阅读说明：本技术 一种用于堆芯捕集器的牺牲混凝土及其制备方法 (Sacrificial concrete for reactor core catcher and preparation method thereof ) 是由 褚洪岩 蒋金洋 王凤娟 高李 秦健健 史文芳 王群 于 2021-09-23 设计创作，主要内容包括：本发明公开一种用于堆芯捕集器的牺牲混凝土及其制备方法,该牺牲混凝土的主要组成为：水泥575∽625份、石英砂1200∽1300份、赤铁矿石700∽800份、水200∽220份、减水剂7∽10份、氧化锶0∽10份。本发明制备工艺简单,采用常规的搅拌技术即可制备出流动性、强度、耐高温性能优良的牺牲混凝土。本发明制备的牺牲混凝土能够减小放射性物质～(89)Sr和～(90)Sr的释放量,从而能够提高严重事故情况下核电站的安全性。本发明制备的牺牲混凝土不仅可以用于目前第三代核电站的堆芯捕集器中,还可以用于未来第四代核电站的堆芯捕集器中,具有广泛的工程应用价值。(The invention discloses a sacrificial concrete for a reactor core catcher and a preparation method thereof, and the sacrificial concrete mainly comprises the following components: cement 575-625, quartz sand 1200-1300, hematite 700-800, water 200-220, water-reducing agent 7-10 and strontium oxide 0-10. The preparation process is simple, and the sacrificial concrete with excellent flowability, strength and high temperature resistance can be prepared by adopting the conventional stirring technology. The sacrificial concrete prepared by the invention can reduce radioactive substances 89 Sr and 90 sr is released, thereby enabling to improve the safety of the nuclear power plant in case of a severe accident. The sacrificial concrete prepared by the invention can be used in the reactor core catcher of the third-generation nuclear power station at present and the reactor core catcher of the fourth-generation nuclear power station in the future, and has wide engineering application value.)

1. The sacrificial concrete for the reactor core catcher is characterized by mainly comprising the following raw materials in parts by weight: cement 575-625, quartz sand 1200-1300, hematite 700-800, water 200-220, water-reducing agent 7-10 and strontium oxide 0-10;

the water is tap water or drinking water, and meets the requirements of concrete water standards (JGJ 63-2006);

the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, the appearance is colorless to light yellow, the density is 1.05-1.15 g/ml, the solid content is more than or equal to 40 percent by mass fraction, the pH value is 4 +/-2, and the water reducing rate is more than or equal to 30 percent;

the preparation method comprises the following steps:

(1) uniformly mixing cement, quartz sand and strontium oxide to obtain a mixed material M1;

(2) adding hematite into the mixed material M1, and stirring to obtain a uniformly mixed material M2;

(3) and adding a mixed solution of water and a water reducing agent into the uniformly mixed material M2, stirring to obtain a uniformly mixed material M3, and then carrying out molding maintenance to obtain the sacrificial concrete for the reactor core catcher.

2. The sacrificial concrete for core catcher as claimed in claim 1, wherein said cementIs aluminate cement, Al thereof₂O₃75% or more of SiO₂The content is less than or equal to 0.5 percent.

3. The sacrificial concrete for core catcher as claimed in claim 1, wherein the silica sand is high quality silica powder of SiO thereof₂The content is more than or equal to 99 percent, and the particle size is 0 mm-5 mm.

4. The sacrificial concrete for a core catcher as claimed in claim 1, wherein the hematite ore is a high quality hematite ore of Fe₂O₃The content is more than or equal to 92%, and the grain diameter is 5 mm-8 mm.

5. The sacrificial concrete for a core catcher as claimed in claim 1, wherein the strontium oxide is in the form of powder having a SrO content of 95% or more.

6. The method for preparing sacrificial concrete for a core catcher as claimed in claim 1, wherein: adding cement, quartz sand and strontium oxide into the forced single-horizontal-shaft concrete mixer in the step (1), and selecting the mixing speed of 40-50 r/min and the mixing time of 5-8 min to obtain a mixed material M1; in the step (2), the hematite is added into the mixed material M1 for 6-8 minutes to obtain mixed material M2; in the step (3), firstly, half of water is mixed with all the water reducing agents, the mixture is uniformly stirred, then the uniformly mixed solution is added into the mixed material 2, then the other half of water is used for cleaning the container for containing the water reducing agents, the water is added into the mixed material M2 after cleaning, the mixing time is 8-12 minutes, and then the sacrificial concrete can be obtained through molding and maintenance.

Technical Field

The invention relates to a nuclear power material, in particular to sacrificial concrete for a reactor core catcher and a preparation method of the material.

