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WO1992003748A1 - Procede et dosimetre passif pour la mesure par integration de la fraction de produits de desintegration du radon dans l'air - Google Patents

Procede et dosimetre passif pour la mesure par integration de la fraction de produits de desintegration du radon dans l'air Download PDF

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Publication number
WO1992003748A1
WO1992003748A1 PCT/DE1991/000645 DE9100645W WO9203748A1 WO 1992003748 A1 WO1992003748 A1 WO 1992003748A1 DE 9100645 W DE9100645 W DE 9100645W WO 9203748 A1 WO9203748 A1 WO 9203748A1
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WIPO (PCT)
Prior art keywords
detectors
radon
chambers
passive
passive dosimeter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/DE1991/000645
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German (de)
English (en)
Inventor
Andreas Guhr
Olaf Sarenio
Original Assignee
Unabhaengiges Lab Fuer Strahlu
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Application filed by Unabhaengiges Lab Fuer Strahlu filed Critical Unabhaengiges Lab Fuer Strahlu
Publication of WO1992003748A1 publication Critical patent/WO1992003748A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/17—Circuit arrangements not adapted to a particular type of detector
    • G01T1/178—Circuit arrangements not adapted to a particular type of detector for measuring specific activity in the presence of other radioactive substances, e.g. natural, in the air or in liquids such as rain water

