1. Accident analysis for HCLL TBM • Lise-Lotte Spontón • Studsvik Nuclear AB, Association Euratom - VR • Kick-off-meeting, Garching, 9 October 2006

2. Accident sequence • TBM ex-vessel LOCA + in-vessel He and water LOCA. • Ex-vessel break in the TBM He cooling loop during normal operation, • He loop emptying into TCWS vault. • The plasma is not shut down. • Temperature of TBM module increases until rupture, • time of rupture has to be estimated, • estimated time will depend on temperature and pressure • In-vessel break in TBM He cooling loop towards plasma, causing plasma disruption and break in FW water cooling loop, • all at the same time, • by-pass from VV into TCWS vault. • Question: Is the LiPb-loop assumed ruptured at the same time?

3. Accident sequence, cont. • TBM ex-vessel LOCA + in-vessel He and water LOCA. • Reaction between water/steam and LiPb produces hydrogen • Maximum possible hydrogen production, with available LiPb inventory is about 2.5 kg. • Question: Use maximum hydrogen production possible (2.5kg)? • Possible hydrogen explosion/detonation in VV or TCWS vault, depending on flow direction in by-pass • study concentration of hydrogen in VV and TCWS vault • Dust and tritium might reach the TCWS vault.

4. Tool • Fusion MELCOR1.8.5 will be used for the calculations. • Question: How to model liquid Lithium Lead? • Brad Merill has run MELCOR using ATHENA properties file for liquid LiPb. Not properly QAd and benchmarked yet. • Alternative to model LiPb as a solid heat structure.

5. Input model • Studsvik has got MELCOR models including: 1) VV, FW coolant loop, DT, VVPSS, Port Cell, Gallery, etc. 2) TCWS vault and connected rooms no input describing the TBM and loopInput 1) is not complete and needs to be checked. Needs to be up-dated according to latest SADL. • Question: What SADL version should be used? • Version on the ITER website: 4.0.3, date 26 Sept. 2003. • Question: Take into account new set-points for DT and VVPSS?