Cementys Newsletter 2015 – N°2

Cementys Newsletter 2015 – N°2

 



Edito

 

Monitoring in order to extend operation life of nuclear power plants
The worldwide average age of nuclear power plants (NPP) is 29 years. Most of NPP were built with a 40 year operating lifetime hypothesis. Therefore plant life extension has become a major issue for the operators.
The main ageing effects of nuclear reactor components are well-known degradations of physical properties : fatigue, stress corrosion, fretting, fouling, thermal and irradiation embrittlement. Due to long term ageing processes, concrete structures are also concerned by life extension issues.A majority of replaceable components
Effective methods of surveillance of the material sensitivity should be implemented during operation to evaluate the ageing process of the equipments. Some items are critical for safety, others are part of a critical system and candidate for run-to-failure or production loss.
Continuous surveillance is the basis for timing and effective maintenance, repair and replacement, within a reliable and cost-effective condition monitoring based maintenance strategy.
High added-value technologies such as optical fiber can optimize the service life maintenance : one application is the thermal mapping of steam generator so as to locate and measure internal deposits on the internal surface (Cementys ThermoLux® SG).Reactor vessels and confinement buildings are difficult to replace
The fast neutrons exposure surveillance of the reactor vessel surface (ferritic steel) helps to optimize the loading process of fuel assemblies in order to control the irradiation embrittlment and extand the remaining lifespan. Testing reactor vessel encapsulated specimens added to various non-destructives evaluations of components are part of a large periodic in-service inspection program.
Precast confinement buidling is subject to concrete creep and hoop tendon relaxation causing prestress losses and concrete micro-cracks.A systematic approach to monitor and analyze these phenomena is the only suited method to cope with the ageing process of the confinement building and concrete structures.
Our expertise in concrete investigations identifies the failure modes and potential irreversible damages over time. Our measurement solutions confirm a « normal » behaviour of a nuclear infrastructure.
This « monitoring know-how » is well-known by French Nuclear Operator EDF, dixit Alexis COURTOIS (Nuclear Concrete Structure Expert) :
« EDF starts monitoring its energy prodution infrastructures during construction : hydroelectric dams, confinement buildings and cooling tower structures. The investigation data collection and analysis provides structural health diagnosis and prognosis. These informations enable EDF to be compliant with its safety regulatory requirements and to ensure a long-tem and optimal asset management. The EDF engineering branch has developed a recognized know-how from the design of a monitoring system to data processing, characterizing the structural health integrity and anticipating the possible maintenance activities ».Not all the sensing technologies are adapted for long-term surveillance
Vibrating wire sensors have a strong track record for confinement building instrumentation : MicroVib® RR (Cementys product : strain extensometer resistant to radiation) can insure long-term measurement (back ground of more than 50 years in France with such vibrating wire sensors).
Optical fiber sensors are also good candidates for long term monitoring strategies. With a track record of 20 years, it represents a good solution to provide long-term measurement in harsh and low-radiation environments. With this technology, it is now possible to measure, with no restrictions, all along of an optical fiber : vibration, strain and temperature : real-time shape of prestressed hoop tendons (Cementys SensoLux® TM) is an example, or vibrating noise mapping of the confinement building or components (Cementys SensoLux® DAS).
Last generations of NPP (APR1400, VVER1200, AP1000, EPR) already benefit from these technologies so as to increase again their safety level.
Making durable the existing nuclear infrastructure to ensure the installed power capacity and increasing the sustainability of next built reactors are the main goals of monitoring programs and lifetime management.

Louis Elcabache
Nuclear & Military Business Development Manager
louiselcabache@cementys.com

Autonomous DTS Interrogator

Cementys is presenting its new optical fiber leak detection system, SensoLux DETECT®
Composed of a Raman DTS interrogator and our 10 miles SensoLux DETECT® cable, our automated and autonomous leak detection system is well adapted for the surveillance of pipelines (water, GNL, gas, etc) or infrastructures such as dikes or dams. Leak detection is effective through temperature distributed measurements all along the SensoLux DETECT® cable, using either passive or active method. Such an autonomous system powered by a solar panel measures liquid leakage every meter with a range of more than 10 miles.

GC’2015 Days
18th & 19th March

The French Association of Civil Engineers (AFGC) is organizing a GC’2015 Technical Workshop dealing with “ecologic and economic transitions for civil engineers”.
Such an event will gather key players in the civil engineering French community to exchange on the latest evolutions of scientific and technical expertise.

Cementys will present a scientific poster : “Surveillance of large bridges by optical fiber sensors”.
The structural health monitoring of the Wadi Leban bridge in Saudi Arabia : a 100% optical fiber instrumentation.

CFBR 2015
8th & 9th April

Cementys share its experience feedbacks on Offshore Structure Monitoring.
During the CFBR symposium (French comity on dams and reservoirs), Cementys will share its exeprience feedback concerning the instrumentation of the Tanger Med II offshore dyke. Many papers dealing with dam and dyke monitoring will be presented. Fabien Neugue, Lead Engineer in charge of the Tanger Med II project, will present his paper “Structural Health Monitoring of the Offshore dikes of Tanger Med II harbor : monitoring of the differential settling and motions of stand-alone concrete gravity based structures (GBS)” on the 9th of April in Chambéry.

Humidity control inside sleeves of pre-stressing cables

Cementys is in charge of monitoring the dehumidification process of the pre-stressing cable sleeves (by thermal and hygrometric monitoring) of the EPR nuclear reactor at… Read more

Topographic surveillance of the Carmes church in Marseille

A restoration of the Grands Carmes neighborhood caused soil movement and settlement of the foundations, which lead to a tilt in the bell tower and the presbytery. Before taking… Read more

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