JPS60213894A - High-temperature cobalt adsorbing filtering medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a high-temperature cobalt adsorbent using a metal suitable for high-temperature balt removal from a nuclear reactor secondary coolant (hereinafter referred to as reactor water). It is.

C゛Technical background of the invention and its problems] When removing cobalt ions dissolved in reactor water, which is the key to radiation exposure, the conventional method using ion exchange resin is to avoid thermal decomposition of the ion exchange resin.゜'C, 70Ql
ad) must be cooled down to below the heat-resistant temperature (approximately 60°C) through a heat exchanger and a cooler. .

This results in heat loss through the heat exchanger. Therefore, to reduce exposure, improve cobalt removal, i.e. rope.

When the flow rate is increased, the heat loss increases in proportion to this, resulting in a decrease in the thermal efficiency of the plan.

Therefore, there is a need for a high-temperature cobalt removal system with no heat loss that can remove dissolved cobalt under high temperature and high pressure without cooling the reactor water.

For high-temperature cobalt removal, an inorganic adsorbent that can adsorb cobalt under high temperature and high pressure is used instead of the ion exchange resin. For example, metal oxide systems such as titanium oxide-iron oxide (ferrite, etc.) and zirconium oxide are considered optimal, and other metal acid salts such as zirconium phosphate and tin tungstate are also promising.

In order to utilize inorganic adsorbents for high-temperature cobalt removal, it is essential to use them as furnace materials. The following methods can be used to make furnace materials.

(1) A single inorganic adsorbent is formed into a granular or block-like furnace material by sintering or the like.

(2) Using a heat-resistant and corrosion-resistant carrier in the form of granules or porous blocks, the inorganic adsorbent is supported on its surface.

(3) Using a heat-resistant and corrosion-resistant metal formed into granules, fibers, nets, etc., an oxide film (inorganic adsorbent) of the metal is generated on the surface.

Reactor materials obtained by methods (1) and (2) tend to break or peel off during long-term use under high temperature and high pressure, and part of the inorganic adsorbent flows out of the column as a suspension, causing the reactor There are drawbacks that are brought into the world.

On the other hand, the furnace material obtained by method 3) has a dense surface metal oxide, which is an inorganic adsorbent, and is strongly bonded to the base material, so it is similar to that obtained by method (1) and (2) above. , the inorganic adsorbent hardly flows out, and has excellent practicality as an adsorption furnace material.

However, reactor materials using metal have the following drawbacks as adsorbents for reactor water due to the metal material. That is, metal materials inevitably contain cobalt impurities due to their raw materials and their refining processes, and this impurity cobalt adversely affects the cobalt purification performance of metal furnace materials. This means that the dissolved cobalt concentration in the target reactor water is 10 to 50 p, p, t.
Cobalt is an extremely small amount of impurity in metal materials (50
This is because the elution cobalt concentration due to 1s000p, p1m or so) is also on the order of p, p, and t. For example, when adsorbing reactor water with a dissolved cobalt concentration of 20 p, p, t,
Cobalt eluted from impurity cobalt in metal furnace material is 5p,
If p and t exist, even if the removal rate of dissolved cobalt is 99%, the actual cobalt removal rate will be 2O-(
20X(1-0,99)+5)/20X100=74%
It will drop to .

The metal reactor materials used for high-temperature reactor water adsorption are heat-resistant and corrosion-resistant alloy materials such as stainless steel, heat-resistant steel, and Zircaloy, or pure metal materials such as nickel, titanium, zirconium, and aluminum. The material also contains cobalt as an impurity, and the above-mentioned impediment to the cobalt purification performance is unavoidable.

[Purpose of the invention]

An object of the present invention is to provide a high-temperature cobalt adsorption furnace material using metal that eliminates cobalt elution and dramatically improves cobalt removal performance.

[Summary of the invention]

The present invention relates to an adsorption furnace material in which a heat-resistant and corrosion-resistant metal is formed into a granular, fibrous, net-like, or porous shape suitable for a column furnace material, and an oxide film layer is formed on the surface of the shaped metal. By extracting and removing the impurity cobalt F from the oxide film layer and reducing the cobalt concentration in the oxide film layer from the impurity cobalt concentration in the metal material, the elution of cobalt to the treated object is prevented, and the This product has improved cobalt removal performance from water.

[Embodiments of the invention]

The metal furnace material of the present invention will be described in detail below with reference to an embodiment shown in the drawings. FIG. 1 is a diagram showing the microstate and effects of a conventional metal furnace material and a metal furnace material of the present invention.

In the figure, 1 is a metal material (cobalt impurity is 50 to 1
1000pp), stainless steel, heat-resistant steel.

Alloys such as Zircaloy, nickel, titanium,
It is obtained by molding a heat-resistant and corrosion-resistant metal selected from pure metals such as zirconium and aluminum into a granular, fibrous, net, or porous shape suitable for column operation. This metal material 1 is subjected to oxidation treatment 2, whereby the metal oxide film 3 is removed from the metal material 1.
generated on the surface of This is a conventional metal furnace material, and its microstate is shown in Figure 1. There are several methods for oxidizing metal materials, such as chemical oxidation treatment using chemicals, anodic oxidation treatment using electrolysis, high-temperature furnace treatment, and hydrothermal oxidation treatment using high-temperature water dissolved oxygen. good. Since the cobalt impurity in the produced oxide JLA has the same concentration as the metal material 1 (50 to 1.000 p, pom), cobalt <+ elutes into the reactor water (5 to 20 p, pom).
p, t ), giving the aforementioned obstacles.

The metal reactor material of the present invention is characterized in that the impurity cobalt in the produced oxide film is removed in order to eliminate cobalt (C14) eluted into the reactor water. That is, as shown in the figure, the conventional metal furnace material is subjected to a refining treatment 5 to extract and remove impurity cobalt from the generated oxide film 3, and to form a cobalt unmixed oxide film 3.
' (1p, p, m or less). The metal reactor material of the present invention obtained through such refining treatment has a significantly lower cobalt impurity in the oxide film involved in cobalt adsorption than that of the metal material, and the elution of cobalt <+ into the reactor water is sufficient. Less (less than or equal to ip, p, ). Therefore, it becomes possible to dramatically improve the cobalt removal rate, which has been difficult with conventional metal furnace materials. In addition, as the purification treatment 5 for metal furnace materials, methods such as chemical purification treatment in which impurity cobalt is eluted and removed with an extraction solution using a mineral acid or organic acid, or hot water purification treatment in which impurity cobalt is eluted and removed under high-temperature and high-pressure water. There is.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the microstate and its effects in an example of a high-temperature cobalt adsorption furnace material using metal according to the present invention. 1... Metal material 2... Oxidation treatment 3... Oxide coating 3'... Oxide coating 5 from which impurity cobalt has been removed...
・Refining treatment (7317) Representative Patent Attorney Noriyuki Chika 0! E
or 1 person) No.

Claims (2)

[Claims] (1) In an adsorption furnace material in which a heat-resistant and corrosion-resistant metal is formed into a shape suitable for a column furnace material and an oxide film layer is formed on the surface of the formed metal, impurity cobalt is extracted and removed from the oxide film layer, and the metal A high-temperature cobalt adsorption furnace material using metal, characterized in that the cobalt concentration in the oxide film layer is lower than the impurity concentration in the material. (2) Heat-resistant and corrosion-resistant metals include stainless steel and heat-resistant steel. Alloys such as Zircaloy or nickel, titanium
Selected from pure metals such as zirconium and aluminum. The high-temperature cobalt adsorption furnace material according to claim 1, characterized in that a metal material is used.