October 12, 2006 EURISOL Radiological Safety for the J-PARC Project Hiroshi Nakashima J-PARC J-PARC Facility Materials and Life Science Experimental Facility Hadron Beam Facility Nuclear Transmutation 500 m Neutrino to Kamiokande Linac (350m) 3 GeV Synchrotron (25 Hz, 1MW) 50 GeV Synchrotron (0.75 MW) J-PARC = Japan Proton Accelerator Research Complex Joint Project between KEK and JAERI Secondary particles from high energy proton reaction Nuclear & Particle Physics at 50 GeV R&D toward Transmutation at 0.6 GeV Materials & Life Sciences at 3 GeV T2K Experiment Intense neutrino beam by 100 times at KEK 12 GeV PS T2K = Tokai to Kamioka Muon neutrino beam J-PARC (Kamioka) ντ νe Change to Change to νµ νµ (Tokai) Disappearance of νµ ↔ High Statistics T2K （Five year data at KEK-PS can be measured within a few weeks at J-PARC ） Detection of νe at Super Kamiokande↔ Totally new experiment Materials and Life Science Experimental Facility Neutron and Muon Neu tro Building dimension : Width : 70m n Sc atte ri n Target remote handling room Length : 146m g Fa cilit Height : 30m y 1M W Exp. Hall Height : 22m Spa llati o Cooling systems (Basement) n Ta r ge Mu t St atio on Sci Pro n en c eF acil it ton b eam y Sp alla Ex per ime 23 neutron beam lines will be Installed in experimental halls under present design. tion tar Merc get ury n ta l ha line 3GeV, 1MW proton beam ll Mu Sc rap er on pr o duc tion ta r get Transmutation Experimental Facilities TEF-P: Transmutation Physics Experimental Facility TEF-P: Transmutation Physics Experimental Facility TEF-T: ADS Target Test Facility TEF-T: ADS Target Test Facility 10W Critical Assembly 200kW Laser Charge Exchange Shield Pb-Bi Target Characteristics of J-PARC from the view point of safety Characteristics ・High beam power (up to 1MW) ・High beam energy (up to 50GeV) ・Large-scale accelerator complex (about 3.2 km in length) Radiation problems ・Widely distributed radiation source ・Thick shield ・Activation etc… Safety issues Design method is basically simplified method, Detailed method for complicated geometry.(1) Confinement of activated air during operation. (2) Ventilation after cooling-down. Closed cycle for cooling water and mercury. Release after measuring T activity. Underground(3) Design criteria for soil should have been decided. Target issues(4) Nuclear heating, Activation, Radiation damage, Pressure wave Design Criteria ・ Controlled Area: 12.5µSv/h 1/2 of regulation (1mSv/40h:1week) ・ In-site： 0.25µSv/h 1/2 of regulation (250µSv/500h:3 months） ・ Site boundary Radiation: 50µSv/ year 1/20 of regulation (1mSv/year ） ・ Gasious waste: Regulation Concentration and total amount by government and local government ・ Liquid waste: Regulation Concentration and total amount by government and local government ・ Soil activation: 5mSv/h No regulation. Assumption of beam loss distribution 50GeV Dump： 7.5 kW ： Collimator： 4 kW ： Septum： 1 kW ： Beam Dump： 1 kW ： Analize r： 0.35kW ： 3-50BT Scraper ： 450 W Septum： 1 kW ： Beam Dump： 4 kW ： Extraction： 1.13 kW ： 5 0 GeV Dump ： 750 kW D400-4a: 2 kW D400-4b:5.4 kW T1 target： ： 225 kW Neutron Facility ：1 MW Injection ：135 W S62-1: 11 W S72-1: 19 W D200-1: 0.11 kW Extraction： 7.5 kW ： D400-2: 4 kW D450-1:0.6 kW D400-3a:0.6 kW D400-3b:5.4 kW Planed beam loss Scraper： 450 W ： Dump:3 kW Muon Facility T1 target： 37 kW ： Scraper： 37 kW ： T2 target： 37kW ： BeamTransport： 37kW ： 1 nA/m 0.5 W/m 1.0 W/m ＞2.3 W/m Criteria of hands on maintenance (1) Simplified methods For