JPH08271636A - Method and container for measurement of spontaneous gamma ray dose at bottom of sea or lake - Google Patents

Abstract

PURPOSE: To provide a measuring container which is useful to detect the boundary of geological features, the crushing zone of a fault or the like, to analyze a crushing degree and an opening degree and to analyze the continuity conditions or the like at the bottom of the sea or a lake. CONSTITUTION: As a detection body for a detector, the crystal of Na 1 in which the diameter and the height of a crystal are 12.7cm or higher is used. Ten or more detectors are used for one station, and a measuring container 3 is formed in such a way that its bottom face is a cylindrical shape and that its grounding part is a thin plane. The bottom of the measuring container is not dragged, measuring containers are installed at an interval of 1 to 2m on an arbitrary course 10, and the course 10 is set in such a way that a plane distribution can be analyzed. When the position of a barge 15 is to be confirmed, the bare is positioned by GPS method using two measuring instruments and by a macroscopic optical wave measuring method. When the barge 15 is to be moved and fixed, two or four winches 13 are used, the lengths of wire ropes 14 between anchors 12 and the winches 13 are adjusted so as to fixed the barge. When its position is to be confirmed, a sound wave transmitter 8 is used. When the measuring container 3 is to be lowered, a crane 16 is used, the measuring container 3 is landed so as to control its lowering speed and its lowering position while observing the bottom part of the sea with a light and a television camera and confirming the present position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring gamma dose emitted from radionuclides existing inside or on the surface of the sea / lake bottom, and a measuring container therefor.

[0002]

2. Description of the Related Art The method of analyzing the surface geology by measuring the surface distribution of gamma doses emitted from the three nuclides contained in the surface layer with a Nal detector is described in 1964 by Adams & Fryer (The Natural Rad
iationEnvironment, The University of Chicago Press
p.557) and its use on the seabed in Bow in 1972.
ie, etc. have picked it up and used it for sea floor pollution analysis and surface geological analysis around the nuclear facilities. In the latter measurement method,
Detectors 1-2 with Nal crystals with diameter and height of 10-12.7 cm
The method of dragging a book to the seabed is used. This detector takes about 1 hour to obtain the primary gamma dose of each nuclide with an accuracy of 1%. Therefore, this method can detect fault fracture zones and It is difficult to analyze detailed geological changes such as open cracks with a width of several meters or less.

[0003]

[Problems to be Solved by the Invention] Even high-energy gamma rays of 1.1 to 2.6 Mev emitted from natural radionuclides contained in the surface layer at the sea / lake bottom have a large gamma-ray shielding effect in sea / lake water, The measured gamma dose is about 1/10 of the gamma dose on land with the same surface.
Furthermore, when the distance from the bottom of the sea / lake is 10 cm, this gamma dose decreases to about 50 to 65% on the surface layer, and to 20 cm to 25 to 40%. Therefore, in order to obtain a highly accurate gamma dose in the sea / lake bottom in a short time, it is necessary to increase the gamma ray counting efficiency of the detector, increase the number of detectors, and bring the detectors as close to the bottom surface layer as possible. You will need it.

In order to set a large number of detectors under safe geometric conditions, a method of housing the detectors in a measuring container is used. In this case, if the material of the measuring container is iron, the gamma dose is 50 to 60% at a thickness of 1 cm and at a thickness of 2 cm.
Since it will be reduced to 26-42%, it will be necessary to deal with the thickness of the material of the measuring container.

The measuring container should be installed at a desired position, which is at a sufficient interval for the target analysis, under the conditions where it is difficult to determine the position on the sea or lake, and when the influence of water flow and wind waves is large. , It is necessary to establish a method that can be installed more accurately.

[0006] The main purpose of the present invention is to
It is on the surface of the sea / lake bottom that is required for exploration of natural gas, geothermal heat, groundwater, various ores, tunnel construction under the sea / lake, analysis of leakage mechanism from wells and artificial lakes, and earthquake / landslide prediction research. It is intended to be useful for detecting geological boundaries, fault crush zones, open cracks, etc., and analyzing their crush degree and openness, as well as continuous states at the sea / lake bottom. Regarding the method of analyzing from the measured value of natural gamma dose for these purposes, the applicant of the present invention has already applied for a patent on March 7, 1995, including the case of land.

In view of the above, the present invention provides a detection function necessary for surveying the sea / lake bottom by the above-mentioned method, a measurement container that houses the detection function, and a measurement method therefor.

[0008]

The present invention provides a gamma dose emitted from various radionuclides existing in and on the surface layer at an arbitrary energy range under an arbitrary energy range at an arbitrary point on the sea / lake bottom. On the other hand, it is a method of performing detailed measurement in a plane with high efficiency in a short time, and for that purpose, it is composed of the following conditions.

