NuMI Internal Review

1
Technical Components

• NuMI Beamline
• Radiation Safety Issues
• Radiation Safety Coordinator
• Nancy Grossman
• FNAL
• July 12, 2001

2
Outline

• Overview
• Gate Locations
• Radiation Safety Monitors/Equipment
• Critical Devices
• Access
• Prompt Radiation
• Groundwater Protection
• Air and Water Monitoring
• Component Activation

3
Radiation Safety Overview
4
Gates Fences

• Probable location of interlocked
• gates ( ) and locked fences ( )
• Gutter, Pipes
• Vacuum pump
• RAW water system
• Interlocked radiation detector

5
Radiation Safety Monitors/Equipment

• Presently envision 3 interlocked detectors
• Upstream shaft area
• Power Supply Room
• Hadron Absorber/Bypass tunnel area
• Frisker, portable survey meter, and radioactivity
  class meter
• (3 sets)
• Near upstream shaft interlocked gate area
• Near downstream bypass tunnel interlocked gate
  area
• Target Hall horn work area
• 2 stack monitors
• Pre-Target Hall stack
• Target Hall/Decay Region stack
• MOU with the ESH Section is being drafted to
  cover
• Equipment needed for NuMI
• Air and water monitoring

6
Critical Devices

• Primary Critical Device Lambertsons (iLAM60) in
  MI extraction
• Lambertsons power supply will be turned off
• Beam will stay in MI and oscillate (off-center)
  and probably eventually scrape off on something
• Secondary Critical Device First set of bend
  magnets (eHV101)
• HV101 power supplies will be turned off
• MARS runs show that there are no problems with
  groundwater or personnel protection in the Pre
  Target region when one or both critical devices
  are tripped off and beam is extracted to NuMI.

7
Access

• NuMI Beam, No Access
• Carrier Tunnel, Pre-Target, Target Hall, Decay
  Tunnel, Hadron Absorber Cavern, Muon Alcoves
• NuMI Beam Access
• Base of Target Hall Shaft
• Power Supply RAW Rooms
• RAW Room may have locked door.
• Bypass tunnel to some extent (determine final
  gate location when run and do measurements)
• MINOS Cavern
• MI Beam NuMI Access
• Everywhere but the Carrier Tunnel (and upstream)
• Carrier Tunnel will have a Captured Key (or
  similar) door.

8
Prompt Radiation

• Labyrinth and penetration exit dose rates
• Labyrinth source terms where bulk shielding is
  present (dark blue text) are not well known
  (factor of 10)
• MARS simulation of the Target Pile has at least 1
  foot less steel on all sides than the present
  design (yellow shading)

9
Groundwater Protection Primary Beam

• Open apertures and Autotune will help keep
  beam nominal and clean
• Enable beam extraction to NuMI only when
  conditions are nominal (Beam Extraction Permit)
• Magnet currents within nominal limits this pulse
• Limit on beam loss last pulse and integrated beam
  loss (beam loss monitors, Beam Loss Budget
  System)
• Interlocked radiation detectors
• Clean Main Injector beam
• Detailed simulations (MARS14) of the primary
  beamline and possible accident and DC
  (continuous) loss conditions have been studied.
• Magnet power supply regulation levels needed to
  keep losses minimal are obtainable.
• Strong indication that beam loss monitors (BLM)
  signals closely track groundwater activation
  levels.
• Plan to test as much of the Extraction Beam
  Permit System and Beam Loss Budget System as
  possible in the P150 line starting this year.

10
Groundwater Protection Primary Beam

• Preliminary MARS14 Primary beamline results,
  accident losses

11
Groundwater Protection Primary Beam

• Preliminary MARS14 Primary beamline results,
  normal operation
• Determine worst loss locations for normal
  operation
• Leads to power supply regulation (and Main
  Injector beam) requirements
• With presently envisioned power supply
  regulation
• All normal (DC) losses in the primary beam region
  are at least an order of magnitude below what is
  necessary to meet the groundwater regulations.
• Main Injector emittance tails and position
  stability
• No beam loss if less than 3 mm horizontal orbit
  shift (vertical requirements are very loose)
• Modeled range of emittance and tails
• No beam loss if ? 40? emittance with tails
• Expect 20? emittance with tails to 40?
• Beam loss monitors look to be very good for
  tracking groundwater activation.
• Use Beam Loss Budget System to keep track of
  losses.
• Long loss monitors in the carrier tunnel and at
  every possible loss point.

12
Groundwater Protection Secondary Beam

• Hadron Absorber values need to be updated for the
  present cavern and Hadron Absorber design.

13
Airborne Activation

• Radioactive Air calculations are being revisited
  with the present detailed Target Hall design.
• Site-wide permit submitted including NuMI
  operations in 3/99
• Goal for NuMI is lt 45 Ci/year
• 0.025 mrem/year (1/4 continuous monitoring
  limit)
• Previous NuMI estimates were 40 Ci/year
• Majority of the air activation occurs inside the
  Target Pile
• Closed system at negative pressure relative to
  the air outside the shield.
• Preliminary calculations based on re-circulation
  
• _at_ 2250 cfm ventilation, leakage _at_1500 cfm-gt 20
  Ci/year
• Have a variable rate ventilation system from the
  Target Hall to the decay vent.
• Measurements of air activation will be made early
  on and the ventilation rate can be adjusted (and
  the target pile can be better sealed if
  necessary)

14
RAW Water

• RAW Water System calculations are in progress.
• Preliminary Results
• Target Hall RAW water system
• Change once per year
• Maximum estimates 4000 Ci/yr, 20 mCi/ml
• Discussions with Don Cossairt that this is OK.
• Alarms to the alarm console in MCR and loss of
  the beam permit for leak.
• Decay Pipe RAW water system
• Most likely last lifetime of NuMI
• Maximum estimates 11 mCi, 700 pCi/ml
• FRCM Guidelines not get over 0.67 mCi/ml in RAW
  systems
• Water will be sampled periodically to check
  levels, alarm systems for water loss, procedures
  for access to RAW Room.

15
Residual Activation

• MARS Residuals 30 days irradiation, 1 day cool
  down (_at_2E13protons/sec)