bulk shielding ・ Moyer model (KEK parameter: H0, λ)[＞1GeV] ・Tesch’s equation[<1GeV] For streaming ・Nakamura/Uwamino’s equation ・DUCT-III（Shin’s equation) For skyshine ・Stapleton’s equation Monte-Carlo codes ・PHITS, MARS, MCNPX Parameters ・Dose conversion factor Radiation Activity H igh-en ergy pa rt icle flu x Residual nuclei PHITS, MCNPX, MARS (En>20MeV, Ei>1MeV i=p, pion, meson) Neu t ron sour ce for low en er gy calculation Nuclear decay data set Neutron flux Particle flux 2nd-γ−ray Nu clea r deca y DCHAIN-SP 2001 Nuclear Production X’sect Low-en ergy pa rt icle flu x MCNP (E n<20MeV, 2 nd -γ−r ay) Air,Wat er Neu t ron t ra ns port X’sect for low en er gy Dose Site boundary In site Controlled area Devices γ−ray from residual nuclei γ−ray transport QAD-CGGP2, MCNP Residual Activity Dose due to residual nuclei Benchmark analyses ・Thick Target neutron Yield (TTY) LANL, KEK, etc. ・Beam dump KEK, BNL/AGS ・Deep penetration TIARA, BNL/AGS ・Streaming TIARA, NIMROD, KEK ・Skyshine comparison Comparison of neutron attenuation between simplified and detailed methods 10 Effective dose [mSv/h] 実効線量 10 10 10 10 10 10 10 10 4 3 M ARS Moyer M odel 2 1 0 -1 -2 -3 1.5GeV 5W Concrete shield -4 100 200 300 400 500 線源からの距離source Distance from the [cm] 600 700 AGS Shielding Experiment Concrete 5.0m Proton Steel Target 2.0m 3.3m Steel 3.7m AGS shielding experiment AGS Experiment (Neutron deep penetration experiments) Source neutrons : Mercury by 2.83- and 24-GeV-protons. 10 10 -28 Exp. NMTC/JAM (In-medium) MCNPX -29 -30 209 204 Bi(n,6n) 10 10 10 10 Bi -31 -32 24 GeV Concrete Lateral -33 -34 0 50 100 150 200 250 300 350 400 Shield Thickness [cm] Reaction Rate / Proton / Target Nucleus Reaction Rate / Proton / Target Nucleus 10 10 10 10 10 10 10 10 -29 Exp. NMTC/JAM (In-medium) MCNPX -30 -31 209 204 Bi(n,6n) Bi -32 -33 24 GeV IRON Lateral -34 -35 0 50 100 150 200 Shield Thickness [cm] Agreement within a factor of two 250 TIARA experiment 16 Neutron Dose Equivalent Rate Neutron Dose Equivalent Rate （μSv h-1 µA-1） 10 6 10 1st leg 2nd leg 3rd leg 5 Cu 80mmφ×12mm ｔ 7.5 10 4 Exp．(Bonner) DUCT-Ⅲ 10 3 Cal.(MCNPX) 10 2 4.5 Cal.(NMTC/MCNP) 10 1 7.5 10 0 3.5 4.8 Proton Ep ： MeV 68 10 -1 0 5 10 15 Distance　(m) (Unit: m ) Agreement within a factor of two/three 20 25 30 Activation Estimation Estimation from measurements at existing facilities, e.g. KEK, etc. Activation estimation for devices and soils Detailed estimation by PHITS-DCHAIN/SP/2001. Activation estimation for air Calculation of average proton and neutron fluxes by PHITS. Activation cross section evaluated from measured and calculated by INC/GEM. Activation estimation for cooling-water Calculation of leaked proton and neutron fluxes by PHITS. Activation cross sections evaluated from measured and calculated by INC/GEM. Cross Sections for Activation Estimation Tritium production cross sections 10 H production [mb] 10 10 1 INC/GEM LAH ET Experim ent adopted 0 -1 10 1 2 3 4 10 10 10 Proton energy [M eV] 10 10 O(p,t)reaction 2 1 INC/GEM LAH ET Experiment adopted 0 3 10 N(p,t)reaction 2 3 H production [mb] 10 10 5 10 -1 10 1 2 3 4 10 10 10 P roton energy [MeV] 10 5 AGS activity experiment Mass distribution of Hg irradiated by proton Cross Section [mb] 10 3 10 2 10 1 10 24 GeV (Present) 2.8 GeV (Present) 1.6 GeV (96 Gloris) 24 GeV (PHITS) 2.83 GeV (PHITS) 1.6 GeV(PHITS) 0 -1 10 0 50 100 150 Mass Number 200 250 (2) Handling of activity produced in air 【Typical nuclei produced in air】 13N（T 11 15 1/2 9.97min.）