Long Term Out-of-pile Thermocouple Tests in Conditions Representative for Nuclear Gas-cooled High Temperature Reactors

During irradiation tests at high temperature, failure of commercial Inconel 600 sheathed thermocouples is commonly encountered. To understand and remediate this problem, out-ofpile tests were performed with thermocouples in carburizing atmospheres which can be assumed to be at least locally representative for High Temperature Reactors. The objective was to screen those thermocouples which would consecutively be used under irradiation. Two such screening tests have been performed with a set of thermocouples embedded in graphite (mainly conventional Type N thermocouples and thermocouples with innovative sheaths) in a dedicated furnace with helium flushing. Performance indicators such as thermal drift, insulation and loop resistance were monitored and compared to those from conventional Type N thermocouples. Several parameters were investigated: niobium sleeves, bending, thickness, sheath composition, temperature as well as the chemical environment. After the tests, Scanning Electron Microscopy (SEM) examinations were performed to analyze possible local damage in wires and in the sheath. The present paper describes the two experiments, summarizes results and outlines further work, in particular to further analyze the findings and to select suitable thermocouples for qualification under irradiation.JRC.F.5-Nuclear Reactor Safety Assessmen

New Temperature Monitoring Devices for High-temperature Irradiation Experiments in the High Flux Reactor Petten

Within the European High Temperature Reactor Technology Network (HTR-TN) and related projects a number of HTR fuel irradiations are planned in the High Flux Reactor Petten (HFR), The Netherlands, with the objective to explore the potential of recently produced fuel for even higher temperature and burn-up. Irradiating fuel under defined conditions to extremely high burn-ups will provide a better understanding of fission product release and failure mechanisms if particle failure occurs. After an overview of the irradiation rigs used in the HFR, this paper sums up data collected from previous irradiation tests in terms of thermocouple data. Some R&D for further improvement of thermocouples and other on-line instrumentation will be outlined.JRC.DDG.F.4-Safety of future nuclear reactor

Squamous cell carcinoma arising in a giant epidermal cyst: a case report.

Epidermal cysts are commonly encountered in surgical practice. Malignant degeneration of epidermal sebaceous cyst is uncommon. The authors report the case of a 38-year Filipino woman presenting with a voluminous sebaceous cyst of the left buttock. Ultrasonography and computer tomography were made preoperatively without any hint of eventual malignant degeneration. Marginal excision was performed with direct closure of the skin. The histological examination revealed epidermal sebaceous cyst with squamous cell carcinoma in situ, which is a quite rare, but well known complication occurring in sebaceous cysts.info:eu-repo/semantics/publishe

Long term out-of-pile thermocouple tests in conditions representative for nuclear gas-cooled high temperature reactors

During irradiation tests at high temperature failure of commercial Inconel 600 sheathed thermocouples is commonly encountered. As instrumentation,in particular thermocouples are considered safety-relevant both for irradiation tests and for commercial reactors, JRC and THERMOCOAX joined forcesto solve this issue by performing out-of-pile tests with thermocouples mimicking the environment encountered by high temperature reactor (HTR) in-core instrumentation. The objective was to screen innovative sheathed thermocouples which would consecutively be tested under irradiation. Two suchscreening tests have been performed in high temperature environment (i.e. temperature in the range 1100–1150◦C) with purposely contaminated heliumatmosphere (mainly CH4, CO, CO2, O2impurities) representative for high temperature reactor carburizing atmospheres. The first set of thermocouplesembedded in graphite (mainly conventional N type thermocouples and thermocouples with innovative sheaths) was tested in a dedicated furnace atTHERMOCOAX lab with helium flushing. The second out-of-pile test at JRC with a partly different set of thermocouples replicated the original test forcomparison.Performance indicators such as thermal drift, insulation resistance and loop resistance were monitored. Through these long-term screening teststhe effect of several parameters were investigated: niobium sleeves, bending, diameter, sheath composition as well as the chemical environment. SEMexaminations were performed to analyze local damage (bending zone, sheath).The present paper describes the two tests, sums up data collected during these tests in terms of thermocouple behavior and describes further instru-mentation testing work with fixed point mini cells for qualification under irradiation.JRC.E.2-Safety of Irradiated Nuclear Material

