{"id":3114,"date":"2026-05-31T15:29:11","date_gmt":"2026-05-31T13:29:11","guid":{"rendered":"https:\/\/fluiidd.com\/two-phase-void-fraction-use-case-framatome\/"},"modified":"2026-07-20T13:10:31","modified_gmt":"2026-07-20T11:10:31","slug":"two-phase-void-fraction-use-case-framatome","status":"publish","type":"page","link":"https:\/\/fluiidd.com\/en\/two-phase-void-fraction-use-case-framatome\/","title":{"rendered":"Two-phase void fraction – Use case Framatome"},"content":{"rendered":"
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Two-phase void fraction measurement at 330 bar, with Framatome and the CEA<\/strong><\/h1>\n<\/div><\/div>\n\n
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Quantifying the void fraction in the hot leg of a pressurized water reactor, under extreme conditions and with no moving parts, to validate accident simulation codes.
A partnership between Framatome, the CEA and fluiidd.<\/p>\n<\/div><\/div>\n\n

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View the results<\/a><\/div>\n<\/div>\n<\/div>\n<\/div>\n\n
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In a nutshell<\/p>\n<\/div><\/div>\n\n

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Client:<\/p>\n<\/div><\/div>\n<\/div>\n\n

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Framatome \u00d7 CEA - an industrial and research partnership in the French nuclear sector<\/p>\n<\/div><\/div>\n<\/div>\n<\/div>\n\n

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Sector:<\/p>\n<\/div><\/div>\n<\/div>\n\n

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Nuclear energy - Reactor safety
Experimental thermal-hydraulic research<\/p>\n<\/div><\/div>\n<\/div>\n<\/div>\n\n

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The challenge:<\/p>\n<\/div><\/div>\n<\/div>\n\n

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Experimentally validate the calculation codes for a loss-of-coolant accident (LOCA) by quantifying the two-phase void fraction in the hot leg of a Pressurized Water Reactor (PWR) primary circuit<\/p>\n<\/div><\/div>\n<\/div>\n<\/div>\n\n

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The solution:<\/p>\n<\/div><\/div>\n<\/div>\n\n

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Adapt and evaluate the fluiidd scanner on a test loop under extreme conditions, to validate the sensor's robustness and measurement accuracy<\/p>\n<\/div><\/div>\n<\/div>\n<\/div>\n\n

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The result:<\/p>\n<\/div><\/div>\n<\/div>\n\n

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Sensor validated under extreme conditions
Void fraction quantified from 0% to 100%, in steps of 10%<\/p>\n<\/div><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n

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Quantifying the two-phase void fraction under high pressure:
a critical challenge for energy production<\/h2>\n<\/div><\/div>\n\n

In nuclear safety, a detailed understanding of thermal-hydraulic behavior, particularly in accident scenarios, is a top-priority regulatory and scientific requirement. The loss-of-coolant accident (LOCA) is the most studied scenario in the industry. But modeling is not enough: a simulation code is only valuable when compared against real measurements, under near-process conditions. Hence the obstacle: how can you measure a void fraction, and thus track the progression of the accident, in a circuit at extreme pressure and temperature? <\/p>\n

This is the subject of the partnership between Framatome, designer of French nuclear reactors, the CEA, a nuclear research organization, and fluiidd.<\/p>\n<\/div><\/div>\n\n

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nuclear reactors in operation in France <\/h5><\/div>\n<\/div>\n\n
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major nuclear accidents worldwide<\/h5><\/div>\n<\/div>\n\n
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155 bars <\/strong><\/p>\n<\/div><\/div>\n\n

the primary circuit pressure of a PWR<\/p>\n<\/div><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n

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The Challenge<\/p>\n<\/div><\/div>\n\n

3 constraints that rule out standard instrumentation<\/h2>\n<\/div><\/div>\n<\/div>\n\n
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Operating conditions that rule out standard instrumentation<\/h3>\n<\/div><\/div>\n\n

The test loop operates at pressures reaching 330 bar and high temperatures. No commercially available sensor was able to withstand these stresses while maintaining void fraction measurement accuracy. <\/p>\n<\/div><\/div>\n<\/div>\n\n

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The absolute requirement for measurement with no moving parts<\/h3>\n<\/div><\/div>\n\n

In a primary circuit, each mechanical component is a point of risk. The specifications required instrumentation that could be integrated into a custom spool piece, with no moving parts, designed to withstand repeated pressure and temperature stresses. <\/p>\n<\/div><\/div>\n<\/div>\n\n

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Qualify robustness before using any data<\/h3>\n<\/div><\/div>\n\n

Before even considering data exploitation, the absolute priority was to demonstrate that the sensor survived the loop conditions. Mechanical qualification was an essential prerequisite. <\/p>\n<\/div><\/div>\n<\/div>\n<\/div>\n<\/div>\n\n

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\"SCAN42<\/span><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n
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The Solution<\/p>\n<\/div><\/div>\n\n

Deployment method:
from defining the phenomena to mechanical validation<\/h2>\n<\/div><\/div>\n\n

The deployment was carried out on the Benson loop with a view to later installation on PKL, a facility that reproduces at 1:1 height scale the geometry and thermal-hydraulic conditions of a four-loop 1,300 MW nuclear power plant.<\/p>\n<\/div><\/div>\n\n

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