A method for the interim verification of radioactive sources in a radioactive environment laboratory

Abstract

The present invention relates to the technical field of radiation environment monitoring, and specifically discloses a method for the interim verification of radioactive sources in a radioactive environment laboratory, including the following steps: Step 1: Inspect the appearance of the radioactive source to determine whether there is damage. If damage occurs, it is determined that the verification fails and the source is scrapped; if the appearance is intact, proceed to the next step; Step 2: Use a radiation detector to measure the activity of the radioactive source, and compare the measurement result with the activity of the previous verification certificate after decay correction. If the result is determined to be satisfactory, the interim verification of the radioactive source passes; if the result is determined to be unsatisfactory, recalibrate with a third-party calibration agency. The method of the present invention can keep the radioactive source in a controlled state and ensure the accuracy of the detection results.

Description

Technical Field

[0001] The present invention belongs to the technical field of radiation environmental monitoring, and particularly relates to a method for the interim verification of radioactive sources in a radioactive environmental laboratory. Background Art

[0002] A radioactive source is a material or substance commonly used in a radioactive environmental laboratory for calibrating measurement device configurations and evaluating measurements. Therefore, the radioactive source being in a controlled state plays a decisive role in the work quality of an environmental monitoring laboratory.

[0003] According to "CNAS-CL01:2018 General Requirements for the Competence of Testing and Calibration Laboratories" 6.4.10, when interim verification is required to maintain confidence in the performance of equipment, it shall be carried out according to procedures. Interim verification refers to the operation carried out during the use of equipment or between two adjacent calibrations to verify whether its functions or metrological characteristics can continuously meet the method requirements or specified requirements according to the specified procedures.

[0004] Since radiation measurement equipment in a radioactive environmental laboratory needs to be calibrated using a radioactive source, and the radioactive source is constantly in the decay process with the radioactive activity continuously decreasing, it is difficult to meet the guarantee of the stability of the reference material in the above standards. Currently, there is no standard method for stipulating the interim verification of radioactive sources in the laboratory.

[0005] According to Document 1 [Huang Cheng, Lu Liming, Liu Guoping, etc. Application of Conventional Control Chart in the Interim Verification of Reference Materials [J]. Occupation and Health, 2008, 24(18): 1893-1895], this laboratory uses a long-term quality control chart for the interim verification of reference materials. This method requires long-term cumulative data. For general reference materials, the time interval between two calibrations is two years. Therefore, the interim verification is also carried out once every two years, which is not conducive to data acquisition and will make it difficult to verify the stability of the reference material.

[0006] Document 2 [Zhang Hong. Discussion on the Interim Verification of Reference Materials in Environmental Laboratories [J]. Resources Conservation and Environmental Protection, 2015, (12): 115.] selects to send the reference material to a qualified calibration institution or conduct inter-laboratory sample comparison to judge the stability of the reference material. This method is difficult to implement. External calibration loses the meaning of internal laboratory control, increases the workload and laboratory expenses, and there is a large uncertainty in inter-laboratory comparison between external laboratories. In addition to the differences between reference materials, it is also related to large errors caused by measurement equipment, personnel, weighing tools, etc.

[0007] In view of the above actual situation, there is an urgent need to design a method for the interim verification of radioactive sources in a radioactive environmental laboratory. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for the interim verification of radioactive sources in a radioactive environmental laboratory, so as to solve the problem that there is no applicable method for the stability control of radioactive sources in a radioactive environmental laboratory.

[0009] The technical solution of the present invention is as follows:

[0010] A method for the interim verification of radioactive sources in a radioactive environmental laboratory, comprising the following steps:

[0011] Step 1: Check the appearance of the radioactive source

[0012] Check the appearance of the radioactive source to determine whether there is damage. If damage occurs, it is determined that the verification fails and the source is scrapped; if the appearance is intact, proceed to the next step;

[0013] Step 2: Measurement and determination

[0014] Use a radiation detector to measure the activity of the radioactive source, and compare the measurement result with the activity of the previous verification certificate after decay correction;

[0015] If the result is determined to be satisfactory, the interim verification of the radioactive source passes;

[0016] If the result is determined to be unsatisfactory, re-calibrate with a third-party calibration agency.

[0017] In Step 2, the result is determined by calculating the En value:

[0018]

[0019] Where:

[0020] En: Result determination value;

[0021] x: Measured value of the source activity;

[0022] X: Calibration certificate activity of the source after decay correction;

[0023] U x : Expanded uncertainty of the measured value;

[0024] U X : Expanded uncertainty of the decay correction verification value;

[0025] If |En| ≤ 1, the result is satisfactory and the interim verification of the radioactive source passes; if |En| > 1, the result is unsatisfactory and re-calibrate with a third-party calibration agency.

[0026] The calibration certificate activity X of the source after decay correction is calculated according to the method for evaluating the consistency of two data in the "CNAS-GL002-2018 Guidelines for the Statistical Processing and Competence Evaluation of Proficiency Testing Results".

[0027] The described U x , with coverage factor k = 2, is directly given by the measuring instrument.

[0028] The described U X , with coverage factor k = 2, is given by the source certificate.

[0029] The radiation detector is a high-purity germanium gamma spectrometer.

