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Radiation Protection for Particle Accelerator Facilities: Recommendations of the National Council on Radiation Protection and Measurements PDF

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Preview Radiation Protection for Particle Accelerator Facilities: Recommendations of the National Council on Radiation Protection and Measurements

NCRP REPORT No. 144 RADIATION PROTECTION FOR PARTICLE ACCELERATOR FACILITIES N C R P National Council on Radiation Protection and Measurements NCRP Report No. 144 Radiation Protection for Particle Accelerator Facilities Recommendations of the NATIONAL COUNCIL ON RADIATION PROTECTION AND MEASUREMENTS Issued December 31, 2003 Revised March 4, 2005 NationalCouncilonRadiationProtectionandMeasurements 7910WoodmontAvenue,Suite400/Bethesda,Maryland20814-3095 LEGAL NOTICE ThisReportwaspreparedbytheNationalCouncilonRadiationProtectionand Measurements(NCRP).TheCouncilstrivestoprovideaccurate,completeanduseful informationinitsdocuments.However,neithertheNCRP,themembersofNCRP, other persons contributing to or assisting in the preparation of this Report, nor anypersonactingonthebehalfofanyoftheseparties:(a)makesanywarrantyor representation, express or implied, with respect to the accuracy, completeness or usefulnessoftheinformationcontainedinthisReport,orthattheuseofanyinforma- tion,methodorprocessdisclosedinthisReportmaynotinfringeonprivatelyowned rights;or(b)assumesanyliabilitywithrespecttotheuseof,orfordamagesresulting fromtheuseofanyinformation,methodorprocessdisclosedinthisReport,under theCivilRightsActof1964,Section701etseq.asamended42U.S.C.Section2000e etseq.(TitleVII)oranyotherstatutoryorcommonlawtheorygoverningliability. LibraryofCongressCataloging-in-PublicationData NationalCouncilonRadiationProtectionandMeasurements. Radiationprotectionforparticleacceleratorfacilities:recommendationsofthe NationalCouncilonRadiationProtectionandMeasurements. p.cm.--(NCRPreport;no.144) ‘‘IssuedDecember2003.’’ Rev.ed.of:Radiationprotectiondesignguidelinesfor0.1-100MeVparticle acceleratorfacilities.1977. Includesbibliographicalreferencesandindex. ISBN0-929600-77-0 1. Particleaccelerators--Safetymeasures.2.Particleaccelerators--Shielding (Radiation)3.Radiation--Safetymeasures.I.NationalCouncilonRadiation ProtectionandMeasurements.Radiationprotectiondesignguidelinesfor0.1- 100MeVparticleacceleratorfacilities.II.Title.III.Series. TK9340.N392003 621.48--dc22 2003061402 Copyright©NationalCouncilonRadiation ProtectionandMeasurements2003 Allrightsreserved.Thispublicationisprotectedbycopyright.Nopartofthispublica- tion may be reproduced in any form or by any means, including photocopying, or utilizedbyanyinformationstorageandretrievalsystemwithoutwrittenpermission fromthecopyrightowner,exceptforbriefquotationincriticalarticlesorreviews. [FordetailedinformationontheavailabilityofNCRPpublicationsseepage479.] Preface TheNationalCouncilonRadiationProtectionandMeasurements (NCRP) Report No. 51, Radiation Protection Design Guidelines for 0.1–100 MeV Particle Accelerator Facilities, was published in 1977. Sincethen,NCRPhasissuedtworeportsthatdiscussspecificradio- logical protection issues at particle accelerators: NCRP Report No.72, Radiation Protection and Measurements for Low-Voltage NeutronGeneratorsandNCRPReportNo.79,NeutronContamina- tionfromMedicalElectronAccelerators.NCRPReportNo.88,Radia- tionAlarmsandAccessControlSystemsisalsoofinterestforthose who operate accelerators, but until now, there has been no recent attempttoreaddresstheentireissueofacceleratorradiologicalpro- tection in a single report. Inlightofthesignificantexperiencewiththeoperationanddesign ofacceleratorfacilitiesandtheincreasedunderstandingofaccelera- torradiationenvironmentsobtainedoverthepast25y,itwasconsid- ered appropriate to revise NCRP Report No. 51 while maintaining its extremely valuable practical utility. Accordingly,ScientificCommittee46-8wasestablishedandgiven the general charge to ‘‘review and update Report No. 51 to include: new shielding data, extension of the energy range up to the giga- electron volt region, skyshine radiation, transmission of radiation through ducts and labyrinths, induced radioactivity, and envi- ronmental considerations such as radioactive airborne and liquid effluents.’’ Some of the material in this Report is historical and refers to studiesperformedmany decadesago.Insuch cases,thequantities, unitsandreferencesasformattedareretainedintheiroriginalform. This publication was made possible, in part, by Grant Number R24 CA74296-05 from the National Cancer Institute (NCI) and its contentsarethesoleresponsibilityoftheNCRPanddonotnecessar- ily represent the official views of the NCI, National Institutes of Health. Additionally, publication of this Report was supported in part by the Idaho Accelerator Center, a research center of Idaho State University, Pocatello, Idaho. Those who served on Scientific Committee 46-8 were: iii iv / PREFACE Ralph H. Thomas, Chairman University of California Members W. Robert Casey Lester