RU2561316C1 - Complex for tests and periodical check of individual doe monitor - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: claimed complex consists of ionizing radiation sources composed of nuclear-physical installations (NPI): nuclear reactor and thermonuclear neutron generators, ionizing radiation converters arranged at propos between ionizing radiation sources and tested objects. These are intended for formation of model gamma- and neutron-radiation fields approximating neutron energy spectrum and ratio between absorbed neutron- and gamma-radiation (D_n/D_γ) doses and penetrating radiation in equilibrium zone of nuclear and neutron bomb blast on exposed terrain and in average-protected object wherein combat individual doe meters are used. Said NPI incorporate monitoring channels for display the results of metrological certification results of said fields on the basis of absorbed doses of neutron and gamma radiations.

EFFECT: higher accuracy of dosimetry in combat conditions with application of nuclear weapons.

1 dwg, 1 tbl

Description

The invention relates to the field of metrological support for dosimetric monitoring of personnel exposure, operating under conditions of combined neutron and gamma radiation, and can be used for testing and verification of individual dosimeters.

When conducting combat operations in the context of the use of nuclear weapons, to assess the combat effectiveness of personnel and determine the required medical care, constant monitoring of its exposure is necessary. For its implementation, existing and newly developed military dosimeters are used. When developing them in order to determine metrological characteristics: sensitivity to the detected radiation, range and measurement error, preliminary and state tests are necessary. After accepting them for supply, it is necessary to conduct periodic verification in order to confirm the above metrological characteristics.

For testing and periodic verification of military dosimeters, various exemplary calibration facilities are used. Recently, the most widely used installations are: the absorbed dose of neutrons UKPN-1M [1], the absorbed dose of gamma radiation UPGD-2M-D [2]. These installations consist of neutron and gamma radiation sources and devices for their placement and devices for installation at the required distances from sources of verified measuring instruments. At the indicated distances from the sources, the radiation fields are certified for the absorbed dose rates of neutron and gamma radiation. Radionuclide sources are used as radiation sources: in the UKPN-1M installation based on ²⁵² Cf and Pu-Be with an average neutron energy of 1.9 and 3.9 MeV, respectively, in the UPGD-2M-D installation based on ⁶⁰ Co and ¹³⁷ Cs with gamma-ray energies of 1.25 MeV and 660 keV, respectively.

During testing and verification, military dosimeters are installed at certified points of the radiation fields and are irradiated for the required time. The absorbed dose values are determined by multiplying the absorbed dose rate values at the indicated points by the exposure time. The described installations are the closest analogue of the invention and are accepted as its prototype.

The sensitivity of most existing and newly developed military dosimeters when measuring the absorbed dose of neutron radiation depends on the energy of the recorded neutrons (the so-called "course with rigidity"). In addition, when measuring absorbed doses of neutron and gamma radiation, military dosimeters do not have sufficient selectivity for the detected radiation against the background of the accompanying one. This means that the accompanying gamma radiation contributes to the readings of the neutron dosimeter, and neutrons contribute to the readings of the gamma radiation dosimeter.

Military dosimeters designed for individual dosimetric monitoring of personnel exposure in the context of the use of nuclear weapons are used in the equilibrium zone of a nuclear weapon explosion. The fields of ionizing radiation in it have specific characteristics: the energy spectrum of neutrons and the ratio of the absorbed doses of neutrons and gamma radiation (D _n / D _γ ) in the open area and inside a medium-protected armament and military equipment (OVVT). The indicated characteristics are given in [3].

The determination of the metrological characteristics of military dosimeters in the radiation fields of exemplary calibration facilities adopted as a prototype, which differ from real fields, leads to an additional measurement error, comparable to or even exceeding the basic error. To eliminate it, it is proposed to determine the metrological characteristics using a specialized testing complex.

A nuclear reactor with a neutron energy spectrum close to the fission neutron spectrum and a thermonuclear neutron generator were selected as radiation sources in this complex. In the radiation fields of the indicated nuclear physics facilities (NFU), model gamma-neutron radiation fields (PGNIM) are created. They are created in barrier geometry using special radiation transformers from various materials. To accommodate radiation transformers and verified military dosimeters, special equipment is used in the form of racks that can be moved in the hall rooms of the NFU. The monitoring of absorbed doses of neutron and gamma radiation during testing and periodic verification of dosimeters is carried out using the monitoring channels included in the NFU, the readings of which are associated with the results of metrological certification of PHNIM fields for absorbed doses of neutrons and gamma radiation.

