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Radiation. Safety@ISAC SAFERIB Workshop CERN, Oct.30-Nov.1, 2002. L. Moritz TRIUMF 4004 Wesbrook Mall Vancouver, B.C. V6T2A3 Lutz.moritz@triumf.ca. Overview. Short description of ISAC Shielding (tools and verification) Activation (yields and distribution) Target handling
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Radiation.Safety@ISACSAFERIB WorkshopCERN, Oct.30-Nov.1, 2002 L. Moritz TRIUMF 4004 Wesbrook Mall Vancouver, B.C. V6T2A3 Lutz.moritz@triumf.ca
Overview • Short description of ISAC • Shielding (tools and verification) • Activation (yields and distribution) • Target handling • Contamination control • Experience and plans for future
ISAC Parameters Reference Design: 100 A of 500 MeV protons on 95 g cm-2 UC2 Authorization: 100 A of 500 MeV protons on targets Z 82 Application for targets with Z > 82 in preparation Ottawa
Targets (to September 2002) Test only
ISAC at TRIUMF http://www.triumf.ca/isac/is9-00-t.jpg
ISAC Target Stations RIB Initial Installation: West Target Station Installation 2002: East Target Station 500 MeV Protons
Shielding • Bulk Shielding: Point source, line-of- sight attenuation • Complicated geometries: FLUKA • Verification: MCNP, LCS
Point Source, Line-of-sight Attenuation of Prompt Radiation Field Nuclear interaction probability Geometry factor High-energy neutron yield Exponential Attenuation Angular dependence
Parameters fn(Ep), h0,, Nuclear interaction probability, fn Source term, h0 m=0.8 Angular dependence, Attenuation length,
Test: 500 MeV Proton Beam Stop 1.8 m 2.9 m
ISAC Target Shielding (Plan) Concrete (low Na) Radioactive Ion beam Concrete Steel Slits A Cu Beam dump A’ Target Proton beam
0 1m ISAC Target/ion Source Shielding concrete & steel (Section AA’) Service space concrete vacuum seals steel steel steel target ion beam recycled steel
FLUKA simulation Streaming Through Pre-separator Maze Target: 50 g cm-2 UC2 Ep = 500 MeV Ip = 100 mA
Before Pre-separator Maze Added shielding After
Target Module Service Ducts Target/Ion Source
Sv/h Streaming Through Target Vacuum Exhaust Ducts Concrete- steel Air Target: 50 g cm-2 UC2 Ep = 500 MeV Ip = 100 mA steel p
Streaming Through Ducts Concrete- steel Air
Sv/h 1000 350 400 200 105 100 10 140 170 200 115 1 Radiation Fields above Target Andersson-Braun Measurement 100 A on Mo Target Test
Activation • Experimental Cross-sections • Silberberg & Tsao • FLUKA, LAHET, MCNPX • ORIGEN
238U(p,x) Cross Section Comparison at 500 MeV ………… Silberberg & Tsao LCS FLUKA Experimental Spallation Fission Peripheral
Silberberg & Tsao (YIELDX) 500 MeV Protons
FLUKA Simulation (500 MeV protons on UC2 target) UC2 (5.076 g cm-3) H2O p 67 mm 27 mm Ta 18 cm p 1.4 cm UC2 (5.076 g cm-3)
Yields: UC2 target (FLUKA simulation) 18 cm 500 MeV p 1.4 cm UC2 (5.076 g cm-3)
ORIGEN (build-up and decay) Beam On Beam Off
Decays Leading to 210Po 210Po Long-lived Not in ORIGEN Library
ISAC Target Handling Target Maintenance Hall
Maximum g-field Outside ITMH ~10 Sv/h @ 1 m 1 mSv/h
ISAC Target Servicing: Hot Target storage pit Cells Target storage pit Hot Cells
Contamination Control • Ventilation System • Production of Radioactivity in Air • Typical Release Rates • Production of Volatile Radioactivity • Vacuum Exhaust Handling
Secondary Filters Primary Filters Ventilation System Stack Air pressure depression relative to outside Fan Standby Fan Target Service Space Presep. Cave Mass Separator Room Experimental Hall Services Hot Cell Service Room Hot Cell Target Maintenance Hall
Production in Pre-separator Vault (3000 hours per year, 100mA on 238UC2 target)
Production in Target Service Space (3000 hours per year, 100 A on 238UC2 target)
Production of Volatiles Cl/Ar b+ Ne Target I/Xe Hg Rb/Kr volatiles
MP Vacuum Exhaust System MP TP TIS MP HEPA filter TP TP Exit modules TP Operating storage Charcoal filter TP TP Pre-separator Secondary Slits Primary MP TP Mass-separator Long-term storage
Experience • Contamination Issues • Collective Dose
One (!) Contamination Incident(June 2000) Hot Cell Target Station Nb target 1 Ta target 2 No contamination after step 1 Uniform contamination after step 1 No other significant contamination since June 2000
TRIUMF Collective Dose So far ISAC has had no significant impact on TRIUMF collective dose Start of ISAC operation
Future Plans • Task Force to pursue licensing for actinide targets • Proposed test station to measure yields and transport properties of alpha-emitters • Proposed second proton beam line to feed second target station