HJ 1157-2021Technical specification for the measurement of environmental gamma radiation dose rate (English PDF)

4.1 Purpose of measurement

Environment Radiation dose rate measurement is an integral part of radiation environment monitoring, and its main purpose is.

a) Provide data for estimating the external exposure dose of radiation generated by radiation sources in the environment to key groups of people or members of the public.

b) Provide information for verifying whether the radiation or effluent release of the radiation source meets the requirements of regulations, standards and management limits.

c) Monitor the status of radiation sources and provide warnings for abnormal or unexpected situations.

d) Obtain information on the environmental natural background level of radiation and changes in environmental radiation levels caused by human activities.

e) Provide radiation level information for nuclear and radiation emergency response decision-making.

4.2 Measurement requirements

4.2.1 Radiation environmental quality monitoring generally refers to the investigation of natural or artificial radiation levels and changing trends throughout the country or within a certain area.

4.2.2 Environmental radiation level surveys nationwide or within a certain area, usually with grids with appropriate distances evenly distributed, and the grid size is average Optional 25 km×25 km, 10 km×10 km, 5 km×5 km or smaller areas, buildings, roads and fields located in the same grid point Point, environment radiation dose rate measurement can be carried out together.

a) Field measurement point selection

1) The lawn in the city, the grass in the park, and certain islands, mountains, virgin forests and other places that are not easily affected by human activities, it is possible to select and set points appropriately and measure regularly.

2) The point should be far away from tall trees or buildings, and the distance from nearby tall buildings should be greater than 30 m.

3) The topography of the site should be flat, open, free of stagnant water, bare soil or covered by vegetation, avoid choosing the surface soil in the environment to change Location (such as dirt, gravel, concrete, asphalt, etc.).

b) When carrying out road surveys, the points should be set on the center line of the road.

c) When carrying out indoor measurement, the point should be set at the position where the personnel stay for the longest time or the indoor center position.

d) Other

1) The measurement results are related to the ground (including surrounding buildings), groundwater level, soil composition and water content, rainfall, snow and ice cover, tides, release the ground subsidence of radioactive materials, the precipitation of emissive gas, and the diffusion conditions are related to environmental factors. Pay attention to their influence when measuring; avoid other surrounding the influence of natural or man-made factors on the measurement results, such as lakes and beaches, near the storage yards of bricks, ore and cinder, etc., for special attention measurement Point, can not be subject to these restrictions.

2) The selection of the measurement time should be representative. In the field measurement, the measurement is generally not carried out in rainy day, snowy day, after rain and within 6 h after snowy day.

the amount.

4.2.3 For the automatic monitoring station of radiation ambient air for continuous measurement, the following points should be paid attention to when selecting points.

a) The location of the points should be representative, taking into account the layout of the area and population factors, and taking full account of the representativeness of the region and the representativeness of the resident dose.

b) The construction plan of the area should be fully integrated. Once the location is determined, it should generally not be changed to ensure the continuity and comparability of the measurement data.

c) Comprehensive consideration should be given to guarantee conditions such as point power supply, lightning protection, waterproof flooding, communication, traffic, and safety. In principle, the electricity supply adopts the city the voltage stability is better than ±10%; it has a stable wired data communication link and wireless communication signal for the communication department; it is advisable to use fences and other hand the segment establishes a relatively independent site space.

4.2.4 When performing continuous measurement, the relevant local meteorological parameters, such as temperature, humidity, wind speed, wind direction, rainfall (snow) amount, etc., should be obtained simultaneously.

4.2.5 The environmental measurement points around nuclear facilities should be centered on the nuclear facility, divided into sectors according to different distances and directions.

Layout in principle, where crowds often stop in areas where key people are located, on the plant boundary closest to nuclear facilities, and on plant boundaries that dominate the wind direction.

The places to stay and the places where the maximum landing concentration is outside the factory are densely distributed. Continuous measurement of the periphery of large nuclear facilities such as nuclear power plants and spent fuel reprocessing facilities the location is generally centered on nuclear facilities, covering 16 azimuths in the Yanyu Planning Area (the coastal nuclear power plant is located on the sea side as needed.

