توسعه یک سیستم تجزیه و تحلیل شبیه سازی سه بعدی برای مکانیزم کنترل PWR میله درایو

A 3-D virtual analysis system to analyze the motion of control rod drive mechanism (CRDM) was developed. The analysis system consists of a 3-D model established as per the actual dimensions and interfaces of CRDM parts and a routine to calculate the forces acting on the mechanism, and was verified by mock-up test using the same equipment as the actual product. The analysis system is useful for functional evaluation in maintenance or to factor out root causes in the case of malfunction of CRDM.

Control rod drive mechanism (CRDM) (Fig. 1) is an important equipment to drive control rods vertically to control the negative reactivity of a reactor. CRDM is mounted on a reactor vessel closure head. CRDM mechanical subassembly called latch assembly is submerged in a primary coolant inside the pressure boundary and is activated by magnetic force sequentially generated by CRDM drive coils outside the pressure boundary. Direct access is not allowed for the latch assembly without a cutoff operation of the pressure boundary. It is important for plant management to establish method to factors out root causes in case of malfunction of CRDM which have been reported in several plants a year or to monitor aging trend of CRDM. The motion of CRDM can be evaluated from coil current of drive coils and sound traces from operational test data in outage duration of plant that show aspects of the motion of CRDM (Fig. 2). But this existing evaluation method to confirm the completion and timings of each sequential motions of CRDM cannot provide enough information for quantitative evaluation of motion of CRDM and for future maintenance plan. To establish the quantitative evaluation method for the motion of CRDM, 3-D virtual dynamic analysis simulator to simulate the motion of CRDM was developed.

The 3-D dynamic analysis simulator was developed to evaluate quantitatively the motion of CRDM. The 3-D simulator was verified to finely simulate the CRDM motion including its sensitivity against variable parameters. The 3-D simulator to perform the virtual tests will contribute to effective and quantitative evaluation and also reduce the efforts significantly to factor out root causes against delay or malfunction of CRDM.