Background

In modern nuclear power engineering, the reactor core catcher can provide an additional protective barrier for a nuclear power station, so that the safety of the nuclear power station is improved. In the event of a severe nuclear accident, the in-vessel core catcher is primarily used to receive, localize and cool the core melt. Sacrificial concrete is a major component of core catcher, a material that plays an important role in the cooling and localization of core melt. Although a certain amount of literature discloses sacrificial concrete preparation technology at home and abroad at present, the sacrificial concrete prepared by the prior art has the problem of poor high-temperature resistance. Under the condition of serious nuclear power accidents, the temperature of the molten material in the reactor core can reach more than 3000 ℃, so the temperature of the use environment of the sacrificial concrete is very high. If the high temperature resistance of the sacrificial concrete is poor, the residual compressive strength of the sacrificial concrete is reduced under the action of high temperature, and the service life of the sacrificial concrete is shortened. In addition, the poor high temperature resistance of the sacrificial concrete can also lead to the increase of the internal porosity, and further lead to the high erosion rate thereof, thereby leading to the increase of the risk of radioactive substance leakage under the severe nuclear power accident condition.

Disclosure of Invention

The purpose of the invention is as follows: in order to overcome the disadvantages of the prior art, the present invention provides a sacrificial concrete for a core catcher and a method for preparing the same.

The technical scheme is as follows: in order to achieve the purpose, the invention discloses sacrificial concrete for a reactor core catcher and a preparation method thereof, wherein the sacrificial concrete is mainly prepared from the following raw materials in parts by weight:

cementFractional mixing quartz sandHematite oreWater and waterWater reducing agentStrontium oxideAnd (4) portions are obtained.

The cement is aluminate cement and Al thereof₂O₃75% or more of SiO₂The content is less than or equal to 0.5 percent.

The quartz sand is high-quality quartz powder, SiO thereof₂The content is more than or equal to 99 percent, and the particle diameter is

The hematite ore is high-quality hematite ore, and Fe thereof₂O₃The content is more than or equal to 92 percent, and the grain diameter is

The water is tap water or drinking water, and meets the requirements of concrete water standards (JGJ 63-2006).

The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, the appearance is colorless to light yellow, and the density isThe solid content is more than or equal to 40 percent, the pH value is 4 +/-2, and the water reducing rate is more than or equal to 30 percent.

The strontium oxide is powdery, and the SrO content of the strontium oxide is more than or equal to 95 percent.

The preparation method of the sacrificial concrete for the reactor core catcher comprises the following steps:

(1) uniformly mixing cement, quartz sand and strontium oxide to obtain a mixed material M1;

(2) adding hematite into the mixed material M1, and stirring to obtain a uniformly mixed material M2;

(3) and adding a mixed solution of water and a water reducing agent into the uniformly mixed material M2, stirring to obtain a uniformly mixed material M3, and then carrying out molding maintenance to obtain the sacrificial concrete for the reactor core catcher.

In the step (1), cement, quartz sand and strontium oxide are added into a forced single horizontal shaft concrete mixer, and the mixing speed is selected to beRpm, mixing time ofObtaining a mixed material M1 after minutes;

in the step (2), hematite is added into the mixed material M1 for mixing timeObtaining a mixed material M2 after minutes;

in the step (3), firstly, half of water is mixed with all the water reducing agents and stirred uniformly, then the uniformly mixed solution is added into the mixed material 2, then the other half of water is used for cleaning the container for containing the water reducing agents, and then the water is added into the mixed material M2 after cleaning, wherein the mixing time is set asAnd after that, the sacrificial concrete can be obtained by forming and curing.

Compared with the prior art, the sacrificial concrete for the reactor core catcher has good working performance, the expansion degree is more than 560mm, and the flowability requirement of self-compacting concrete is met; the compressive strength of the material is more than 40MPa, which is improved by more than 33% compared with 30MPa required by the prior art, the durability of the material can be obviously improved, and the service life of the material is prolonged; it has a relative residual compressive strength of 30% or more at 1000 deg.CCompared with the prior art, the high-temperature-resistant composite material is improved by more than 10%, and the high-temperature-resistant performance is greatly improved. Furthermore, the technique enables the reduction of radioactive substances in severe accident situations, compared to the prior art⁸⁹Sr and⁹⁰the amount of Sr released.

The technical effects are as follows: the preparation process is simple, and the sacrificial concrete with excellent flowability, strength and high temperature resistance can be prepared by adopting the conventional stirring technology. The sacrificial concrete for the reactor core catcher has excellent working performance and is convenient for engineering construction; the relative residual compressive strength of the sacrificial concrete is greatly improved, and the high-temperature resistance of the sacrificial concrete is obviously improved. SrO doped in the sacrificial concrete can reduce radioactive substances in the case of serious accidents⁸⁹Sr and⁹⁰the amount of Sr released. The sacrificial concrete prepared by the invention can be used in the reactor core catcher of the third-generation nuclear power station at present and the reactor core catcher of the fourth-generation nuclear power station in the future, and has wide engineering application value.

