AMERICAN NATIONAL STANDARD ANSI/ISA-67.04.01-2006 (R2011) Setpoints for Nuclear Safety-Related Instrumentation Reaffirmed 13 October 2011 Copyright 2011 ISA.-All-rights reserved. st andar d999 ANSI/ISA-67.04.01 - 2006 (R2011) 2 ANSI/ISA-67.04.01-2006 (R2011) Setpoints for Nuclear Safety-Related Instrumentation ISBN: 978-1-937560-15-7 Copyright 2011 by ISA - The International Society of Automation. All rights reserved. Not for resale. Printed in the United States of America. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying recording, or otherwise), without the prior written permission of the Publisher. ISA 67 Alexander Drive P. O. Box 12277 Research Triangle Park, North Carolina 27709 USA Copyright 201.1. ISA...All rights reserved. st andar dggo ANSI/ISA-67.04.01 - 2006 (R2011) Preface This preface, as well as all footnotes and annexes, is included for information purposes and is not part of ANSI/ISA-67.04.01-2006 (R2011). The standards referenced within this document may contain provisions which, through reference in this text, constitute requirements of this document. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this document are encouraged to investigate the possibility of applying the most recent editions of the standards indicated within this document. Members of IEC and ISO maintain registers of currently valid International Standards. ANSI maintains registers of currently valid U.S. National Standards. This document has been prepared as part of the service of isA toward a goal of uniformity in the field of instrumentation. To be of real value, this document should not be static but should be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms and asks that they be addressed to the Secretary, Standards and Practices Board; ISA; 67 Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549-8411; Fax (919) 549-8288; E-mail: [email protected]. The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (Sl) in particular, in the preparation of instrumentation standards. The Department is further aware of the benefits to USA users of ISA standards of incorporating suitable references to the Sl (and the metric system) in their business and professional dealings with other countries. Toward this end, this Department will endeavor to introduce Sl-acceptable metric units in all new and revised standards, recommended practices, and technical reports to the greatest extent possible. Standard for Use of the International System of Units (Sl): The Modern Metric System, published by the American Society for Testing & Materials as IEEE/ASTM SI 10-97, and future revisions, will be the reference guide for definitions, symbols, abbreviations, and conversion factors. It is the policy of isA to encourage and welcome the participation of all concerned individuals and interests in the development of IsA standards, recommended practices, and technical reports. Participation in the IsA standards-making process by an individual in no way constitutes endorsement by the employer of that individual, of isA, or of any of the standards, recommended practices, and technical reports that IsA develops. Instrument setpoint drift is a problem that has led to numerous abnormal occurrence reports (now referred to as "Licensee Event Reports"). Section 50.36, "Technical Specifications," of Code of Federal Regulations, Title 10, Chapter 1, Part 50, Washington, D.C., 1987, requires that, where a Limiting Safety System Setting (LssS) is specified for a variable on which a safety limit has been placed, the setting be so chosen that automatic protective action will correct the most severe ab