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LH2 Safety Issues

LH2 Safety Issues. 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

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LH2 Safety Issues

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  1. LH2 Safety Issues 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 FNAL LH2 Safety Panel Wes Smart (chair) Jim Kilmer Jim Priest Del Allspach (consultant)

  2. Catagories for FNAL LH2 Mucool Safety Review • Civil construction • Absorber windows • Vacuum vessel windows • Safety controls systems • Electrical safety of hydrogen areas

  3. 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

  4. 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

  5. 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 Windows (2)

  6. 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”

  7. Instrumentation Safety 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 Temperature/density uniformity inside LH2 Safety instrumention inside vacuum area Detectors for cooling measurements

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