JP3377503B2 - Glass melting furnace for high level radioactive liquid waste - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass melting furnace used for vitrifying high-level radioactive liquid waste. [0002] High-level radioactive liquid waste generated after reprocessing of spent nuclear fuel has extremely high radiation and decay heat, and is difficult to dispose of as a liquid.
4 is fed into a glass melting furnace 1 having a structure as shown in FIG. 4, where it is packed with a glass material such as borosilicate glass in a corrosion-resistant stainless steel container called a canister c while being melted at a high temperature. It is planned that after being stabilized as a solid, it will be naturally cooled for a certain period of time and then disposed of deep underground. As shown in the figure, this glass melting furnace 1
The inner bottom of the furnace main body 2 is narrowed in a funnel shape (square pyramid shape), and a flow-down hole 3 for flowing molten glass in the furnace 2 at its lowermost end.
And a pair of main electrodes 5 and 5 and auxiliary electrodes 6 and 6 provided therein. After the high-level radioactive liquid waste and the glass raw material are introduced from an inlet 7 provided on the ceiling wall of the furnace main body 2, first, an electric current is applied between the main electrodes 5 and 5 so that the vicinity of the surface layer is obtained. Fully dissolve the high-level radioactive liquid waste and the glass raw material, and then apply electricity between the auxiliary electrodes 6 and 6 located therebelow to melt the high-level radioactive liquid waste and the glass raw material in the lower layer thereof, Finally, the bottom electrode 4
Then, electricity is passed between the main electrodes 5 and 5 to melt the whole, and then the downflow nozzle 8 extending from the downflow hole 3 is heated by the surrounding electric heating coil 9 to melt and extract the solidified glass clogged therein. As a result, the molten glass in the furnace 2 is caused to flow down into the canister c located below the furnace 2 and is hermetically contained therein as a vitrified body. [0005] The gas generated in the melting furnace 1 is exhausted as an off-gas from an exhaust port 7a.
The radioactive material is completely collected and removed by an A filter or the like, rendered harmless, and then released into the atmosphere. The furnace body 2 of the glass melting furnace 1, particularly the inner wall thereof, is made of a refractory brick which is excellent in heat resistance in nature. It is conceivable that a crack is generated by the impact and a part of the crack falls off as brick waste and flows down to the downflow hole 3 side as shown in FIG. For this reason, as shown in FIG.
Is formed not in a slope along the wall surface but in a flat portion. The flat portion has a structure in which the falling down of the brick dust is prevented by blocking the fall of the brick dust. I have. However, when the periphery of the flow-down hole 3 (the top of the bottom electrode 4) is formed as a flat portion, a metal sludge (metal oxide) having a high specific gravity such as ruthenium or palladium deposited from a high-level radioactive waste liquid in a melting process. Is difficult to flow out, accumulates on the flat portion, grows along the inclined surface, and eventually reaches the auxiliary electrode 6 or the main electrode 5 to cause a short-circuit of current and lose its function. Can be considered. Accordingly, the present invention has been devised to effectively solve such a problem, and has as its object to smooth the flow of metal sludge and to prevent blockage by brick debris. To provide a novel high-level radioactive liquid waste glass melting furnace. [0010] In order to solve the above-mentioned problems, the present invention provides a furnace body made of a refractory brick, which has a funnel-shaped inner bottom and a bottom electrode at the lowermost end thereof. the falling hole flowing down the molten glass in the furnace to the central portion <br/> Bei example of the bottom electrode, causes deflate the funnel-shaped upper surface of the bottom electrode about its falling hole, the top of the bottom electrode Contact in the glass melting furnace of high-level radioactive liquid waste having a brick scrap receiving in order to prevent blockage of the flow-down hole by brick scraps of the refractory bricks
The brick debris receiver is spaced at a certain distance above the bottom electrode.
Is supported in a floating state with a gap from the downflow hole at the center.
A cylindrical waste receiving body having a small diameter passage hole and
The waste is positioned so that the hole is positioned substantially coaxially on the downflow hole.
A rod-shaped support member for horizontally supporting the receiving main body from the furnace wall side . [0011] it is possible to smoothly flow down the metals sludge, it is possible to reliably prevent clogging of falling hole by practitioners Kawarakuzu. Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows the vicinity of the furnace bottom of a glass melting furnace 1 according to the present invention. In the figure, reference numeral 2 denotes a furnace body, 4 denotes a bottom electrode provided on the furnace bottom, and 3 denotes this bottom. Electrode 4
A downflow hole 10 provided at the center of is a brick waste receiver provided on the bottom electrode 4. As shown in the figure, the bottom electrode 4 has a top surface 4a which is depressed in a funnel shape around the downflow hole 3.
It has a flush structure continuous with the inclined surface (furnace wall surface) 2a of the furnace body 2. On the other hand, the brick waste receiver 10 is formed of a heat-resistant non-metallic material, for example, ceramic or the like, and has a cylindrical waste receiver main body 12 having a through hole 11 in the center portion. A plurality of (four in the present embodiment) support members 13, 13, 1 extending radially from the side surface
3 and 13. The support members 13, 13, 13,
13 are the inclined surfaces (furnace wall surfaces) of the furnace body 2 respectively.
Cylindrical offcut receiving body 12 by contact with the 2a side bottom collector
It is supported in a state of being floated on the pole 4 at a predetermined interval, and the passage hole 11 is located substantially coaxially on the flow-down hole 3 on the bottom electrode 4 side. Further, the passage hole 11 on the side of the dust receiving body 12 is provided.
And the gap A2 between the dust receiving body 12 and the inclined surface (furnace wall surface) 2a of the furnace body 2 are smaller than the hole diameter B of the flow-down hole 3 on the bottom electrode 4 side, and , Most of which flows down through the downflow hole 3. Therefore, in the glass melting furnace 1 of the present invention having such a structure, the upper surface of the bottom electrode 4 is
Is formed in a funnel shape so as to be continuous with the inclined surface (furnace wall surface) 2a of the furnace main body. Flows smoothly to the side. Therefore, the metal sludge does not accumulate on the furnace bottom (on the bottom electrode 4) as in the conventional structure, and inconveniences such as a short circuit can be reliably avoided. On the bottom electrode 4, a brick dust receiver 10 is provided.
Is provided, even if large brick debris that closes the flow-down hole 3 falls off, this is caught by the brick waste receiver 5 and does not reach the flow-down hole 3. Inconvenience such as blockage can also be reliably prevented. Since the high-level radioactive liquid fed into the furnace body 2 has been filtered in advance to remove its solids, most of the solids that block the flow-down hole 3 in the furnace. Since it is generated brick waste, there is little need to consider solid matter other than brick waste. According to the above summary the present invention, it is possible to capture it is possible to perform the stream of metallic sludge smoothly, the brick scrap lead to blockage of the flow under the hole in advance. As a result, short-circuiting due to metal sludge and blockage of the flow-down hole due to brick debris can be reliably avoided. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an embodiment in the vicinity of a bottom electrode of a glass melting furnace according to the present invention. FIG. 2 is a plan view showing one embodiment near the bottom electrode of the glass melting furnace according to the present invention. FIG. 3 is an explanatory view showing a configuration of a conventional glass melting furnace. FIG. 4 is a sectional view taken along line XX in FIG. 3; FIG. 5 is a partially enlarged view showing a Y part in FIG. 3; FIG. 6 is a partially enlarged view showing a state in which the upper surface of the bottom electrode is funnel-shaped. [Description of Signs] 2 Furnace main body 3 Flow-down hole 4 Bottom electrode 10 Brick waste receptacle 11 Passage hole 12 Waste receptacle body 13 Support member

