CN104614753A - Medium surface radon exhalation rate continuous measurement method and apparatus - Google Patents

Abstract

The invention discloses a medium surface radon exhalation rate continuous measurement method and apparatus. The method includes the steps of Step 1 measuring the initial radon concentration C0; Step 2 calculating the medium surface radon exhalation rate; determining A, B and the equivalent decay constant lambda e through the following method: the relationship of radon concentration in a radon collection shield at the n and n-1 measurement is: Cn=A+BCn-1; (b1) in a radon cumulation process: as shown in the description; (b2) in a radon dynamic equilibrium process: as shown in the description. The medium surface radon exhalation rate continuous measurement method and apparatus can achieve continuous measurement and is high in measurement efficiency.

Description

A kind of method and apparatus of continuous coverage radon eduction rate on medium furface

Technical field

The present invention relates to a kind of nuclear radiation detection technology, particularly a kind of method of fast and reliable continuous coverage radon eduction rate on medium furface and measurement mechanism.

Background technology

The radioactivity of the radon that precipitation rate of radon refers to unit area, unit interval dielectric surface is separated out.Radon release rate is by the impact of the temperature of sampling condition and environment, humidity and air pressure conditions, and make the accuracy of measurement result be difficult to control, measurement result is often difficult to reproduce and compare.But radon release rate is the key link evaluating waste-rock yard, Tailings Dam anti-radon covering regulation effect in Decommissioning of Uranium Mining/milling Facilities, is also the means finding source item during environmental pollution of radon is administered.GB " code for indoor environmental pollution control of civil building engineering (2013 editions) "-GB50325-2010 come into force on June 1st, 2011 using soil and building materials radon release rate as the basic means controlling Indoor Niton Pollution.The continuous reliable measurements of precipitation rate of radon is raising China environmental pollution of radon monitoring and evaluation level, building materials radon release rate and level of control, take radon as the important guarantee of the resources observation of tracer nuclide, earth science research and earthquake prediction level.

The method of a kind of measuring media based on static collection surface precipitation rate of radon is provided in patent of invention " method of measuring media surface precipitation rate of radon and device ", though can stop a leak, antidiffusion, the interference of Environmental Radon and thoron, the method adopts accumulative to measure precipitation rate of radon, affect less by external condition, although have higher measuring accuracy, but the method is in order to improve measuring accuracy at present, repetitive measurement, A and B is calculated by least square method, finally obtain λ e and J, do not survey precipitation rate of radon continuously, only just for radon eduction rate on medium furface single measurement.The change (half life period of radon is 3.825d) of precipitation rate of radon can not be responded fast in patent of invention " method of closed loop continuous coverage precipitation rate of radon ", there is serious delay effect, be difficult to the rapid response to customer's need that realization take radon as the earthquake prediction of tracer nuclide etc.

Therefore, the method and apparatus designing a kind of continuous coverage radon eduction rate on medium furface is necessary.

Summary of the invention

Technical matters to be solved by this invention is to provide a kind of method and apparatus of continuous coverage radon eduction rate on medium furface, and the method and apparatus of this continuous coverage radon eduction rate on medium furface can realize continuous coverage, measures efficiency high.

The technical solution of invention is as follows:

A method for continuous coverage radon eduction rate on medium furface, comprises the following steps:

Step 1: measure initial radon consistence C ₀;

Open in flow rate sampling test environment (being the external environment condition of dielectric surface) of sampling pump 0.1-12L/min containing radon air, sample time is Δ T, the radon consistence of collection radon cover and initial radon consistence C when the radon consistence now in measuring chamber is initial time t=0 ₀;

Step 2: calculation medium surface precipitation rate of radon;

B () first determines A, B and equivalent decay constant λ e by the following method:

To there is perforate and be with the collection radon cover of agitating function to be buckled in testing medium surface; Be that T takes multiple measurements the concentration of radon in collection radon cover with the time interval;

N-th and n-1 time measure collection radon cover in radon concentration between pass be: C _n=A+BC _n-1;

Wherein n is natural number;

C _nfor the concentration of radon in the collection radon cover in t=n*T moment;