In FIG. 1 shows the structure of the complex for testing and periodic verification of military individual dosimeters, where:

1 - nuclear reactor

2 - thermonuclear neutron generator,

3 - racks for placement of radiation transformers and tested dosimeters,

4 - radiation transformers,

5 - model fields PGNIM,

The complex consists of a nuclear reactor 1 and a neutron generator 2. In the immediate vicinity of them are racks 3 to accommodate radiation transformers 4 and test dosimeters. Using transformers, model fields of PGNIM 5 are created. Two fields are created at the reactor. The fields of neutron and gamma radiation are formed in them, which are close in the neutron energy spectrum and the ratio Д _n / Д _γ to the radiation fields in the equilibrium zone of the explosion of atomic ammunition in the open area (PGNIM-1) and in the medium-protected OVVT (PGNIM-2). Similar fields (PGNIM-3) and (PGNIM-4) for the equilibrium explosion zone of a neutron munition are created on a thermonuclear neutron generator.

Radiation transformers are sets of discs made of various materials. Their composition, thickness of the disks and the sequence of their location are determined by the NFU, in the radiation fields of which they are used, and by the type of PHNIM model fields that need to be created. For example, at the BARS-1 nuclear reactor [4] and SNEG-13 generator [5], the transformers shown in Table 1 are used. The diameters of the disks are determined by the required dimensions of the fields of the PNIM. For PGNIM created at other NFUs, the compositions of radiation transformers will be different.

The PHNIM fields are in the form of a truncated cone, the small base of which coincides with the outer surface of the radiation transformer. The radiation fields in them are certified by the energy spectrum of neutrons and by absorbed doses of neutron and gamma radiation. For certification in the energy spectrum of neutrons, the neutron activation method is used, based on the use of a set of neutron activation detectors, a radiometric setup for measuring their activities and a spectrum reconstruction program [6]. Certification of PHNIM for absorbed doses of neutron and gamma radiation is carried out using standard dosimetric measurement tools. Its results are presented on the readings of the monitoring channels that are part of the NFU, which are used to control the values of absorbed doses during testing of military dosimeters.

The use of the proposed test complex for testing and periodic verification of military dosimeters of the proposed complex will make it possible to get rid of the additional error due to the difference in the radiation fields in the test volumes of the installations adopted as a prototype from the real fields in which dosimeters are used, and thereby improve the accuracy of personal radiation monitoring composition.

Information sources

1. Installation testing neutron radiation UKPN-1M. Manual. Noginsk experimental plant "Etalon". 1984 year

2. Installation test dosimetric gamma radiation UPGD-2M-D. Manual. Research Institute "Dose". Moscow-Zelenograd. 2010 year

3. Nuclear explosion physics: In 2 vols. Volume 1. Explosion development. Ministry of Defense of the Russian Federation. Central Institute of Physics and Technology. - M.: Science, Fizmat Publishing House, 1997.

4. A.V. Lukin. Physics of pulsed nuclear reactors. - Snezhinsk: Publishing House of the RFNC - VNIITF, 2006.P. 64.

5. V.D. Kovalchuk, V.M. Bagaev, B.C. Troshin, V.I. Trotzik and other SNEG-13 neutron generator. Characteristics of neutron and photon fields. JETP, vol. 104, no. 2 (8), p. 2577-2589, 1993.

6. Kramer-Ageev EA, Tikhonov EG, Troshin B.C. Activation methods of neutron spectrometry. M .: Atomizdat, 1976.

Claims (1)

A complex for testing and periodic verification of military individual dosimeters, consisting of sources of ionizing radiation and racks for placing test dosimeters, characterized in that nuclear-physical installations (NFU) are selected as sources of ionizing radiation: a nuclear reactor and a thermonuclear neutron generator, and the composition of the complex were additionally introduced for the formation of model fields of gamma and neutron radiation, similar in neutron energy spectrum and the ratio of absorbed neutron doses and gamma radiation (D _n / D _γ ) to the fields of penetrating radiation in the equilibrium zone of the explosion of atomic and neutron munitions in an open area and in a medium-protected facility that use military individual dosimeters, ionizing radiation transformers, which are located on racks between sources of ionizing radiation and test objects, moreover, the transformers are made in the form of a set of disks with a diameter providing the required dimensions of the test volume, of various materials and various thicknesses, composition which are determined by the types of applied NFU and simulated fields, as well as monitoring channels that are part of the NFU, used to control the dosimetric characteristics of neutron and gamma radiation during testing and verification of military individual dosimeters.