A. Slaback, Jr. Brookhaven National Laboratory National Institute of Upton, New York Standards and Technology Gaithersburg, Maryland J. Donald Cossairt Fermi National Accelerator Geoffrey B. Stapleton Laboratory Thomas Jefferson National Batavia, Illinois Accelerator Facility Newport News, Virginia Keran O’Brien Northern Arizona State William P. Swanson* University Lawrence Berkeley National Flagstaff, Arizona Laboratory Berkeley, California Norman Rohrig National Engineering and Environmental Laboratory Idaho Falls, Idaho Consultants Lutz E. Moritz Vaclav Vylet TRIUMF, National Laboratory Duke University Medical forParticle and Nuclear Center Physics Durham, North Carolina Vancouver, Canada Advisor David R. Perry Rutherford Appleton Laboratory Chilton, Oxon, United Kingdom NCRP Secretariat Constantine J. Maletskos, Consultant (1998–2003) Thomas M. Koval, Senior Staff Scientist (1993–1998) James A. Spahn, Senior Staff Scientist (1986–1993) Cindy L. O’Brien, Managing Editor The Council wishes to express its appreciation to the Committee members for the time and effort devoted to the preparation of this Report. Thomas S. Tenforde President *deceased Contents Preface ........................................................................................ iii Executive Summary ................................................................ 1 1. Introduction ......................................................................... 5 1.1 Purpose............................................................................. 6 1.2 Scope................................................................................. 6 1.3 Particle Accelerator Safety ............................................. 7 1.4 Regulatory and Advisory Agencies ................................ 7 1.4.1 Federal Regulation ............................................... 8 1.4.2 State Regulation ................................................... 8 1.4.3 Local (County, City) Regulation .......................... 9 1.4.4 Advisory Organizations ........................................ 9 1.4.4.1 International Agencies ............................ 9 1.4.4.2 National Organizations ........................... 10 1.5 Radiological Protection Standards ................................. 10 2. Particle Accelerators and Accelerator Facilities ........ 12 2.1 Particle Accelerators—Definitions ............................... 12 2.2 Classification of Particle Accelerators .......................... 12 2.3 Brief Historical Review ................................................. 13 2.4 Accelerator Radiation .................................................... 17 2.5 Ion and Electron Sources .............................................. 18 2.6 Particle Accelerating Schemes ...................................... 19 2.7 Beam Delivery Systems ................................................ 23 2.8 Beam Stops .................................................................... 24 2.9 Auxiliary Systems.......................................................... 25 2.9.1 High-Voltage and Microwave Power Supplies .. 25 2.9.2 Cooling Systems .................................................. 27 2.9.3 Vacuum Systems ................................................. 27 2.10 Summary of the General Specifications and Parameters of Accelerators ........................................... 28 2.11 Applications of Accelerators ......................................... 28 2.12 Future Developments in Accelerators ......................... 29 2.13 Siting and Layout .......................................................... 29 v vi / CONTENTS 3. Sources of Ionizing Radiation from Accelerators ...... 33 3.1 Introduction ..................................................................... 33 3.2 General Considerations................................................... 35 3.3 Radiation Production at Electron Accelerators ............. 39 3.3.1 General .................................................................. 39 3.3.2 Electron Beams ..................................................... 40 3.3.3 Photon Fields ........................................................ 41 3.3.3.1 External Bremsstrahlung ....................... 41 3.3.3.2 High Energies .......................................... 49 3.3.4 Neutron Production .............................................. 59 3.3.5 Muon Production................................................... 62 3.3.6 Electromagnetic Cascade ..................................... 65 3.4 Radiation Protection at Proton Accelerators ................. 70 3.4.1 General .................................................................. 70 3.4.2 Proton Beams ........................................................ 73 3.4.3 Neutron Yields ...................................................... 73 3.4.3.1 Neutron Production at Low Energies (E (cid:1) 200 MeV) ......................................... 74 3.4.3.2 Neutron Production at Intermediate Energies (200 MeV (cid:1) E (cid:1)1 GeV) ......... 