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 National Council on Radiation Protection and Measurements 7910 Woodmont Avenue, Suite 400/Bethesda, Maryland 20814-3095 LEGAL NOTICE This Report was prepared by the National Council on Radiation Protection and Measurements (NCRP). The Council strives to provide accurate, complete and useful information in its documents. However, neither the NCRP, the members of NCRP, other persons contributing to or assisting in the preparation of this Report, nor any person acting on the behalf of any of these parties: (a) makes any warranty or representation, express or implied, with respect to the accuracy, completeness or usefulness of the information contained in this Report, or that the use of any informa- tion, method or process disclosed in this Report may not infringe on privately owned rights; or (b) assumes any liability with respect to the use of, or for damages resulting from the use of any information, method or process disclosed in this Report, under the Civil Rights Act of 1964, Section 701 et seq. as amended 42 U.S.C. Section 2000e et seq. (Title VII) or any other statutory or common law theory governing liability. Library of Congress Cataloging-in-Publication Data National Council on Radiation Protection and Measurements. Radiation protection for particle accelerator facilities : recommendations of the National Council on Radiation Protection and Measurements. p. cm. -- (NCRP report ; no. 144) ‘‘Issued December 2003.’’ Rev. ed. of: Radiation protection design guidelines for 0.1-100 MeV particle accelerator facilities. 1977. Includes bibliographical references and index. ISBN 0-929600-77-0 1. Particle accelerators--Safety measures. 2. Particle accelerators--Shielding (Radiation) 3. Radiation--Safety measures. I. National Council on Radiation Protection and Measurements. Radiation protection design guidelines for 0.1- 100 MeV particle accelerator facilities. II. Title. III. Series. TK9340.N39 2003 621.48--dc22 2003061402 Copyright © National Council on Radiation Protection and Measurements 2003 All rights reserved. This publication is protected by copyright. No part of this publica- tion may be reproduced in any form or by any means, including photocopying, or utilized by any information storage and retrieval system without written permission from the copyright owner, except for brief quotation in critical articles or reviews. [For detailed information on the availability of NCRP publications see page 479.] Preface The National Council on Radiation Protection and Measurements (NCRP) Report No. 51, Radiation Protection Design Guidelines for 0.1–100 MeV Particle Accelerator Facilities, was published in 1977. Since then, NCRP has issued two reports that discuss specific radio- logical protection issues at particle accelerators: NCRP Report No. 72, Radiation Protection and Measurements for Low-Voltage Neutron Generators and NCRP Report No. 79, Neutron Contamina- tion from Medical Electron Accelerators. NCRP Report No. 88, Radia- tion Alarms and Access Control Systems is also of interest for those who operate accelerators, but until now, there has been no recent attempt to readdress the entire issue of accelerator radiological pro- tection in a single report. In light of the significant experience with the operation and design of accelerator facilities and the increased understanding of accelera- tor radiation environments obtained over the past 25 y, it was consid- ered appropriate to revise NCRP Report No. 51 while maintaining its extremely valuable practical utility. Accordingly, Scientific Committee 46-8 was established and given 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 studies performed many decades ago. In such cases, the quantities, units and references as formatted are retained in their original form. This publication was made possible, in part, by Grant Number R24 CA74296-05 from the National Cancer Institute (NCI) and its contents are the sole responsibility of the NCRP and do not necessar- 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 J. Donald Cossairt Gaithersburg, Maryland Fermi National Accelerator Geoffrey B. Stapleton Laboratory Thomas Jefferson National Batavia, Illinois Accelerator Facility Keran O’Brien Newport News, Virginia Northern Arizona State William P. Swanson* University Lawrence Berkeley National Flagstaff, Arizona Laboratory Norman Rohrig Berkeley, California National Engineering and Environmental Laboratory Idaho Falls, Idaho Consultants Lutz E. Moritz Vaclav Vylet TRIUMF, National Laboratory Duke University Medical for Particle 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