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Nuclear fuel pellet having enhanced thermal conductivity, and preparation method thereof

An enhanced thermal conductivity technology, which is applied in the direction of reactor fuel elements, reactor fuel materials, nuclear engineering, etc., can solve the problems that the composition cannot be prepared, and achieve the effect of enhanced plasticity, low preparation cost and simple preparation method

Active Publication Date: 2016-06-22
JOINT CO AKME ENG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0028] However, the above methods cannot produce nuclear fuel pellets with simple composition and good thermal conductivity (i.e. higher than the reference data) at elevated temperature

Method used

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  • Nuclear fuel pellet having enhanced thermal conductivity, and preparation method thereof
  • Nuclear fuel pellet having enhanced thermal conductivity, and preparation method thereof
  • Nuclear fuel pellet having enhanced thermal conductivity, and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0051] The preparation method of thermal conductivity-enhanced nuclear fuel pellets in this embodiment is as follows:

[0052] When uranyl nitrate solution and ammonia solution are added to the buffer solution at the same time, the deposition process begins at 55-60±2°C in the following two pH stages. In the first stage, the pH is maintained at 6.5-6.7. In the second stage, The pH is between 9.0 and 10.5, forming the final precipitate polyammonium polyuranate (PUA); calcination is carried out at 600 to 680°C until UO 2 Reduction; melting of metal uranium at a temperature higher than 1150°C; sintering at 1750°C in a trace amount of hydrogen-nitrogen liquid phase medium until the formation of metal clusters. Sintering in a liquid medium results in the desired porosity and pellet structure. This kind of UO can be identified by X-ray photon spectrometer 2 The new structure of the core block and the additional U-U chemical bond structure: the core block structure has small pores ...

Embodiment 2

[0054] The preparation method of thermal conductivity-enhanced nuclear fuel pellets in this embodiment is as follows:

[0055] When uranyl nitrate solution, metal additives and ammonia solution are added to the buffer at the same time, the deposition process begins at 55-60±2°C in the following two pH stages. In the first stage, the pH is maintained at 7.0-7.2, and in the In the second stage, the pH is between 8.0 and 8.5, and the final precipitate is ammonium polyuranate (PUA). The metal additive is selected from chromium, and the chromium acts as a catalyst, which can catalyze the uranium dioxide nanometer near it during the pellet sintering process. The particles are partially reduced to produce metal uranium; metal uranium is melted at a temperature higher than 1150 °C; sintering is carried out at 1750 °C in a trace amount of hydrogen-nitrogen liquid phase medium until metal clusters are formed. Sintering in a liquid medium results in the desired porosity and pellet struct...

Embodiment 3

[0057] The nuclear fuel pellets of this embodiment are prepared according to the following conventional methods:

[0058] Under the action of mechanical stirring, add 0.5wt% 4-amino-1,2,4-triazole (abbreviated as triazole) to the uranium dioxide powder prepared by conventional method; Press sintering of pellets; during sintering, ammonium-containing triazole radical ions decompose to release hydrogen, which causes a reduction reaction of uranium dioxide in its surrounding area, resulting in the formation of metal clusters and substoichiometric combinations inside the pellets metal uranium melts at a temperature higher than 1150°C; sintering is carried out at 1750°C in a trace amount of hydrogen-nitrogen liquid phase medium until metal clusters are formed, and the result of sintering in liquid phase medium is to form the required Porosity and Pellet Structure. This kind of UO can be identified by X-ray photon spectrometer 2 The new structure of the core block and the addition...

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Abstract

The invention relates to nuclear physics, and specifically to reactor fuel elements and units thereof, and particularly to the composition of solid ceramic fuel elements based on uranium dioxide, intended for and exhibiting characteristics for being used in variously-purposed nuclear reactors. The result consists in a more reliable, special structure and a simple composition of uranium dioxide without heterogeneous fuel pellet additives, approaching the characteristics of a monocrystal having enhanced, and specifically exceeding reference data, thermal conductivity as temperature increases, and a simple production method thereof. The result is achieved in that pores of between 1 and 5 microns in size are distributed along the perimeters of grains in the micro-structure of each metal cluster in a nuclear fuel pellet, and in that located within the grains are pores which are predominantly nano-sized. In addition, the metal clusters comprise between 0.01 and 1.0 percent by mass. The invention provides for a method of preparing a nuclear fuel pellet, including precipitating metal hydroxides, in two stages, having different pH levels. Uranium metal is melted at a temperature exceeding 1150 DEG C, sintering is carried out in an insignificant amount of liquid phase at a temperature ranging between 1600 and 2200 DEG C in a hydrogen medium until forming uranium dioxide, the structure of which includes metal clusters dispersed therein. An X-ray photon spectroscope is used for identifying the new structure of the UO2 pellet and the additional U-U chemical bond.

Description

technical field [0001] The invention relates to the field of nuclear energy industry, in particular to nuclear fuel elements and units thereof, in particular to the composition of uranium dioxide-based solid ceramic fuel elements applicable to multipurpose reactors. Background technique [0002] Russian Patent No.2467411RU (published date: 2010 / 11 / 20) discloses a nanostructured nuclear fuel pellet (a specific embodiment), which is formed by pressing and sintering mixed powder of uranium compound particles and nano-diamond, and has a uniform effective size and density. In addition, the pellet can also be formed by pressing and sintering mixed powder of uranium-plutonium compound and nano-diamond. [0003] Although the above-mentioned nuclear fuel pellets have improved strength and heat resistance, thermal conductivity is low. Additionally, when at UO 2 or (U, Рu) О 2 When more than 1% of nano-diamonds are introduced into the fuel, the effective density of nuclear fuel wil...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G21C3/58
CPCG21C3/044G21C3/58G21C3/623G21C21/02G21C3/045Y02E30/30
Inventor 伊丽娜·塞米勇诺夫娜·库利纳加撤斯拉夫·凡斯里维奇·波波夫夫拉迪米尔·尼科拉维奇·鲁米雅塞夫阿莱克桑德·伊耿聂维奇·鲁桑诺夫斯德邦·塞格维奇·罗格夫塞德·米发索维奇·萨里克普罗夫
Owner JOINT CO AKME ENG
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