ISO INTERNATIONAL STANDARD 23018 First edition 2022-05 Group-averaged neutron and gamma- ray cross sections for radiation protection and shielding calculations for nuclear reactors Sections efficaces multigroupes neutrons et gammas pour les calculs de radioprotection associés aux réacteurs nucléaires Reference number IS0 23018:2022(E) Tso @ ISO 2022 IS0 23018:2022(E) COPYRIGHT PROTECTED DOCUMENT @IS02022 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. Iso copyright office CP 40i : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +41 22 749 01 11 Email: [email protected] Website: www.iso.org Published in Switzerland ii @IS02022-Allrightsreserved IS0 23018:2022(E) Contents Page Foreword iv 1 Scope. 1 2 Normative references 1 3 Terms and definitions 1 4 Abbreviations and acronyms. .2 5 Preparation of group-averaged neutron and gamma-ray cross sections .3 5.1 Evaluated nuclear data files. 3 5.2 Checking of evaluated nuclear data files. 3 5.3 Energy ranges and materials of importance 3 5.4 Group-averaging techniques. 3 5.4.1 General 3 5.4.2 Fine-group structures. 3 5.4.3 Pointwise weighting function 3 5.4.4 Self-shielding treatment 4 5.4.5 Collapsed-group cross sections 4 5.5 Upscattering cross sections. 4 5.6 Legendre order of scattering 4 6 Verification and validation of cross sections 4 Verification of cross-section sets 6.1 4 6.2 Validation of cross-section sets... 5 Annex A (informative) Information on group-averaged neutron and gamma-ray cross section verification, validation, libraries, and generation 6 Bibliography 9 iii IS02022-Allrightsreserved