JPS6277446A - Electrode alloy for glass melting furnace - Google Patents

Abstract

PURPOSE:To manufacture an electrode having superior corrosion resistance and a high m.p. by using a Cr-Ni-Co-Fe alloy having a specified composition as a material for an electrode used to cake fission products in used nuclear fuel by a glass caking method. CONSTITUTION:An alloy having a composition consisting of, by weight, 24-45% Cr, 5-15% Ni, <20% Co, 0.005-0.5% Al, 0.1-2% Ti, 0.1-1% Mn, 0.01-0.8% Si and the balance Fe is used as a material for an electrode used in a glass melting furnace when high-level waste liquor produced by the reprocessing of used nuclear fuel is caked by a glass caking method by which superior safety and storage stability are provided. An electrode having a higher m.p. than a conventional electrode of 'Inconel 690(R)' and also having superior corrosion resistance is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to improvements in electrode materials used in glass melting furnaces in f2 soot solidification technology for level control waste liquid generated by reprocessing spent nuclear fuel.

[Technical background of the invention and its problems]

The radioactive materials contained in spent nuclear fuel, such as fission products, are separated from nuclear materials during the reprocessing process, and are solidified and stored in various ways after being compressed and treated as waste liquid. Currently, as one of the solidification methods, a vitrification treatment method is being considered that is safe and storable. This vitrification treatment technology is being actively researched in various countries.

Among the vitrification processing techniques, there is a method for melting glass that utilizes the norl heat generated by direct electricity supply from electrodes to waste liquid and glass raw materials. This electrode has 100
Exposure to the harsh corrosive environment of molten glass at temperatures above 0°C
Therefore, the life of the electrode is a major factor in determining the life of the melting furnace.

Conventionally, metal molybdenum, tin oxide, graphite, and the like have been considered as electrode materials for glass melting furnaces, but all of these have one drawback: their corrosion resistance in molten glass. For this reason, as a result of various studies, Inconel 690, which is relatively corrosion resistant, is currently being used in 4-pilot, 2-piece, etc. However, the melting point of Inconel 690 is about 135
Since the temperature is 0°C, which is lower than that of molybdenum, etc., there is a drawback that the operating conditions for the furnace are limited.

[Purpose of the invention]

The present invention has been made to eliminate the above-mentioned drawbacks! ,
Has corrosion resistance equal to or higher than Inconel 690,
In addition, the 4M alloy for glass melting furnaces of the present invention, which has a melting point of at least 50° C. or higher, is intended to be used as a direct material for glass melting furnaces.
5-45chi, Nf: 5-15%, co: 20 fb or less.

AL: 0.005-0.5%, Ti: 0.1
~2%, Mn: 0°1~1ch, Si: 0.01
-0.8%, with the remainder essentially consisting of Fe.

Such alloys are inconel 69 in molten glass.
Inconel 690 has better good resistance than Inconel 690, and its melting point is at least 50°C higher than Inconel 690.

The reason why the composition of each component is limited to the above range in the present invention will be explained below.

Cr is basically an element for maintaining the corrosion resistance of the alloy according to the invention. The reason why the total Cr content is 25 to 45% is because if it is less than 25%, corrosion resistance in molten glass cannot be maintained, while if it exceeds 45%, the alloy becomes brittle and the workability is significantly reduced. be.

Ni is an element that, together with Cr, improves the corrosion resistance of the alloy and improves the workability. Ni content 5~
The reason why it is set at 15 inches is because if it is less than 5 inches, it is not possible to fully improve the corrosion resistance and workability of the alloy, and if it exceeds -15 inches, it becomes difficult to raise the melting point of the alloy compared to Inconel 690. .

Both Al and Ti are elements added for the purpose of completely improving the corrosion resistance of the alloy in molten glass. The reason why the amount of Al added is 0.005 to 0.5 inch is because if it is less than 0.005 inch, the effect of improving corrosion resistance is small;
This is because, if the content exceeds 50%, a phase harmful to corrosion resistance will precipitate. The reason why the amount of Ti added is set to 0.1 to 2% is the same as in the case of Al.

Mn is an element added as a deoxidizing agent. The reason why Mn is added in an amount of 0.1 to 1% is because if it is less than 0.1%, it is not effective as a deoxidizing agent, whereas if it exceeds 1%, it becomes difficult to melt the alloy.

Sl is also an element added to improve the corrosion resistance of the alloy. The reason why the amount of Si added is set to 0.01 to 0.8% is that less than 0.01% gold has little effect on improving the corrosion resistance of the alloy, while if it exceeds 0.8% gold, the alloy becomes brittle. .

The reason for having less than 20 units of CO and the remainder being essentially Fe (that is, unavoidable impurities of Fe and P, S, and Sn@) is because
Cr-Ni-Fe-Co alloy is Inconel 690
This is because it has a higher melting point.

CO-containing lid? The reason why it is set to 20% or less is because if it exceeds 20%, workability will deteriorate.

Note that in the alloy according to the present invention, the addition i of C, which has the effect of improving strength, is not particularly limited;
If the amount of addition is too large, coarse carbides will be formed at the grain boundaries,
Since there is a possibility that corrosion resistance may deteriorate, it is desirable that the content be 0.5% or less.

[Embodiments of the invention]

An alloy having the composition shown in Table B12 below was completely melted.

Note that Comparative Example 1 is Inconel 690. These alloys were subjected to an immersion test to evaluate their corrosion resistance. In this immersion test, each alloy was immersed in an aluminum crucible in simulated embryo waste glass at 1270° C. for 7 days, and then the thinning behavior was investigated. 1. The melting points of each alloy were also measured. The weight loss and melting point are also listed in the table below.

As is clear from the above table, all of the alloys of Inconel Examples 1 to 3 have less thickness loss than Inconel 690 (Comparative Example 1), have a resistance of 5N, and have a melting point of 50°C or higher.
μ is rising. Further, the amount of thinning was significantly smaller than that of Comparative Example 2.3, which was not based on the composition of the present invention, and the melting point was also high in addition to the +:vf resistance.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to provide a metal for glass bath melting furnaces that has good eating properties and a good melting point, and as a result, it is possible to stabilize the operation conditions of glass melting furnaces. This has a remarkable effect.

Claims (1)

[Claims] Cr: 25-45%, Ni: 5-15%, Co
: 20% or less, Al: 0.005-0.5%, Ti: 0
．． 1-2%, Mn: 0.1-1%, Si: 0.01-0
．． An electrode alloy for a glass melting furnace, characterized in that the electrode alloy contains 8% Fe and the remainder substantially consists of Fe.