1. 1 MICE Absorbers work package MPB – 17/04/15 RAL Tom Bradshaw Vicky Bayliss Mike Courthold Matt Hills Andy Nichols Roy Preece Mark Tucker Steve Watson DL Steve Griffith Trevor Hartnett Ian Mullacrane Adrian Oates Chris White Oxford John Cobb Wing Lau Stephanie Yang Imperial College Victoria Blackmore

2. Contents Focus Coils Recap Contract Absorbers & hydrogen infrastructure Hardware progress Review outcomes Relief line issue Schedule 2

3. FC recap 3 FC#1 suffers from deficient magnetic performance, probably due to problems with coil potting Currently mothballed in R9 FC#2 trained to full current Currently installed in beamline Both modules are thermally imperfect and have internal helium leaks However, the above issues are non-critical

4. FC#2 – PSU problems During training, the power supply unit (AMI 430) would go into an emergency ramp-down mode after an average of 30 hours DL have been investigating the cause: Not due to errant communications from other components in the rack Unit trips at any current setting, including 0A Latest theory is that the FC load on the R9 electrical infrastructure made the system too sensitive to mains disturbances (see plot below) Expectation is that the problem will not be seen in the MICE Hall 4 5A 5.30am

5. FC contract 5 FC#2 has been accepted for full price FC#1 has been accepted with a 50% discount on the final payment (£13k) Both modules were officially accepted on 4 th March 2015, initiating the 2 year warranty period This is important because the LH2 turrets have not been tested Importantly, MICE have maintained a good relationship with the manufacturer throughout the recent ‘wrangles’

6. LH2 system - review 6 Held in mid-January, chaired by ISIS Included attendees from ISIS, RAL SHE group, CERN (Jon Gulley) and Birmingham Uni (John Dowell) 19 recommendations and 13 comments Approval given for various proposed system changes Approval given for final sign-off process (as per R&D programme) Maintenance plan, training programme for operators and completion of outstanding HAZOP actions Revisit calculations regarding the ability of the system to cope in the event of absorber window failure

7. LH2 system – relief line 7 Two failure modes considered by review in considerable detail Vacuum loss, leading to boil-off of LH2 inside absorber - acceptable Absorber window rupture, leading to boil-off of LH2 inside vacuum space – some uncertainties Second scenario was considered by M. Green and S. Yang in 2004 but assuming that the relief system would be of sufficient diameter to effectively negate pipe pressure drop – this is not the physical reality Calculations by Stephen Harrison of ISIS show that pressure rise is significantly higher than anticipated – calculation needs more refinement but it looks like final answer will be between 5 and 8 bar. Windows nominally designed for FoS of 4 on PRV pressure (1.6 bar) = 6.4 bar FEA says windows manufactured to specification will actually burst between 9 and 11 bar Burst tests carried out to date were at 8 bar

8. LH2 system – relief line cont… 8 Working group has considered this and tentatively agreed that a Factor of Safety of 2 would be acceptable, pending: Approval from ISIS and Technology nominated engineers Discussions with an independent safety expert or consultant A Factor of Safety of 2 with the current setup would probably require: Confidence in a pressure rise no greater than 5 bar – unlikely due to small bore welded pipework Windows that can withstand a minimum of 10 bar – unlikely due to expected optimism in FEA Plan of action Use direct and large-bore pumping line as relief line, bypassing turbo pump with a burst disk Redo calculations accordingly – expected to show a considerably reduced pipe impedance Carry out further burst tests on windows to better understand FEA errors Plan for success – install ‘best’ safety windows in the expectation that they will be proved safe

9. Absorbers 9 Baseline absorber plan is now: Assume that Step IV starts with LiH absorber However, until the July shutdown when the LiH absorber would be installed, the hydrogen absorber will remain in the FC to allow commissioning work to progress This will reduce technical risk from a mid-Step IV hydrogen commissioning period Downside is that initial “empty” runs will now include an empty hydrogen absorber and 4 beam windows Hydrogen absorber Two windows and majority of MLI assembled Proof testing to be carried out shortly Insulation over windows tentatively agreed at 5 layers of MLI (~0.19% of one rad length) LiH absorber Stored in R9, regularly flushed with argon Support structure design task ongoing

10. Schedule 10 March April May June South PRY installation North PRY installation - Hydrogen safety approval - Absorber installed - Absorber proof tested - Hydrogen system tested with helium July - Completion of hydrogen infrastructure - Window burst test

11. Questions? 11