Radiation Safety Design for the J-PARC Project

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					                                          ICRS10
                                          May 9-14, 2004

     Radiation Safety Design for
        the J-PARC Project
     -High Intensity Proton Accelerator Project-


H. Nakashima, Y. Nakane, F. Masukawa, N. Matsuda,
        T. Oguri, H. Nakano, N. Sasamoto
      Japan Atomic Energy Research Institute

   T. Shibata, T. Suzuki, T. Miura, M. Numajiri,
         N. Nakao, H. Hirayama, S. Sasaki
  High Energy Accelerator Research Organization
                                                          J-PARC Facilities
                                                        Nuclear and Particle Physics
                Materials and Life Science
                                                          Experimental Facility
                 Experimental Facility

   Nuclear
Transmutation




                                                                   Neutrino to
                                                                   Kamiokande

                                  3 GeV Synchrotron            50 GeV Synchrotron
                                    (25 Hz, 1MW)                   (0.75 MW)
                  Linac
                 (350m)
                                    J-PARC = Japan Proton Accelerator Research Complex
                   Configuration of the Accelerator Complex




                       600MeV      3GeV          50GeV
                        LINAC    Synchrotron   Synchrotron
Average Current        666μA       333μA         15μA
 Beam Power            0.4MW       1MW          0.75MW
  Frequency             50Hz        25Hz         0.3Hz
Size of Facility        460m       350m          1570m
                                          Characteristics of J-PARC

   Characteristics
   ・High beam power (up to 1MW)
   ・High beam energy (up to 50GeV)
   ・A large-scale accelerator complex (about 3.2 km in length)

   Radiation problems
   ・Widely distributed radiation source
   ・A thick shield
   ・Many ducts
   ・etc…

On the other hand,
  shielding methods with high accuracy were strongly required for a
  detailed design study.
                                                Design Criteria, etc.

  Design criteria
・Controlled Area              :12.5μSv/h (1/2 of 1mSv/week)
・ In-site                     :0.25μSv/h (1/2 of 1mSv/year)
・Site boundary Radiation      :50μSv/ year (1/20 of 1mSv/year)
             Gas              : Regulation
            Liquid            : Regulation


  Operation time(Calculation condition):
・LINAC, 3GeV Synchrotron                            :5500h
・50GeV Synchrotron                                  :5000h
・Materials and Life Science Experimental Facility   :5000h
・Nuclear and Particle Experimental Facility         :4000h
                                                                     Beam loss distribution

                                                                       :
                                                             50GeV Dump: 7.5 kW
                                            3-50BT Scraper
                                            : 450 W                       :
                                                                Extraction: 1.13 kW
                           :
                     Septum: 1 kW
                               :
                     Beam Dump: 4 kW
           :
 Collimator: 4 kW
        :
 Septum: 1 kW
             :
 Beam Dump: 1 kW
                                                                                                      5 0 GeV Dump
          :
 Analize r: 0.35kW
                                                                                                      : 750 kW
      D400-4a: 2 kW
      D400-4b:5.4 kW                                                                                         :
                                                                                                    T1 target:
                                                                                                    225 kW

                                        Injection            Neutron Facility
                                        :135 W                :1 MW                             :
                                                                                      Extraction: 7.5 kW
 S62-1: 11 W
                       D400-2: 4 kW
 S72-1: 19 W
                       D450-1:0.6 kW
 D200-1: 0.11 kW
                       D400-3a:0.6 kW
                       D400-3b:5.4 kW                                                          1 nA/m
                                              Dump:3 kW
Planed beam loss                  :
                           Scraper: 450 W
                                                        Muon Facility                          0.5 W/m
                                                                 :
                                                        T1 target: 37 kW
                                                               :
                                                        Scraper: 37 kW                          1.0 W/m
                                                                 :
                                                        T2 target: 37kW
                                                                       :
                                                        BeamTransport: 37kW                   >2.3 W/m

                                                                        Criteria of hands on maintenance
                             Shielding design principle

 Underground

 Shields are basically ordinary concrete and soil.
Partially steel.

 Ground surface is uncontrolled area.
Controlled area on surface is restricted on extraction
point.

 Design method is basically simplified method,
Detailed method for complicated geometry
                                        Estimation items

Source and Bulk Shielding
 Beam line, beam dump and target

Streaming
 Duct, pathway….

Skyshine
 Underground Facility, ….

