CN107272044B

CN107272044B - A kind of measurement85The interior Gas Filled Detector of Kr

Info

Publication number: CN107272044B
Application number: CN201710548485.1A
Authority: CN
Inventors: 曾军; 王红侠; 向永春; 郝樊华; 迮仁德; 向清沛; 罗飞; 胡根
Original assignee: Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics
Current assignee: Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics
Priority date: 2017-07-07
Filing date: 2017-07-07
Publication date: 2019-01-15
Anticipated expiration: 2037-07-07
Also published as: CN107272044A

Abstract

The invention discloses a kind of measurements⁸⁵The interior Gas Filled Detector of Kr, it includes: valve, stainless steel casing, reflection isolation film, plastic scintillant, optocoupler mixture, photomultiplier tube, integrated nuclear electronics module.Detector is mounted in shield, and sample is enriched with by inventiona gas treatment module, is filled with closed sample room after purification.⁸⁵The β ray that Kr is released is collected to form scintillation light by plastic scintillant, after photomultiplier tube amplifies, is integrated nuclear electronics module record.After recording data transmission to PC terminal, by the way that analysis can be obtained in sample with background ratio⁸⁵Kr activity information.Compared with existing gamma ray spectrometer measurement method, which can be incited somebody to action⁸⁵The detection limit of Kr reduces about 3 magnitudes；Compared with traditional gas detector, which changes sample composition insensitive.It can be widely applied to radioactivity in nuclear power plant's gaseous effluent⁸⁵The quantitative analysis of Kr.

Description

A kind of measurement85The interior Gas Filled Detector of Kr

Technical field

The present invention relates to radioactivity⁸⁵Kr field of measuring technique, more particularly to it is a kind of for being put in nuclear power plant's gaseous effluent Penetrating property⁸⁵The interior Gas Filled Detector of Kr measurement.

Background technique

Nuclear energy be counted as solving mankind's current and future for a period of time in energy crisis most promising technological means it One, nuclear safety is the important leverage that nuclear undertaking develops in a healthy way.For nuclear power plant's day-to-day operation, the monitoring of effluent discharge amount is to protect Hinder the important measures of nuclear safety.National nuclear facility department and unit of operation of nuclear power plant always attach great importance to, and take a variety of Technical measures are monitored the artificial radionuclide in effluent.However due to measurement means and measuring instrument development level Limitation, nuclear power plant operate normally in⁸⁵The emission level of Kr lacks always effective monitoring means.It can only be according to national related (GB 6249-2011) regulation is estimated by the half value of detection limit, nuclear power plant's inert gas is as a result caused to discharge The excessively high statistics of amount, gaseous state radioactive effluent is to the radiation effect of surrounding people and environment during exaggerating nuclear power plant's operation.

Inert gas discharges activity measurement in nuclear power plant of country gaseous effluent at present, is based on gas on-site sampling experiment Room analysis is completed.Its process is to be sampled first using 3L gas bomb, is then transported in hot laboratory using height Off-line measurement is carried out on pure germanium gamma ray spectrometer.Due to⁸⁵The γ branching ratio of Kr is very low (only 0.434%), and HpGe detection efficient is not Height, in addition size selective sampling pair⁸⁵The interference of Kr characteristic peak.So that this attainable detection of measurement method limits higher, about 50k Bq/m³~100k Bq/m³.In practice, this method only atmospheric monitoring system (ETY) in exhaust treatment system (TEG) and containment It can be monitored when agreement discharge⁸⁵Kr, and nuclear auxiliary building ventilating system (DVN) chimney continuously discharges⁸⁵Kr content is generally below Detection limit, cannot achieve pair⁸⁵The accurate quantitative analysis of Kr.

Summary of the invention

Excessively high problem is limited for detection existing for gamma ray spectrometer measuring system, is penetrated the present invention provides a kind of by detecting β Line detects the interior inflation of limit to reduce⁸⁵Kr detector.