(1) The detector body of the detector is better than other detector bodies.
Nal has a diameter and height of 12.7 cm or more with a condition that the counting efficiency for gamma rays in the Mev range is remarkably high and the energy resolution is 7% or less that is a resolution that can satisfactorily classify several types of gamma rays of interest. Is used.

In order to evaluate the desired amounts of several kinds of gamma rays in the detector with an error of 1%, a measuring time of about 60 minutes is required for each measuring point. To make this time a few minutes,
Use 10 or more detectors for measurement at one measurement point.

(2) The measuring container is a cylindrical shape having a bottom area where all the bottoms of the detectors can be set up and arranged so that the detectors come close to the bottom of the sea or lake, and the bottom part where the detectors contact is other. The surface is thinner than the bottom surface of the.

(3) In order to increase the degree of adhesion to the sea / lake bottom,
The measurement is performed by closely adhering to the measurement points without dragging on the bottom of the sea or lake. The measurement is carried out by setting an arbitrary survey line at an interval of 1 to 2 m, and the survey line is set so that the plane distribution of the target state can be analyzed.

(4) The measurement container is installed at the measuring point by deciding the position of the pedestal loaded with the measurement container so that the measurement container is brought close to the primary position, and then the winch on the pedestal lowers the measurement container. Close to.

(5) Confirmation of the position of the pier on the sea / lake is 2
Macroscopic positioning is performed by the GPS method using a table, and detailed positioning is performed by a light wave measurement method between two or more bases and measuring instruments on the pontoon.

(6) Two or four winches are used to move and fix the ship to the target position against fluctuations of the pontoon due to sea / lake currents or wind waves, and the wire between the anchor and the winch is used depending on the degree of their influence. The method is to stretch and fix the rope.

(7) To confirm the position on the sea / lake bottom, a method of obtaining the positional relationship with the pontoon using a signal transmitted from a sound wave transmitter installed in the measuring container is used.

(8) A winch is used to descend the measuring vessel from a ship whose position is fixed, and a measurement is performed by observing the sea bottom with a light provided on the measuring vessel and a TV camera and confirming the current position by the above method. Land the vessel while controlling the sedimentation speed and location of the vessel.

[0018]

[Example] Detector and measuring device (see FIGS. 1 and 2) The Nal detector 1 has a Nal crystal 2 having a diameter and height of 12.7 cm.
Use 12 with a resolution of 5 to 7%.

The detector 1 is juxtaposed to the bottom surface of the measuring container 3, and the bottom surface 4 of the measuring container is made flat, and its bottom thickness is 33.
However, the bottom surface portion 5 for accommodating and placing the detector 1 has a thickness of 5 mm due to spot facing. The thinner the bottom portion 5 that houses this detector, the better, but the thickness is determined in consideration of the relationship with the water depth.

A light 6 and a television camera 7 are installed outside the measuring container 3, and a sound wave transmitter 8 and a high-voltage power wave height selector 9 are provided inside the measuring container 3. The irradiation angle of the TV camera was 62 degrees.

Setting of measurement line and measurement time Three measurement lines 10 that cross the assumed fault at intervals of approximately 800 m are installed at 200 m in each extension, and measurement points 11 are set on the measurement line 10 at intervals of 2 m. The score was 303 points. By setting the measurement time at one station to 500 seconds, each measured gamma dose could be kept within an error of about 1%.

Positioning of the Ship In FIG. 3, two GPS devices indicated by E and F are used.
It shows a method of positioning the signals from the artificial satellites A to D as indices, and each measurement point could be measured within an error range of 1 to 3 m every few seconds. In addition, in the light wave measurement method that connects the two bases indicated by G and H to the measuring machine I on the pier 15, every few seconds,
The position of 0.1m unit was confirmed.

Anchors on both ends of the survey line 10 and in the direction intersecting with it.
This anchor and winch 1 using the method of dropping 12,12,12,12
In the method of operating the wire ropes 14,14,14,14 between 3,13,13,13, the pontoon 15 was positioned.

Positioning of Measuring Container The measuring container 3 on the pedestal 15 is placed on the crane after positioning the pedestal.
It was hung with 16 and a wire rope 17, and as shown in FIG. 3, it was landed while considering the observation by the light 6 and the TV camera 7 and the direction and depth indicated by the sound wave of the sound wave transmitter 8. The error was 0.4m at maximum, and 80% could be set within ± 0.1m.

A sound wave receiver J is installed on the pontoon 15, and the positional relationship between the sound wave receiver J on the ship and the sound wave receiver J is known from the sound wave transmitted from the sound wave transmitter 8.

[0026]

The measuring method according to the present invention has a depth of several 100 m.
It is possible to know the gamma doses emitted from various radionuclides existing inside or on the surface of the surface at any point on the sea / lake bottom up to high energy efficiency in a short time for any energy range.

