LH2 Safety Issues for MICE

• O2/LH2 separation• No Ignition sources near LH2• Adequate ventilation• Affects:

• Windows: absorbers and vacuum• Primary and secondary vacuum volumes• Support structure absorber/focussing

coil• Instrumentation (experiment and

monitors)• Cryogenic operation• Laboratory area

• Cooling concerns:1. Minimizing window thickness/no. of

windows2. Uniform heat maintainance of LH2

Catagories for FNAL LH2 Mucool Safety

Review1. Civil construction

2. Absorber windows

3. Vacuum vessel windows

4. Safety controls systems

5. Electrical safety of hydrogen areas

Safety Codes and Standards for FNAL Mucool

LH2 SystemFERMILAB STANDARDS (FESHM)

• “Guidelines for the Design, Review and Approval of Liquid Cryogenic Targets”

• “Liquid Hydrogen System Guidelines”

• “Storage and Use of Flammable Gases”

• “Cryogenic System Review”

• “Oxygen Deficiency Hazards”

• Other…Pressure Vessels, Dewars, Electrical, etc.

NATIONAL CODES

• ASME Code

• National Electric Code

• National Fire Protection Association Code

• Compressed Gas of America Standard

• ISA Application of Safety Instrumented Systems

FNAL Safety Requirements for Windows

Absorber Windows

Design:

• Internal WAMP = 25 psid

• FEA showing max. allowable stress < 0.25 UTS (this is waived by meeting the performance tests below)

• Material certification

• Window engineering/design drawing

Tests:

• Room temperature tests per UG-100 of the ASME code and room temp. burst test.

• Liquid nitrogen test – burst test per UG-101 of the ASME code

Note: The LH2 circuit safety relief system includes 2 valves with a 10psid set point. In addition, a PLC-controlled vent valve will be installed

FNAL Safety Requirements for Windows (2)

Vacuum Windows

Assumption: Design assumes that the beampipe attaches to absorber vacuum windows, therefore vacuum exists on both sides of the windows

Design:• Internal WAMP = 25 psid• External MAWP = 15 psid• FEA showing maximum allowable stress is <2/3

Sy or < 0.4 Su

• Material certification• Window drawing

Tests:

1. Burst test 5 vacuum windows at room temp. to demonstrate a burst pressure of at least 75 psid for all samples. (pressure exerted on interior side of vacuum volume).

2. Non-destructive tests at room temperature:

a. External pressure to 25 psid to demonstrate no failures: no creeping, yielding, elastic collapse/buckling or rupture

b. Other absorber vacuum jacket testing to ensure its integrity

FNAL Safety Requirements for Controls

Safety Interlocks (Quadlog PLC) and Controls (Apacs)

Functions:

• Control operations of the LH2 system

• Safety interlocks for the LH2 system

• Safety actions in the case where flammable gas or ODH conditions are detected

System design:

• Design requires knowledge of equipment value in the experimental hall

• An estimate of failuer severity and frequency will be made as well as the consequences to personnel and equipment

• The overall risk will be evaluated to determine a “Safety Integrity Level” (SIL).

• The SIL will determine the safety controls architecture (level of redundancy required) per ANSI/ISA-84.01, “Application of Safety Instrumented Systems for the Process Industries”

Instrumentation Safety

• Temperature/density uniformity inside LH2

• Safety instrumention inside vacuum area

• Detectors for cooling measurements

Safety Issues:

1. Limits the amount of energy/(area or vol) 2. Physical size of the signal feedthroughs3. Distance away from target (e.g. VLPC

readouts)4. Seals from signals to electronics:

wiresfiberstubes