80 3.4.3.3 Neutron Production at High Energies (E (cid:2) 1 GeV) ............................................. 80 3.4.4 Muon Production................................................... 98 3.4.5 Hadronic (Nuclear) Cascade ................................ 101 3.4.5.1 General ..................................................... 101 3.4.5.2 Qualitative Description of the Hadronic Cascade .................................................... 102 3.4.6 Radiation Environment ........................................ 103 3.4.6.1 Neutron Energy Spectra ......................... 105 3.4.6.2 Spectra Outside Accelerator Shielding .. 108 3.5 Radiation Production at Accelerators of Positive Ions . 112 3.5.1 General .................................................................. 112 3.5.2 Light Ions .............................................................. 113 3.5.3 Heavy Ions............................................................. 118 3.6 Radioactivation at Accelerators...................................... 132 3.6.1 General .................................................................. 132 3.6.2 Activation by Low-Energy Particles .................... 133 3.6.3 Activation by High-Energy Particles ................... 136 4. Radiation Shielding at Accelerators .............................. 146 4.1 Introduction ..................................................................... 146 4.2 Theory of Radiation Transport ....................................... 148 4.2.1 Introduction ........................................................... 148 4.2.1.1 Construct of the Boltzmann Equation ... 150 CONTENTS / vii 4.2.1.2 Approximate Solutions of the Boltzmann Equation ............................... 152 4.2.2 Computer Codes for Shielding Calculations ....... 154 4.2.2.1 The Monte-Carlo Method ...................... 154 4.2.2.2 MARS ..................................................... 156 4.2.2.3 EGS4 Code System ................................ 156 4.2.2.4 FLUKA ................................................... 157 4.2.2.5 NMTC/HETC ......................................... 157 4.2.2.6 MCNP ..................................................... 158 4.2.2.7 Integrated Tiger Series ......................... 158 4.2.2.8 MORSE-CGA ......................................... 158 4.2.2.9 TOMCAT ................................................ 159 4.2.2.10 MUSTOP ................................................ 159 4.2.2.11 MUCARLO ............................................. 159 4.2.2.12 MUON89 ................................................ 160 4.2.2.13 SHIELD11 ............................................. 160 4.2.2.14 PHOTON ................................................ 160 4.2.2.15 STAC8 .................................................... 160 4.2.2.16 SKYSHINE-KSU ................................... 161 4.2.2.17 SKYSHINE III....................................... 161 4.2.2.18 TRIPOLI ................................................ 161 4.3 Practical Shield Design ................................................... 161 4.3.1 General .................................................................. 161 4.3.2 Photon Transmission ............................................ 163 4.3.3 Neutron Transmission .......................................... 167 4.3.4 Scattering—Albedo ............................................... 178 4.3.5 Scatter Paths......................................................... 179 4.4 Radiation Goals and Area Occupancy and Use Factors .............................................................................. 183 4.5 Determination and Specification of the Beam-Loss Terms ............................................................................... 185 4.6 Shielding of Electron Accelerators in the Energy Range from 1 to 100 MeV ............................................... 188 4.6.1 Source Term for Simple Accelerators .................. 189 4.6.1.1 Workload .................................................. 190 4.6.1.2 Primary and Secondary Barriers and the Orientation (Use) Factor .................. 191 4.6.1.3 Occupancy Factor .................................... 191 4.6.2 Primary Barriers for Photons .............................. 191 4.6.3 Secondary Barriers for Photons ........................... 194 4.6.3.1 Leakage Radiation .................................. 194 4.6.3.2 Scattered Photons ................................... 194 4.6.4 Shielding Against Neutrons ................................. 195 viii / CONTENTS 4.7 Shielding of Large Electron Accelerator Facilities at Higher Energies (E (cid:2) 100 MeV) .................................... 197 4.7.1 Review of Source Terms ....................................... 197 4.7.1.1 Electromagnetic Cascade ........................ 197 4.7.1.2 Neutron Source Terms and Attenuation .............................................. 198 4.7.2 Design of High-Intensity Beam Stops and Walls ...................................................................... 202 4.7.3 Distributed Loss Issues ........................................ 204 4.7.3.1 Synchrotron-Radiation Facilities ........... 