritium inventory from trapping at neutron damage in tungsten should be small in ITER (8 g at lifetime). B. Wampler, ITPA Amsterdam 2009

6. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Simultaneous He irradiation

7. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Simultaneous He irradiation

8. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Simultaneous He irradiation

9. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Simultaneous He irradiation

10. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Conclusion at ITPA meeting Amsterdam The general conclusion of the session was: while several interesting scientific aspects of retention in tungsten are still unresolved and worthy of further investigation, from an ITER viewpoint the retention channel in tungsten is small. When tungsten is exposed to mixtures of helium and deuterium this already small amount of retention is further reduced and therefore retention is tungsten is not considered to be a major concern for ITER operation. The effect of retention in pre-damaged tungsten was also investigated and the migration of tritium deep into the bulk was estimated from experimental measurements to be small (on the order of a few grams during the lifetime of ITER). The only outstanding issues concerning tungsten retention are the effects of transient heat loads and the influence of mixed material surfaces for retention in the underlying bulk tungsten.

11. J. Roth, EU PWI TF, SEWG Fuel Retention, Cadarache, June 15, 09 Further research priorities 1.Refine ITER prediction (MIT mini-meeting) : High priorityReport B. Lipschultz Participants (JAEA, FZJ, UCSD, IPP, Kyushu, CEA, MIT, UofT, Sandia, ITER, JET, FOM) 2.Fuel retention machine database : High priorityDSOL E.Tsitrone Participants (FZJ, MIT, CEA, IPP, JET) 3.Ion cyclotron wall cleaning : High priorityDSOL V. Philipps Participants (VR, FZJ, MIT, CEA, IPP, JET) 4.Disruption flash heating : Med. priority Participants (CAE, UCSD, UKAEA, ITER, JET) 5.Capability and risks of removing C : Med. PriorityReport J. Davis Participants (UofT, VR, FZJ, CEA, IPP, JET) 6.Isotope exchange : Med. PriorityDSOL T. Loarer Participants (JAEA, MIT, CEA, IPP, INL, Kyushu, FZJ, JET) 7.T removal by heating to 350C : High priorityReport J. Roth Participants (MIT, CEA, UCSD, IPP, INL, Sandia, UKAEA) 8.Retention in gaps : Med. PriorityDSOL K. Krieger Participants (FZJ, IPP, INL, UKAEA, Kyushu, JET) 9.Influence of mixed species on retentionDSOL R. Doerner Participant (UCSD, IPP, Kyushu, FZJ, JAEA, UofT, JET) 10. Preparation for the JET ILW experiment Participant (JET TFs, IPP, MEdC, TEKES, UK, SCK-CEN, IST, VR, Estonia, AEV Latvia)