Activation
 Air, water, target, devices and wall
                           Methods for bulk shielding

Simplified methods
 ・Moyer model (KEK H0, λ)[>1GeV]
 ・Tesch’s equation[<1GeV]

Monte-Carlo codes
 ・PHITS, MARS, MCNPX(>20MeV)
 ・MCNP(<20MeV)

Parameters
 ・Dose conversion factor
                                  Calculation flow in detailed method
   Radiation                                          Activity

High-energy particle flux
     PHITS, MCNPX, MARS                              Residual
      (En>20MeV, Ei>1MeV                             nuclei
         i=p, pion, meson)
                                                                              Nuclear decay
                                                                              data set
        Neutron
        source for             Neutron flux
        low energy             Particle flux                            Nuclear decay
        calculation            2nd-γ−ray
                                                                        DCHAIN-SP 2001

Low-energy particle flux                             Nuclear
                                                                             γ−ray from
                                                     Production
      MCNP                                           X’sect                  residual
    (En<20MeV, 2nd-γ−ray)                                                    nuclei
                                               Air,Water        Devices
                                                                          γ−ray transport
        Neutron                                                             QAD-CGGP2, MCNP
        transport            Dose                   Residual Activity
        X’sect for           Site boundary
         low energy          In site                                        Dose due to
                             Controlled area                                residual nuclei
Comparison of neutron attenuation between simplified
                                and detailed methods
                               4
                          10

                               3
                          10

                               2                                       M ARS
                          10
           実効線量 [mSv/h]




                                                                       Moyer M odel
                               1
                          10

                               0
                          10

                               -1
                          10
 Effective dose




                               -2
                          10             1.5GeV 5W
                                         Concrete shield
                               -3
                          10

                               -4
                          10
                                   100     200       300       400       500     600   700

                                                       線源からの距離 [cm]
                                                      Distance from the source
                                                                                                                                        Bulk shielding problem
AGS Experiment (Neutron deep penetration experiments)
Source neutrons : from mercury by 2.83- and 24-GeV-protons.
                                           -28
                                          10
                                                                Exp.                                                              -29
                                                                                                                                 10                   Exp.
Reaction Rate / Proton / Target Nucleus




                                                                                       Reaction Rate / Proton / Target Nucleus
                                           -29
                                          10                    NMTC/JAM (In-medium)                                                                  NMTC/JAM (In-medium)
                                                                MCNPX                                                             -30
                                                                                                                                 10                   MCNPX
                                           -30
                                          10                        209      204                                                  -31
                                                                                                                                 10                       209          204
                                                                      Bi(n,6n) Bi                                                                            Bi(n,6n) Bi
                                           -31
                                          10                                                                                      -32
                                                                                                                                 10

                                           -32                                                                                    -33
                                          10                                                                                     10

                                           -33       24 GeV                                                                       -34
                                                                                                                                 10         24 GeV
                                          10
                                                     Concrete                                                                                IRON
                                                                                                                                  -35
                                           -34        Lateral                                                                    10         Lateral
                                          10
                                                 0    50 100 150 200 250 300 350 400                                                    0      50      100     150     200   250
                                                          Shield Thickness [cm]                                                                  Shield Thickness [cm]


                                                                 Agreement within a factor of two
                                                      Streaming

Simplified method
      Nakamura-Uwamino’s Formula

Simplified code with albedo method
      DUCT-III newly developed, based on Shin’s eq.

Monte Carlo method
     PHITS,MCNPX,MARS, etc.

Benchmarking with experiments
     1) TIARA experiment
     2) NIMROD experiment
                                                                                                                      TIARA experiment
               16                                                                                          Neutron Dose Equivalent Rate
                                                                                    10 6

                                                                                                 1st leg        2nd leg                  3rd leg




                                      Neutron Dose Equivalent Rate (μSv h-1 µA-1)
                                                                                    10   5




                                                                                    10 4                                            Exp.(Bonner)
             Cu
                              7.5
      80mmφ×12mm t                                                                                                                  DUCT-Ⅲ
                                                                                    10 3
                                                                                                                                    Cal.(MCNPX)

                                                                                    10 2                                            Cal.(NMTC/MCNP)

4.5           7.5                                                                   10 1

                                                                                    10 0
              Proton
                              4.8




                                                                                    10 -1
      3.5




                                                                                             0              5        10        15        20        25   30
            Ep :68 MeV                                                                                                    Distance (m)
                         (Unit: m )
                    Agreement within a factor of two/three
                                             Skyshine

For Site boundary
 ・ Skyshine estimation:Stapleton’s formula
     For experimental facilities : SHINE-III
     For detailed estimation : PHITS, MCNPX, etc.
                      Effective conversion
           Energy   attenuation   factor
           (MeV)     length (m) (fSv・m2)
             200        438        12.1
             600        543        13.6
            1000        622        14.4
           15000        670        14.7
           50000        670        14.7
                                        Comparison of neutron skyshine dose attenuation among
                                                               simplified and detailed methods
                                        1E-11
Dose equivalent( µSv/ source neutron)
                                    )




                                                                           3GeV Monte Carlo
                                        1E-12                              3GeV SHINE-III
                                                                           3GeV Stapleton
                                                                           600MeV Monte Carlo
                                        1E-13                              600MeV SHINE-III
                                                                           600MeV Stapleton
                    /




                                        1E-14
               (




                                        1E-15


                                        1E-16


                                        1E-17
                                                0      500          1000          1500          2000
                                                                             ( )
                                                         Distance from source( m)

