Safety level electric ball valve

Abstract

The invention relates to the technical field of a valve, in particular to a safety level electric ball valve for a pebble-bed high-temperature reactor. The ball valve comprises a valve body, a left valve seat assembly, a valve ball, a right valve seat assembly, a blind flange, a magnetic actuator and an electric device. The electric ball valve adopting the technical scheme has the advantages that the dynamic sealing of a valve rod and a valve seat is changed into the static sealing, and the reliable sealing on high-temperature, high-pressure and high-radioactivity helium atmosphere at the pressure boundary part of the reactor in the service life of a pebble-bed high-temperature nuclear power station can be met.

Description

technical field [0001] The invention belongs to the technical field of valves, in particular to a safety electric ball valve applied to a pebble bed high temperature reactor. Background technique [0002] The pebble bed high-temperature gas-cooled reactor uses spherical fuel elements to pass through the core multiple times to achieve non-stop continuous operation. During the operation of the reactor, a certain amount of spent fuel and fuel balls that have not reached the target burnup need to be discharged from the core every day. The latter accounts for the vast majority, and needs to be transported back to the core by means of helium-carrying pneumatic force to continue reaction and recirculation. reactivity. In the fuel loading and unloading system entering and leaving the core, the first valve on the fuel ball pipeline is located at the reactor pressure boundary and belongs to the safety level valve. Different from other safety-level valves, in addition to performing t...

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Problems solved by technology

However, the valve seat and the O-ring seal in the valve stem in the ball valve structure are all soft sealing materials, which are difficult to operate at high temperatures above 260°C for a long time, and the radiation resistance dose of all soft sealing materials is less than or equal to 1X10 5 Gy, while the safety ball valve on the ball flow pipeline in the fuel loading and unloading system must meet the radiation resistance dose ≥ 1×10 due to the passage of fuel balls with high radiation dose. 6 ~10 7 Gy's request

Therefore CN102606760A announces that the polyether sulfone ketone valve seat seal and the valve stem seal with O-ring used in the nuclear first-class electric ball valve announced by CN102606760A cannot be used for the safety grade ball valve on the ball flow pipeline in the fuel handling system. Special requirements for high temperature and radiation resistance

[0004] Chinese invention patent CN102734486A "a low-temperature ball valve combined sealing device" discloses a combined sealing ball valve suitable for low temperature, which adopts a bellows and a polytetrafluoroethylene elastic sealing ring valve seat to change the dynamic sealing into a static sealing to solve the internal problem of the valve. Leakage problem, at the same time, cams are set on the upper and lower valve stems to control the movement of the elastic valve seat to prolong the sealing life. The control cam is a small circle circumscribed by a square that is tangent to a large circle, and the corresponding sphere is also tangent to four vertical surfaces; other static sealing parts use O-ring seals are used. These elastic seals cannot meet the high temperature, strong radioactive and fluid helium seals. This patent also uses the valve stem packing seal, and the super-permeable helium gas can easily move from the valve stem. Seal leakage, and the wear of the valve stem on the packing under the dynamic seal and the impact of high radiation dose on the performance of the packing will further aggravate the leakage of helium

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