NUREG/CR-6998, Review of Information for Spent Nuclear Fuel
Total Page:16
File Type:pdf, Size:1020Kb
NUREG/CR-6998 4u .s.- r(i c ORNLITM-2007/229 United States Nuclear Regulatory Commission ProtectingPeople and the Environment for ZpM HuDear Fuel Burnsup Cansflrma~ian Office of Nuclear Regulatory Research AVAILABILITY OF REFERENCE MATERIALS IN NRC PUBLICATIONS NRC Reference Material Non-NRC Reference Material As of November 1999, you may electronically access Documents available from public and special technical NUREG-series publications and other NRC records at libraries include all open literature items, such as NRC's Public Electronic Reading Room at books, journal articles, and transactions, Federal http://www.nrc.cgov/reading-rm.html. Publicly released Register notices, Federal and State legislation, and records include, to name a few, NUREG-series congressional reports. Such documents as theses, publications; FederalRegister notices; applicant, dissertations, foreign reports and translations, and licensee, and vendor documents and correspondence; non-NRC conference proceedings may be purchased NRC correspondence and internal memoranda; from their sponsoring organization. bulletins and information notices; inspection and investigative reports; licensee event reports; and Copies of industry codes and standards used in a Commission papers and their attachments. substantive manner in the NRC regulatory process are maintained at- NRC publications in the NUREG series, NRC The NRC Technical Library regulations, and Title 10, Energy, in the Code of Two White Flint North FederalRegulations may also be purchased from one 11545 Rockville Pike of these two sources. Rockville, MD 20852-2738 1. The Superintendent of Documents U.S. Government Printing Office These standards are available in the library for Mail Stop SSOP reference use by the public. Codes and standards are Washington, DC 20402-0001 usually copyrighted and may be purchased from the Intemet: bookstore.gpo.gov originating organization or, if they are American Telephone: 202-512-1800 National Standards, from- Fax: 202-512-2250 American National Standards Institute 2. The National Technical Information Service 11 West 42nd Street Springfield, VA 22161-0002 New York, NY 10036-8002 www.ntis.gov www.ansi.org 1-800-553-6847 or, locally, 703-605-6000 212-642-4900 A single copy of each NRC draft report for comment is Legally binding regulatory requirements are stated available free, to the extent of supply, upon written only in laws; NRC regulations; licenses, including request as follows: technical specifications; or orders, not in Address: Office of Administration NUREG-series publications. The views expressed Reproduction and Mail Services Branch in contractor-prepared publications in this series are U.S. Nuclear Regulatory Commission not necessarily those of the NRC. Washington, DC 20555-0001 E-mail: [email protected] The NUREG series comprises (1) technical and Facsimile: 301-415-2289 administrative reports and books prepared by the staff (NUREG-XXXX) or agency contractors Some publications in the NUREG series that are (NUREG/CR-XXXX), (2) proceedings of posted at NRC's Web site address conferences (NUREG/CP-XXXX), (3) reports http:/!www.nrc.qov/readinq-rm/doc-collectionsinuregs resulting from international agreements are updated periodically and may differ from the last (NUREG/IA-XXXX), (4) brochures printed version. Although references to material found (NUREG/BR-XXXX), and (5) compilations of legal on a Web site bear the date the material was accessed, decisions and orders of the Commission and Atomic the material available on the date cited may and Safety Licensing Boards and of Directors' subsequently be removed from the site. decisions under Section 2.206 of NRC's regulations (NUREG-0750). DISCLAIMER: This report was prepared as an account of work sponsored by an agency of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any employee, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product, or process disclosed in this publication, or represents that its use by such third party would not infringe privately owned rights. *U.S.NRC NUREG/CR-6998 United States Nuclear Regulatory Commission ProtectingPeople and the Environment Review of Information for Spent Nuclear Fuel Burnup Confirmation Manuscript Completed: June 2009 Date Published: December 2009 Prepared by B.B. Bevard, J.C. Wagner and C.V. Parks (ORNL) M. Aissa (NRC) Oak Ridge National Laboratory Managed by UT-Battelle, LLC Oak Ridge, TN 37831-6170 M. Aissa, NC Project Manager NRC Job Code Y6517 Office of Nuclear Regulatory Research ABSTRACT The Interim Staff Guidance on burnup credit (ISG-8, revision 2) for pressurized-water-reactor spent nuclear fuel in storage and transport