H2 Safety Review - response

paul drummMICE VC, March 29th,2006

Osaka CM

• Point by point answers were shown by Yury in Osaka

• Mostly in agreement with review• One or two places where robust

(analytical) answers are needed.

• My thoughts and suggestions…in red

Review Item Response

1 The use of the bolted connections for the absorber module windows, with pressure monitoring between the two indium seals was considered to be an appropriate choice given the practical experience of this type of seal within a vacuum environment.

An issue for the absorber group – and we should reflect an answer from them?

2 The use of a non-flammable super insulation material within the hydrogen system should be investigated.

This will be done – we will use polyimide material. Is there any impact?

3 The effect of helium on the performance of the hydride bed should be investigated as a matter of urgency as this may impact the design. However, the need to maintain a positive pressure in the system, to avoid oxygen ingress, was agreed.

This has been investigated with the manufacturer and there is no effect. Document?

4 Quality control, configuration management and security of the hydrogen system software need to be assured.

Agreed – but what is the proposal?

5 Positive independent feedback of valve positions etc. should be implemented in the control system.

Agreed

6 It is recommended that the build up of explosive atmospheres within the Hall as well as within the test rig be fully considered and that compliance with The Dangerous Substances and Explosive Atmospheres Regulations 2002 and the European Directives ATEX 137 (procedures) and ATEX 95 (equipment) is addressed.

We will implement external hydrogen sensors. We have considered the release of hydrogen into the hall and incorporated fans and vents in the roof space. Is this a sufficient answer? Are there places where H gas can accumulate despite the fans/vents?

7 Although the estimated volume of gaseous hydrogen in the cryogenic system is less than 2% of the total volume of the Hall, there can be local concentrations that exceed this particularly at the ceiling level due to the fact that the hydrogen will rise. Suitable venting should be provided.

This has already been considered and fans and vents are being installed in the roof space. As above

8 Hydrogen detectors and oxygen depletion sensors should be installed in the Hall, with associated evacuation alarms. Upon detection of hydrogen within the Hall, all non-compliant electrical systems should be automatically shut down. Certain sub-systems such as evacuation lighting, ventilation and safety systems should be made compliant and remain operational.

Agreed. What is the implication? Does this mean all systems in the hall are to be shutdown? And does this affect ISIS? Are there safety systems that should not be shutdown? This needs to be reviewed.

9 The reliable performance of the hydrogen detectors and oxygen depletion detectors, within the atmosphere in which they will be required to work, must be assured (type of sensor, location, maintenance, etc.).

This was an issue as we planned to have hydrogen sensors in the exhaust line of the exhaust pumps where they could suffer from contamination. The sensors will be subject to a maintenance schedule. What is the life cycle of a sensor? I don’t know how to assess this.

*The original assesment was that the hydrogen zone did not extend out of the absorber vessel/pipe work. Is this changed or can the original view be defended?

10 Suitable Uninterruptible Power Supplies (UPS) should be provided for the control and safety systems.

Agreed.

11 The location of vent pipe outlets, particularly their height above the roof, should be designed to prevent fire hazards (the industry standard is 3m).

Implemented.

12 Suitable fire detection and extinguishing equipment should be provided in the Hall.

There is lab policy on this which will be followed.

13 It is recommended that the procedures for access to the Hall should be reviewed.

Agreed

14 A permit to work system should be adopted for people who need to work in the MICE Hall.

Agreed

15 Suitable personal protective equipment (fire retardant / anti-static clothing and footwear) should be worn in the Hall when hydrogen is present in the system.

Agreed – a policy will be developed as part of the overall risk assessment.

16 Activities permitted to be carried out in the Hall whilst liquid hydrogen is present should be carefully considered (for example, hoisting and rigging activities should be prevented).

Agreed

17 Clearly defined operating procedures which include responses to abnormal conditions should be developed and presented at the operations review.

Agreed

18 All persons involved with operating the hydrogen system must be trained in both safety aspects and operating procedures.

Agreed. What are the terms of the proposed training?

19 Consideration should be given to procedures to be adopted in worst case scenarios such as crane accidents, aeroplane crash etc.

Agreed. What are the chosen worst case scenarios to be investigated?

20 The CERN safety system (DSS) for LHC experiments could be studied as a possible basis for the MICE safety system.

This will be investigated. This needs a mechanism for discussion? D&S?

Finally• Additional items in report not covered in above list:

• The Panel concluded that the HAZOP study as presented is incomplete. A full HAZOP study, and a failure modes effects analysis (FMEA) carried out with the aid of an external specialist, should be completed as a priority.

• What are the terms of the request to AP on the HAZOP? The findings of these studies and the response of the MICE team should be independently examined before the designs finalised and accepted.

• Keep this in mind! We may have an idea of this, but how is this to be done?

• We wish to stress that the above remarks are restricted to the safety issues associated with the handling of liquid hydrogen. We have not considered the wider risks that may be encountered in carrying out the R&D activity. We suggest that a full qualitative risk assessment is undertaken by the MICE team to ensure that all hazards have been identified.

• Presumably this should also have explicit agreement?

• Finally, the Panel is of the opinion that no further external safety review of the Hydrogen Delivery System, R&D stage, is required before the proposed operations review, provided that the HAZOP study and FMEA are satisfactorily completed.

• We agree with the MICE team that a review of how the Hydrogen Delivery System interacts with an absorber focus coil module as well as with the full control and interlock system of the MICE experiment will be needed before the implementation of the next stage.

Operating procedures, systems of work RISK Assessment FMEA HAZOP

Timetable

• Review response at D&S– meeting being arranged ~soon!

• Finalise Response ~mid April

• Response sent to TB EB RAL Management ~ end April

• Timely discussions in D&S group