Measurement of the invention⁸⁵The interior Gas Filled Detector of Kr, including valve, shield, stainless steel casing, plastic scintillant, Optocoupler mixture, fastening interface, damping silica gel, photomultiplier tube, integrated nuclear electronics module, further include sample introduction and stream wash channel, Closed sample room, reflection isolation film, the valve is mounted on sample introduction and stream is washed on channel；The closed sample room is located at stainless steel Between shell and plastic scintillant；The reflection isolation film is vaporized on plastic scintillant surface, and closed sample room and plastics are dodged Bright body separates；The photomultiplier tube is coupled by optocoupler mixture with plastic scintillant, and its rear end connects integrated nuclear electronics mould Block；The shield is wrapped in the outer layer of entire detector.

The closed sample chamber shape is truncated cone-shaped, and sample introduction one end is less than measurement one end, it is dead both to have reduced detector in this way Volume, the stream for being also conducive to be measured rear closed sample room are washed.

The stainless steel casing and plastic scintillant are tightly connected by way of adhesive and mechanical press, it is ensured that detection Device can keep air-tightness for a long time within the scope of the positive and negative air-pressure of wide scope.

The plastic scintillant has good machining property, and thickness should guarantee that β radial energy deposits whole energy Amount, makes detector have lower background again, and the result of optimization design is 3mm ~ 8mm.

The reflection isolation film is the compact metal composite membrane of atom deposition method preparation, coating material difference from inside to outside For aluminium oxide, aluminium, thicknesses of layers adds up to 300nm ~ 500nm.

The shield uses multi-layer compound structure, and main shield material is 5cm old lead, the internal layer of lead successively liner 1mm The polyethylene of cadmium, the copper sheet of 2-5mm and 3mm；The outer wall of lead wraps up stainless steel, plays support fixed function.

A kind of measurement that the present invention announces⁸⁵The interior Gas Filled Detector of Kr will be to be measured by optimizing structure design⁸⁵Kr gas It introduces inside detector, realizes the beta-ray measurement bigger to branching ratio.Also, background level is reduced using multiple technologies approach, It can be by existing measurement method⁸⁵Kr detection limit reduces about 3 magnitudes, is hopeful to realize and continuously discharge to DVN chimney⁸⁵Kr The accurate measurement of content.

Detailed description of the invention

Fig. 1 is structural block diagram of the invention.

Specific embodiment

To make the object, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment one by one The present invention is described in further detail.

A kind of measurement⁸⁵The interior Gas Filled Detector embodiment of Kr:

Referring to Fig. 1, measurement of the invention⁸⁵The interior Gas Filled Detector of Kr, including inventiona gas treatment module 1, valve 2, sample introduction with Stream wash channel 3, shield 4, stainless steel casing 5, closed sample room 6, reflection isolation film 7, plastic scintillant 8, optocoupler mixture 9, Fasten interface 10, damping silica gel 11, photomultiplier tube 12, integrated nuclear electronics module 13, PC terminal 14.

The inventiona gas treatment module 1 washes channel 3 with stream with sample introduction by valve 2 and is connected, and function is realization pair⁸⁵Kr gas Sampling, enrichment and transfer；The valve 2 is mounted on sample introduction and stream is washed on channel 3, and valve is opened in gas transfer process, turns It moves and completes late gate closing；The closed sample room 6 is between stainless steel casing 5 and plastic scintillant 8；The reflection isolation Film 7 is vaporized on 8 surface of plastic scintillant, and closed sample room 6 and plastic scintillant 8 are separated；The photomultiplier tube 12 passes through Optocoupler mixture 9 is coupled with plastic scintillant 8, and its rear end connects integrated nuclear electronics module 13, as ORTEC company produces Digi-base；The integrated nuclear electronics module 13 is connect by USB line or cable with PC terminal 14, and PC terminal 14 is equipped with Measurement control software realizes control and data processing to entire measurement process；The shield 4 is wrapped in entire detector Outer layer.

The detection efficient of detector must be demarcated before measurement, the method for calibration can use relative detection efficiency.It is first It first passes through reactor irradiation or other modes obtains⁸⁵Kr unstripped gas, using the proportional counter tube measurement irradiation gas of known end effect Body specific activity takes certain volume marked gas to be filled with detector, calculates detection efficient by measuring net count.

