MICE RF Module Safety

1
MICE RF Module Safety
MICE Collaboration Meeting February 12, 2005

• Steve Virostek
• Lawrence Berkeley National Laboratory

2
Introduction

• RF Module safety plan and hazard analysis is in
  the preliminary stages of development
• Safety issues will be addressed by the MICE
  Design and Safety Review Group
• Approach will be consistent with safety planning
  under way for the AFC Module
• Hazards are being identified during initial phase
• Upcoming tasks perform a hazard analysis and
  develop the safety document

3
RF Module Overview
Cryo-cooler

Vacuum Vessel
Coupling Coil
RF Cavity
Be Window
RF Couplers
Vacuum Pump/Manifold
Support Structure
4
RF Module Safety Topics

• X-rays and RF fields
• Magnetic fields
• Beryllium windows
• Coupling coil hazards
• Magnetic loads

• Vessel structural integrity
• Cavity sparking
• RF coupler windows
• Proximity to AFC Module
• Cooling water in vacuum

5
Preliminary Hazard Assessment

• X-rays and RF fields
• Radiation hazard to personnel during operation
• Shielding to be incorporated along the beamline
• RF interlocks prevent access during operation
• Coupling coil hazards
• Vessel rupture magnet lead voltages quenching
  issues
• Coils are vacuum insulated in their own vessel
  designed in accordance with the pressure vessel
  code
• Coil design includes appropriate quench
  protection that will limit the magnet lead
  voltages to 10 V

6
Preliminary Hazard Assessment

• Beryllium windows
• Hazardous material thin window rupture hazard
• Unlikely to produce airborne particles
• Connection through vacuum manifold prevents
  differential pressure on windows
• Magnetic Fields
• Magnetic field hazard to personnel during
  operation
• Shielding to reduce fields in publicly accessible
  areas
• Interlocks prevent access during operation

7
Preliminary Hazard Assessment

• Magnetic Loads
• Large magnetic forces are reacted to the module
  vessel during operation and various quench
  scenarios
• Structural FEA used to design load carrying
  components
• Unbalanced loads on RF/AFC Module assembly will
  be reacted to the floor through RF Module support
• Vessel structural integrity
• Vessel subject to vacuum possible overpressure
  loads
• Design will be per the appropriate pressure
  vessel code
• Pressure relief valve prevents excessive
  overpressure

8
Preliminary Hazard Assessment

• Cavity Sparking
• Sparking, multipactoring high RF fields produce
  more dark current and extra thermal load on
  absorbers
• Heat load is estimated to be less than a few
  watts
• Monitor with vacuum gages and spark detectors
• RF coupler windows
• Ceramic window failure can vent the vessel and
  cavities
• Catastrophic failure is unlikely usual mode is a
  crack resulting in a slow leak (no shockwave,
  easily detected)
• Pressurized N2 will prevent O2 from entering
  system

9
Preliminary Hazard Assessment

• Proximity to AFC module
• Be windows are adjacent to AFC modules
• Window fracture would exert no shockwave or
  vacuum loads on the absorber (no window
  differential pressure)
• RF power can be shut down very quickly
• Cooling water in vacuum
• Water line rupture could cause overpressure in
  vessel
• Vacuum vessel contains continuous tubes only a
  small leak is much more likely than a full
  rupture
• Detect w/vacuum gages (PRV, RF interlock, water
  valves)