CN104407371B - In a kind of liquid lead bismuth alloy210The rapid detection system and method for Po concentration - Google Patents

Abstract

The present invention relates in liquid lead bismuth alloy²¹⁰The rapid detection system and method for Po concentration, by measurement²¹⁰The Characteristic γ ray that Po decays are produced, in quantitative analysis liquid lead bismuth alloy²¹⁰Po contents.The positive effect of the present invention is：Propose that a kind of principle is simple, manipulation type is strong²¹⁰Po concentration analysis detecting system and method, it is adaptable to which liquid lead bismuth alloy is in the fast reactor primary Ioops cooling agent of cooling agent²¹⁰The quick detection of Po concentration.

Description

In a kind of liquid lead bismuth alloy210The rapid detection system and method for Po concentration

Technical field

The present invention relates to a kind of analysis detecting system and method, by gamma-rays energy spectrum analysis, realize liquid lead bismuth alloy In²¹⁰The quick detection of Po concentration.

Background technology

In fast neutron reactor of the liquid lead bismuth alloy for cooling agent, neutron irradiation bismuth can be produced²¹⁰Po, due to²¹⁰Po With extremely toxic property, in reactor operation or retired period, need in reactor pressure vessel and primary Ioops²¹⁰Po is carried Separation is taken, is thus produced in liquid lead bismuth alloy²¹⁰The analysis detection demand of Po.

²¹⁰There is Po very strong α to radiate, and the half-life is 138.3 days.²¹⁰The traditional analysis detection method of Po include calorimetry, Alpha energy spectrum or α counting methods.Calorimetry is suitable for small volume but the big sample of heat release amount, in sample²¹⁰The radioactive activity of Po needs Curie's level is reached, reasonable certainty of measurement could be obtained, and as the time for reaching stable thermal equilibrium is longer, calorimetry is surveyed Amount²¹⁰Po can not meet the detection requirement of quick analysis.The sensitivity of alpha energy spectrum or the measurement of α counting methods is very high, but²¹⁰Po partly declines Phase is shorter, and specific activity is larger, therefore alpha energy spectrum or α counting methods are commonly used to measure²¹⁰The extremely low sample of Po contents.And α particles Penetration capacity it is weak, can not block between testing sample and detector probe, it is necessary to carry out the measurement of closely open type, therefore Alpha energy spectrum or α counting methods are surveyed²¹⁰Po there is also the problem of detector easily pollution.

The content of the invention

It is an object of the invention to：Overcome the deficiencies in the prior art, there is provided in a kind of liquid lead bismuth alloy²¹⁰Po concentration Rapid detection system and method, in realizing liquid lead bismuth alloy²¹⁰The quick detection of Po concentration.

The technology of the present invention solution：

1st, in a kind of liquid lead bismuth alloy²¹⁰The rapid detection system of Po concentration, its system features are to include：Sample tap, Press, gamma detector, corresponding electronics equipment, data handling system；Entered using press after the sample cooling that sample tap is obtained Row compacting, the thin slice after compacting are detected before being arranged on detector, and detectable signal is through corresponding electronics equipment and data Processing system process, is obtained in liquid lead bismuth alloy by analytical calculation²¹⁰Po concentration.

2nd, in a kind of liquid lead bismuth alloy²¹⁰The method for quick of Po concentration, its method characteristic are to include following step Suddenly：

(1) sample a certain amount of liquid lead bismuth alloy and solidify its natural cooling；

(2) the solid lead bismuth alloy after solidification is pressed into the uniform sheet of certain thickness and size with press；

(3) solid lead bismuth alloy thin slice is arranged on before gamma detector probe；

(4) in gamma detector detection solid lead bismuth alloy thin slice²¹⁰The Characteristic γ ray of Po transmittings；

(5) detectable signal is obtained after electronics equipment and data handling system carry out signal transacting and data processing Gamma intensity；

(6) calculate analysis to obtain in liquid lead bismuth alloy²¹⁰Po contents.

The sampling amount of step (1) the liquid lead bismuth alloy is 5g～10g；

The solid lead bismuth alloy sheet thickness that the step (2) is suppressed is 0.5mm；

The installation of the step (3) makes the side and sample room of the non-detection window of gamma detector be surrounded by lead screen layer, Reduce gamma-rays background；

What the step (4) measured²¹⁰The energy of Po Characteristic γ rays is 803.1keV.