Therefore, exploration of oil, natural gas, geothermal, groundwater, ores under the sea / lake, tunnel construction under the sea / lake, analysis of leakage mechanism from wells, artificial lakes, etc., earthquake / landslide prediction research, etc. It is necessary to detect the geological boundary of the sea / lake bottom surface, fault crush zones, and open cracks, and to analyze the crushing degree and openness of the sea / lake bottom, and to analyze the continuous state of the sea / lake bottom. It can be widely used as a measuring method.

[Brief description of drawings]

[Fig. 1] Front view of measuring container

[Figure 2] Plan view of the above

FIG. 3 is an exemplary diagram showing a measuring method.

[Explanation of symbols]

 1 Nal detector 2 Nal crystal 3 Measuring container 4 Bottom part 5 Thin bottom part 6 Light 7 TV camera 8 Sound wave transmitter 9 High-voltage power wave height sorter 10 Measuring line 11 Measuring point 12 Anchor 13 Winch 14 Wire rope 15 Ship 16 Crane 17 Wire rope A, B, C, D Artificial satellite E, F GPS device G, H Base I Measuring machine J Sound wave receiver

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 2, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art A method of analyzing the surface geology by measuring the surface distribution of gamma doses emitted from the three nuclides contained in the surface layer with a Nal detector is described in Adams & Freee in 1964.
r (The Natural Radiation E
nvironment, TheUniversity
of Chicago Press p. 557) and its use on the seabed was Bowie in 1972.
Have been used for pollution analysis and surface geological analysis of the sea floor around nuclear facilities. In the latter measuring method, a method of dragging one or two detectors having a Nal crystal having a diameter and a height of 10 to 12.7 cm to the seabed is used. This detector takes about 1 hour to obtain the primary gamma dose of each nuclide with an accuracy of 1%. Therefore, this method can detect fault fracture zones and it is difficult to width, such as opening of fractures is <br/> analyzing detailed geological changes in less than several m.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

[0003]

Even gamma high energy of 1.1~2.6Mev emitted from the natural radioactive nuclides, including the surface layer in the sea, lake [0005] In the sea, lake large 蔽 effect shielding of gamma rays The gamma dose acting and measured is about 1 / g of the gamma dose on land where the surface is in the same state.
Becomes 10. Furthermore, at a distance of 10 cm from the bottom of the sea / lake, this gamma dose is about 50-65% on the surface, 20c.
When the distance is m, it is reduced to about 25 to 40%. Therefore, in order to obtain a highly accurate gamma dose in the sea / lake bottom in a short time, it is necessary to increase the gamma ray counting efficiency of the detector, increase the number of detectors, and bring the detectors as close to the bottom surface layer as possible. You will need it.

Claims (2)

[Claims] 1. The gamma dose emitted from various radionuclides existing inside or on the surface of the sea at an arbitrary point of the sea / lake bottom is classified into a specific energy range in a highly efficient and planar manner within a short time. In the measuring method, all the detectors are cylindrical with a bottom area capable of standing on the bottom, and the bottom part where the detector contacts is a flat plate surface thinner than the other bottom parts, and the detector is Na in the Nal detector
l Crystal is large with a diameter and height of 12.7 cm or more and has a resolution of 7%
A measuring container that contains 10 or more of the following: 2. The gamma dose emitted from various radionuclides existing inside or on the surface of the sea at an arbitrary point on the sea or lake bottom is detailed in a planar manner with high efficiency within a short time for each energy range. A measuring method consisting of the following conditions to be measured. (1) The detector shall be a Nal detector, and the Nal crystal used shall be large in diameter and height of 12.7 cm or more and have a resolution of 7% or less, and 10 or more of them shall be stored in the measuring container. (2) The measuring container shall be a cylindrical shape with a bottom area that allows all detectors to stand on the bottom of the measuring container, and the bottom part in contact with the detector shall be a flat plate surface thinner than other bottom parts. . (3) Measurement is performed in units of measurement points, and measurement points can be
It is provided at arbitrary intervals of 2m and the survey line is set so that the plane distribution of the target state can be analyzed. (4) To set the measuring container on the desired measuring point, determine the position of the pedestal on which the measuring container is loaded to bring it closer to the primary position, and lower the measuring container with a winch on the pedestal to bring it to the secondary position. Let (5) To confirm the position of the pontoon, use the GPS method that uses two units to make the primary approach, and make the secondary approach using the optical wave measurement method between two or more bases and the measuring instruments on the pier. (6) Moving or fixing the position of the ship is either two or four provided on the ship.
Using a single winch, the wire rope between the anchor and winch is expanded and contracted and fixed according to the sea and lake flow velocity and wind speed. (7) To confirm the installation position of the measurement container, determine the positional relationship with the sound wave receiver on the pontoon using the sound waves emitted from the sound wave transmitter installed in the measurement container. (8) The measuring vessel descends from the ship by crane, and the sea bottom is observed by the light and TV camera equipped with the measuring vessel and the position of the measuring vessel, while controlling the sedimentation speed and setting position of the measuring vessel.・ Land on the bottom of the lake.