REMOTE SAMPLING AND ANALYSIS OF HIGHLY RADIOACTIVE SAMPLES IN SHIELDED BOXES

摘要

The sampling procedure used for highly radioactive coolant water is associated with high risk of personnel irradiation and uncontrolled radioactive contamination. Remote sample manipulation with provision for proper radiation shielding is intended for safety enhancement of the sampling procedure. The sampling lines are located in an isolated compartment, a shielded box. Various equipment which enables remote or automatic sample manipulation is used for this purpose. The main issues of development of the shielded box equipment intended for a wider ranger of remote chemical analyses and manipulation techniques for highly radioactive water samples are considered in the paper. There were three principal directions of work: 1. Transfer of chemical analysis performed in the laboratory inside the shielded box; 2. Prevalence of computer-aided and remote techniques of highly radioactive sample manipulation inside the shielded box; 3. Increase in control over sampling and determination of thermal-hydraulic parameters of the coolant water in the sampling lines The developed equipment and solutions enable remote chemical analysis in the restricted volume of the shielded box by using ion-chromatographic, amperometrical, fluorimetric, flow injection, phototurbidimetric, conductometric and potentiometric methods. Extent of control performed in the shielded box is determined taking into account the requirements of the regulatory documents as well as feasibility and cost of the technical adaptation of various methods to the shielded box conditions. The work resulted in highly precise determination of more than 15 indexes of the coolant water quality performed in on-line mode in the shielded box. It averages to 80% of the total extent of control performed at the prototype reactor plants. The novel solutions for highly radioactive sample handling are implemented in the shielded box (for example, packaging, sample transportation to the laboratory, volume measurement). The shielded box is equipped with radiation resistant video cameras provided for additional visual inspection. All the acquired information including visual images is sent to the workstation of an operator who controls handling of highly radioactive samples. Authorized participants of chemical control are able to supervise the sampling procedure and process the obtained results via local area network owing to inclusion of the workstation in the common data acquisition, processing and storage system. The paper describes the developed equipment and solutions and discusses the issues related to development of the local computer-aided chemical control system.