Main Steam Discharge Isolation Valve

The Main Steam Discharge Isolation Valve adopts an integrated design with a symmetrically arranged pilot control mechanism, featuring a compact structure and reasonable spatial arrangement to enhance the seismic resistance of the valve. The valve consists of a main valve, manual isolation valve, manual pilot valve, piston chamber pressure measurement isolation valve, solenoid pilot valve, etc., and is equipped with valve position analog measurement devices and valve position open/close detection devices, enabling remote control and monitoring.

In 2022, it passed the industry scientific and technological achievement assessment. The assessment committee concluded that the developed Main Steam Discharge Isolation Valve is successful, fills a domestic technical gap, achieves advanced international levels in major performance indicators, with some indicators surpassing foreign products, and can be promoted and applied in HPR1000 (Hualong One) and other nuclear power units. "HPR1000 (Hualong One) Nuclear Power Main Steam Discharge Isolation Valve" was recognized as the fourth batch of major technological equipment in the energy field in 2024.

(1) Main Technical Parameters

Product Model: H2J54C-550-350

Nominal Diameter: DN350 (14″)

Nominal Pressure Class: Class 550

Design Pressure: 8.9 MPa

Design Temperature: 316°C

Working Medium: Steam, steam-water mixture, or water

Safety Class: Safety Class 2

Quality Assurance Requirement: Q1

Seismic Category: Category I (Operability)

Service Life: 60 years

Cycle Life: 1000 cycles

Fundamental Frequency: >50 Hz

Seismic Acceleration: Three directions (4g, 4g, 4g)

Opening Time: ≤1.8 s (opening dead zone time ≤1.5 s, opening action time ≥0.1 s)

Closing Time: <20 s

Mass Flow Rate: 1060 t/h ≤ Q ≤ 1272 t/h

Full Open Valve Pressure Drop: ≤0.535 MPa

Minimum Opening Pressure: 0.14 MPa

(2) Scope of Application

The Main Steam Discharge Isolation Valve (H2J54C-550-350) is mainly used in the Steam Discharge to Atmosphere (VDA) System of pressurized water reactor nuclear power plants to perform isolation functions, residual heat removal, and overpressure protection functions.

Main Functions: (1) Isolate the steam side of the Steam Generator (SG) under the condition of excessive steam flow increase or steam line rupture to limit Reactor Coolant Pump (RCP) overcooling; (2) In Steam Generator Tube Rupture (SGTR) conditions, increase the VDA setpoint of the corresponding SG after partial cooling is completed to limit radioactive release; (3) When VDA is required for residual heat removal or overpressure protection, VDA needs to be able to open quickly for discharge.

(3) Application Status of Achievements

Dalian Dago Valve Co., Ltd. and China Nuclear Power Engineering Co., Ltd. signed supply contracts for the Lufeng Project Units 5 and 6 LOT190ce VDA Main Steam Discharge Isolation Valve in 2021; and signed supply contracts for the Fangchenggang Project Units 5 and 6 LOT190ce VDA Main Steam Discharge Isolation Valve in 2023.

(4) Intellectual Property Status

3 authorized invention patents (A Test Device and Test Method for Dynamic Performance of Pilot-Type Steam Discharge Isolation Valve for Nuclear Power, Main Steam Discharge Isolation Valve, Double-Piston Pilot-Type Angle Globe Valve with Spring Return Structure), 3 authorized utility model patents (A Multi-Position and Displacement Detection Device, A Double-Piston Pilot-Type Angle Globe Valve with Spring Return Structure, A Main Steam Discharge Isolation Valve), 1 paper published in "Valve" Issue 5, 2023: "High Reliability Fast Opening Main Steam Discharge Isolation Valve", Article Number: 1002-5855 (2023) 05-0530-06.

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