Definitions

  • the invention relates to a method and a passive dosimeter for integrally measuring the proportion of radon decay product in the air.
  • the known methods can be divided into two large groups, active and passive measuring systems.
  • Active measuring systems are predominantly equipped with electrically operated functional units, such as pumps, control and evaluation electronics, and therefore require an energy supply. They generally consist of a detector-filter combination and an air suction device for filter application or for enriching the radon decay products on the detector surface itself. Semiconductors detectors, scintillation counters, thermoluminescence detectors, electret detectors or solid-state track detectors are used as detectors. With dosimeters of this type, statements can be made about the activity concentrations and / or the potential alpha energy concentration of the donor decay products in the air. Radon gas concentrations are measured by air sampling with special ionization chambers, scintillation chambers, and electret chambers. Activated carbon process or 2-filter methods.
  • Active measuring systems for radon decay products are mainly used in mining for short-term measurements of a few minutes (SAAS report 267) and as continuously operating devices, due to the high costs, for environmental measurements of up to one month (SAAS report 342).
  • active measuring systems are used to determine the weight condition used.
  • active devices for radon decay product measurements for individual dosimetric monitoring of people working underground are known (Feddersen, Ch., Dissertation A of the Faculty of Technical Sciences of the Bergakademie Freiberg, 1986: electronic personal dosimeter with miniature pump and semiconductor detector; "Proc.
  • Passive measuring systems mainly use solid-state detectors, in some cases also thermoluminescence detectors, electret detectors and activated carbon.
  • the dosimeters require no power supply, have no moving parts and no electronic assemblies.
  • So-called diffusion chambers are known from the measuring principle and the technical designs.
  • the radon naturally diffuses through an opening, which is closed with a filter for the radon decay products, into a chamber in which one or more passive detectors are located.
  • the radon concentration in the air can be determined from the measurement effect of these detectors and the measurement conditions after suitable calibration of the system ("Hucl.Instr.
  • Open, alpha-sensitive detectors without housings or in unclosed housings are also known. With them, only qualitative statements about the existing total alpha activity possible. They are often used, without specially assembled dosimeters, for screening measurements in buildings to determine the order of magnitude of the radon equilibrium concentration.
  • the sensitivity of open detectors shows a strong dependence on the state of equilibrium between radon and its short-lived decay products. Therefore, when estimating the radon equilibrium concentration from the measurement signal of open detectors, deviations of 100 to 200% from the true value can be expected.
  • the concentrations of radon and its decay products in the air are subject to strong local, daily and seasonal fluctuations.
  • many known active measuring systems only allow short-term statements based on a few minutes of measuring time. Therefore, short-time measurements can easily lead to a complete misjudgment of the actual radiation situation. Reliable statements can only be derived from measurements over longer periods of time, from a few weeks to half a year and longer.
  • Continuously operating active measuring systems for determining the radon decay product content in the air are very expensive and have a complex measuring and o? * Ertetechnik. "They are, therefore, ch. Only for selected supervision ⁇ gsauf synthetic used.
  • the separation of the radon and its decay products requires consideration of the observation conditions and the registration properties of the detector (Urban, M., "Proc. 13th Intern.Conf. On SSNTD's", Rome 1985) or the use of special nuclide collection or separation methods, such as electric fields ("Health Physics Society, 30th Annual Meetin", 1985, TPM-D3) or absorber films in front of the detectors during the irradiation.
  • the invention has for its object to provide a method and a passive dosimeter for integrally measuring the radon decay product content in the air, using highly alpha-sensitive, passive detectors for measurement and evaluation and thereby corresponding to different sensitivities or necessary exposure times the application are guaranteed.
  • the object is achieved in that measurements are carried out with pairs of identical detectors located in close proximity to one another, one of the detectors arranged in pairs being isolated from the air from the radon decay products and the detectors subsequently being evaluated, and wherein Statements about the radon decay product portion or the potential alpha energy concentration of an arbitrary mixture of short-lived radon decay products in the air can be derived from the difference signal of the same pair of detectors.
  • the radon concentration and the equilibrium factor with regard to the potential alpha energy can be derived from this measurement signal and the difference signal of the detectors which are identical in pairs.
  • alpha-sensitive detectors in the form of solid-state track detectors, preferably polydiethylene glycol bis (allyl carbonate) or / and polycarbonate detector films or thermoluminescence detectors, preferably thin-layer LiF: Mg, Cu, P is measured.
  • the solution comprises a passive dosimeter, in which the same detectors are exchangeably arranged in pairs in geometrically identical chambers of the same volume which are in close proximity to one another, the chambers having the same diffusion openings and one of the chambers with one of the detectors arranged in it Radon decay isolating filter is covered.
  • the diffusion openings are preferably arranged in a cover closing the respective chamber.
  • the chambers can consist of an electrically conductive material, such as carbon mixed or coated with plastic, or a metal or a plastic with a special additive, which ensures a uniform electrostatic charging of the housing.
  • the detectors in the chambers prefferably be covered by the same thin conductive foil, such as an aluminized plastic foil.
  • the filter advantageously consists of a thin, low-density polyethylene film or a hydrophobic glass fiber filter.
  • the surfaces of the diffusion openings can be changed optionally and can also be partially covered on one or more sides.
  • An expedient form of the formation of the dosimeter, particularly in the form of a personal dosimeter, is that the chambers are arranged directly next to one another.
  • a further possibility is provided in that the chambers are arranged directly one above the other, the lower chamber being covered by the filter isolating the detectors in it from radon decay products.
  • the detector is preferably arranged in the upper chamber in the cover containing the diffusion openings of the lower chamber.
