numi radiation and environmental protection
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NuMI Radiation and Environmental Protection. NBI2006 - 6th International workshop on Neutrino Beams and Instrumentation September 5-9, 2006 Mike Martens Fermilab. Environmental Concerns. Groundwater Protection NuMI tunnel is in an Aquifer Surface Water - PowerPoint PPT PresentationTRANSCRIPT
NuMI Radiation and Environmental Protection
NBI2006 - 6th International workshop onNeutrino Beams and Instrumentation
September 5-9, 2006
Mike MartensFermilab
Page 2NBI 2006 Mike Martens
fEnvironmental Concerns
• Groundwater Protection– NuMI tunnel is in an Aquifer
• Surface Water– Sump water is pumped from NuMI tunnel to the surface
• Air Emissions– Air from Target Chase and Absorber region are vented to the surface
– This is done after a long passage through the decay pipe to reduce the radioactivity levels of short lived radionuclides
• Component Activation– Personnel Protection, Hot Handling, etc.
•All of this is important and has our attention•Was expected during the design phase of NuMI•Being re-evaluated for the SNuMI upgrades•Much of this is “Standard Stuff” for beamlines
I will say a few words on Tritium Production since this became an important topic as we started NuMI operations
Page 3NBI 2006 Mike Martens
fChronology
Savannah Subdivision
NuM
IN
uMI
Indian Creek
• Last November detectable levels of tritium were measured in the Indian Creek discharge from the Fermilab.
– First observation ever of tritium in any water flowing off our site
– Indian Creek flows through the Savannah subdivision
– Measured 3.3 pCi/ml (site boundary) DOE regulatory limit for surface
water is 2000 pCi/ml (20 pCi/ml for drinking water)
• Task Force established and mitigation implemented
• Currently measurements are all below the detection limit of < 1 pCi/ml
Page 4NBI 2006 Mike Martens
fIndian Creek Measurements
http://www.fnal.gov/pub/about/community/chart.html
• The immediate source of tritium in Indian Creek in November was identified as water leaking into the creek from a damaged pipe connecting Main Injector ponds C and D.
• The pipe was pumped out and blocked off: Currently under repair
Page 5NBI 2006 Mike Martens
fNuMI as Source of Tritium
• Water flowing into the NuMI enclosure is collected in the MINOS cavern and pumped to the surface– ~175 gallons per minute– Design protects the aquifer by bringing tritiated water to the surface
Sump discharge and holding tank
Page 6NBI 2006 Mike Martens
f
Concrete Walls
Concrete Shielding Blocks
Chiller
Target Chase Cooling
Cool air flows upstream on outside of pile, then downstream in the chase Target Pile
In practice some air exchanged between target chase and target hall
Page 7NBI 2006 Mike Martens
f
EAV-2 EAV-3SR-3
Absorber Hall
Decay Passage
Target Hall
Target Chase
Chiller Condensate
Drain To Sump
Chiller
ChillerCondensate
Page 8NBI 2006 Mike Martens
fChiller Condensate Collection
Chiller Condensate Tank
Page 9NBI 2006 Mike Martens
fCondensate Collection
0
5
10
15
20
25
30
35
11/24/2005 12/24/2005 1/23/2006 2/22/2006 3/24/2006
Ho
ldin
g t
ank
trit
ium
pC
i/m
l Sump Holding Tank
Chase SEALED/OPEN
Re-circ fan ON/OFF
Chiller ON/OFF
beam POT e17/day
Page 10NBI 2006 Mike Martens
f
EAV-2 EAV-3SR-3
Absorber Hall
Decay Passage
Target Hall
Target Chase
Dehumidification
Desiccant UnitDrain To Sump
Dry Air
Humid Air
Page 11NBI 2006 Mike Martens
fDesiccant Units
Page 12NBI 2006 Mike Martens
fDehumidification Results
0
5
10
15
20
25
30
35
11/24/2005 12/24/2005 1/23/2006 2/22/2006 3/24/2006 4/23/2006 5/23/2006 6/22/2006 7/22/2006 8/21/2006
Ho
ldin
g t
ank
trit
ium
pC
i/ml Sump Holding Tank
EAV2-3 fans ON/OFF
Chase SEALED/OPEN
Re-circ fan ON/OFF
Chiller ON/OFF
Dehum ON/OFF
beam POT e17/day
Page 13NBI 2006 Mike Martens
fSummary of Mitigation
• As of November 2005 the major contributor to tritium within our surface waters is water being pumped out of the NuMI enclosure.– 175 gpm @ ~30 pCi/ml in November – Result: Essentially all Fermilab surface waters are in 1-5 pCi/ml range
• In December 2005 we identified a major contributor within the enclosure: condensate from an air conditioning unit in the target area.– Represents ~60% of the November concentration.– Condensate is being collected and disposed (1-2 gph).– Result: Holding tank levels between 10-25 pCi/ml.
• In March 2006 installed de-humidifers in the target hall – Prevents tritiated humidity from passing through the decay hall and
mixing with the tunnel water– Result: Holding tank levels are between 5-6 pCi/ml