Detailed Description

The present invention is further illustrated by the following specific examples, which are intended to be purely exemplary of the invention and are not intended to limit its scope, as various equivalent modifications of the invention will become apparent to those skilled in the art after reading the present invention and fall within the scope of the appended claims. In addition, the experimental results of the examples are also compared, and the advantages of the invention are emphasized.

The raw materials used in the examples meet the following requirements:

the cement is CA80 aluminate cement and Al thereof₂O₃77.8% of SiO₂The content is 0.37%.

The quartz sand is high-quality quartz powder, SiO thereof₂99.3% in content and having a particle diameter of

Hematite ore is a high-quality hematite ore, the Fe of which₂O₃The content is 94.1%, and the particle diameter is

The water is tap water.

The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, is light yellow in appearance, has the density of 1.10g/ml, and has the solid content of 45.5 percent, the pH value of 5 and the water reducing rate of 33.5 percent in mass fraction.

The strontium oxide was in the form of powder and had a SrO content of 96.4%.

Example 1

The sacrificial concrete for the reactor core catcher comprises the following components in parts by weight:

600 parts of cement, 1250 parts of quartz sand, 750 parts of hematite, 210 parts of water, 8 parts of a water reducing agent and 0 part of strontium oxide.

The preparation method comprises the following steps:

(1) weighing required materials including cement, quartz sand, hematite, water, a water reducing agent and strontium oxide;

(2) wetting the stirrer and all the tools and moulds to be used;

(3) sequentially adding the weighed cement, quartz sand and strontium oxide into a forced single-horizontal-shaft concrete mixer, selecting the mixing speed of 45 revolutions per minute, mixing for 6 minutes, and uniformly mixing to obtain a mixed material M1;

(4) adding hematite into the mixed material M1 in the step (3), mixing for 7 minutes, and uniformly stirring to obtain a mixed material M2;

(5) firstly, mixing half of water with all the water reducing agents, uniformly stirring, then adding the uniformly mixed solution into the mixed material M2, then cleaning the water reducing agent containing container by using the other half of water, then adding the water into the mixed material M2 after cleaning, mixing for 10 minutes, and then carrying out forming maintenance to obtain the sacrificial concrete.

Example 2

The sacrificial concrete for the reactor core catcher comprises the following components in parts by weight:

595 parts of cement, 1250 parts of quartz sand, 750 parts of hematite, 210 parts of water, 8 parts of a water reducing agent and 5 parts of strontium oxide.

The preparation method comprises the following steps:

(1) weighing required materials including cement, quartz sand, hematite, water, a water reducing agent and strontium oxide;

(2) wetting the stirrer and all the tools and moulds to be used;

(3) sequentially adding the weighed cement, quartz sand and strontium oxide into a forced single-horizontal-shaft concrete mixer, selecting the mixing speed of 45 revolutions per minute, mixing for 6 minutes, and uniformly mixing to obtain a mixed material M1;

(4) adding hematite into the mixed material M1 in the step (3), mixing for 7 minutes, and uniformly stirring to obtain a mixed material M2;

(5) firstly, mixing half of water with all the water reducing agents, uniformly stirring, then adding the uniformly mixed solution into the mixed material M2, then cleaning the water reducing agent containing container by using the other half of water, then adding the water into the mixed material M2 after cleaning, mixing for 10 minutes, and then carrying out forming maintenance to obtain the sacrificial concrete.

Example 3

The sacrificial concrete for the reactor core catcher comprises the following components in parts by weight:

590 parts of cement, 1250 parts of quartz sand, 750 parts of hematite, 210 parts of water, 8 parts of a water reducing agent and 10 parts of strontium oxide.

The preparation method comprises the following steps:

(1) weighing required materials including cement, quartz sand, hematite, water, a water reducing agent and strontium oxide;

(2) wetting the stirrer and all the tools and moulds to be used;

(3) sequentially adding the weighed cement, quartz sand and strontium oxide into a forced single-horizontal-shaft concrete mixer, selecting the mixing speed of 45 revolutions per minute, mixing for 6 minutes, and uniformly mixing to obtain a mixed material M1;

(4) adding hematite into the mixed material M1 in the step (3), mixing for 7 minutes, and uniformly stirring to obtain a mixed material M2;

(5) firstly, mixing half of water with all the water reducing agents, uniformly stirring, then adding the uniformly mixed solution into the mixed material M2, then cleaning the water reducing agent containing container by using the other half of water, then adding the water into the mixed material M2 after cleaning, mixing for 10 minutes, and then carrying out forming maintenance to obtain the sacrificial concrete.

