The Design And Development Of Continuous Level Monitoring System Calibration Tool In Nuclear Power Plant

The utilization of nuclear energy is one of the greatest achievements in the development of human science and technology in twentieth Century. The development of nuclear power plays an important role in promoting social and economic development, improving energy structure, reducing the emission of carbon dioxide and other greenhouse gas. China's nuclear power started in the last century in 80 s which has become more mature after more than 20 years efforts.Even so, mentioning nuclear power plants, people will think of nuclear safety issues immediately.There have been too many serious nuclear accidents in history which resulted in significant personnel and economic losses. Especially the Fukushima accident in Japan which make great impact on the development of nuclear power.After the Fukushima accident, the nuclear power plants in service or under construction made a number of improvements for safety issues aiming at the security hidden danger exposed in Fukushima accident.One of the improvements is the change of the spent fuel pit monitoring instruments.The instruments are not nuclear grade,without seismic treatment and can not guarantee the normal operation of the serious accident before.By comparing the measurement parameters of the available equipment and analyzing installation and information display feasibility, this subject determines to select the CL86+ continuous liquid level monitoring system of FCI company in USA finally. The system can run in accident state and provide the liquid level and temperature signal of the spent fuel pool which are used as a basis for judging the timing of water injection in the spent fuel pit.The instruments need to calibrate to ensure the instruments meet the process requirements before the instruments put into operation.For the time the debugging tool is the VeriCal control box, using the "pressure calibration method" to debug the instruments.But the VeriCal control box has a lot of problems.This paper analyzes the structure of CL86+ continuous level monitoring system and combines with the principle of "pressure calibration method" to solve these problems and finally develops a new set of debugging tools. Through the on-site verification proves the tools can achieve the CL86+ continuous level monitoring system debugging function which improves the test quality and reduces the risk of test.