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Gerardi, Craig

Publications and source records attributed to Gerardi, Craig.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Fiscal Year 2018 Sodium-CO2 Interaction Test

An experiment campaign was continued in Fiscal Year 2018 in the Argonne National Laboratory (Argonne) SNAKE facility that investigated the interactions between supercritical carbon dioxide (sCO 2 ) and sodium through injection of sCO 2 into an open surface sodium pool. Two of fifteen previous SNAKE tests revealed that self-plugging of the leakage path/nozzle occurs at higher initial sodium temperatures of about 500 ºC due to chemical reactions involving CO 2 , sodium, and sodium-CO 2 reaction products. At lower sodium temperatures, the interaction phenomena involve consumption of injected CO 2 and formation of an agglomerated mass of reaction products without self-plugging. The FY 2018 test investigated interactions at an intermediate initial sodium temperature of about 411 ºC, representative of the interior of a sodium-to-CO 2 heat exchanger in a Sodium-Cooled Fast Reactor (SFR) sCO 2 Brayton Cycle energy conversion system. The experiment was successfully conducted and did not show self-plugging as evidenced by a sustained chemical reaction between the injected CO 2 and sodium and consumption of CO 2 .

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2018

Development of Process for Cleanup of Sodium-CO 2 Reaction Products

This study describes Argonne’s recent experience in cleaning several kilograms of sodium mixed with solid reaction products formed bysodium-CO 2 interaction. One of the reaction products is carbon monoxide (CO) and precautions have to be taken to protect personnel from exposure to CO. Ethanol was an effective method to clean and dispose of small amounts of residual reaction products embedded in a sodium matrix. Ideally, the residual sodium should be melted out of the parts as possible in order to reduce the amount of time it would take to clean with ethanol since this process is slow.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

FY2017 Sodium-CO2 Interaction Tests

An experimental campaign was carried out in Fiscal Year 2017 in the ANL SNAKE facility that investigated the interaction between sCO 2 and sodium through injection of sCO 2 into a sodium-filled diffusion-bonded heat exchanger channel mock-up. This successful experiment demonstrated that a sustained chemical reaction between the injected CO 2 and sodium occurred at temperatures representative of the cold leg of an intermediate heat transport system for a SFR-to-sCO 2 Brayton Cycle energy conversion system. Evidence of the chemical reaction included: exothermic heatup of localized regions of the test vessel, production of carbon monoxide, consumption of CO 2 and production of solid reaction products that were observed during post-test examination. This experimental result was consistent with previous SNAKE experiments. Two of fourteen previous SNAKE tests confirmed that self-plugging of the leakage path/nozzle could occur at higher initial s odium temperatures due to chemical reactions involving CO 2 , sodium, and sodium-CO 2 reaction products. The remaining tests, including the one carried out in Fiscal Year 2017, began with low er initial temperatures and did not self-plug. A new model was developed to determine the reaction rate constant for sCO 2 injections into sodium by calculating the increase of bulk sodium temperature. This model will be developed further and used to simulate the behavior of reactor-scale sodium-to-sCO 2 heat exchanger failures.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2017

Experimental studies on metallic fuel relocation in a single-pin core structure of a sodium-cooled fast reactor

Experiments dropping molten uranium into test sections of single fuel pin geometry filled with sodium were conducted to investigate relocation behavior of metallic fuel in the core structures of sodium-cooled fast reactors during a hypothetical core disruptive accident. Metallic uranium was used as a fuel material and HT-9M was used as a fuel cladding material in the experiment in order to accurately mock-up the thermo-physical behavior of the relocation. The fuel cladding failed due to eutectic formation between the uranium and HT-9M for all experiments. The extent of the eutectic formation increased with increasing molten uranium temperature. Voids in the relocated fuel were observed for all experiments and were likely formed by sodium boiling in contact with the fuel. In one experiment, numerous fragments of the relocated fuel were found. In conclusion, it could be concluded that the injected metallic uranium fuel was fragmented and dispersed in the narrow coolant channel by sodium boiling

