發(fā)布時(shí)間：2018-06-13 06:59

  本文選題：裝飾建筑材料 + 核素��； 參考：《四川大學(xué)》2003年博士論文

【摘要】： 如果使用天然放射性核素比活度增高的建筑材料，室內(nèi)空氣中劑量率就相應(yīng)升高。但目前對(duì)于建材的輻射劑量還缺乏較精確的定量表示，從一定程度上制約了建筑材料這種持續(xù)性低劑量照射對(duì)公眾健康影響的研究。 本研究對(duì)幾類建筑裝飾材料的輻射劑量學(xué)模式及其放射性核素限量進(jìn)行了研究，并找到一種可用于已建住房裝飾建筑材料放射性水平檢測(cè)判斷的檢測(cè)篩選方法。得到如下結(jié)論。 1．給出了各類裝飾建筑材料的輻射劑量模式 由于各種裝飾材料的厚度、密度和核素活度濃度都不一樣，它們的核素放射性比活度—空氣吸收劑量率轉(zhuǎn)換因子應(yīng)有很大差別；同時(shí)，土壤作為半無限大的體源，其空氣吸收劑量率轉(zhuǎn)換因子較裝飾材料這種有限大的體源要大得多。顯然，建筑裝飾材料不能近似采用室外土壤的轉(zhuǎn)換因子。要較準(zhǔn)確地反應(yīng)各類裝飾建材對(duì)室內(nèi)空氣吸收劑量率的貢獻(xiàn)，必須考慮各類材料本身的特性。本研究用蒙特卡羅方法的應(yīng)用程序EGSnrc計(jì)算出幾類飾材的核素比活度—室內(nèi)空氣吸收劑量轉(zhuǎn)換系數(shù)。得到各類飾材的Y外照射劑量學(xué)計(jì)算模式如下： 花崗石 (?)=0.0648C_(Ra)+0.0750C_(th)+0.0516C_K 拋光磚 (?)=0.0273C_(Ra)+0.0376C_(th)+0.0227C_K 彩釉磚 (?)=0.0190C_(Ra)+0.0215C_(th)+0.0171C_K 式中，(?)為空氣吸收劑量率，nGyh~(-1)；C_(Ra)、C_(th)、C_K分別為各類材料中~(226)Ra、 四川大學(xué)博士學(xué)位論文 ”勺h和氣的放射性比活度，Bqkg一，;式中的常數(shù)分別為各類材料中鞠系、腳h 系和，0K的核素放射性比活度一空氣吸收劑量率轉(zhuǎn)換因子(nGyh-l/Bqkg一，). 用該模式算出的空氣吸收劑量率與實(shí)測(cè)值一致。而用UNSCEAR(聯(lián)合國(guó)原 子輻射效應(yīng)科學(xué)委員會(huì))報(bào)告給出的土壤Y外照射劑量計(jì)算模式算出的裝飾材 料的空氣吸收劑量率與實(shí)測(cè)值相差很大。說明該模式更符合實(shí)際。 2.推導(dǎo)出各類裝飾建材的放射核素限t 由于裝飾材料不能使用土壤的劑量模式。同時(shí)，Ic即(國(guó)際放射防護(hù)委 員會(huì))和U王A(國(guó)際原子能機(jī)構(gòu))都已明確我國(guó)《放射衛(wèi)生防護(hù)基本標(biāo)準(zhǔn)》 GB 4792一1984對(duì)公眾的劑量限值不適用于天然放射性，而我們的國(guó)家標(biāo)準(zhǔn)仍使 用土壤的劑量轉(zhuǎn)換因子和公眾的年劑量限值來推導(dǎo)建筑材料的核素限量。顯 然，要較合理地限制裝飾材料對(duì)公眾的照射，必須使用裝飾材料本身的劑量模 式，以及可用于天然源的年劑量限值。本論文根據(jù)三類不同裝飾材料核素比活 度一空氣吸收劑量轉(zhuǎn)換因子，對(duì)花崗石和拋光磚使用ICRP第82號(hào)報(bào)告“在持 續(xù)照射情況下公眾的防護(hù)一委員會(huì)輻射防護(hù)體系應(yīng)用于由天然源和長(zhǎng)壽命放 射性殘存物引起的可控制的輻射照射”:用于單一源的輻射防護(hù)最優(yōu)化的年劑 量約束不大于每年0.3msv，對(duì)彩釉磚使用“含放射性物質(zhì)消費(fèi)品”的年有效 劑量限制O.05msv。得到各類裝飾材料的天然放射性核素限制式為: 花崗石: Y外照射限制:Cth/570+C、/660+C‘/830蕊1 內(nèi)照射限制:C、/200簇l 拋光磚: Y外照射限制:Cth/1140+C、/1570+Q/1890蕊1 內(nèi)照射限制:CRa/200續(xù)1 彩釉磚:Y外照射限制:Ctn/332 內(nèi)照射限制:釉面料中 +C、/375+ 2腸Ra的比活度 CK/417蕊1 C澎1000蕊1 雖然本論文推導(dǎo)Y外照射限制采用的年劑量限值較現(xiàn)行國(guó)家標(biāo)準(zhǔn)的小，本 論文給出的花崗石和拋光磚的外照射限制都較現(xiàn)行國(guó)家標(biāo)準(zhǔn)要寬，這是因?yàn)楸?四川大學(xué)博士學(xué)位論文 論文算出的這些飾材天然放射性核素比活度一空氣吸收劑t轉(zhuǎn)換因子要比現(xiàn)行 國(guó)家標(biāo)準(zhǔn)采用的土坡劑t轉(zhuǎn)換因子小得多。彩釉磚由于采用“含放射性物質(zhì)消 費(fèi)品”的附加年劑t限值，加上表層釉面的放射性水平較高，它的外照射限制 較現(xiàn)行國(guó)家標(biāo)準(zhǔn)要嚴(yán)格一些;內(nèi)照射限制也與現(xiàn)行國(guó)家標(biāo)準(zhǔn)完全不同。 3.建立起裝飾建材的無損檢測(cè)篩選方法并給出了結(jié)果判斷篩選值 根據(jù)核素衰變綱圖，對(duì)天然放射性核素均勻分布的材料來說，，幻勺h、226Ra、 氣的Y比活度就與單位質(zhì)t材料中的。、p輻射水平有固定的關(guān)系，這時(shí)，由 于單位質(zhì)盤材料中的Q、p輻射水平與其表面的。、p水平有確定的關(guān)系，而 表面。、p輻射水平可以在其表面無損側(cè)出。