Present invention advantage compared with prior art is：

(1)²¹⁰The gamma activity branching ratio of Po is very low, only about ten a ten thousandths, therefore²¹⁰The gamma-ray measurement of Po is usually It is ignored.In lead bismuth fast reactor primary Ioops coolant media, with high relative contents²¹⁰Po concentration so that by measuring feature Gamma intensity determines²¹⁰Po concentration is possibly realized.Liquid lead bismuth alloy has temperature height, density is big, thermal conductivity is good, fusing point is low The characteristics of, in direct measurement liquid lead bismuth alloy²¹⁰The Characteristic γ ray intensity of Po, needs to design heating and thermal insulation layer in sample room Liquid lead bismuth alloy temperature is maintained, and semi-conductor type gamma detector is particularly with gamma detector needs low temperature environment contradiction, and sample Product room limited space needs additional shielding, also so that in direct measurement liquid lead bismuth alloy²¹⁰The Characteristic γ ray intensity of Po is stranded It is difficult.In addition liquid lead bismuth alloy viscosity is big, easily stains shuttle and forms fixed background.

For this purpose, present invention employs after the cooling of liquid lead bismuth alloy, certain thickness Solid Lead bismuth is pressed into press Alloy sheet, by detecting what is launched in solid-state lead bismuth alloy thin slice²¹⁰Po Characteristic γ ray intensity, obtains solid-state lead bismuth alloy In²¹⁰Po concentration.A kind of benefit of measurement solid-state lead bismuth alloy thin slice be not easy to stain sample room and instrument formed it is fixed this Bottom, and solid-state lead bismuth alloy hardness it is low so that compacting solid lead bismuth alloy thin slice be easily achieved, compacting flakiness can reduce Lead bismuth alloy improves certainty of measurement to gamma-ray self-absorption.

(2) as calorimetry, alpha energy spectrum or α counting methods are surveyed²¹⁰The limitation of Po, one kind of the present invention are closed for liquid lead bismuth Jin Zhong²¹⁰The system and method that Po concentration quickly analyzes detection, by rational sample pre-treatments technological design, and are visited using γ Survey device measurement²¹⁰The Characteristic γ ray that Po decays are produced, in realizing liquid lead bismuth alloy²¹⁰The quick detection of Po.

(3) principle of the invention is simple；Analysis process is short, analyze speed is fast, and analysis precision is high；Suitable for lead bismuth fast reactor one time In the coolant media of road²¹⁰The quick detection of Po concentration, is also applied for the ADS system (accelerators that liquid lead bismuth alloy is cooling agent Drive subcritical system) in primary Ioops coolant media²¹⁰The quick detection of Po concentration.

Description of the drawings

Flowcharts of the Fig. 1 for the composition frame chart and the inventive method of present system.

Specific embodiment

As shown in figure 1, present system contains following part：

(1) sample tap, sample tap are acquisition primary sample；

(2) press, carries out compression process to primary sample after cooling；

(3) gamma detector, for detecting gamma-rays；

(4) electronics equipment, for being pre-processed to detectable signal and being processed；

(5) data handling system, for obtaining data and processing data, obtains gamma intensity.

As shown in figure 1, the present invention realizes that flow process is as follows：

(1) sample a certain amount of liquid lead bismuth alloy and solidify its natural cooling；

(2) the solid lead bismuth alloy after solidification is pressed into the uniform sheet of certain thickness and size with press；

(3) solid lead bismuth alloy thin slice is arranged on before gamma detector probe；

(4) in gamma detector detection solid lead bismuth alloy thin slice²¹⁰The Characteristic γ ray of Po transmittings；

(5) detectable signal is obtained after electronics equipment and data handling system carry out signal transacting and data processing Gamma intensity；

(6) calculate analysis to obtain in liquid lead bismuth alloy²¹⁰Po contents.

Embodiment 1：The specific embodiment citing of the present invention given below.

(1) energy calibration and efficiency calibration are carried out to gamma detector using standard gamma source, is obtained near 803.1keV, detector Efficiency is 9.6%；

(2) a small amount of liquid lead bismuth alloy is taken on stainless steel metal plate from liquid lead bismuth alloy vessel, treat which is naturally cold But solidify, its quality is called 8.2g；

(3) the solid lead bismuth alloy after solidification is pressed into the uniform sheet of 0.5mm thickness with press, 0.5mm thickness Thin slice can ensure that²¹⁰The Characteristic γ ray of Po transmittings is fully penetrated；

(4) solid lead bismuth alloy thin slice is popped one's head in installed in gamma detector；

(5) gamma spectrum measures the gamma intensity of 803.1keV in solid lead bismuth alloy thin slice, detects gamma-rays within 600 seconds Count 1126；

(6) it is calculated in liquid lead bismuth alloy²¹⁰Po contents, computing formula are as follows：

In formula,

A(²¹⁰Po) --- in sample²¹⁰The mass percent of Po, dimension are 1；

I (γ) --- gamma-ray counting is detected, dimension is 1；

T(BR)——²¹⁰The gamma activity branching ratio of Po, dimension is 1；

ε (γ) --- gamma detector used has considered space exploration efficiency and detection to gamma-ray detection efficient The intrinsic detection efficient of device, dimension is 1；

T --- detection time, dimension are the second (s)；

λ --- decay coefficient, represents one²¹⁰There is the probability for decaying in Po within the unit interval, dimension is s^-1；

M --- molal weight, refers to the amount of unit material²¹⁰The quality that Po has, dimension are gmol^-1；

NA --- avogado constant (Avogadro's constant, symbol：NA), refer to 0.012 kilogram¹²Include in C 's¹²The atomic quantity of C, takes 6.023 × 10 during general calculating²³, dimension is mol^-1；

M --- liquid lead bismuth alloy sampling quality, dimension are gram (g).

