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Title: Comparison of Reg. Guide 1.99 fluence attenuation methods

Abstract

U.S. Regulatory Guide 1.99 Revision 2 (U.S. Nuclear Regulatory Commission, 1988, 'Radiation Embrittlement of Reactor Vessel Materials,' Regulatory Guide 1.99, Revision 2, Washington, D.C.) provides for the use of two substantially different methods for determining through-wall fluence in nuclear reactor pressure vessels. One method is a generic attenuation curve based on a simplistic exponential decay equation. Partly due to the simplicity of its application, the generic attenuation method is predominantly used for licensing calculations. However, it has a limitation in that at increasing distances away from the core belt-line, it becomes increasingly less accurate because it cannot account for neutron streaming effects in the cavity region surrounding the pressure vessel. The other attenuation method is based on a displacement per atom (dpa) calculation specific to the reactor vessel structure. The dpa method provides a more accurate representation of fluence attenuation through the reactor pressure vessel (RPV) wall at all elevations of the pressure vessel because it does account for neutron streaming in the cavity region. A requirement for using the dpa method, however, is an accurate flux solution through the RPV wall. This requirement has limited the use of traditional transport methods, such as discrete ordinates, that are limited bymore » their treatment of cavity regions (i.e., air) outside the pressure vessel wall. TransWare Enterprises, under the sponsorship of EPRI and BWRVIR has developed an advanced three-dimensional transport methodology capable of producing fully converged flux solutions throughout the entire reactor system, including in the cavity region and primary shield structures. This methodology provides an accurate and reliable determination of through-wall fluence in boiling water reactor (BWR) and pressurized water reactor (PWR) pressure vessels, thus allowing the dpa method to be implemented with high reliability. Using this advanced 3-D methodology, this paper presents comparisons of the generic and dpa attenuation methods at critical locations in both BWR and PWR pressure vessel walls. (author)« less

Authors:
 [1]
  1. TransWare Enterprises Inc., 1565 Mediterranean Dr., Sycamore, IL 60178 (United States)
Publication Date:
Research Org.:
American Society for Testing and Materials - ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA, 19428-2959 (United States); European Working Group on Reactor Dosimetry - EWGRD, SCK.CEN, Mol (Belgium)
OSTI Identifier:
22086977
Report Number(s):
INIS-US-13-ISRD-14-P1-11
TRN: US13V0038045424
Resource Type:
Conference
Resource Relation:
Conference: ISRD-14: 14. International Symposium on Reactor Dosimetry, Bretton Woods, NH (United States), 22-27 May 2011; Other Information: Country of input: France; 3 refs.
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; ATOMIC DISPLACEMENTS; ATTENUATION; BWR TYPE REACTORS; DISCRETE ORDINATE METHOD; DOSIMETRY; EMBRITTLEMENT; EPRI; EQUATIONS; LICENSING; NEUTRONS; NUCLEAR DECAY; PRESSURE VESSELS; PWR TYPE REACTORS; REACTOR VESSELS; REGULATORY GUIDES; RELIABILITY; SHIELDS

Citation Formats

Jones, E N. Comparison of Reg. Guide 1.99 fluence attenuation methods. United States: N. p., 2011. Web.
Jones, E N. Comparison of Reg. Guide 1.99 fluence attenuation methods. United States.
Jones, E N. 2011. "Comparison of Reg. Guide 1.99 fluence attenuation methods". United States.
@article{osti_22086977,
title = {Comparison of Reg. Guide 1.99 fluence attenuation methods},
author = {Jones, E N},
abstractNote = {U.S. Regulatory Guide 1.99 Revision 2 (U.S. Nuclear Regulatory Commission, 1988, 'Radiation Embrittlement of Reactor Vessel Materials,' Regulatory Guide 1.99, Revision 2, Washington, D.C.) provides for the use of two substantially different methods for determining through-wall fluence in nuclear reactor pressure vessels. One method is a generic attenuation curve based on a simplistic exponential decay equation. Partly due to the simplicity of its application, the generic attenuation method is predominantly used for licensing calculations. However, it has a limitation in that at increasing distances away from the core belt-line, it becomes increasingly less accurate because it cannot account for neutron streaming effects in the cavity region surrounding the pressure vessel. The other attenuation method is based on a displacement per atom (dpa) calculation specific to the reactor vessel structure. The dpa method provides a more accurate representation of fluence attenuation through the reactor pressure vessel (RPV) wall at all elevations of the pressure vessel because it does account for neutron streaming in the cavity region. A requirement for using the dpa method, however, is an accurate flux solution through the RPV wall. This requirement has limited the use of traditional transport methods, such as discrete ordinates, that are limited by their treatment of cavity regions (i.e., air) outside the pressure vessel wall. TransWare Enterprises, under the sponsorship of EPRI and BWRVIR has developed an advanced three-dimensional transport methodology capable of producing fully converged flux solutions throughout the entire reactor system, including in the cavity region and primary shield structures. This methodology provides an accurate and reliable determination of through-wall fluence in boiling water reactor (BWR) and pressurized water reactor (PWR) pressure vessels, thus allowing the dpa method to be implemented with high reliability. Using this advanced 3-D methodology, this paper presents comparisons of the generic and dpa attenuation methods at critical locations in both BWR and PWR pressure vessel walls. (author)},
doi = {},
url = {https://www.osti.gov/biblio/22086977}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jul 01 00:00:00 EDT 2011},
month = {Fri Jul 01 00:00:00 EDT 2011}
}

Conference:
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