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Title: Reducing the cobalt inventory in light water reactors

Abstract

Reducing the cobalt content of materials used in nuclear power plants is one approach to controlling the radiation fields responsible for occupational radiation exposure; corrosion of steam generator tubing is the primary source in pressurized water reactors (PWRs). Wear of the cobalt-base alloys used to hardface valves (especially feedwater regulator valves) and as pins and rollers in control blades are the primary boiling water reactor (BWR) sources. Routine valve maintenance can also be a significant source of cobalt. Wear, mechanical property, and corrosion measurements led to the selection of Nitronic-60/CFA and PH 13-8 Mo/Inconel X-750 as low-cobalt alloys for use as pin/roller combinations. These alloys are currently being tested in two commercial BWRs. Measurements show that Type 440C stainless steel wears less than the cobalt-base alloys in BWR feedwater regulator valves. Sliding wear tests performed at room temperature in simulated PWR water showed that Colmonoy 74 and 84, Deloro 40, and Vertx 4776 are attractive low-cobalt hardfacing alloys if the applied loads are less than or equal to103 MPa. The cobalt-base alloys performed best at high loads (207 MPa). Ongoing laboratory studies address the development and evaluation of cobalt-free iron-base hardfacing alloys and seek to improve the wear resistance ofmore » cobalt-base alloys by using lasers. Reducing cobalt impurity levels in core components that are periodically discharged should also help reduce radiation fields and disposal costs.« less

Authors:
Publication Date:
Research Org.:
Electric Power Research Institute, 3412 Hillview Avenue, P.O. Box 10412, Palo Alto, California 94303
OSTI Identifier:
5952654
Resource Type:
Journal Article
Journal Name:
Nucl. Technol.; (United States)
Additional Journal Information:
Journal Volume: 68:1
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; 36 MATERIALS SCIENCE; BWR TYPE REACTORS; MATERIALS TESTING; COBALT BASE ALLOYS; RADIATION EFFECTS; WEAR RESISTANCE; PWR TYPE REACTORS; CORROSION; COST; FEEDWATER; IMPURITIES; INCONEL X750; LASERS; MAINTENANCE; MECHANICAL PROPERTIES; MOLYBDENUM; OCCUPATIONAL SAFETY; RADIATION DOSES; REACTOR CORES; REACTOR MATERIALS; VALVES; VERY HIGH PRESSURE; ALLOYS; CHEMICAL REACTIONS; CHROMIUM ALLOYS; COBALT ALLOYS; CONTROL EQUIPMENT; DOSES; ELEMENTS; EQUIPMENT; FLOW REGULATORS; HYDROGEN COMPOUNDS; INCONEL ALLOYS; IRON ALLOYS; MATERIALS; METALS; NICKEL ALLOYS; NICKEL BASE ALLOYS; OXYGEN COMPOUNDS; REACTOR COMPONENTS; REACTORS; SAFETY; TESTING; TITANIUM ALLOYS; TRANSITION ELEMENTS; WATER; WATER COOLED REACTORS; WATER MODERATED REACTORS; 210100* - Power Reactors, Nonbreeding, Light-Water Moderated, Boiling Water Cooled; 210200 - Power Reactors, Nonbreeding, Light-Water Moderated, Nonboiling Water Cooled; 360103 - Metals & Alloys- Mechanical Properties; 360106 - Metals & Alloys- Radiation Effects

Citation Formats

Ocken, H. Reducing the cobalt inventory in light water reactors. United States: N. p., 1985. Web.
Ocken, H. Reducing the cobalt inventory in light water reactors. United States.
Ocken, H. 1985. "Reducing the cobalt inventory in light water reactors". United States.
@article{osti_5952654,
title = {Reducing the cobalt inventory in light water reactors},
author = {Ocken, H},
abstractNote = {Reducing the cobalt content of materials used in nuclear power plants is one approach to controlling the radiation fields responsible for occupational radiation exposure; corrosion of steam generator tubing is the primary source in pressurized water reactors (PWRs). Wear of the cobalt-base alloys used to hardface valves (especially feedwater regulator valves) and as pins and rollers in control blades are the primary boiling water reactor (BWR) sources. Routine valve maintenance can also be a significant source of cobalt. Wear, mechanical property, and corrosion measurements led to the selection of Nitronic-60/CFA and PH 13-8 Mo/Inconel X-750 as low-cobalt alloys for use as pin/roller combinations. These alloys are currently being tested in two commercial BWRs. Measurements show that Type 440C stainless steel wears less than the cobalt-base alloys in BWR feedwater regulator valves. Sliding wear tests performed at room temperature in simulated PWR water showed that Colmonoy 74 and 84, Deloro 40, and Vertx 4776 are attractive low-cobalt hardfacing alloys if the applied loads are less than or equal to103 MPa. The cobalt-base alloys performed best at high loads (207 MPa). Ongoing laboratory studies address the development and evaluation of cobalt-free iron-base hardfacing alloys and seek to improve the wear resistance of cobalt-base alloys by using lasers. Reducing cobalt impurity levels in core components that are periodically discharged should also help reduce radiation fields and disposal costs.},
doi = {},
url = {https://www.osti.gov/biblio/5952654}, journal = {Nucl. Technol.; (United States)},
number = ,
volume = 68:1,
place = {United States},
year = {Tue Jan 01 00:00:00 EST 1985},
month = {Tue Jan 01 00:00:00 EST 1985}
}