205 4.7.3.2 Photon Shielding Experiments ............... 208 4.7.3.3 Generalized Loss Model .......................... 212 4.8 Proton Accelerators—Transverse Shielding.................. 213 4.8.1 Particle Yields from the Proton-Nucleus Interaction ............................................................. 214 4.8.2 Proton Energies Below 3 GeV.............................. 216 4.8.3 Proton Energies Above 3 GeV—The Moyer Model ..................................................................... 218 4.8.3.1 Introduction ............................................. 218 4.8.3.2 Generalized Formulation of the Moyer Model ........................................................ 219 4.8.3.3 Determination of the Moyer Model Parameters............................................... 222 4.8.3.3.1 Attenuation Parameter ........... 222 4.8.3.3.2 Angular-Relaxation Parameter ................................ 223 4.8.3.3.3 Source-Strength Parameter .... 224 4.8.3.4 Practical Examples.................................. 226 4.8.3.4.1 Point Source ............................. 226 4.8.3.4.2 Infinite Uniform Line Source . 227 4.8.3.4.3 Finite Uniform Line Source.... 228 4.8.3.5 Conclusions and Limitations of the Moyer Model ............................................ 229 4.9 Proton Accelerators—Forward Shielding .................... 232 4.9.1 Proton Energies Below 3 GeV ............................ 232 4.9.2 Hadronic Cascade Above 3 GeV ......................... 232 4.9.3 Muon Shielding ................................................... 239 4.10 Shielding Materials ....................................................... 242 4.10.1 Earth .................................................................. 243 4.10.2 Concrete ............................................................. 244 4.10.3 Other Hydrogenous Materials .......................... 246 4.10.4 Steel.................................................................... 249 4.10.5 Special Materials ............................................... 252 4.10.5.1 Materials of High Atomic Number .... 252 4.10.5.2 Materials of Low Atomic Number ..... 254 CONTENTS / ix 4.10.6 Special Considerations ...................................... 254 4.11 Tunnels, Labyrinths and Ducts ................................... 255 4.11.1 Introduction ....................................................... 255 4.11.2 Design Example for Photons Using Albedos ... 257 4.11.3 Straight Penetrations—Neutrons and Photons............................................................... 258 4.11.4 Transmission of Neutrons Through Labyrinths ......................................................... 259 4.11.5 Transmission of Neutrons Through Curved Tunnels .............................................................. 266 4.11.6 Door Design ....................................................... 267 5. Techniques of Radiation Measurement at Particle Accelerators .......................................................................... 269 5.1 Introduction to Radiation Dosimetry at Particle Accelerators...................................................................... 269 5.2 Special Consideration of the Techniques of Radiation Dosimetry in Accelerator Environments ....................... 272 5.3 Application of ‘‘Conventional Techniques’’ to Measurements in Accelerator-Radiation Environments .. 273 5.3.1 Introduction ........................................................... 273 5.3.2 Ionization Chambers ............................................ 273 5.3.3 Geiger-Mueller Counters ...................................... 275 5.3.4 Thermoluminescence Dosimeters ........................ 276 5.4 Neutron Dosimetry at Particle Accelerators ................. 276 5.4.1 Introduction ........................................................... 276 5.4.2 Passive Detectors Used for Neutron Dosimetry . 277 5.4.2.1 Thermoluminescence Dosimeters ........... 277 5.4.2.2 Nuclear Emulsions .................................. 279 5.4.2.3 Activation Detectors ................................ 280 5.4.2.4 Threshold Detectors ................................ 281 5.4.2.5 Moderated Detectors ............................... 285 5.4.2.6 Track-Etch Detectors .............................. 287 5.4.2.7 Bubble Detectors ..................................... 289 5.4.3 Active Detectors Used for Neutron Dosimetry ... 291 5.4.3.1 Moderated Detectors ............................... 291 5.4.3.2 Fission Counters...................................... 297 5.4.4 Neutron Spectrometry .......................................... 299 5.4.4.1 Bonner Spheres ....................................... 299 5.4.4.2 Spectrum-Unfolding Methods ................. 301 5.4.4.3 Proton-Recoil Counters ........................... 303 5.5 Mixed-Field Dosimetry.................................................... 304 5.5.1 Introduction ........................................................... 304 5.5.2 Recombination Chambers .................................... 305

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