casks, issued in 2002 by the U.S. Nuclear Regulatory Commission's Spent Fuel Project Office, recommends an out-of-core bumup measurement to confirm the reactor record and compliance with the assembly bumup value used for cask loading acceptance. This recommendation is intended to prevent unauthorized loading (i.e., misloading) of assemblies due to inaccuracies in reactor burnup records and/or improper assembly identification, thereby ensuring that the appropriate subcritical margin is maintained. The purpose of this report is to detail information and issues relevant to preshipment burnup measurements when using bumup credit in pressurized-water-reactor spent nuclear fuel transport and storage casks. In particular, this report reviews the role of burnup measurements in the regulatory guidance for demonstrating compliance with bumup loading criteria, burnup measurement capabilities and experience, generation and accuracy of utility burnup records, fuel movement and misloading experience, and the consequences of misloading assemblies in casks designed for burnup credit. iii CONTENTS Page AB ST R AC T ................................................................................................................................................ iii L IST O F FIGU R E S .................................................................................................................................... vii L IST OF T A B L E S ....................................................................................................................................... ix EX ECU TIV E SU M MA RY .......................................................................................................................... xi AB B REV IA T IO NS ..................................................................................................................................... xv 1 INTRODUCTION ......................................................... 1 2 ROLE OF BURNUP MEASUREMENTS IN DEMONSTRATING COMPLIANCE WITH BURNU P LOADING CRITERIA .................................................................................................... 3 3 OUT-OF-CORE BURNUP MEASUREMENTS-EXPERIENCE AND CAPABILITIES ........ 5 3.1 MEASUREMENT TECHNIQUES .......................................................................................... 5 3.2 PRACTICAL AND OPERATIONAL CONSIDERATIONS ................................................. 6 3.3 ISSUES AFFECTING MEASUREMENT EQUIPMENT ACCURACY ............................... 6 3.4 MEASUREMENT SYSTEMS USED AT COMMERCIAL NUCLEAR PLANTS ............... 8 3.4.1 Fork D etector System s ................................................................................................... 9 3.4.2 High-Resolution Gamma-Ray Spectroscopy .............................................................. 14 3.4.3 Summary of U.S. Out-of-Core Measurement Results ................................................. 15 3.5 CERENKOV RADIATION MONITORING DEVICES ...................................................... 17 3.6 COMMENTS ON INTERNATIONAL PRACTICES AND REGULATIONS .................... 19 3.6.1 Summary of Current Practices and Regulatory Requirements ...................... 20 3 .6 .2 Sum mary ........................................................................................................................... 23 4 REACTOR BURNUP RECORDS: GENERATION AND ACCURACY ...................................... 25 4.1 B A C K G R O U N D ......................................................................................................................... 25 4.2 THERMAL POWER MEASUREMENT ............................................................................... 26 4.3 IN-CORE POWER DISTRIBUTION MEASUREMENT .......................................................... 27 4.4 IN-CORE MEASUREMENTS PROCESSING ...................................................................... 29 4.4.1 Flux M ap Processors ................................................................................................... 29 4.4.2 R eactor A nalysis Codes ............................................................................................. 31 4.4.3 Regular Validation of Reactor Analysis Codes ............................................................ 32 4.5 IN-CORE BURNUP MEASUREMENT ACCURACY ........................................................ 34 4.6 SU MM A R Y ................................................................................................................................ 38 v CONTENTS (CONTINUED) Page 5 CONSEQUENCES OF FUEL ASSEMBLY MISLOADING ........................................................ 39 6 FUEL MOVEMENT AND MISLOADING EXPERIENCE .........................................................