The preparation processes of the above 3 examples are completely the same, except that the cement 600 parts and the strontium oxide 0 parts are used in example 1, the cement 595 parts and the strontium oxide 5 parts are used in example 2, the cement 590 parts and the strontium oxide 10 parts are used in example 3, the sum of the cement and the strontium oxide in the three examples is 600 parts, and the strontium oxide content is increased in sequence.

Performance detection

The working performance of the sacrificial concrete in the embodiment is measured according to the national standard GB/T14902-. Measuring 28-day compressive strength of the sacrificial concrete according to the national standard GB/T50107-2010, heating a sacrificial concrete test piece cured for 28 days by using a muffle furnace, setting the heating rate to be 5 ℃/min, keeping the temperature of the sacrificial concrete test piece constant for two hours at the high temperature of 1000 ℃ after the temperature is raised to 1000 ℃, cooling the sacrificial concrete test piece in the muffle furnace, and measuring the compressive strength of the sacrificial concrete test piece after the temperature is cooled to the room temperature. The relative compressive strength of a sacrificial concrete is the ratio of its compressive strength at 1000 c to its compressive strength at room temperature. Measuring the enthalpy change of the sacrificial concrete according to thermogravimetric comprehensive analysis, measuring the decomposition temperature of the sacrificial concrete according to a high-temperature experiment, and combining the two experiments to obtain the decomposition enthalpy change of the sacrificial concrete. The experimental results of this example are shown in table 1 below.

TABLE 1 measurement results

As can be seen from table 1 above, the expansion degree of the sacrificial concrete in the embodiment is greater than 560mm, which satisfies the requirement of the working performance of the self-compacting concrete. In the embodiment, the minimum value of the 28-day compressive strength of the sacrificial concrete is 40.3MPa, which is 34.3% higher than the 30MPa required by the prior art, which shows that the durability of the sacrificial concrete is improved, so that the service life of the sacrificial concrete can be prolonged. In the embodiment, the relative residual compressive strength of the sacrificial concrete is over 30 percent, and is improved by over 10 percent compared with the prior art, which shows that the high-temperature resistance of the sacrificial concrete is greatly improved. In the embodiment, the decomposition enthalpy of the sacrificial concrete is higher than that of the prior art, which shows that the fusion rate of the sacrificial concrete is lower than that of the prior art, so that the safety of a nuclear power station can be improved.

As to the incorporation of SrO in sacrificial concrete for radioactive substances in gas in severe accident situations⁸⁹Sr and⁹⁰the influence of Sr, because this experiment has the characteristics of ultra-high temperature and ultra-high radiation, prototype experimental study can not be carried out at present. However, according to the results of the numerical simulation experiment, the radioactive materials in examples 2 and 3 were compared with those in example 1⁸⁹Sr and⁹⁰the Sr release amount is reduced by 10 percent and more than 18 percent in sequence, which indicates that the technology can reduce radioactive substances⁸⁹Sr and⁹⁰sr releases the amount, thereby improving the safety of the nuclear power station in the case of a serious accident.

Although the expansion degree, 28-day compressive strength, relative residual compressive strength and decomposition enthalpy of the sacrificial concrete are slightly reduced along with the increase of the doping amount of the strontium oxide, all parameters of the sacrificial concrete prepared by the technology are still greatly improved compared with the prior art. In addition, with the increase of the doping amount of the strontium oxide, radioactive substances can be enabled⁸⁹Sr and⁹⁰the Sr release amount is gradually reduced, so that the safety of the nuclear power plant in the case of a severe accident can be improved. It can be seen from the results of the examples that the technology has substantial progress.

In addition, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention. If modifications or equivalents are made to the technical examples of the present invention by those of ordinary skill in the art without departing from the spirit of the present invention, the scope of the present invention is defined by the claims.

The reason why the decomposition enthalpy change of the sacrificial concrete increases, resulting in a decrease in the erosion rate thereof, is explained below:

according to the theory of heat transfer, the relationship between the erosion rate of sacrificial concrete and the heat flux transferred to its interior is shown by the following equation:

V＝Q/(ρ×A×ΔH) (1)

in the above formula, V is the erosion rate of the sacrificial concrete, Q is the heat flux transferred to the inside of the sacrificial concrete, a is the erosion area of the sacrificial concrete, and Δ H is the decomposition enthalpy change of the sacrificial concrete.

As can be seen from the above formula (1), the erosion rate of sacrificial concrete is inversely proportional to its enthalpy change of decomposition. This indicates that: as the enthalpy change of decomposition of the sacrificial concrete increases, the erosion rate of the sacrificial concrete is caused to decrease.