、 C（ T1/2 20.4min.）、 O （T1/2 2.04min.)、 41Ar（ T 3 7 1/2 1.83hour）、 H（ T1/2 12.3year）、 Be（ T1/2 53.3day） 【Handling】 ・Confinement in accelerator room during operation （Circulation for cooling） （Negative pressure and monitoring in buffer region ） ・Decay of nuclei with short life after operation ・Remove 7Be with HEPA filter in ventilation eqipment Negative pressure and monitoring 【Confinement system】 Way, Duct(Door, Caulking） Accelerator room (Contaminated area) Buffer region （Controlled area） Outside （Uncontrolled area） (3) Design criteria for activation of soil (groundwater) • Groundwater should be regarded as uncontrolled water. • The level of trivial individual effective dose equivalent would be in the range of 10-100 μSv per year. “Principles for the Exemption of Radiation Sources and Practices from Regulatory Control”, IAEA safety series No.89 “International Baisc Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources”, IAEA safety series No.115 • Criterion for environmental impact due to nuclei generated in soil and groundwater by this facility : 10μSv/y at site boundary Estimation procedure for transition of radionuclide Assumption for estimation ○ Irradiation time ○ Behave of groundwater ○ Moving distance ○ Dilution ratio ○ Release ratio ○ Retardation factor Facility Uncertainty ○ Accuracy of estimation for production ○ Values of soil analysis ○ Porosity ○ Velocity of groundwater Irradiation time Radionuclide produced in soil and groundwater Dissolution Distribution coefficient Release ratio Porosity 1. 2. 3. Radionuclide dissolved into groundwater Velocity of groundwater Moving distance Retardation factor Release ratio Radionuclide in groundwater at site boundary Effective dose≦10μSv/y ≦ μ Production of radio nuclide in soil and water around accelerator facilities Radionuclide generated in soil solve in groundwater Radionuclide solved out in groundwater make the transition to site boundary Criteria from estimated results for shielding calculation n Average dose and radio nuclide activity on shielding surface are about 10 mSv/h and 1.6 Bq/g, respectively. They are equivalent to 10μSv/y at site boundary. n Design criteria are defined 5mSv/h and 0.8Bq/g, which are half of estimated values. Natural radioactivity of soil : about 0.8Bq/g Uncertainty ：about 0.1Bq/g (4) Mercury target issues Vertical cross section of MLF Specification • 3GeV, 1MW, 25Hz Proton beam • Mercury target of 1.4m3 • Three moderator with liquid hydrogen of 260l Magnetite Concrete • Shield of about 10,000t • Movable target structure Target Trolley φ 9740 Mercury target design Estimation of nuclear heating Distribution of nuclear heat on horizontal plane around mercury target Nuclear heating results n n Peak heat density [W/cm3] Heat Load [kW] l Target 533.9 l Reflector 196.4 l Reflector plug 11.0 l Moderator • H2 • H2O 4.2 18.9 l Proton beam window Inconel-718 310 l Target 630 Hg l 320 SS-316L l Reflector 6.0 Al l Moderator 3.4 Al l Proton beam window 3.1 l Water-cooled shield 94.2 l 1.2 H2 l Helium vessel 28.1 l Water-cooled shield 0.8 SS-316L l Helium vessel 0.2 SS-316L l Shield ~10.0 l Total ~ 900 kW Values for 1 MW @ the PBW Results of induced activity in target TARGET Decay curve for Hg 1 MW - 5000 hr. operation, 48 hr. cooling Major radioactivity in mercury Nuclide H-3 12.3 y 92.0 I-125 59.4 d 15.0 Xe-122 20.1 h 1.3 Xe-127 36.4 d 13.0 Hg-194 Decay curve for SS-316 Container Half-Life Activity [TBq] 520 y 0.3 Hg-195g 9.9 h 94.0 Hg-195m 