$A=\frac{\mathrm{JS}}{{\mathrm{\λ}}_{e}V}(1-e^{-{\mathrm{\λ}}_{e}T}),$ $B=e^{-{\mathrm{\λ}}_{e}T};$

J is measured medium surface precipitation rate of radon;

S is the floorage of collection radon cover;

V represents the cumulative volume of collection radon cover (also known as collection radon chamber) and measuring chamber;

Through repetitive measurement, adopt least square method determination formula C _n=A+BC _n-1a and B; And try to achieve ${\mathrm{\λ}}_e=-\frac{\ln B}{T};$

Again with as the separation of radon accumulation and radon homeostasis process; Measuring Time corresponding process is radon accumulation, corresponding process is radon homeostasis process;

(b1) in radon accumulation, $J=-A\frac{V\ln B}{\mathrm{TS}}(1-B);$

(b2) at radon homeostasis process,

The flow rate 2L/min of sampling pump.

Δ T is not less than 1 minute.Preferred Δ T is 500 seconds.

As preferably, T is not less than 10 minutes.

T is 15 minutes.

A device for continuous coverage radon eduction rate on medium furface, comprises emanometer (5) and the collection radon cover (1) of spiral-lock on testing medium surface (6);

Collection radon cover is provided with leak holes (1-4), has stirrer (1-1) in collection radon cover;

There is in emanometer measuring chamber (5-1);

The collection radon cover of collection radon cover connecting hole (1-3) and the measuring instrument of emanometer connecting hole (5-2) of bleeding of bleeding is connected by inlet pipe connection (3);

Collection radon cover return-air connecting hole (1-2) of collection radon cover is connected by return-air connecting pipe (2) with the measuring instrument return-air connecting hole (5-3) of emanometer;

Aforesaid method is adopted to measure testing medium surface precipitation rate of radon.

Inlet pipe connection is provided with radon daughter filtrator (4).

Beneficial effect:

The method of precipitation rate of radon continuous coverage provided by the invention, compared with traditional measuring method, has and measures situation of change easy and simple to handle, to respond precipitation rate of radon fast.Tradition accumulative measures precipitation rate of radon, affect less by external condition, although have higher measuring accuracy, but the method only can be used for radon eduction rate on medium furface single measurement at present, do not measure after radon consistence reaches mobile equilibrium in collection radon cover, the change of monitoring precipitation rate of radon continuously can not be realized.Existing closed loop precipitation rate of radon continuous coverage scheme, does not only have radon release rate in accumulation, but also can not the situation of change of real-time response precipitation rate of radon, adopts hermetic collection radon cover λ _εless, the radon consistence in collection radon cover is higher, can not respond the situation of change of precipitation rate of radon in this measuring process in time.The collection radon cover of perforate band agitating function is adopted in this programme, the perforate of collection radon cover is to improve the amount of leakage collecting radon in collection radon cover, band agitating function makes radon consistence in collection radon cover even on the one hand, to guarantee that the radon consistence sampling finish time in measuring chamber is identical with radon consistence in collection radon cover, more be conducive to the leakage collecting radon in radon cover on the other hand, thus make the effective decay constant λ collecting radon in radon cover _εincrease.Can be drawn by (8) formula, when under the condition that collection radon enclosure volume V and floorage S is certain, as effective decay constant λ _εtime larger, measure the subtle change of radon consistence C (n) obtained, the value J just energy rapid reaction of eduction rate, and then realize fast and reliable continuous coverage precipitation rate of radon.The program adopts cycle sampling and measures the process combined, and kinetic measurement is converted into static measurement, not only ensures the accurate of radon concentration monitoring result, also helps the life-span extending sampling pump.

Scheme 1[and patent of invention " method of measuring media surface precipitation rate of radon and device "] described in method can only be used for carrying out single measurement to radon eduction rate on medium furface, do not measure after in collection radon cover, radon consistence reaches mobile equilibrium, scheme 2[and patent of invention " method of closed loop continuous coverage precipitation rate of radon "] in mention after measuring period, number was greater than i, radon consistence in collection radon cover is only relevant with the change of eduction rate, concrete how many all after dates are not described, specify that in this programme that the process of precipitation rate of radon is measured in radon cumulative measurement precipitation rate of radon and mobile equilibrium.Can be drawn by (8) formula, when under the condition that collection radon enclosure volume V and floorage S is certain, as effective decay constant λ _εtime larger, measure the subtle change of radon consistence C (n) obtained, the value J energy rapid reaction of eduction rate, and then respond the change of precipitation rate of radon fast.