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2016

Fiber Optic Distributed Sensors for High-resolution Temperature Field Mapping

The reliability of computational fluid dynamics (CFD) codes is checked by comparing simulations with experimental data. A typical data set consists chiefly of velocity and temperature readings, both ideally having high spatial and temporal resolution to facilitate rigorous code validation. While high resolution velocity data is readily obtained through optical measurement techniques such as particle image velocimetry, it has proven difficult to obtain temperature data with similar resolution. Traditional sensors such as thermocouples cannot fill this role, but the recent development of distributed sensing based on Rayleigh scattering and swept-wave interferometry offers resolution suitable for CFD code validation work. Thousands of temperature measurements can be generated along a single thin optical fiber at hundreds of Hertz. Sensors function over large temperature ranges and within opaque fluids where optical techniques are unsuitable. But this type of sensor is sensitive to strain and humidity as well as temperature and so accuracy is affected by handling, vibration, and shifts in relative humidity. Such behavior is quite unlike traditional sensors and so unconventional installation and operating procedures are necessary to ensure accurate measurements. This paper demonstrates implementation of a Rayleigh scattering-type distributed temperature sensor in a thermal mixing experiment involving two air jets at 25 and 45 °C. We present criteria to guide selection of optical fiber for the sensor and describe installation setup for a jet mixing experiment. We illustrate sensor baselining, which links readings to an absolute temperature standard, and discuss practical issues such as errors due to flow-induced vibration. This material can aid those interested in temperature measurements having high data density and bandwidth for fluid dynamics experiments and similar applications. We highlight pitfalls specific to these sensors for consideration in experiment design and operation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Experimental Study of Molten Metallic Fuel Relocation in Sodium-Filled Fuel Structures

The Prototype Generation-IV Sodium-cooled Fast Reactor (PGSFR) is being developed by Korea Atomic Energy Research Institute (KAERI). While their design incorporates inherent safety features demonstrated in the landmark Shutdown Heat Removal Test (SHRT) conducted at EBR-II including a large pool configuration and uranium alloy fuel, it is still necessary to evaluate metal fuel relocation and theirs consequences in case of postulated core disruptive accidents. Extensive data regarding fuel relocation in sodium from both in-pile and out-of-pile tests were obtained for oxide fuels in the 1960's - 1970's, while few studies of metallic fuel behavior were performed because of concerns that metallic fuel could not achieve high burnup due to the irradiation induced swelling problem. Following new metal fuel design development that mitigated the swelling problem, experiments regarding interaction of molten metal fuels and liquid sodium have been conducted by several researchers. Most studies that were conducted using metal simulants in various liquids concluded that the molten metals were heavily fragmented after liquid contact and the dominant factors governing the fragmentation were superheating and latent heat of fusion of the molten metal fuel. Gabor et al. conducted experiments using kilogram quantities of various molten uranium alloys in an open sodium pool configuration. They found that the metal fuel fragments were basically in forms of filaments and sheets with a high bed voidage in the order of 0.9. Their calculation indicated that the debris beds formed by relocated metal fuels in an open sodium pool would be largely coolable by conduction heat transfer; and even if deep beds were to form, convective heat transfer and boiling heat transfer could preclude further melt penetration. Although Gabor's tests are useful in evaluating the coolability of relocated metal fuels during a postulated accident in a SFR, they focused on late phase behavior in which the core material relocates downward through the core support plate into the inlet plenum where the structures are more open and thus consistent with the open pool configuration. There is still a knowledge gap related to nature of metal fuel fragmentation and relocation within the fuel assembly structures. Argonne National Laboratory (ANL) is planning to conduct experiments regarding metal fuel relocation in the core structures which mock up the PGSFR's fuel assembly design. In the present study, preliminary tests for demonstration of melting and injecting the metal fuel were conducted using copper. Metal fuel relocation experiments with single fuel pin test section are planned to be conducted for understanding the flow and freezing behavior of the molten metal fuel in a narrow sodium channel and for evaluating the coolability of the relocated fuel. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