41.5 h 120.0 Hg-197g 64.1 h 1,600.0 Hg-197m 23.8 h 230.0 Hg-203 46.6 d 2,300.0 Radiation damage:DPA results n Maximum DPA for 1 MW, 5000 hr l Proton beam window: l Mercury target: l Moderator: l Reflector: l Water-cooled shield: l Helium Vessel: 4.0 10.0 3.0 3.5 ~ 0.03 ~ 0.01 Inconel-718 SS-316L Aluminum alloy Aluminum alloy SS-316L SS-316L Pitting formation(1) Negative pressure is generated nearby the interface between liquid and solid metals. Bubble core are created on the interface. The bubble becomes bigger. Due to unsteady condition along mercury surface, bubble collapse occurs Microjet impact against solid interface. The pressure beyond the yield stress for localized deformation. Pits are formed as impact erosion. Pitting formation (2) Isolated pits 103 104 Combined pits 105 20µm µ 106 107 Erosion by pitting Pitting damage data are accumulated up to over 10 million Pitting formation 1.2 Power For Probability -10-50510-4-20240200400600-10-50510 the 1st target A-profile =8.8J/cc at 1MW Qmax 0.8 0.6 0.4 ( Flat-type) 0.2 0 1 Power, MW Failure probability Power, MW Failure probability 1 1.2 Power For Probability -10-50510-4-20240200400600-10-50510 the 1st target B-profile =16J/cc at 1MW Qmax 0.8 0.6 0.4 (Gaussian-type) 0.2 2007 2008 2009 2010 2011 2012 2013 Year For a target(2500h) 0.5MW ΣPf=0.7%, Σdose=1 dpa 0.8MW ΣPf=60%, Σdose=1.6 dpa 1MW ΣPf=99.9%, Σdose= 2dpa 0 2007 2008 2009 2010 2011 2012 2013 Year For a target(2500h) 0.5MW ΣPf=6%, Σdose=1.8 dpa 0.8MW ΣPf=99.9%, Σdose=2.9 dpa 1MW ΣPf=99.9%, Σdose= 3.6dpa Failure probability of Hg vessel window was estimated as taking the fatigue strength degradation due to pitting and radiation damages into account. FP is strongly dependent on the beam power and profile. In particular, the effect of pitting damage becomes prominent over 0.5 MW. Summary J-PARC is a large-scale experimental facility consisting mainly of a highintensity, high-energy proton accelerator of top world class. In order to secure safety, many kinds of techniques are applied. ・Shielding design methods ・Confinement system ・Underground water issues ・Target issues: Activity management, Damage estimation, Pitting issue As the first step of a safety review, we obtained an approval for use of LINAC. Safety review will be done for approval in use of other facilities: 3GeVRCS, 50GeVMR, MLF, NP and ν, in near future. The validation of the shielding design method for the second phase: ADS, is already started. KEK TTY experiment 100 15゜ (x1) 1.5-GeV-protons：Tungusten target NE213 φ 12.7x t 12.7cm 90º 120º 60º 150º 30º 15º S01 4m P01 v P1 1.5 m . 2.0 m . C1 S02 Pilot U P2 P02 NE102A W Target 15x15x20 cm3 Beam Dump Neutron Flux (/Lethargy/sr/proton) NE102A 17 x 17 x t1 cm 10-1 30゜ (x0.1) 10-2 60゜ (x10 ) 10-3 90゜ (x10 ) 10-4 120゜ (x10 ) 10-5 150゜ -5 (x10 ) -2 -3 -4 10-6 Ep 1.5 GeV -> W NMTC/JAM Free NNCS NMTC/JAM Inmedium NNCS MCNPX+LA150 MARS -7 10 -1 0 1 10 10 10 102 Neutron Energy (MeV) 103 Comparison of neutron skyshine dose attenuation among simplified and detailed methods （ ／ ） Dose equivalent（µSv／source neutron） 1E-11 3GeV Monte Carlo 3GeV SHINE-III 3GeV Stapleton 600MeV Monte Carlo 600MeV SHINE-III 600MeV Stapleton 1E-12 1E-13 1E-14 1E-15 1E-16 1E-17 0 500 1000 1500 Distance from source（ m） （ ） Agreement within a factor of two 2000 J-PA R C Co nstruc tio n S c hed ule Y e ar Item s JFY 2 00 1 J FY 20 02 JFY 2 00 3 JFY 200 4 J FY 20 05 E P o wer Fe ed Ac c. 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