Research On Safety Design Of Neutron Beam Gate Control System

Neutron Beam Line Switch Assembly is used to cut off the neutron beams that could prevent people from its radiation threat in the neutron Laboratory hall. It is a very important radiation safety barrier, whose reliability directly relates to personal safety in the laboratory hall; It is a complex engineering system, which is not only responsible for control tasks of the 20 shutters and the power system drived by water hydraulic system, but also responsible for the communication with PPS, ecr, and other systems as a logic protection function; Its control system is the soul of the whole Assembly, especially for such a huge and complex system, and the impact of the control system is much crucial. So, how to design a safe and reliable control system is an important task. As the traditional design methods based on experience cannot satisfy the requirements of designing a complex control system, In view of this, this paper aims to explore a design process based on modern method, which also take safety factors into the design process.Neutron Beam Line Switch Assembly is not only a set of non-standard equipment with many innovative technologies and developments, but also an engineering product that must serve for 40 years in the nomal state. It not only needs to meet the needs of its functional requirements, but also needs to consider the maintenance and engineering problems in the process of working. In order to meet this need, this paper put forward a parallel development process of the whole life designing with safety factor and takes the development of Neutron Beam Line Switch Assembly Control System as an example to prove that it is scientific and efficient.This whole-life parallel development process took various considerations and constraints of the system’s whole life as an engineering product during designing stages, and it is an efficient design method for complex system especially. It divided project task into three levels (functional requirements, constraints and user pursuit) scientifically, and established project task demand pyramid model, which could guide designing during other stages conveniently; In the concept exploration stage, based on the independence and information axiom of axiomatic design theory, the scheme of initial design model could be evolved into the best state; In scheme optimization stage, in order to ensure system reliability and safety, this method put system reliability evaluation and risk analysis into intrinsical safety design, and considered human factors, component factors, maintainability, producibility and other constraint conditions in all design stages, which could help to improve the system reliability and avoid unnecessary safety risks by using methods like redundancy design, interlock and so on; In parameter design stage, with the help of computer technologies, it used simulation and established virtual environment to imitate the real system and validate the design, which helped to reduce time and cost of testing and debugging, and provide reliable quality assurance for the project; As an engineering product with 40 years’life, this system needed a series of comprehensive safeguards, which could provide powerful quality assurance and theoretical support for repair and maintenance. In addition, this paper put forward a software design process for this control system based on UML idea, which helped to meet the needs of customers on software functions and operations.Based on this design process, the scheme of this control system had been successfully accomplished, which fully considered human factors, component factors, maintenance and other risk factors. Based on intrinsical safety design, this process put system reliability evaluation and comprehensive risk analysis into designing, which helped to guarantee the system reliability and ensure that the design was scientific and comprehensive. Part of the scheme had been applied to some corresponding function tests, which had obtained full affirmation. But, this project was still being developed and debugging and there maybe many other problems in practice. It still needs to verify and improve in the future work, as some deficiencies and safe risks may also exist. Only in this way, this control system could guarantee the whole equipment’ safety and work for 40 years in good state.