# Presentation: 070496

## 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:
- Minimizing window thickness/no. of windows
- Uniform heat maintainance of LH2

## Catagories for FNAL LH2 Mucool Safety Review

- Civil construction
- Absorber windows
- Vacuum vessel windows
- Safety controls systems
- Electrical safety of hydrogen areas

## Safety Codes and Standards for FNAL  Mucool LH2 System

- _FERMILAB 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:
- 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).
- Non-destructive tests at room temperature:
- External pressure to 25 psid to demonstrate no failures: no creeping, yielding, elastic collapse/buckling or rupture
- 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 feedthroughs
- 3. Distance away from target (e.g. VLPC readouts)
- 4. Seals from signals to electronics:
- 		wires
- 		fibers
- 		tubes