SG primary side main pipeline anti foreign object blocking plate

SG (Steam Generator) is a heat exchange device in pressurized water reactor nuclear power plants. It transfers the heat generated by the reactor from the primary side to the secondary side, turning the water in the secondary circuit into steam to drive the steam turbine generator set to generate electricity.

During maintenance and overhaul, blocking plates that do not withstand system pressure should be installed at the inlet and outlet of the evaporator's coolant to prevent foreign objects from entering the primary side pipeline during construction. But the primary side medium of the evaporator is boron containing water, and the radiation dose, temperature, and humidity in the chamber are all high. To minimize the radiation exposure of operators, the blocking plate design should be suitable for single person operation and make the implementation of the operation simple and fast.

The 300MW original blocking plate of Qinshan Plant 1 is an imported equipment with a weight of 30kg. It has a complex structure and is difficult to disassemble and assemble, requiring two people to operate together. It is prone to hooking rope like objects and has poor safety; When conducting non-destructive testing on equipment, the fixing bolts of the blocking plate have an impact on the equipment, affecting the progress of major repairs, and there is also a risk of bolt detachment.

Sanke Nuclear Power was fortunate enough to undertake the upgrade and development task of the blocking plate. After repeated argumentation, the technical key points have been determined as follows:

1. Circular three panel folding structure with stopper and stopper positioning, no need for careful calibration, fast and time-saving.

2. Use TC4 titanium alloy with high rigidity, high strength, low density, and corrosion resistance, with a total weight controlled below 20Kg. The parts are impact resistant and do not require surface treatment;

3. The installation process only involves placement and does not require screws for fixation; After installation, the blocking plate is flat and sealed, and the dirt generated during SG maintenance will not enter the pipeline.

Application effect: The installation test of the blocking plate proves that the effect is significantly improved. The average installation time has been shortened to 35 seconds, with the fastest being only 28 seconds, greatly reducing the radiation exposure of personnel. The blocking plate is easy to operate, easy to install, structurally reasonable, and safe and reliable when in place. It has received high praise from users in terms of structure, weight, strength, and effectiveness. Not only can it completely replace imported blocking plates, but it also has innovation in many aspects and great promotion and application value.