MIPO meeting 120515 Exec summary Working group satisfied

MIPO meeting 12/05/15

Exec summary • Working group satisfied in integrity of absorber vessel and windows, pending review of reports – – • • • Working group satisfied with ability of revised relief system to limit pressure rise to below half of the window burst pressure Working group agreed that third HAZOP can be substituted with a formal change control procedure, completed retrospectively for the various system changes Absorber now fully installed in FC – • Proof test at 2. 2 bar showed evidence of minor plastic deformation but measurements were within error bars of instrumentation Burst test of safety window successfully completed, with the window failing at 7. 66 bar, in line with expectations Leak rate currently at 3 x 10 -8 mbar. l/s Installation took 2 weeks, longer than expected. This was due to the amount of MLI work and some problems with fitting the end flange. Having learned from this: – – – Dismantling the absorber would take 2 days Re-assembly would take a week - 2 days preparatory work and 3 days to install in the FC Although we haven’t found any indium leaks on this installation, any reinstallation schedule should take this into account – an extra week is suggested

Window testing Burst test • • • Pneumatic test off-site Burst at 7. 66 bar. g (110 psi) FEA for this window predicted 9. 66 bar. g which is a 20% overestimate – this was anticipated We have two measured analysed spare windows (#005 – absorber; #008 – safety 2) We have two further delivered windows but they have not had FEA carried out to date Proof test • • • Absorber pressurised to 2. 2 bar. g in FC#1 bore No measureable leak via sniff or pressure drop Laser used to measure distance from datum to centre of window at start and end of test – – – Displacement of 0. 09 mm (mean of 5 measurements each time) Accuracy of laser stated as 0. 5 mm Equivalent measurement to FC vessel resulted in similar mean displacement

Relief system revision • • • Pressure rise on as-installed system calculated as between 5 -8 bar – expected to be a bit optimistic Working group agreed on target of Fo. S of 2 - with window test results, this means an allowable pressure rise of 4. 25 bar Proposed change to relief system uses the pumping line instead of a dedicated relief line – – – • • All large bore pipework Will include a bypass burst disk for the turbo pump Will also include relief valves in parallel with backing pump Pressure rise is now calculated at 4. 3 bar and this is reckoned to be conservative now Proposal accepted and procurement now going ahead

Absorber installation • Absorber installed – – – • • Window flange to FC flange measurement of 265 mm Problem encountered when trying to fit end flange; interference with pipes of around 10 mm – – – • 4 blankets of MLI around vessel body Half a blanket (5 layers) over windows 2 blankets wrapped around pipes 1 blanket wrapped around instrumentation cables Excess cable coiled and hung using mylar ‘slings’ – no visible touches to warm surfaces Not understood at all Quick fix solution of a stand-off flange cannibalised from the other FC works Downside is the flange now sticks out beyond the FC envelope – bellows have to be fitted to FC first now Leak testing is still progressing but is looking very positive so far – 3 x 10 -8 mbar. l/s on a rough vacuum

Going forwards • • System hardware all agreed and understood in principle Orders (nearly) all placed and lead times are acceptable Lots of paperwork to complete but should be manageable by the end of June Desire to start cooling the absorber at the earliest opportunity – • I will make a declaration of confidence in the system (i. e. recommend that first Step IV absorber run can revert to hydrogen) when the following is achieved: – – – • Depends on hose and cable installation schedules Clear evidence that the system thermal performance is satisfactory (helium cooldown below 20 K) Significant progress on paperwork, including draft operating procedures Good understanding of any remaining hydrogen infrastructure work (transfer line, bottle platform) I hope to be in a position to do this before the middle of June – This gives several weeks float before ultimate deadline of start of July for the planned installation of the Li. H absorber