In sum, the method and apparatus of continuous coverage radon eduction rate on medium furface of the present invention can realize continuous coverage, measures efficiency high.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of continuous coverage radon eduction rate on medium furface device.

Fig. 2 is measuring process principle schematic.

Label declaration:

1, radon cover is collected

1-1 agitator, 1-2 collection radon cover return-air connecting hole, 1-3 collection radon cover is bled connecting hole, 1-4 leak holes

2, return-air connecting pipe

3, inlet pipe connection

4, radon daughter filtrator

5, emanometer

5-1 measuring chamber, 5-2 measuring instrument is bled connecting hole, measuring instrument return-air connecting hole

6, testing medium surface

Embodiment

Below with reference to the drawings and specific embodiments, the present invention is described in further details:

A method for continuous coverage radon eduction rate on medium furface, comprises the following steps:

Step 1: measure initial radon consistence C ₀;

Open in flow rate sampling test environment (being the external environment condition of dielectric surface) of sampling pump 0.1-12L/min containing radon air, sample time is Δ T, the radon consistence of collection radon cover and initial radon consistence C when the radon consistence now in measuring chamber is initial time t=0 ₀;

Step 2: calculation medium surface precipitation rate of radon;

C () first determines A, B and equivalent decay constant λ e by the following method:

To there is perforate and be with the collection radon cover of agitating function to be buckled in testing medium surface; Be that T takes multiple measurements the concentration of radon in collection radon cover with the time interval;

N-th and n-1 time measure collection radon cover in radon concentration between pass be: C _n=A+BC _n-1;

Wherein n is natural number;

C _nfor the concentration of radon in the collection radon cover in t=n*T moment;

$A=\frac{\mathrm{JS}}{{\mathrm{\λ}}_{e}V}(1-e^{-{\mathrm{\λ}}_{e}T}),$ $B=e^{-{\mathrm{\λ}}_{e}T};$

J is measured medium surface precipitation rate of radon;

S is the floorage of collection radon cover;

V represents the cumulative volume of collection radon cover and measuring chamber;

In radon accumulation, through repetitive measurement, adopt least square method determination formula C _n=A+BC _n-1a and B; And try to achieve

Again with as the separation of radon accumulation and radon homeostasis process; Measuring Time corresponding process is radon accumulation, corresponding process is radon homeostasis process;

(b1) in radon accumulation, $J=-A\frac{V\ln B}{\mathrm{TS}}(1-B);$

(b2) at radon homeostasis process,

The flow rate 2L/min of sampling pump.

Δ T is not less than 1 minute.

As preferably, T is not less than 10 minutes.

T is 15 minutes.

A device for continuous coverage radon eduction rate on medium furface, comprises emanometer 5 and the collection radon cover 1 of spiral-lock on testing medium surface 6;

Collection radon cover is provided with leak holes 1-4, has stirrer 1-1 in collection radon cover;

There is in emanometer measuring chamber 5-1;

The collection radon cover of collection radon cover connecting hole 1-3 and the measuring instrument of the emanometer connecting hole 5-2 that bleeds that bleeds is connected by inlet pipe connection 3;

The collection radon cover return-air connecting hole 1-2 of collection radon cover is connected by return-air connecting pipe 2 with the measuring instrument return-air connecting hole 5-3 of emanometer;

Aforesaid method is adopted to measure testing medium surface precipitation rate of radon.

Inlet pipe connection is provided with radon daughter filtrator 4.

The method of continuous coverage precipitation rate of radon, it comprises measuring process and computing method.