New Temperature References and Sensors for the Next Generation of Nuclear Power Plants

In preparation for the new challenges posed by the higher temperature environments which are likely to be encountered in the next generation of nuclear power plants, to maintain the safety and to ensure the long-term reliability of such plants, it is crucial that new temperature sensors and methods for in-situ measurement are investigated and developed. This is the general objective of the first workpackage of the joint research project, ENG08 MetroFission, funded in the framework of the European metrology research program. This paper will review the results obtained in developing and testing new temperature sensors and references during the course of the project. The possible continuation of these activities in the future is discussed.JRC.G.I.3-Nuclear Fuel Safet

Long length SPNDs and Distributed Optical Fiber Sensors for Severe Accident remote monitoring & their contribution to Nuclear Safety in the post-Fukushima context

International audienceThe Fukushima-Daiichi nuclear accident of March 2011, and the subsequent loss of internal power supplies after the NPP (Nuclear Power Plant) water flooding caused by the tsunami, leaving the operator TEPCO with almost no information from the reactor pits, demonstrates that safety must always prevail.Accordingly, the French public authorities initiated the RSNR research program, to stimulate and fund new R&D projects to improve the safety of nuclear reactors in service and those of future NPPs.The DISCOMS project (Distributed Sensing for Corium Monitoring and Safety) aimed at developing and testing innovative and passive sensors dedicated to Nuclear Safety, namely an instrumented pole equipped with long length SPNDs (Self-Powered Neutron Detectors)-Thermocouple poles, and Distributed Optical Fiber Sensors, to be installed ex-core in both the reactor pit and concrete floor. The sensors, remotely operated from a safe place, will not only provide additional information during the Severe Accident, but also in post-accidental situation, even in case of loss of all power supplies.The modelling of a 60 year normal operation followed by a Severe Accident for two generations of reactors (Gen II, Gen III) permitted to demonstrate that ex-core long length SPNDs can identify different scenarios: reactor shut down, Normal Operation, Severe Accident without corium relocation, and Severe Accident with corium pouring on the concrete floor.Long length SPNDs were designed and manufactured, along with their electronics, to measure low currents ranging from 1 pA to 100 nA collected under radiations, and qualified in a research reactor with fluxes compliant with modelled scenarios.Optical Fibers Sensor cables are devoted to monitor the Molten Core - Concrete Interaction (MCCI): temperature and strain profiles can be provided in the concrete depth by embedded cables, as a result of using the Raman DTS, Brillouin and Rayleigh OFDR reflectometry techniques, based on the analysis of the backscattered light in single-mode optical fibers, for distributed measurements potentially up to 1000°C with Brillouin instrumentations. Additionally, such sensor cables can be used as fuses with telecom or photon counting OTDRs to detect corium vicinity.Sensor cables and radiation resistant optical fibers have been selected and tested to comply with the radiation conditions in the reactor pits as depicted by the modelling.A final MCCI experiment with prototypical corium, performed at the VULCANO CEA facility, involving also two instrumented SPNDs-Thermocouple poles, has demonstrated the ability of both kinds of sensors and corresponding instrumentations to deliver useful information about the corium status and its progression through the concrete

Long length SPNDs and Distributed Optical Fiber Sensors for Severe Accident remote monitoring & their contribution to Nuclear Safety in the post-Fukushima context

