Experimental study on eutectic reaction between fuel debris and reactor structure using simulant materials

The effect of implanting 57Fe ions on the crystal structure of Nb–Zr alloys has been studied using Mössbauer spectroscopy on 57Fe nuclei and X-ray diffraction. As a result of implantation, a metastable structure was formed in the Nb–Zr alloy. The XRD data indicated a decrease in the crystal lattice parameter of niobium; that is, there was a compression of the niobium planes when implanted with iron ions. Mössbauer spectroscopy revealed three states of iron. The singlet indicated a supersaturated Nb(Fe) solid solution; the doublets characterized the diffusion migration of atomic planes and crystallization of voids. It was shown that the values of the isomer shifts in all three states did not depend on the implantation energy, which indicates the invariance of the electron density on the 57Fe nuclei in the studied samples. The resonance lines of the Mössbauer spectra were significantly broadened, which is typical for materials with low crystallinity and a metastable structure that is stable at room temperature. The paper discusses the mechanism of radiation-induced and thermal transformations in the Nb–Zr alloy, which leads to the formation of a stable well-crystallized structure. A Fe2Nb intermetallic compound and the Nb(Fe) solid solution formed in its near-surface layer, while Nb(Zr) remained in the bulk.

show abstract

“…Developing structural materials for operating and prospective nuclear plants is a very complex scientific and technical task [ 1 , 2 , 3 ].…”

Section: Introductionmentioning

confidence: 99%

Mössbauer and X-ray Studies of Radiation-Induced Processes in Nb–Zr Alloys Implanted with 57Fe Ions

2023

View full text Add to dashboard Cite

show abstract

“…During the past decades, studies focusing on heat transfer within debris beds were performed [32][33][34][35][36][37][38][39][40][41]. In these investigations, in general, the initial debris bed shape was supposed to be homothetically piled [37], cylindrical [38], heap-like [40,41], and Gaussianshaped [39] or conical [16,[42][43][44].…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Mechanisms of Debris Bed Formation Behavior in Severe Accidents of Sodium-Cooled Fast Reactors: Experimental and Modeling Studies

Cheng

2023

Applied Sciences

Self Cite

View full text Add to dashboard Cite

A Sodium-cooled Fast Reactor (SFR) is one of the optimized candidates in Generation IV nuclear reactor systems, but safety is an essential issue for SFR development and application. Most knowledge was accumulated through SFR safety investigations, especially for Core Disruptive Accidents (CDAs). During the CDA of SFRs, the molten materials in the core region are likely to discharge into subcooled sodium and form a debris bed on the lower region of the reactor vessel. Noticing that elaboration on the characteristics and mechanisms of Debris Bed Formation (DBF) behavior should be essential for the subsequent analysis of debris bed coolability and accident progression through various experimental and modeling studies, much knowledge was obtained during the past decades. Motivated to promote future investigations on CDAs of SFRs, the previous experiments and modeling studies on DBF behavior are systematically reviewed and discussed in this paper. The experimental results showed that the flow-regime and accumulated-bed characteristics during DBF were influenced by varying parameters and realistic conditions. Through the modeling studies, several empirical models were proposed for predicting the flow regime and accumulated-bed characteristics in DBF. In addition, to promote further development of research, the future prospects concerning DBF behavior are also described.

show abstract

“…Mechanisms of eutectic reaction between the materials which accelerates the RPV failure is important to understand. In the past, study on eutectic reaction between fuel debris and reactor structure using simulant material was carried out [16]. The objective of this study is to analyze the interaction between molten fuel and electrical tube at the bottom head of a BWR, by using MPS-LER.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Molten Uranium With Electrical Penetrating Tube of a Boiling Water Reactor During Severe Accident

Wulandari

Sutanto

Mustari

2020

gnd

View full text Add to dashboard Cite

INTERACTION OF MOLTEN URANIUM WITH ELECTRICAL PENETRATING TUBE OF A BOILING WATER REACTOR DURING SEVERE ACCIDENT. Fukushima accident was the first severe accident of a BWR type which the core was melted leading to RPV failure at the bottom head. Regarding its complex structures of the bottom head, the scheme of failure is different from that of previous reactor severe accidents that ever happened (i.e. TMI-2 and Chernobyl accidents). There is a lot of penetration tubes through the bottom head leading to a complex interaction between corium and the structures. Eutectic reaction is possible to happen due to high temperature leading to a rapid failure of the RPV. Therefore, it is important to understand the phenomenon of interaction between corium and the structures. In this study, an interaction between molten uranium and structure of electrical tube, one of the penetration tubes, was analyzed by using MPS-LER method. Fluid dynamics of the MPS-LER simulation was validated by experiments of fluid flow by using water and oil.Calculation results of the fluid flow showed a good agreement with that of experiments.The MPS-LER was applied to calculate the penetration rate of molten uranium which flowed through the wall of the electrical tube at the bottom head of a BWR. The penetration rate was high due to eutectic reaction. The rate achieved 555.56 µm/s. Conservatively, it took less than 1 minute of time for the molten uranium to melt the tube wall with a thickness of 1.232 cm.

show abstract

Experimental study on eutectic reaction between fuel debris and reactor structure using simulant materials

Cited by 9 publications

References 30 publications

Mössbauer and X-ray Studies of Radiation-Induced Processes in Nb–Zr Alloys Implanted with 57Fe Ions

Mössbauer and X-ray Studies of Radiation-Induced Processes in Nb–Zr Alloys Implanted with 57Fe Ions

Characteristics and Mechanisms of Debris Bed Formation Behavior in Severe Accidents of Sodium-Cooled Fast Reactors: Experimental and Modeling Studies

Interaction of Molten Uranium With Electrical Penetrating Tube of a Boiling Water Reactor During Severe Accident

Contact Info

Product

Resources

About