  • the main advantage of the solution according to the invention consists in the direct determination of the load-relevant radon decay product content of the air without the aid of the highly error-corrected were liable to assume average equilibrium factors in connection with radon measurements alone. Further advantages are the simple structure, the small dimensions and the low weight of the dosimeter, the low manufacturing and detector evaluation costs as well as the negligible influence of the dosimeter measurement signals by environmental influences.
  • the detectors to be used are easy to use and can be evaluated safely. Once the detectors have been replaced, the dosimeter can be reused.
  • a further embodiment of the invention consists in arranging a closure cover which can be displaced in the longitudinal direction on the dosimeter, said cover having openings through which the diffusion openings are opened or closed.
  • openings correspond in their position and the number of layers and the number of diffusion openings. It is also possible for a single opening to be arranged, the inside diameter of which is somewhat larger than the outer circumferential line around the diffusion openings.
  • the closure cover can be connected to the housing via a sliding seat, the closure cover with its side walls encompassing a bead-like covering on the upper edge of the housing.
  • section 6-6 section 6-6 according to FIG. 5.
  • the drawings show the passive dosimeter in a schematic representation. To illustrate the opening, the detectors 3, the filter 6 and the foils 7 in particular are shown thicker. The actual thickness of a poly-diethylene-glycol bis (allyl carbonate) detector 3 is approximately 0.9 mm and that of the filter 6 made of low-density polyethylene is approximately 30 ⁇ m and that of the hydrophobized glass fiber filter is 350 ⁇ m. As explained below, it is necessary for the chambers 2 to have the same volume. This can be done in a simple manner by increasing the volume of the corresponding chamber 2 by the volume of the filter 6.
  • a passive dosimeter which has two chambers 2 arranged closely next to one another in a housing 1 having.
  • the chambers 2 are geometrically identical and have the same volume. This is the basis of the measuring principle.
  • a detector 3 is arranged at the bottom of both chambers 2.
  • a group of detectors 3 of different alpha sensitivity can also be arranged in a chamber 2. It is essential, however, that the same detectors 3 or groups of detectors 3 are arranged in both chambers 2.
  • a film 7, preferably a thin aluminized plastic film, can lie on the detectors 3. This improves the reproducibility of the measurements.
  • a fuse 8, for example a snap ring is installed above the detectors 3, which fixes the detector 3 to the bottom of the chamber 2 and at the same time enables its easy replacement.
  • a filter 6 is arranged under the cover 4, so that the diffusion openings 5 are sealed by it.
  • the filter 6 preferably consists of a low-density polyethylene film or a hydrophobic glass fiber filter. While the radon decay products are retained by the filter 6, a radon gas concentration compensation between the ambient air and the interior of the chamber 2 takes place in a few minutes.
  • the number of diffusion openings 5 and thus the gas exchange surface can be different. Different sensitivities or necessary exposure times of the dosimeter can thus be implemented in a simple manner.
  • FIG. 2 Another exemplary embodiment of a passive dosimeter is shown in FIG. 2 in conjunction with FIG. 4.
  • the geometrically identical chambers 2 of the same volume are arranged one above the other in the housing 1.
  • the detector 3 is located in the bottom of the chamber 2.
  • the film 7 and the fuse 8 have been omitted. It is of course also possible to use these elements with this structure.
  • the detector 3 located in the upper chamber 2 is located in the cover 4 of the lower chamber 2, which at the same time forms the bottom of the upper chamber 2. It is also essential for the structure that the structure in both chambers 2 is identical for the same volume. If the detector 3 is arranged in the bottom of the upper or the cover 4 of the lower chamber 2, then the two chambers 2, the diffusion openings 5 can only be arranged in that part of the respective cover 4 which is not covered by the detector 3.
  • the basic structure of such a cover 4 is clear from FIG. 4, diffusion openings 5 being arranged in the edge zone and detector 3 being arranged in the center of the cover 4.
  • the filter 6 is arranged in the lower chamber 2.
  • the dosimeter can be opened by means known per se, for example the chambers 2 can be screwed together.
  • the etching trace density on the detector in the chamber with filter film in front of the diffusion openings was used as the measuring signal with regard to the radon concentration and the difference in the etching trace densities on the detectors in the chamber without and with fil as the measuring signal regarding the potential alpha energy concentration of the radon decay products ⁇ ter film used in front of the diffusion openings.
  • the slight error in the sensitivity of the dosimeter when determining the exposure-relevant potential alpha energy concentration of any mixture of short-lived radon decay products in the air surrounding the dosimeter during the exposure determined in a wide range of different ways Equilibrium conditions, allows wide use as an individual dosimeter in an elevated and rapidly changing radon / radon decay product atmosphere.
  • the exposure time of the dosimeter is to be selected according to the specific monitoring task.
  • the dosimeter as a personal dosimeter.
  • a holding clip is arranged on the back of a dosimeter according to FIG. 1.
  • the same can be attached to the clothing.
  • further measurement points for parallel or other measurements can be provided.
  • thermoluminescent detectors for example, to measure the external gamma radiation dose, it is also possible to arrange exchangeable, highly sensitive thermoluminescent detectors in the housing 1.
  • the detectors 3 which are identical in pairs and are located in close proximity to one another, in fixed measuring points in the rooms to be monitored.
  • the closure cover 9 has openings 10 through which the diffusion openings 5 can be opened or closed.
  • the design and arrangement of the openings 10 can be different. It is thus possible to design these as individual bores (FIG. 5, left side) or as a single large opening 10 (FIG. 5, right side).
  • the position of the individual bores corresponds to the position of the diffusion openings 5.
  • its inner diameter is slightly larger than the outer circumferential line around the diffusion openings. This training has the advantage that a secure closure is guaranteed even in dark tunnels.
  • locking elements known per se can be arranged between the closure cap 9 and the housing 1 in a manner not shown.
  • FIG. 6 shows a sliding seat 11, the closure cover 9 with its side walls encompassing a bead-like thickening on the upper edge of the housing 1.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Measurement Of Radiation (AREA)