International audienceThe Fukushima-Daiichi nuclear accident of March 2011, and the subsequent loss of internal power supplies after the NPP (Nuclear Power Plant) water flooding caused by the tsunami, leaving the operator TEPCO with almost no information from the reactor pits, demonstrates that safety must always prevail.Accordingly, the French public authorities initiated the RSNR research program, to stimulate and fund new R&D projects to improve the safety of nuclear reactors in service and those of future NPPs.The DISCOMS project (Distributed Sensing for Corium Monitoring and Safety) aimed at developing and testing innovative and passive sensors dedicated to Nuclear Safety, namely an instrumented pole equipped with long length SPNDs (Self-Powered Neutron Detectors)-Thermocouple poles, and Distributed Optical Fiber Sensors, to be installed ex-core in both the reactor pit and concrete floor. The sensors, remotely operated from a safe place, will not only provide additional information during the Severe Accident, but also in post-accidental situation, even in case of loss of all power supplies.The modelling of a 60 year normal operation followed by a Severe Accident for two generations of reactors (Gen II, Gen III) permitted to demonstrate that ex-core long length SPNDs can identify different scenarios: reactor shut down, Normal Operation, Severe Accident without corium relocation, and Severe Accident with corium pouring on the concrete floor.Long length SPNDs were designed and manufactured, along with their electronics, to measure low currents ranging from 1 pA to 100 nA collected under radiations, and qualified in a research reactor with fluxes compliant with modelled scenarios.Optical Fibers Sensor cables are devoted to monitor the Molten Core - Concrete Interaction (MCCI): temperature and strain profiles can be provided in the concrete depth by embedded cables, as a result of using the Raman DTS, Brillouin and Rayleigh OFDR reflectometry techniques, based on the analysis of the backscattered light in single-mode optical fibers, for distributed measurements potentially up to 1000°C with Brillouin instrumentations. Additionally, such sensor cables can be used as fuses with telecom or photon counting OTDRs to detect corium vicinity.Sensor cables and radiation resistant optical fibers have been selected and tested to comply with the radiation conditions in the reactor pits as depicted by the modelling.A final MCCI experiment with prototypical corium, performed at the VULCANO CEA facility, involving also two instrumented SPNDs-Thermocouple poles, has demonstrated the ability of both kinds of sensors and corresponding instrumentations to deliver useful information about the corium status and its progression through the concrete

Long length SPNDs and Distributed Optical Fiber Sensors for Severe Accident remote monitoring & their contribution to Nuclear Safety in the post-Fukushima context

International audienceThe Fukushima-Daiichi nuclear accident of March 2011, and the subsequent loss of internal power supplies after the NPP (Nuclear Power Plant) water flooding caused by the tsunami, leaving the operator TEPCO with almost no information from the reactor pits, demonstrates that safety must always prevail.Accordingly, the French public authorities initiated the RSNR research program, to stimulate and fund new R&D projects to improve the safety of nuclear reactors in service and those of future NPPs.The DISCOMS project (Distributed Sensing for Corium Monitoring and Safety) aimed at developing and testing innovative and passive sensors dedicated to Nuclear Safety, namely an instrumented pole equipped with long length SPNDs (Self-Powered Neutron Detectors)-Thermocouple poles, and Distributed Optical Fiber Sensors, to be installed ex-core in both the reactor pit and concrete floor. The sensors, remotely operated from a safe place, will not only provide additional information during the Severe Accident, but also in post-accidental situation, even in case of loss of all power supplies.The modelling of a 60 year normal operation followed by a Severe Accident for two generations of reactors (Gen II, Gen III) permitted to demonstrate that ex-core long length SPNDs can identify different scenarios: reactor shut down, Normal Operation, Severe Accident without corium relocation, and Severe Accident with corium pouring on the concrete floor.Long length SPNDs were designed and manufactured, along with their electronics, to measure low currents ranging from 1 pA to 100 nA collected under radiations, and qualified in a research reactor with fluxes compliant with modelled scenarios.Optical Fibers Sensor cables are devoted to monitor the Molten Core - Concrete Interaction (MCCI): temperature and strain profiles can be provided in the concrete depth by embedded cables, as a result of using the Raman DTS, Brillouin and Rayleigh OFDR reflectometry techniques, based on the analysis of the backscattered light in single-mode optical fibers, for distributed measurements potentially up to 1000°C with Brillouin instrumentations. Additionally, such sensor cables can be used as fuses with telecom or photon counting OTDRs to detect corium vicinity.Sensor cables and radiation resistant optical fibers have been selected and tested to comply with the radiation conditions in the reactor pits as depicted by the modelling.A final MCCI experiment with prototypical corium, performed at the VULCANO CEA facility, involving also two instrumented SPNDs-Thermocouple poles, has demonstrated the ability of both kinds of sensors and corresponding instrumentations to deliver useful information about the corium status and its progression through the concrete