Reducing the cobalt inventory in light water reactors
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.
- Research Organization:
- Electric Power Research Institute, 3412 Hillview Avenue, P.O. Box 10412, Palo Alto, California 94303
- OSTI ID:
- 5952654
- Journal Information:
- Nucl. Technol.; (United States), Vol. 68:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
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