# Presentation: 170044

## Technical Components

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

## Outline

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

## Radiation Safety Overview

## Gates & Fences

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

## 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 ES&H Section is being drafted to cover:
-  Equipment needed for NuMI
- Air and water monitoring

## Critical Devices

- _Primary Critical Device_: Lambertsons (i:LAM60) 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 (e:HV101)
- 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.

## 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.

## 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)
*Preliminary MARS14 simulation of the present Target Pile shield design is nearly complete*
*MARS14 can more accurately determine the source terms outside of thick shielding (factor of 3?)*

## 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.

## Groundwater Protection: Primary Beam

- _Preliminary_ MARS14 Primary beamline results, _accident losses_:

## 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.**

## Groundwater Protection: Secondary Beam

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

## 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 < 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: **
**@ 2250 cfm ventilation, leakage @1500 cfm-> ~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)

## 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 Ci/ml in RAW systems
- 	Water will be sampled periodically to check levels, alarm systems for water loss, procedures for access to RAW Room.

## Residual Activation 

- MARS Residuals: 30 days irradiation, 1 day cool down (@2E13protons/sec)