The process of A, fast and reliable continuous coverage precipitation rate of radon: open sampling pump Q L/min (conventional 2L/min, containing radon air Δ T (the being not less than 1 minute) time in flow rate sampling test environment (being the external environment condition of dielectric surface) 0.1-12L/min), the radon consistence of collection radon cover and initial radon consistence C when the radon consistence now in measuring chamber is initial time t=0 ₀,

Be that V-Δ V[V represents the cumulative volume integrating radon cover and measuring chamber by its volume of perforate band agitating function again], floorage is buckled in testing medium on the surface as the collection radon cover of S, again an airtight measuring chamber (volume is Δ V) and collection radon cover are connected to form a loop, when after collection certain time interval T-Δ T, the flow rate of opening sampling pump Q L/min, by long-pending radon chamber and the radon mixing Δ T time in measuring chamber, amasss the radon consistence C of radon chamber when the radon consistence now in measuring chamber is moment T ₁, then again with T (being greater than 10min) for one-period repeated measurement, radon consistence data C in the collection radon cover that can record a series of constant duration _n, in collection radon cover, the change of radon consistence divides 2 processes: namely radon accumulation is measured and the measurement of radon homeostasis process, and its measuring process as shown in Figure 2.

B, computing method:

In collection radon cover, the available formula of change (1) of radon consistence describes:

$\frac{\mathrm{dC}\left(t\right)}{\mathrm{dt}}=\frac{\mathrm{JS}}{V}-\mathrm{\λC}\left(t\right)-\mathrm{RC}\left(t\right)---\left(1\right)$

the change of radon consistence is caused for the unit time precipitate into radon in collection radon cover; J is measured medium surface precipitation rate of radon; S is the floorage of collection radon cover.λ is the decay constant (2.1 × 10 of radon ^-6s ^-1); R is leakage and the antidiffusion rate of radon, and t is the time of collection radon.

Make λ _e=λ+R, λ _efor equivalent decay constant; Radon consistence is C (t), i.e. the t=0 moment, integrates the concentration of radon in radon cover as C ₀.(1) solution of formula is

$C\left(t\right)=\frac{\mathrm{JS}}{{\mathrm{\λ}}_{e}V}(1-e^{{\mathrm{\λ}}_{e}t})+C_0{e}^{-{\mathrm{\λ}}_{e}t}---\left(2\right)$

Carry out the continuous coverage that the time interval is T, then the following relation of change of radon consistence in adjacent twice measuring set radon cover:

$C_n=\frac{\mathrm{JS}}{{\mathrm{\λ}}_{e}V}(1-e^{-{\mathrm{\λ}}_{e}T})+C_{n-1}{e}^{-{\mathrm{\λ}}_{e}T}---\left(3\right)$

Order $A=\frac{\mathrm{JS}}{{\mathrm{\λ}}_{e}V}(1-e^{-{\mathrm{\λ}}_{e}T}),$ $B=e^{-{\mathrm{\λ}}_{e}T},$ Then have:

C _n＝A+BC _n-1(4)

(1) radon accumulation is measured

Radon accumulation is measured, in (2) formula time, i.e. Measuring Time in order to improve measuring accuracy, repetitive measurement, calculates A and B by least square method, finally obtains λ e and J.

$J=-A\frac{V\ln B}{\mathrm{TS}}(1-B)---\left(5\right)$

${\mathrm{\λ}}_e\frac{\ln B}{T}---\left(6\right)$

(2) radon homeostasis process is measured

Radon homeostasis process is measured, in (2) formula time, i.e. Measuring Time

$C_n\≈\frac{\mathrm{JS}}{V{\mathrm{\λ}}_e}---\left(7\right)$

The J calculated according to (6) formula in radon cumulative measurement process above again obtains:

$J=\frac{C_{n}V{\mathrm{\λ}}_{\mathrm{\ϵ}}}{S}---\left(8\right)$

The measurement mechanism that said method adopts is made up of the collection radon cover of perforate band agitating function, draft tube, muffler, stirrer and emanometer, being connected with the measuring chamber in emanometer with muffler by draft tube of the collection radon cover of perforate band agitating function.

Experimental verification:

This measuring method and device are measured at the enterprising joining line of University Of Nanhua's precipitation rate of radon No. 1 standard set-up, measurement result is as shown in table 1.