Design), the environmental radiation dose rate generated by artificial radionuclides in the plume and surface sediments should be considered. Should choose some that are not susceptible to nuclear the measurement points affected by the facility are used as control points.

4.2.6 For nuclear technology utilization facilities operating intermittently, measurements should be carried out under normal operating conditions of the facility. The measurement points should be representative, the location where the environment radiation dose rate level is relatively high can be determined through patrol survey; the location should consider factors such as radiation source release and transfer route; should Focus on personnel staying for a long time and weakly protected locations. When the building where the facility is located is a single-storey building, the distribution of points should consider the effect of sky scattering on measurement the impact of results.

4.2.7 For the measurement of heap leaching uranium mining and metallurgical facilities, the points are usually arranged in grids with appropriate spacing within 5 km of the mining area, so that the grid density does not miss the source.

Item is the principle. It can be done by means of patrol surveys to encrypt survey points in areas with high radiation levels, usually including tailings (slag) warehouses, waste rock yards, at the boundary of the wind direction facilities under the exhaust shafts, the nearest residential areas around the facilities, and roads that are easy to spill minerals, etc.; in-situ leaching uranium mining and metallurgical facilities survey, pass it is often arranged around the factory boundary and the nearest residential area.

4.2.8 The measurement of associated radioactive mining and smelting facilities is usually located within a range of 3 to 5 km around the mining area.

4.2.9 Emergency measurement

4.2.9.1 In the event of an accident, a quick response should be made in accordance with the prepared emergency plan. Nuclear power plant nuclear accident environment radiation dose rate measurement, refer to HJ 1128 for execution.

4.2.9.2 Use the existing multiple measurement methods and means, select the appropriate instrument for the measurement range and energy response, and quickly determine the impact of the accident Scope and environment Radiation dose rate level.

5.1 Formulation of measurement plan

5.1.1 The measurement plan should generally include the purpose, scale and scope of the measurement, the type of radiation source to be measured, the surrounding environment, and the frequency of measurement.

Principles and requirements for point layout, instruments and methods used, measurement procedures, data processing methods and statistical inspection procedures, work records and results Fruit evaluation, quality assurance, etc. The measurement points should be arranged according to the purpose of measurement, combined with the source and exposure route, population distribution and human activities.

Choose carefully.

5.1.2 Nuclear fuel cycle facilities other than spent fuel reprocessing facilities, and associated radioactive mine development and utilization facilities, etc., environmental radioactive agents the measurement scheme of the measurement rate can be simplified appropriately. Some instruments containing radioactive sources used in some practices, such as radiation sources with relatively low potential hazards, should be properly shielded Under strict custody and control, there is no need to formulate environmental radiation dose rate measurement plan.

5.2 General requirements for instrument specifications

The instrument used for environmental radiation dose rate measurement should have the following main performances.

a) Range. The lower limit of the range should not be higher than 1×10-8 Gy/h; the upper limit of the range should be selected according to the type and activity of the radiation source.

In the case of measurement, ensure that the upper limit of the range meets the requirements, generally not less than l×10-2 Gy/h.

b) Relative inherent error.

At 1.1, the instrument should be overhauled and re-verified/calibrated), where A0 and A are verification/calibration and measurement time respectively.

The net response value of the instrument to the same test source (the decay correction of the test source needs to be considered); if the instrument has no test source, the value is taken as 1];

gammaR-the average value of the readings measured by the instrument (the conversion coefficient of air kerma and surrounding dose equivalent refers to JJG 393, using 137Cs when using 60Co and 60Co as the verification/calibration reference radiation source, the conversion coefficients are respectively 1.20 Sv/Gy and 1.16 Sv/Gy), Gy/h;

k3-the correction factor for shielding cosmic rays of buildings, 0.8 for buildings, 0.9 for bungalows, and 1 for fields and roads;

cD --The cosmic ray response value at the measuring point (due to the altitude and latitude of the measuring point the surface is different, the response value of the instrument to the cosmic ray at the measuring point needs to be corrected. Refer to the specific calculation and correction method.

