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Title: Localized Corrosion of a Neutron Absorbing Ni-Cr-Mo-Gd Alloy

Abstract

The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory (INL), has developed a new nickel-chromium-molybdenum-gadolinium structural alloy for storage and long-term disposal of spent nuclear fuel (SNF). The new alloy will be used for SNF storage container inserts for nuclear criticality control. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section. This alloy must be resistant to localized corrosion when exposed to postulated Yucca Mountain in-package chemistries. The corrosion resistance properties of three experimental heats of this alloy are presented. The alloys performance are be compared to Alloy 22 and borated stainless steel. The results show that initially the new Ni-Cr-Mo-Gd alloy is less resistant to corrosion as compared to another Ni-Cr-Mo-Gd alloy (Alloy 22); but when the secondary phase that contains gadolinium (gadolinide) is dissolved, the alloy surface becomes passive. The focus of this work is to qualify these gadolinium containing materials for ASME code qualification and acceptance in the Yucca Mountain Repository.

Authors:
; ; ;
Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
DOE - NE
OSTI Identifier:
911134
Report Number(s):
INEEL/CON-05-02578
TRN: US0704412
DOE Contract Number:
DE-AC07-99ID-13727
Resource Type:
Conference
Resource Relation:
Conference: Corrosion 2005,Houston, TX,04/03/2005,04/07/2005
Country of Publication:
United States
Language:
English
Subject:
36 - MATERIALS SCIENCE; ABSORPTION; ALLOYS; CONTAINERS; CORROSION; CORROSION RESISTANCE; CRITICALITY; CROSS SECTIONS; GADOLINIUM; NEUTRONS; NUCLEAR FUELS; PERFORMANCE; STAINLESS STEELS; STORAGE; THERMAL NEUTRONS; YUCCA MOUNTAIN; SPENT FUELS; corrosion rate; gadolinium; neutron absorbing material; nickel-based alloy; Yucca Mountain

Citation Formats

R.E. Mizia, T. E. Lister, P. J. Pinhero, and T. L. Trowbridge. Localized Corrosion of a Neutron Absorbing Ni-Cr-Mo-Gd Alloy. United States: N. p., 2005. Web.
R.E. Mizia, T. E. Lister, P. J. Pinhero, & T. L. Trowbridge. Localized Corrosion of a Neutron Absorbing Ni-Cr-Mo-Gd Alloy. United States.
R.E. Mizia, T. E. Lister, P. J. Pinhero, and T. L. Trowbridge. Fri . "Localized Corrosion of a Neutron Absorbing Ni-Cr-Mo-Gd Alloy". United States. doi:. https://www.osti.gov/servlets/purl/911134.
@article{osti_911134,
title = {Localized Corrosion of a Neutron Absorbing Ni-Cr-Mo-Gd Alloy},
author = {R.E. Mizia and T. E. Lister and P. J. Pinhero and T. L. Trowbridge},
abstractNote = {The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory (INL), has developed a new nickel-chromium-molybdenum-gadolinium structural alloy for storage and long-term disposal of spent nuclear fuel (SNF). The new alloy will be used for SNF storage container inserts for nuclear criticality control. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section. This alloy must be resistant to localized corrosion when exposed to postulated Yucca Mountain in-package chemistries. The corrosion resistance properties of three experimental heats of this alloy are presented. The alloys performance are be compared to Alloy 22 and borated stainless steel. The results show that initially the new Ni-Cr-Mo-Gd alloy is less resistant to corrosion as compared to another Ni-Cr-Mo-Gd alloy (Alloy 22); but when the secondary phase that contains gadolinium (gadolinide) is dissolved, the alloy surface becomes passive. The focus of this work is to qualify these gadolinium containing materials for ASME code qualification and acceptance in the Yucca Mountain Repository.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Apr 01 00:00:00 EST 2005},
month = {Fri Apr 01 00:00:00 EST 2005}
}