Abstract

La présente invention se rapporte à un procédé pour la mesure par intégration de la fraction de produits de désintégration du radon dans l'air à l'aide de détecteurs (3) servant à apporter la preuve de la présence du rayonnement alpha du radon et de ses produits de désintégration alpha-actifs à courte durée de vie. Selon l'invention, on obtient ce résultat par le fait que la mesure est effectuée au moyen d'une paire de détecteurs (3) identiques, se trouvant à proximité immédiate l'un de l'autre. Chacun des détecteurs (3) disposés en paire est isolé par rapport aux produits de désintégration du radon provenant de l'air, puis analysé, et de cette façon il est possible, sur la base du signal différentiel de la paire de détecteurs (3) identiques, d'obtenir des informations sur la fraction de produits de désintégration du radon ou bien sur la concentration d'énergie alpha potentielle d'un mélange quelconque de produits de désintégration du radon à courte durée de vie présents dans l'air. A cet effet est utilisé un dosimètre passif, de sorte que la paire de détecteurs (3) identiques est disposée de manière interchangeable dans des chambres (2) géométriquement identiques de même volume, se trouvant à proximité immédiate l'une de l'autre, lesdites chambres (2) présentant les mêmes ouvertures de diffusion (5) et l'une des chambres (2) étant munie d'un filtre (6) isolant les détecteurs (3) qu'elle contient contre les produits de désintégration du radon.
PCT/DE1991/000645 1990-08-17 1991-08-09 Procede et dosimetre passif pour la mesure par integration de la fraction de produits de desintegration du radon dans l'air Ceased WO1992003748A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DDAPG01T/343507/5 1990-08-17
DD34350790A DD301847A7 (de) 1990-08-17 1990-08-17 Passives Dosimeter zur integrierenden Messung des Radonzerfallproduktanteiles in der Luft und Verfahren
DEG9105702.7U 1991-05-03

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Publication Number Publication Date
WO1992003748A1 true WO1992003748A1 (fr) 1992-03-05

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DD (1) DD301847A7 (fr)
DE (1) DE9105702U1 (fr)
WO (1) WO1992003748A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2387988C1 (ru) * 2009-02-11 2010-04-27 Открытое акционерное общество "Научно-исследовательский институт технической физики и автоматизации" (ОАО "НИИТФА") Способ контроля концентрации дочерних продуктов распада радона в воздухе

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE202008014821U1 (de) 2008-11-07 2009-01-15 Wismut Gmbh Passives Dosimeter zur Messung von Radon
CN112229689A (zh) * 2020-09-07 2021-01-15 核工业北京化工冶金研究院 一种用于氡子体测量的采样器

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0021081A2 (fr) * 1979-06-30 1981-01-07 Kernforschungszentrum Karlsruhe Gmbh Dosimètre pour la détection du radon et/ou du thoron et de leurs descendants
US4975574A (en) * 1990-01-05 1990-12-04 Henry Lucas Method of and apparatus for measuring the mean concentration of thoron and/or radon in a gas mixture

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0021081A2 (fr) * 1979-06-30 1981-01-07 Kernforschungszentrum Karlsruhe Gmbh Dosimètre pour la détection du radon et/ou du thoron et de leurs descendants
US4975574A (en) * 1990-01-05 1990-12-04 Henry Lucas Method of and apparatus for measuring the mean concentration of thoron and/or radon in a gas mixture

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Applied Radiation and Isotopes, Band 37, Nr. 7, 1986, Pergamon Journals Ltd, Oxford, GB; J. Bigu: "A method for measuring thoron and radon gas concentrations using solid-state alpha-particle detectors", Seiten 567-573, siehe den ganzen Artikel *
Health Physics, Band 51, Nr. 4, Oktober 1986, Pergamon Journals Ltd, Elmsford, NY, US; M. Wilkening: "Seasonal variation of indoor Rn at a location in the southwestern United States", Seiten 427-436, siehe den ganzen Artikel *
Kernenergie, Band 29, Nr. 3, M{rz 1986, Berlin, DE; O. Sarenio et al.: "Passive Langzeitdosimetrie von Radon und seinen kurzlebigen Folgeprodukten auf der Basis elektrochemisch ge{tzter Polykarbonatdetektoren", Seiten 91-95, siehe den ganzen Artikel *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2387988C1 (ru) * 2009-02-11 2010-04-27 Открытое акционерное общество "Научно-исследовательский институт технической физики и автоматизации" (ОАО "НИИТФА") Способ контроля концентрации дочерних продуктов распада радона в воздухе

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Publication number Publication date
DD301847A7 (de) 1994-05-11
DE9105702U1 (de) 1991-08-14

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