                                                    Agreement within a factor of two
                                 Estimation of Radioactivity
Estimation from measurements at existing facilities, e.g. KEK, etc.
Activation estimation for devices
   Detailed estimation by PHITS-MCNP-DCHAIN/SP-QAD.
Activation estimation for air
   Calculation of leaked proton and neutron fluxes by PHITS-
   MCNP.
   Activation cross sections evaluated from measured and
   calculated by INC/GEM.
Activation estimation for cooling-water
   Calculation of average proton and neutron fluxes by PHITS-
   MCNP.
   Activation cross section evaluated from measured and calculated
   by INC/GEM.
                                 Calculation flow in detailed method
   Radiation                                          Activity

High-energy particle flux
     PHITS, MCNPX, MARS                              Residual
      (En>20MeV, Ei>1MeV                             nuclei
         i=p, pion, meson)
                                                                              Nuclear decay
                                                                              data set
        Neutron
        source for             Neutron flux
        low energy             Particle flux                            Nuclear decay
        calculation            2nd-γ−ray
                                                                        DCHAIN-SP 2001

Low-energy particle flux                             Nuclear
                                                                             γ−ray from
                                                     Production
      MCNP                                           X’sect                  residual
    (En<20MeV, 2nd-γ−ray)                                                    nuclei
                                               Air,Water        Devices
                                                                          γ−ray transport
        Neutron                                                             QAD-CGGP2, MCNP
        transport            Dose                   Residual Activity
        X’sect for           Site boundary
         low energy          In site                                        Dose due to
                             Controlled area                                residual nuclei
                                  Evaluated Cross Sections for Activation Estimation

                                           Tritium production cross sections

                         2               N(p,t)reaction                                         2          O(p,t)reaction
                    10                                                                     10




                                                                       H production [mb]
H production [mb]




                         1                                                                      1
                    10                                                                     10


                                              INC/GEM
                         0                    LAH ET                                            0                INC/GEM
                    10                                                                     10
                                              Experiment                                                         LAH ET
                                                                       3


                                                                                                                 Experiment
3




                                              adopted
                                                                                                                 adopted
                     -1                                                                         -1
                10            1      2         3          4        5
                                                                                           10        1     2       3        4        5
                         10       10       10     10          10                                10       10      10      10     10
                                  Proton energy [M eV]                                                   Proton energy [MeV]
3GeV to Neutron Facility and
    50 GeV Beam Transport
                              Estimation of Effective dose on site boundary



                                                                                Nuclear and
                                                           50GeV synchrotron   Particle Physics
                    Central control building                                       Facility

               3GeV synchrotron
                                                                                 6
                                                                                            PS-7
Accelerator-Driven Transmutation
            Experimental Facility
                                                                                            22 μSv/y

                                                       Materials and                  PS-6
                                                       Life Science                  38 μSv/y
    Linac                            PS-1                Facility
                                    32 μSv/y                               PS-5
                                          PS-2                            23 μSv/y
                                        25 μSv/y
                                                  PS-3
                                                21 μSv/y           PS-4
   Design criteria :50μSv/y                                        15 μSv/y            Estimation points
                                                    Summary

J-PARC is a large-scale experimental facility consisting mainly
of a high-intensity, high-energy proton accelerator of top world
class.
Shielding design must become prudent concerning radiation
safety aspect more than for the existing accelerator facilities.
In order to secure safety, attaining economical rationality, the
shielding design and safety evaluations are performed by a
combined method of the simplified and sophisticated methods
with reliable data.
A safety review concerning approval in the use of J-PARC will
start in the near future, and the validity of the shielding design
method will be verified further for the review.
Appendix
                                                                               Neutron effective dose conversion factor

                                                                         1
                                                                    10
Neutron Effective dose conversion factor

                                                                                   ICRP-Pub.74
                                                                                   recommended value
                                                                                   by department of
                                                                                   H ealth Physics (JAERI)
                                           [(µ Sv/h)/(n/cm /sec)]



                                                                         0
                                                                    10
                                           2




                                                                         -1
                                                                    10




                                                                         -2
                                                                    10        -6         -4         -2       0           2        4
                                                                         10         10            10       10       10       10
                                                                                              neutron energy [M eV]
                                                                               NIMROD Experiment
                                                                               12C(n,2n)   Reaction Rate
                                                           10   1
                            2.3
                                                                          1st leg                    2nd leg
                                                           10 0




                                   6.85
     3.8       8.85
                                                           10-1




                                          Attenuation factor
               Concrete
Fe

                                   2.3
                                                           10-2

     Proton  Ep :7 GeV                                     10-3         Exp.

                                                                        DUCT-Ⅲ
                                   2.3



                                                           10-4
     Cu                                                                 Cal.(MCNPX)
10mmφ×50mm t                                               10-5         Cal.(NMTC/MCNP)
                             (Unit: m )
                                                                    0           5          10         15       20
                                                                                      Distance (m)

                          Agreement within a factor of two
         Estimation of radioactivity in cooling water



                                                           Unit:Bq/y
       Linac    3GeV PS   50GeV PS    MLF         NP           sum

3H   9.9×1010   5.2×109   1.5×109    1.0×1011   2.1×1011     4.1×1011


     Other nuclides:22Na、52Mn、54Mn、59Fe、56Co、57Co、58Co、60Co