Conference:
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  • The corrosion properties of Ni-Cr-Mo-Gd alloys that are being developed for use as a neutron-absorbing structural material were examined. The corrosion work was part of a larger alloy development program. The corrosion properties were examined by both electrochemical and longer-term immersion testing in standard test solutions and in simulated solutions used in corrosion testing by the Yucca Mountain Project. The addition of Gd to a Ni-Cr-Mo alloy results in the formation of a gadolinide (Ni5Gd) secondary phase. This phase was observed to preferentially dissolve under electrochemical testing at anodic potentials. The reaction appears to be mostly limited to the secondarymore » phase exposed to the surface. A brief comparison with another neutron-absorbing alloy, borated stainless steel, is made.« less
  • Iron-based amorphous alloy Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} was compared to borated stainless steel and Ni-Cr-Mo-Gd alloy on their corrosion resistance in various high-concentration chloride solutions. The melt-spun ribbon of this iron-based amorphous alloy have demonstrated a better corrosion resistance than the bulk borated stainless steel and the bulk Ni-Cr-Mo-Gd alloy, in high-concentration chloride brines at temperatures 90 deg. C or higher. (authors)
  • In the operation of most power plants, waste heat of flue gases from heavy oil-fired or coal-fired boilers is recovered by economizers and preheaters. These flue gases contain N{sub 2}, O{sub 2}, H{sub 2}O, CO{sub 2}, SO{sub 2}, SO{sub 3}, NO{sub x}, HCl, unburned carbon and fly ashes. The temperatures of the flue gases, which are basically kept at temperatures higher than 200 C, are controlled above the sulfuric acid dewpoint. A new corrosion resistant Ni-Cr-Mo-Ta alloy has been developed with improved corrosion resistance to sulfur dewpoint corrosion. The corrosion tests show that this alloy can be used for heat-exchangersmore » to recover waste heat at low temperatures in fossil fuel-fired power plants. This new alloy, which is composed of 20% chromium, 20% molybdenum, 2% tantalum and balance nickel, shows excellent corrosion resistance to sulfur dewpoint corrosion. The general and localized corrosion resistance behavior of this new alloy has been tested in different candidate solutions such as sulfuric acid solutions with and without active carbon powder, sulfuric-hydrochloric acid mixtures, ASTM G-28 Method B, and Green Death solution. Very excellent corrosion resistance performance against these tests has been shown in the laboratory. Moreover the corrosion resistance of welded joints does not degrade in the as welded condition.« less
  • Nitrogen additions of 0.45 to 0.5 wt % to an austenitic stainless steel containing about 22 Cr, 20 Ni and 6 Mo (all wt %) dramatically enhance its resistance to localized corrosion. The electrochemical behavior of this alloy has been studied as a function of chloride ion concentration and temperature. Also, its corrosion resistance has been compared with that of a similar commercial alloy with normal residual nitrogen of only 0.04 wt %. Compositional analyses of the passivated surface of the high nitrogen alloy show an enrichment nitrogen at the metal-passive film interface, with a binding energy similar to thatmore » of the bulk nitrogen on the fully sputtered surface. The role of nitrogen in enhancing the corrosion resistance is discussed in light of the above results and some recent concepts on passivity.« less
  • The National Spent Nuclear Fuel Program (NSNFP), located at the Idaho National Laboratory, coordinates and integrates management and disposal of U.S. Department of Energy-owned spent nuclear fuel. These management functions include using the DOE standardized canister for packaging, storage, treatment, transport, and long-term disposal in the Yucca Mountain Repository. Nuclear criticality must be prevented in the postulated event where a waste package is breached and water (neutron moderator) is introduced into the waste package. Criticality control will be implemented by using a new, weldable, corrosion-resistant, neutron-absorbing material to fabricate the welded structural inserts (fuel baskets) that will be placed inmore » the standardized canister. The new alloy is based on the Ni-Cr-Mo alloy system with a gadolinium addition. Gadolinium was chosen as the neutron absorption alloying element because of its high thermal neutron absorption cross section. This paper describes a weld development program to qualify this new material for American Society of Mechanical Engineers (ASME) welding procedures, develop data to extend the present ASME Code Case (unwelded) for welded construction, and understand the weldability and microstructural factors inherent to this alloy.« less