因此，只要通過上述關(guān)系，找到 比活度超限值時(shí)對(duì)應(yīng)的表面Q、p放射性水平，以后就可以通過測(cè)得的。、p 水平來判斷樣品的丫放射性是否超限值。這樣就將丫射線強(qiáng)度的測(cè)量問題轉(zhuǎn)化 為表面Q、B射線的強(qiáng)度測(cè)量問題，從而實(shí)現(xiàn)建材較準(zhǔn)確的無損檢測(cè)篩選。由 于天然放射系中最大能t的p射線在建筑裝飾材料中的最大射程大于單塊飾 材的厚度，在對(duì)已裝飾室內(nèi)測(cè)盆時(shí)，測(cè)得的p輻射水平還包括飾材下面主體建 材的貢獻(xiàn)，此時(shí)用測(cè)得的p輻射水平來判斷就會(huì)產(chǎn)生錯(cuò)誤。然而a粒子在材料 中的射程只有幾微米，因此可用材料的表面Q水平與國(guó)家標(biāo)準(zhǔn)內(nèi)、外照射指數(shù) 分類臨界值對(duì)應(yīng)的值，來進(jìn)行無損檢測(cè)篩選結(jié)果的判斷。由于用于表面Q輻射 水平側(cè)量的儀器(進(jìn)口僅萬元人民幣左右)相對(duì)高純鍺Y譜儀(進(jìn)口需要近六 十萬人民幣)來說便宜許多，而且攜帶方便，可用于現(xiàn)場(chǎng)檢測(cè);表面a水平也 不用像Y譜分析那樣
[Abstract]:If natural radionuclides are used for building materials with higher specific activity, the rate of indoor air dose increases correspondingly. However, there is a lack of precise quantitative expression for the radiation dose of building materials, which restricts the study of the health impact of building materials on public health to a certain extent.
In this study, the radiation dosimetry model and the radionuclide limit of several kinds of building decoration materials are studied, and a screening method which can be used to determine the radioactivity level of the built housing materials is found. The following conclusions are obtained.
1. the radiation dose pattern of all kinds of decorative building materials is given.
Because of the thickness, density and nuclide activity concentration of all kinds of decorative materials, their radionuclide radioactivity - air absorption dose rate conversion factor should be greatly different. At the same time, the soil as a semi infinite body source, its air absorption dose rate conversion factor is much larger than that of the limited bulk material such as ornamental material. In order to accurately reflect the contribution of all kinds of decorative materials to indoor air absorption rate, the characteristics of all kinds of materials must be considered more accurately. This study uses the Monte Carlo method EGSnrc to calculate the nuclide activity of several kinds of ornamental materials - indoor air absorbent. The Y external radiation dosimetric calculation models for all kinds of decorative materials are as follows:
Granite (?) =0.0648C_ (Ra) +0.0750C_ (th) +0.0516C_K
Polished brick (?) =0.0273C_ (Ra) +0.0376C_ (th) +0.0227C_K
Colored glazed tiles (?) =0.0190C_ (Ra) +0.0215C_ (th) +0.0171C_K
In the formula, the absorbed dose rate for air is nGyh~ (-1); C_ (Ra), C_ (th), C_K are ~ (226) Ra in all kinds of materials, respectively.
