Water quality low background αβ automatic on-line monitoring system
Key words: waste gas
Water quality low background αβ automatic on-line monitoring system
With the rapid development of our nuclear undertakings, the use of nuclear energy in energy, industry and medicine has been more and more widely, and the speed of the construction of nuclear power plants is also accelerating. However, while nuclear energy brings great benefits to human beings, it also increases the possibility of environmental radioactive pollution and public exposure to radioactive pollution and radiation to varying degrees. Due to the short range of α and β particles, their damage to human body is mainly through inhalation and ingestion of internal irradiation, so the detection of total α and total β radioactive activity in drinking water source is particularly important.
At present, the detection methods of total α total β radioactivity in drinking water source in China are as follows: For manual field sampling, the sample water is sent to the testing laboratory with the polyethylene water sample container, and then added into the beaker for heating, evaporation and concentration, and then transferred into the evaporating dish for high temperature burning with Muffle furnace. After cooling to room temperature, the solid residue at the bottom of the evaporating dish was taken out and scraped, and then placed on the sample tray and put into the sample tray of low background αβ measuring instrument for radioactive activity detection. The process of the traditional method is complicated, and human error and uncertainty factors are large. The online monitoring system independently developed by our company introduces reverse osmosis membrane enrichment and concentration method to complete sample preparation and place it in the sample tray of low background αβ measuring instrument for radioactive activity detection, which can realize automatic sample preparation and online detection and solve the drawbacks of the traditional method of total radioactive water quality detection.
It can be applied to daily online monitoring of total alpha and beta radioactivity in surface drinking water sources, emergency monitoring of water radioactivity in military operations and nuclear emergency conditions, and measurement of drinking water radioactivity in other nuclear units and important departments.
Water quality low background total α, β radiation online monitoring system is a set of low background α, β radiation automatic measuring instrument and water sample pretreatment, data acquisition, control, remote monitoring in one of the online automatic monitoring system. It combines modern communication technology and makes use of the present communication network to automatically transmit the measurement results of the instrument, the operating status of the system, the operating status of each instrument, the system log, the system failure, the instrument failure and other information to the central station in real time.
The monitoring center platform software is the upper management software of the water quality low background total α and β radiation online monitoring system. It uses the existing communication technology and computer network technology to achieve accurate, real-time and rapid communication with the remote base station, and is the command center of the whole system to achieve management, control, analysis and maintenance. Its main purpose is to ensure the normal operation of the system and analyze and process the monitored data, so as to provide data support services for the radiation environment management of drinking water source.
The water quality low background total α and β radiation online monitoring base station management system enables authorized users to set various parameters of monitoring sub-stations according to their needs, such as instrument monitoring frequency, gas washing pipeline frequency, algae removal backwash frequency, fault alarm setting, fault alarm type selection, etc. To complete these operations, you only need to select and set them according to the prompts on the monitoring software of the on-site industrial computer. Even without professional training, you can complete the operations.
As a fully automatic water quality low background total αβ online monitoring system, the importance of the system itself running status record is self-evident, so the system designed the operation log function will be all important events and related operations during the system operation classification storage, detailed record can be captured system failure, instrument failure and alarm information, etc. This section describes the possible causes of the fault and the corresponding solutions. In most cases, onsite maintenance personnel can directly rectify the fault as prompted. Considering the development requirements of water quality low background total α, β online monitoring network, the system is specially reserved with a number of types of communication interface, according to the information transmission protocol required by the owner to change the communication protocol of the system.
|FIG. 1 Water quality low background total α, β online monitoring system
|FIG. 2 Xili Reservoir Station in Shenzhen City
|FIG. 3 Water plant site in Xiaojia Village, Linxia, Gansu
Main detector: zinc sulfide (silver) plastic scintillator (NaI detector can be added for γ spectrum acquisition);
Two independent detector, for the sample online cyclic alternating measurement;
Anti-coincidence detector: large volume plastic scintillator, anti-coincidence efficiency is greater than 99%;
Detection efficiency: The 2π detection efficiency of 90Sr-90Y plane β source is greater than 50%, and the 2π detection efficiency of 241Am plane α source is greater than 70%.
α background: less than 0.03cps; β background: less than 0.2cps;
The lower limit of α and β detection (typical conditions) : 0.05Bq/L;
α, β crosstalk: β ray to α channel crosstalk ratio is less than 1%, α ray to β channel crosstalk ratio is less than 3%;
Thickness of lead shield layer: side plate above 5cm, top and bottom plate above 8cm;
Operating environment: Temperature: -10℃ to 40℃; Relative humidity <90%;
The performance indexes of the online monitoring system for water quality with low background total α and β fully meet the requirements of technical indexes in the national standard GB/T11682-2008 Low background total α and β measuring instrument and the requirements for the detection of total α and total β radioactive volume activity in the Sanitary Standard for Drinking Water of GB5749-2006.
① Water quality low background a and β intelligent online monitoring technology: all-weather automatic intelligent online monitoring of low background a and β radioactive activity of surface water, long-term monitoring data is completely saved, and can be set to query statistics. It can continuously reflect the radioactivity change of the measured water, accurately and timely capture the radioactive pollutant discharge accident and send an early warning signal.
(2) Automatic collection and pretreatment of water samples: The water collection module automatically completes the collection of water samples, and carries out the corresponding pretreatment of the collected water samples, filtering the large particles or organic impurities in the water samples without changing the radiation representative of the water samples.
(3) Automatic cleaning technology of water mining module: The water mining module is equipped with automatic air backblowing, multistage filtration, and the full-length sampling pipe should be equipped with an automatic cleaning system. The cleaning cycle can be set or the automatic backblowing cleaning pipe can be carried out according to the change of turbidity value.
(4) Automatic sample preparation technology: Quantitative collection of water samples, using reverse osmosis membrane group filtering and enrichment of radionuclides in the sample water, and the reverse osmosis membrane group after the enrichment of radionuclides in the sample water drying and weighing the weight of the enriched water impurities, to complete the automatic sample preparation of low background a, β radiation detection of water quality.
⑤ Intelligent flow-type sample preparation control technology: Each sample preparation process is realized automatically by intelligent bionic robot arm, without human intervention, reducing the human error of the system and further improving the reliability of the system.
⑥ Low background a, β radiation detection technology: the main detector using array of zinc sulfide plastic scintillation, anti-conformity detector using plastic scintillation, unique a, β waveform identification algorithm, reduce α, β crosstalk.
Comparison of technical advantages
Lanzhou No.1 waterworks;
Lanzhou Zhongchuan Water Plant
Longnan Wudu Waterworks;
Xili Reservoir, Shenzhen;
Shenzhen East Lake Reservoir;
Xiangjiang River Section, Hengyang, Hunan;
Hunan Yongzhou Qiyang Xiangjiang drinking water section;
Gansu Dingxi Waterworks;
Gansu Linxia Waterworks;
Gansu Gannan Waterworks;
Gansu Pingliang tap water
User Usage report