Pressurizer Valve Piston Opening Before Reactor Overpressure

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Solution Overview

Problem

Conventional pressurizer valves in small modular reactors experience delays in opening, leading to increased pressure in the containment vessel, potentially exceeding the design pressure and damaging the reactor vessel.

Innovation Solution

A pressurizer valve device with a valve piston that automatically opens and closes a communication hole based on internal reactor vessel pressure, discharging steam to the containment vessel to maintain pressure within design limits, using a bellows to separate steam and fluid paths and a valve spring for controlled operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the pressurizer valve is opened only when pressure exceeds design pressure, then the valve opening pressure is maintained, but the response time is delayed and the containment vessel pressure increases

Engineering Contradiction:

Improvevalve opening reliabilityVSAvoidvalve response time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by setting the valve opening pressure lower than the design pressure. This means the pressurizer valve opens before the reactor vessel reaches its maximum design pressure, proactively preventing pressure buildup in the containment vessel. The valve piston is positioned to open at this predetermined lower pressure threshold, ensuring timely steam discharge to the containment vessel before critical pressure levels are reached, thereby avoiding delays and preventing containment pressure excursions.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the pressurizer valve opens at higher pressure to ensure full opening, then the valve opens reliably, but the reactor vessel pressure exceeds design pressure causing damage

Engineering Contradiction:

Improvevalve opening completenessVSAvoidreactor vessel pressure damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements preliminary action by establishing a safe opening pressure threshold that is lower than the design pressure. The valve piston is configured to open at this predetermined pressure level, ensuring that steam is discharged to the containment vessel before the reactor vessel pressure reaches dangerous levels. This proactive approach guarantees complete valve opening occurs at a safe pressure point, preventing both partial opening failures and pressure-induced vessel damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies beforehand cushioning by providing a pressure buffer margin between the valve opening pressure and the design pressure. By setting the opening pressure lower than the design pressure, the system creates a safety cushion that prevents the reactor vessel pressure from reaching critical levels. This pressure buffer ensures that even with pressure fluctuations, the vessel remains well within safe operating limits, preventing damage while ensuring reliable valve operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If the containment vessel pressure increases due to continuous steam discharge, then the pressurizer valve can reopen, but the containment vessel pressure may exceed safe limits

Engineering Contradiction:

Improvevalve reopening capabilityVSAvoidcontainment vessel pressure

Core Design Contradiction:

ProductivityVSStress or pressure

Solution Approach 1:

The patent applies preliminary action by proactively discharging steam to the containment vessel at lower pressure thresholds before the containment vessel pressure becomes problematic. By opening the pressurizer valve at a predetermined pressure lower than design pressure, the system prevents excessive steam accumulation in the containment vessel, thereby avoiding dangerous pressure buildup while maintaining the ability to reopen the valve as needed for pressure control.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Prevents reactor vessel damage by maintaining internal pressure below design limits through timely steam discharge, independent of containment vessel pressure changes, and prevents steam leakage.

Implementation Method 1

a valve piston disposed to be movable in one direction in the interior of the valve housing, and configured to open and close the communication hole depending on a change in a vessel pressure in the reactor vessel

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

the bellows may divide the inner space of the valve housing to block steam from being discharged to the outside

Methodology Applied

Scientific EffectPhysical separation: Physical Containment

Data Source

PatentEP4645341A1Pressurizer valve device and reactor facility including the same

Publication Date: 2025.11.05 KOREA ATOMIC ENERGY RES INST

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AI summary

A pressurizer valve device comprising: a valve housing disposed in a reactor vessel accommodated in a containment vessel, and having a communication hole through which steam in the reactor vessel is introduced, a discharge hole, through which the steam introduced into an interior of the reactor vessel is discharged to the containment vessel, and a connection hole, through which a fluid is introduced; and a valve piston disposed to be movable in one direction in the interior of the valve housing, and configured to open and close the communication hole depending on a change in a vessel pressure in the reactor vessel.