Table 1: continuous coverage result

Measuring condition: V=0.0057m ³, S=0.066m ², T=15min (900s), Δ T=5min (300s) precipitation rate of radon reference value J=1.48Bq/m ²/ s.

Error is comparing between measured value with reference value

NRL-II type is a kind of electrostatic collection formula emanometer (this emanometer and University Of Nanhua's radon chamber standard supervision emanometer PQ2000 measuring result error are within 3.0%) developed by University Of Nanhua oneself.

Mention above in the measure equation of precipitation rate of radon and pointing out, the measurement of eduction rate calculates precipitation rate of radon by measuring not radon consistence in the same time.

Reference value is the mean value that University Of Nanhua's radon chamber is measured for a long time, and the measurement due to eduction rate is subject to the impact of temperature, humidity and air pressure conditions, therefore needs right Radon eduction carry out Real-Time Monitoring.

Claims (7)

1. a method for continuous coverage radon eduction rate on medium furface, is characterized in that, comprises the following steps:

Step 1: measure initial radon consistence C ₀;

Open containing radon air in the flow rate sampling test environment of sampling pump 0.1-12L/min, sample time is Δ T, the radon consistence of collection radon cover and initial radon consistence C when the radon consistence now in measuring chamber is initial time t=0 ₀;

Step 2: calculation medium surface precipitation rate of radon;

A () first determines A, B and equivalent decay constant λ e by the following method:

To there is perforate and be with the collection radon cover of agitating function to be buckled in testing medium surface; Be that T takes multiple measurements the concentration of radon in collection radon cover with the time interval;

N-th and n-1 time measure collection radon cover in radon concentration between pass be: C _n=A+BC _n-1;

Wherein n is natural number;

C _nfor the concentration of radon in the collection radon cover in t=n*T moment;

$A=\frac{\mathrm{JS}}{{\mathrm{\λ}}_{e}V}(1-e^{-{\mathrm{\λ}}_{e}T}),B=e^{{-\mathrm{\λ}}_{e}T};$

J is measured medium surface precipitation rate of radon;

S is the floorage of collection radon cover;

V represents the cumulative volume of collection radon cover and measuring chamber;

In radon accumulation, through repetitive measurement, adopt least square method determination formula C _n=A+BC _n-1a and B; And try to achieve ${\mathrm{\λ}}_e=-\frac{\ln B}{T};$

Again with as the separation of radon accumulation and radon homeostasis process; Measuring Time corresponding process is radon accumulation, corresponding process is radon homeostasis process;

(b1) in radon accumulation, $J=-A\frac{V\ln B}{\mathrm{TS}}(1-B);$

(b2) at radon homeostasis process,

2. the method for continuous coverage radon eduction rate on medium furface according to claim 1, is characterized in that, the flow rate 2L/min of sampling pump.

3. the method for continuous coverage radon eduction rate on medium furface according to claim 2, is characterized in that, Δ T is not less than 1 minute.

4. the method for continuous coverage radon eduction rate on medium furface according to claim 3, is characterized in that, T is not less than 10 minutes.

5. the method for continuous coverage radon eduction rate on medium furface according to claim 4, is characterized in that, T is 15 minutes.

6. a device for continuous coverage radon eduction rate on medium furface, is characterized in that, comprises emanometer (5) and the collection radon cover (1) of spiral-lock on testing medium surface (6);

Collection radon cover is provided with leak holes (1-4), has stirrer (1-1) in collection radon cover;

There is in emanometer measuring chamber (5-1);

The collection radon cover of collection radon cover connecting hole (1-3) and the measuring instrument of emanometer connecting hole (5-2) of bleeding of bleeding is connected by inlet pipe connection (3);

Collection radon cover return-air connecting hole (1-2) of collection radon cover is connected by return-air connecting pipe (2) with the measuring instrument return-air connecting hole (5-3) of emanometer;

The method described in any one of claim 1-5 is adopted to measure testing medium surface precipitation rate of radon.

7. the device of continuous coverage radon eduction rate on medium furface according to claim 5, is characterized in that, inlet pipe connection is provided with radon daughter filtrator (4).