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Naoki Asano 4-4, Muramatsu, Oji, Tokai-mura, Naka-gun, Ibaraki Prefecture Inside the Japan Nuclear Cycle Development Institute Tokai Works (72) Inventor Takayuki Aosawa 1 Shinnakaharacho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Ishikawajima Harima Heavy Industries, Ltd. Yokohama Engineering Center (56) References JP-A-4-161898 (JP, A) JP-A-2000-28790 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) G21F 9/16 C03B 5/027

Claims (1)

(57) [Claims 1] A furnace body made of a refractory brick is narrowed in a funnel shape, and a bottom electrode is provided at the lowest end thereof, and a furnace electrode is provided at the center of the bottom electrode. of example Bei a falling hole flowing down the molten glass, causes deflate the funnel-shaped upper surface of the bottom electrode about its falling hole, obstruction of the flow-down hole on the top of the bottom electrode according to the brick dust of the refractory bricks the glass melting furnace of high-level radioactive liquid waste having a brick scrap receiving to prevent
In the above, the brick waste receiver is placed on the bottom electrode for a certain time.
It is supported in a floating state with a gap between it and the downflow hole at the center.
A cylindrical debris receiving body having a passage hole with a small diameter;
So that the overhole is located substantially coaxially on the downflow hole
A rod-shaped support member that horizontally supports the waste receiving body from the furnace wall side
And a glass melting furnace for high-level radioactive liquid waste.