By t=600s, I (γ)=1126, T (BR)=1.1*10^-5, ε (γ)=9.6%, λ=5.8*10^-8s^-1, M= 210g·mol^-1, NA=6.023 × 10²³mol^-1, m=8.2g brings above-mentioned computing formula into, obtains in sample²¹⁰The quality percentage of Po Than A (²¹⁰Po it is) 1.3*10^-7%.

Embodiment 2：The precision estimation that the present invention given below is applied in lead bismuth fast reactor primary Ioops coolant media.

(1) after the stable operation of lead bismuth fast reactor in primary Ioops coolant media²¹⁰The gross activity activity of Po is for about 10¹⁴Bq is (no With the lead bismuth fast reactor of netron-flux density and scale, there is some difference)；

(2) about 1000 tons of lead bismuth fast reactor liquid lead bismuth alloy cooling agent loading amount, is given according to step 1²¹⁰Po gross activities Activity, in liquid lead bismuth alloy²¹⁰The mean radio concentration about 10 of Po⁵Bq/g；

(3) sample volume is calculated according to 10g,²¹⁰The branching ratio of Po gamma decays is ten a ten thousandths, estimates to obtain 10g liquid Lead bismuth alloy 10 photons of average transmitting per second；

(4) by taking NaI crystal-type gamma ray probes as an example, the detection efficient of gamma detector is considering three-dimensional effect and intrinsic conversion efficiency Afterwards, according to 10% estimation；

(5) sample is measured 10 minutes, about 600 countings, the statistical error about 4% of measurement count can be obtained.

Claims (2)

1. in a kind of liquid lead bismuth alloy²¹⁰The rapid detection system of Po concentration, it is characterised in that include：Sample tap, press, γ Detector, corresponding electronics equipment, data handling system；Suppressed using press after the sample cooling that sample tap is obtained, Thin slice after compacting is detected before being arranged on detector, and detectable signal is through corresponding electronics equipment and data handling system Process, obtained in liquid lead bismuth alloy by analytical calculation²¹⁰Po concentration.

2. in the liquid lead bismuth alloy of detecting system described in a kind of employing claim 1²¹⁰The method for quick of Po concentration, its It is characterised by comprising the following steps：

(1) sample a certain amount of liquid lead bismuth alloy and solidify its natural cooling；

(2) the solid lead bismuth alloy after solidification is pressed into the uniform sheet of certain thickness and size with press；

(3) solid lead bismuth alloy thin slice is arranged on before gamma detector probe；

(4) in gamma detector detection solid lead bismuth alloy thin slice²¹⁰The Characteristic γ ray of Po transmittings；

(5) detectable signal after electronics equipment and data handling system carry out signal transacting and data processing obtains γ and penetrates Line strength；

(6) calculate analysis to obtain in liquid lead bismuth alloy²¹⁰Po contents；

The sampling amount of step (1) the liquid lead bismuth alloy is 5g～10g；

The solid lead bismuth alloy sheet thickness that the step (2) is suppressed is 0.5mm；

The installation of the step (3) makes the side and sample room of the non-detection window of gamma detector be surrounded by lead screen layer；

What the step (4) measured²¹⁰The energy of Po Characteristic γ rays is 803.1keV；

The step (6) calculates the formula of analysis：

$A\left(P_{210}o\right)=\frac{I\left(\mathrm{\γ}\right)}{T\left(BR\right)*\mathrm{\ϵ}\left(\mathrm{\γ}\right)}*\frac{1}{t}*\frac{M}{\mathrm{\λ}*NA}*\frac{1}{m};$

In the computing formula,

A(²¹⁰Po) --- in sample²¹⁰The mass percent of Po, dimension are 1；

I (γ) --- gamma-ray counting is detected, dimension is 1；

T(BR)——²¹⁰The gamma activity branching ratio of Po, dimension is 1；

ε (γ) --- gamma detector used has considered space exploration efficiency and detector to gamma-ray detection efficient Intrinsic detection efficient, dimension are 1；

T --- detection time, dimension are the second (s)；

λ --- decay coefficient, represents one²¹⁰There is the probability for decaying in Po within the unit interval, dimension is s^-1；

M --- molal weight, refers to the amount of unit material²¹⁰The quality that Po has, dimension are gmol^-1；

NA --- avogado constant, dimension are mol^-1；

M --- liquid lead bismuth alloy sampling quality, dimension are gram (g).