HJ 61), Gy/h.

6.1 Measurement record content

Refer to Appendix A for the original measurement records. Record content includes. project name and location, point name and point description, weather conditions, temperature and humidity Degree, measurement date, name, model and number of the measuring instrument, verification/calibration factor, efficiency factor, reading value, measurement value and the standard deviation, the person who measured it, the person who checked it, and the date of data checking, etc. Record the geographic information of the measurement point as needed, and take photos of the measurement site If necessary, record information such as working conditions, altitude, latitude and longitude, and cosmic ray deduction.

6.2 Measurement report

6.2.1 The content of the measurement report includes. measurement object, measurement date, measurement point description, measurement method, instrument name, model and inspection Calibration/calibration information, radiation air absorbed dose rate measurement results, standard deviation or uncertainty, etc.

6.2.2 The measurement report shall be reviewed and issued in accordance with relevant regulations.

7.1 Quality Assurance Plan

The quality assurance plan should include. training, assessment and qualification requirements for personnel; quality control measures for measuring instruments and auxiliary equipment;

Traceability of the value of instruments and inspection sources; quality control measures between laboratories; documents to be provided to prove that the required quality has been achieved and maintained.

7.2 Quality control measures

7.2.1 The measurement personnel need to receive professional training related to environmental radiation dose rate measurement, and can only work after passing the assessment.

7.2.2 Environment Radiation dose rate measuring instruments should be periodically verified/calibrated, or through other methods of value transmission, to ensure that the value can be traced to the country.

Domestic measurement standards; should regularly participate in environmental radiation dose rate measurement and comparison.

7.2.3 For instruments with a high frequency of use and an inspection source, the inspection source shall be used to inspect the working status of the instrument every day during the working period.

7.2.4 When updating the instrument and method, the measurement results of the original instrument and method should be compared with the measurement results of the original instrument and method under typical and extreme radiation field conditions.

In order to maintain the consistency of the data.

7.2.5 Period verification

7.2.5.1 Regularly carry out in a stable indoor radiation field or outdoor environment (for frequently used instruments, 1 time/month is appropriate) Measure and draw quality control charts to check the stability of the environment radiation dose rate measuring instruments.

7.2.5.2 Check the environment with a test source (137Cs or 60Co) at least once a year radiation dose rate measuring instrument k value, k=|Am/A0-1| (Am and A0 are respectively the net response value of the instrument to the test source during period verification and verification/calibration, and the decay correction of the test source needs to be considered). k<=0.1, it is qualified; k >0.1, the instrument should be overhauled and re-verified/calibrated.

7.2.5.3 For emergency measurement environment radiation dose rate measuring instruments, the response to the inspection source shall be measured at least once a quarter.

7.2.6 For large-scale environmental radiation level surveys, at least 3 comparisons should be carried out before, after and during the survey work.

The secondary comparison is carried out at 6-10 points with different radiation levels and regional conditions, preferably with water surface measurement points; when conditions permit, it should be carried out.

Comparison between the same measurement unit; during the use of the instrument, the background measurement should be carried out every day; at the beginning, middle or end of each measurement, Relative to the reading value of the calibration source of the measuring instrument at a fixed position, determine the efficiency factor (k2) of the calibration source of the instrument.

7.2.7 Environment The measurement of radiation dose rate should use the instrument with relatively small inherent error, and the uncertainty evaluation of the measurement result should be included in the instrument the uncertainty of the reading and the uncertainty of the instrument verification/calibration factor, when the cosmic ray response value is deducted from the measurement result, should also be included in the instrument's space.

Uncertainty of the reading of the universe ray response Environment The extended uncertainty of radiation dose rate measurement should generally not exceed 20% (including factor k = 2, the corresponding inclusion probability is about 95%).

7.2.8 Quality assurance activities shall be recorded as required, and the completeness, adequacy and traceability of all recorded information shall be ensured.

7.3 Record filing

The original measurement records, quality assurance records, measurement reports and other important data shall be archived and kept in accordance with regulations.

Certainly, copies of important records must be kept separately.