Doctoral Dissertation of Sichuan University
"Spoon h and the specific radioactivity of the gas, Bqkg 1, the constants in the formula are the bow and foot h of all kinds of materials, respectively.
The radionuclide specific activity of the system and 0K is an air absorbed dose rate conversion factor (nGyh-l/Bqkg 1).
The air absorbed dose rate calculated by this model is consistent with the measured value, while UNSCEAR (United Nations origin) is used.
The scientific report of the sub radiation effect Committee) the decorative material calculated from the Y external radiation dose calculation model of the report.
The air absorbed dose rate of the material is quite different from the measured value, which shows that the model is more practical.
2. deduce the radionuclide limit t of all kinds of decorative building materials
Because decorative materials can not use the dose pattern of soil. At the same time, Ic is the International Radiation Protection Committee.
The U and A of the International Atomic Energy Agency (IAEA) have clearly defined the basic standards for radiological protection in China.
GB 4792 1984 to the public dose limit does not apply to natural radioactivity, and our national standard still makes
The nuclide limit of building materials is derived from the dose conversion factor of the soil and the annual dose limit of the public.
However, to reasonably restrict the exposure of decorative materials to the public, we must use the dose pattern of decorative materials themselves.
And the annual dose limits for natural sources. According to three types of decorative materials, nuclide specific activity
Degree 1 air absorption dose conversion factor for granite and polished tiles using ICRP eighty-second report "hold"
Public protection under continuous exposure. A committee's radiation protection system is applied to natural sources and long-life releases.
Controlled radiation exposure caused by ejection residues: an annual optimization for single source radiation protection
The quantity constraint is not greater than 0.3msv per year, which is effective for the use of "radioactive consumer goods" in coloured glazed tiles.
The natural radionuclide restrictive formula for various decorative materials is O.05msv..
Granite:
Y external exposure limit: Cth/570+C, /660+C '/830 pistil 1
Internal radiation restriction: C, /200 cluster L
Polishing brick:
Y external exposure limit: Cth/1140+C, /1570+Q/1890 pistil 1
Internal radiation restriction: CRa/200 continued 1
Colored glaze brick: Y external irradiation limit: Ctn/332
Internal radiation restriction: Glazed fabric
+C, /375+
Specific activity of 2 intestinal Ra
CK/417 pistil 1
C 1000 stamens 1
Although this paper deduces the annual dose limit of Y external exposure limitation, it is smaller than the current national standard.
The limits of external exposure of granite and polished tiles are wider than those of existing national standards.
Doctoral Dissertation of Sichuan University
The specific activity of these natural radionuclides calculated by the paper is more than that of the air absorbent t conversion factor.
The conversion factor of soil slope agent t used in the national standard is much smaller.
The limit of T added to the product is higher than that of the surface glaze, and its external exposure limits.
It is more stringent than the current national standards, and the internal exposure limits are totally different from the existing national standards.
3. establish a nondestructive testing and screening method for decorative building materials and give the results to determine the screening value.
According to the diagram of radionuclide decay, the magic h, 226Ra, for natural materials with uniform radionuclide distribution,
The Y specific activity of the gas has a fixed relationship with the radiation level of T in the unit P material.
The level of Q and P radiation in the unit material is determined by its surface and P levels.
On the surface, the radiation level of P can be lossless on its surface. Therefore, as long as the above relations are found,
When the specific activity exceeds the limit, the corresponding surface Q and P radioactivity levels will be measured later, P.
In order to judge whether the sample's sub radioactivity is out of limit, the problem of measuring the intensity of the gamma ray is transformed.
For the surface Q, B ray intensity measurement problems, so as to achieve accurate NDT screening of building materials.
In natural radiation, the maximum range of T P ray in building decoration materials is larger than that of single piece.
The thickness of the material is measured in the decorated room, and the measured P radiation level also includes the main building below the decorating material.
The contribution of the material will be erroneous at this time by using the measured P radiation level. However, a particles are in the material.
The range is only a few microns, so the surface Q level of the material can be applied to the national standard and the external exposure index.
The values corresponding to the classification of critical values are used for non-destructive testing of the screening results. As for surface Q radiation
The horizontal lateral volume instrument (imported only around 10000 yuan) is relative to the high purity germanium Y spectrometer (import needs nearly six).
One hundred thousand yuan) is much cheaper, and is easy to carry and can be used for on-site testing. The surface a level is also very low.
Not like Y spectrum analysis
【學(xué)位授予單位】：四川大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2003
【分類號(hào)】：X837

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