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Treatment method of waste graphite crucible

A treatment method and technology for waste graphite, applied in nuclear engineering, radioactive purification, etc., can solve the problems of high cost and heavy workload, and achieve the effect of reducing treatment cost, combustion cost and personnel work intensity.

Pending Publication Date: 2021-04-23
CHINA NUCLEAR BAOTOU GUANGHUA CHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, there is no clear treatment method for low-level waste graphite crucibles. Ashing treatment is usually used for waste graphite. Due to the large number of waste graphite crucibles temporarily stored in the North of CNNC, direct ashing treatment is heavy workload and high cost.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Step 1: Carry out source term investigation on the contaminated layer of the waste graphite crucible to determine the depth of contamination and the degree of contamination on the surface;

[0021] Step 2: Before ashing, the inner surface of the polluted part of the waste graphite crucible is mechanically cut; the polluted part is subjected to ashing treatment, and the non-polluted part is preserved.

[0022] The volume of the waste graphite crucible exceeds 200L, and the wall thickness is relatively thick, which is convenient for cutting.

[0023] The ashing temperature T range of the waste graphite crucible is 650°C ≤ T1 ≤ 800°C, and the heating process is as follows: after rising to 200°C, heat preservation for 1 hour, after heat preservation, continue to heat up, every 100°C heat preservation for 1 hour, the temperature rise and heat preservation time are collectively referred to as reaction Time, the range of reaction time t is 90h≤t≤120h, until the waste graphite ...

Embodiment 2

[0026] Step 1: Carrying out source item investigation on the pollution layer in the waste graphite crucible to determine its pollution elements and pollution degree;

[0027] Step 2: Ashing the graphite crucible, after a certain period of time, the polluted part is all ashed, and the non-polluting part is kept.

[0028] Step three, clean up the non-polluted part.

[0029] The volume of the waste graphite crucible exceeds 200L, and the wall thickness is relatively thick.

[0030] The uranium content on the inner surface of the waste graphite crucible is 20% to 70%, and other elements are mainly C, O and Y.

[0031] In the ashing process of the waste graphite crucible, the outer surface is in contact with the material boat.

[0032] The ashing temperature T range of the waste graphite crucible is 650°C ≤ T1 ≤ 800°C, and the heating process is as follows: after rising to 200°C, heat preservation for 1 hour, after heat preservation, continue to heat up, every 100°C heat preserva...

Embodiment 3

[0034] Embodiment 3: mechanical separation-ashing

[0035] Step 1: Take a waste graphite crucible with an outer diameter of 500 mm, an inner diameter of 400 mm, a height of 620 mm, and a wall thickness of 50 mm for source investigation. The surface activity of the waste graphite crucible after cleaning with a brush is less than 1Bq / cm 2 , when treated to a depth of 10mm, all meet the surface pollution level of less than 0.08Bq / cm 2 , up to the exemption level.

[0036] Step 2: Take a complete graphite crucible to remove the surface oxide layer and then perform preliminary crushing, select a graphite block with a larger area after crushing and cut off the inner surface of 10mm.

[0037] Step 3: After the cut part is crushed for the second time, it is evenly loaded into two boats, each boat is filled with 500g, the ashing temperature is 800°C, the reaction time is 90h, and the air flow rate is 300L / h. The ashed part of the pollution accounts for about 20% of the total mass. ...

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Abstract

The invention belongs to the technical field of radioactive waste treatment, and particularly relates to a treatment method of a waste graphite crucible, which comprises the following steps of: 1, carrying out source item investigation on a polluted layer of a waste graphite crucible to determine the pollution depth and the surface layer pollution degree of the waste graphite crucible; and 2, mechanically cutting the inner surface layer of the polluted part of the waste graphite crucible before ashing, carrying out ashing treatment on the polluted part, and preserving the non-polluted part. Certain technical support is provided for treatment of a polluted layer of a waste graphite crucible with a fixed model and a determined pollution degree. The waste graphite crucible is subjected to mechanical separation-ashing and partial ashing treatment, so that the combustion cost and the operation intensity of personnel can be effectively reduced. Meanwhile, the non-polluted waste graphite crucible is sold according to the price of high-purity waste graphite, the treatment cost is reduced to a greater extent, and the green development concept is met.

Description

technical field [0001] The invention belongs to the technical field of radioactive waste treatment, and in particular relates to a treatment method for waste graphite crucibles. Background technique [0002] In the process of scientific research and production of nuclear fuel elements, a large amount of waste graphite crucibles are produced. Ashing treatment methods are often used for waste graphite at home and abroad. The volume reduction ratio of waste graphite after ashing can reach 160:1. The incineration ash produced is an inorganic inert substance, which is safe. The performance can be improved, which is good for disposal. [0003] At present, there is no clear treatment method for low-level waste graphite crucibles. Ashing treatment is usually used for waste graphite. Due to the large number of waste graphite crucibles temporarily stored in the North of CNNC, direct ashing treatment is heavy workload and high cost. Contents of the invention [0004] In view of the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G21F9/30
Inventor 王东昱李玉春朱勇董志平
Owner CHINA NUCLEAR BAOTOU GUANGHUA CHEM IND