[0030] In step 2, place the radioactive source on the source holder of the high-purity germanium gamma spectrometer probe, set the measurement time of the measurement software, perform spectrum analysis, and obtain the measured value x of the radioactive source activity.

[0031] The remarkable effects of the present invention are as follows:

[0032] (1) The method of the present invention proposes a method for the interim verification of radioactive sources in the field of radioactive environmental laboratories.

[0033] (2) Compared with the quality control chart method and the inter-laboratory comparison method, the method of the present invention has higher operability and accuracy.

[0034] (3) The method of the present invention can keep the radioactive source in a controlled state and ensure the accuracy of the detection results.

[0035] Therefore, the method of the present invention has very wide application value in the quality control management of radioactive sources in radioactive environmental laboratories and is worthy of promotion. Description of the Drawings

[0036] Figure 1 It is a flowchart of the embodiment scheme. Detailed Embodiment

[0037] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0038] A method for the interim verification of radioactive sources in a radioactive environmental laboratory includes the following steps:

[0039] Step 1: Check the appearance of the radioactive source

[0040] Check the appearance of the radioactive source to determine whether there is damage. If damage is found, it is determined that the verification fails and the source is scrapped; if the appearance is intact, proceed to the next step;

[0041] Step 2: Measurement and determination

[0042] Use a radiation detector to measure the activity of the radioactive source, compare the measurement result with the activity of the calibration certificate after decay correction, and calculate the En value:

[0043]

[0044] Wherein:

[0045] En: Result judgment value;

[0046] x: Measured value of the activity of the source;

[0047] X: Activity of the calibration certificate after decay correction of the source, calculated according to the method for evaluating the consistency of the two data in the "CNAS - GL002 - 2018 Guidelines for Statistical Processing and Competence Evaluation of Proficiency Testing Results";

[0048] U x : Expanded uncertainty of the measured value, coverage factor k = 2, directly given by the measuring instrument;

[0049] U X : Expanded uncertainty of the decay correction verification value, coverage factor k = 2, given by the source certificate;

[0050] If |En| ≤ 1, the result is satisfactory and the in - service verification of the radioactive source passes;

[0051] If |En| > 1, the result is unsatisfactory and recalibration by a third - party calibration agency is required.

[0052] Embodiment

[0053] Such as Figure 1 shown, a method for in - service verification of radioactive sources in a radioactive environment laboratory includes the following steps:

[0054] Step 1: Check 60 the appearance of the 60Co standard point source, which is intact without damage;

[0055] Step 2: Place 60 the 60Co standard point source on the source support 25 cm from the detector of the high - purity germanium gamma spectrometer, set the measurement time of the measurement software to 500 s, perform spectrum analysis, and obtain the measured value of the radioactive source activity x = 53440, and the relative measurement uncertainty (k = 2) U x = 787.02;

[0056] Compare with the activity X = 52468 after decay correction in the source calibration certificate, and the relative uncertainty (k = 2) U X = 1603.2, and calculate the En value:

[0057]

[0058] |En| = | - 0.544| < 1, the result is satisfactory and the in - service verification of the radioactive source passes.

Claims

1. A method for the interim verification of radioactive sources in a radioactive environment laboratory, characterized in that: It includes the following steps: Step 1: Inspect the appearance of the radioactive source Inspect the appearance of the radioactive source to determine whether there is damage. If damage occurs, it is determined that the verification fails and the source is scrapped; If the appearance is intact, proceed to the next step; Step 2: Measurement and determination Use a radiation detector to measure the activity of the radioactive source, and compare the measurement result with the activity of the previous calibration certificate after decay correction; If the result is determined to be satisfactory, the interim verification of the radioactive source passes; If the result is determined to be unsatisfactory, re-calibrate with a third-party calibration agency; In Step 2, the result is determined by calculating the En value: Where: En: Result determination value; x: Measured value of the source activity; X: Calibration certificate activity of the source after decay correction, calculated according to the method for evaluating the consistency of the two data in the "CNAS-GL002-2018 Guidelines for the Statistical Processing and Competence Evaluation of Proficiency Testing Results"; U x : Expanded uncertainty of the measured value; U X : Expanded uncertainty of decay correction verification value If |En| ≤ 1, the result is satisfactory and the interim verification of the radioactive source passes; if |En| > 1, the result is unsatisfactory and re-calibrate with a third-party calibration agency.

2. A method for the interim verification of radioactive sources in a radioactive environment laboratory according to claim 1, characterized in that: The described U x , with a coverage factor k = 2, is directly given by the measuring instrument.

3. A method for the interim verification of radioactive sources in a radioactive environment laboratory according to claim 1, characterized in that: The described U X , with a coverage factor k = 2, is given by the source certificate.

4. A method for the interim verification of radioactive sources in a radioactive environment laboratory according to claim 1, characterized in that: The radiation detector described is a high-purity germanium gamma spectrometer.

5. A method for the interim verification of radioactive sources in a radioactive environment laboratory according to claim 4, characterized in that: In Step 2, place the radioactive source on the source holder of the high-purity germanium gamma spectrometer probe, set the measurement time of the measurement software, perform spectrum analysis, and obtain the measured value x of the radioactive source activity.

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