Detector one-shot measurement process is: inventiona gas treatment module 1 collects a certain amount of contain⁸⁵Kr sample to be tested gas, passes through place The closed sample room 6 of detector is filled with after reason.⁸⁵It is heavy in plastic scintillant 8 that the β ray that Kr is released when decaying passes through reflection isolation film 7 Product energy, and scintillator is caused to shine.Scintillation light enters photomultiplier tube 12 by optocoupler mixture 9, causes electronics times wherein Increase, forms electric impulse signal.Electric impulse signal amplifies forming in integrated nuclear electronics module 13, and by multi-channel analysis therein Device record.Count information is transmitted to PC terminal 14 by USB line, can be obtained by the comparative analysis with background⁸⁵Kr total ratio Activity information.After being measured, gas pressure in sample room 5 is evacuated to by 100Pa by vacuum pump, is then passed through helium extremely Then air pressure is evacuated to 100Pa again by 1atm, repeatedly repeatedly, the stream of sample room is washed in realization, carries out standard for measurement next time It is standby.

From the foregoing, it will be observed that implementing the present invention, have the advantages that

The present invention provides one kind for radioactivity in nuclear power plant's gaseous effluent⁸⁵The interior inflation scintillator detection of Kr measurement Device.On the one hand, it is designed by cleverly structure, is able to maintain detector within the scope of the positive/negative-pressure of wide scope good airtight Property, prolonged measurement demand can be met.On the other hand, using the plastic scintillant of satisfactory mechanical property, and to its thickness into Row optimization calculates, and has not only ensured to Beta-ray complete collection, but also detector is made to have very low background level.In addition, using gas phase The compact metal composite membrane of sedimentation vapor deposition, can not only effectively improve the collection efficiency of scintillation light, and can be substantially reduced detector Memory effect, it is ensured that the consistency of measurement is repeated several times.The detector and other interior charge air conditioning detectors that the present invention describes (such as proportional counter tube, gas ionization chamber) is compared, and to being filled with, gas sample constituents variation is insensitive, does not need especially complex Process of gas path removes O₂、H₂The electronegative gas such as O；Compared with interior gassy fluid dodges detector, do not need under the conditions of low temperature (liquid nitrogen) Transfer⁸⁵Kr gas.A kind of measurement⁸⁵The interior Gas Filled Detector specific aim of Kr solves in current nuclear power plant effluent⁸⁵Kr activity is fixed The problem of analysis is measured, has processing cost low, small in size, detection efficient is high, and the good advantage of sturdy property is applied to can produce very High science and commercial value.

Claims

1. a kind of measurement⁸⁵The interior Gas Filled Detector of Kr, including valve (2), shield (4), stainless steel casing (5), Plastic scintillation Body (8), optocoupler mixture (9), fastening interface (10), damping silica gel (11), photomultiplier tube (12), integrated nuclear electronics module (13), it is characterised in that: further include that sample introduction and stream wash channel (3), closed sample room (6), reflection isolation film (7)；The valve (2) it is mounted on sample introduction and stream is washed on channel (3)；The closed sample room (6) is located at stainless steel casing (5) and plastic scintillant (8) between；The reflection isolation film (7) is vaporized on plastic scintillant (8) surface, by closed sample room (6) and plastic scintillant (8) it separates；The photomultiplier tube (12) is coupled by optocoupler mixture (9) with plastic scintillant (8), its rear end connection collection nucleation Electronics module (13)；The shield (4) is wrapped in the outer layer of entire detector.

2. measurement according to claim 1⁸⁵The interior Gas Filled Detector of Kr, it is characterised in that: closed sample room (6) shape Shape is truncated cone-shaped, and sample introduction one end is less than measurement one end.

3. measurement according to claim 1⁸⁵The interior Gas Filled Detector of Kr, it is characterised in that: the stainless steel casing (5) with Plastic scintillant (8) is tightly connected by way of adhesive and mechanical press.

4. measurement according to claim 1⁸⁵The interior Gas Filled Detector of Kr, it is characterised in that: the plastic scintillant (8) With a thickness of 3mm ~ 8mm.

5. measurement according to claim 1⁸⁵The interior Gas Filled Detector of Kr, it is characterised in that: the reflection isolation film (7) is The compact metal composite membrane of atom deposition method preparation, thicknesses of layers are 300nm ~ 500nm.

6. measurement according to claim 1⁸⁵The interior Gas Filled Detector of Kr, it is characterised in that: the shield (4) is using more Layer composite construction, is followed successively by stainless steel stent, lead, cadmium, oxygen-free copper, polyethylene from outside to inside.