Numerical assesment of sodium fire incident

Takata, Takashi; Aoyagi, Mitsuhiro; Sonehara, Masateru

IAEA-TECDOC-1972, p.224 - 234, 2021/08

Sodium fire is one of the key issues for plant safety of sodium-cooled fast reactor (SFR) regardless of its size. In general, a concrete structure, which includes free and bonging water inside, is used in a reactor building. Accordingly, water vapor will release from the concrete during sodium fire incident due to temperature increase resulting in a hydrogengeneration even in a dry air condition. The probability of hydrogen generation will increase in accordance with a decrease of a dimension of compartment that corresponds to a small and medium sized or modular reactor (SMR). A numerical investigation of a small leakage sodium pool fire has been carried out by changing a dimension of compartment. Furthermore, numerical challenges to enhance a prediction accuracy of hydrogen generation during sodium fire has also been discussed in the paper.

SNL/JAEA collaboration on sodium fire benchmarking

Clark, A. J.*; Denman, M. R.*; Takata, Takashi; Ohshima, Hiroyuki

SAND2017-12409, 39 Pages, 2017/11

Two sodium spray fire experiments performed by Sandia National Laboratories (SNL) were used for a code-to-code comparison between CONTAIN-LMR and SPHINCS. Both computer codes are used for modeling sodium accidents in sodium fast reactors. The comparison between the two codes provides insights into the ability of both codes to model sodium spray fires. The SNL T3 and T4 experiments are 20 kg sodium spray fires with sodium spray temperatures of 200C and 500C, respectively. The vessel in the SNL T4 experiment experienced a rapid pressurization that caused of the instrumentation ports to fail during the sodium spray. Despite these unforeseen difficulties, both codes were shown in good agreement with the experiments. SPHINCS showed better long-term agreement with the SNL T3 experiment than CONTAIN-LMR. The unexpected port failure during the SNL T4 experiment presented modelling challenges.

Development and validation of Multi-DimensionaI sodium combustion analysis code AQUA-SF

Takata, Takashi; Yamaguchi, Akira

JNC TN9400 2000-065, 152 Pages, 2000/06

JNC-TN9400-2000-065.pdf:6.26MB
JNC-TN9400-2000-065(errata).pdf:0.12MB

ln the liquid metal fast reactor (LMFR) using liquid sodium as a coolant, it is important to evaluate the effect of the sodium combustion on the structure, etc. Most of the previous analytical works are based on a zone model, in which the principal variables are treated as volume-average quantities. Therefore spatial distribution of gas and structure temperatures, chemical species concentration are neglected. Therefore, a multi-dimensional sodium combustion analysis code AQUA-SF (Advanced simulation using Quadratic Upstream differencing Algorithm - Sodium Fire version) has been developed for the purpose of analyzing the sodium combustion phenomenon considering the multi-dimensional effect. This code is based on a multi-dimensional thermal hydraulics code AQUA that employs SIMPLEST-ANL method. Sodium combustion models are coupled with AQUA; one is a liquid droplet model for spray combustion, and the other is a flame sheet model for pool combustion. A gas radiation model is added for radiation heat transfer. Some other models necessary for the sodium combustion analysis, such as a chemical species transfer, a compressibility, are also added. ln AQUA-SF code, bounded QUICK method in space scheme and bounded three-point implicit method in time scheme are implemented. Verification analyses of sodium combustion tests shown in the following have been carried out. (1)pool combustion test (RUN-D1) (2)spray combustion test (RUN-E1) (3)sodium leakage combustion test (Sodium Fire Test-II) (4)smaII-scale leakage combustion test (RUN,F7-1) ln each verification analysis, good agreements are obtained and the validity of AQUA-SF code is confirmed.

Sodium combustion computer code ASSCOPS Version 2.1; User's manual

Ohno, Shuji; Matsuki, Takuo*; ; Miyake, Osamu

JNC TN9520 2000-001, 196 Pages, 2000/01

JNC-TN9520-2000-001.pdf:5.13MB

ASSCOPS (Analysis of Simultaneous Sodium Combustion in Pool and Spray) has been developed for analyses of thermal consequences of sodium leak and fire accidents in LMFBRs. This report presents a description of the computational models, input and output data as the user's manual of ASSCOPS version 2.1. ASSCOPS is an integrated computational code based on the sodium pool fire code SOFIRE II developed by the Atomics International Division of Rockwell International, and on the sodium spray fire code SPRAY developed by the Hanford Engineering Development Laboratory in the U.S. The users of ASSCOPS need to specify the sodium leak conditions (leak flow rate and temperature, etc.), the cell geometries (cell volume, surface area and thickness of structures, etc.), and the atmospheric initial conditions such as gas temperature, pressure, and composition. ASSCOPS calculates the time histories of atmospheric temperature, pressure and of structural temperature.

Development of ceramic liner for FBR building

Himeno, Yoshiaki; Morikawa, Satoshi; Kawada, Koji; Yorita, E.*; Fujiwara, T.*; Kaneshige, T.*; Irie, S.*

PNC TN9410 91-092, 11 Pages, 1991/01

PNC-TN9410-91-092.pdf:1.53MB

To develop a ceramic liner, a selection test of materials, an improvement test of selected material, and a feasibility test of the liner have been conducted.in the selection test, fifty commercially available high temperature cement and ceramics were subjected to thermal shock test (tst), sodium exposure test(set), and sodium flame exposure test (sfet). From test results, alumina/silicon-carbide (AlO-sic)mixture base castable refractory was selected in consideration of material cost, and material availability for a simpler liner construction in the buildings. The selected material was subjected to the improvement test. from the test, proper weight fractions of additives such as alumina cement and silica were determined. Drying conditions were also determined. Finally, a sodium burning pan made of concrete whose inner surfaces were covered with the improved AlO-sic base castable refractory was fabricated and was used for a sodium burning test.

Large-scale test on sodium leak and fire (IV); Test of sodium leak and fire using simulated piping; Run-E2

Morii, Tadashi*; *; *

PNC TN9410 87-088, 59 Pages, 1987/06

PNC-TN9410-87-088.pdf:3.33MB
PNC-TN9410-87-088TR.pdf:3.29MB

A test, Run-E2, of sodium leak from a 1/3.5 scale simulated Na piping of the secondary circuit of Monju was conducted using the SOLFA-2 in the SAPFIRE facilities. In the simulated piping, a leak hole with an area reduced by (1/3.5) from an area of 1/4Dt of the actual piping was made on the upper wall of the piping in advance. In the test, a pressure equal to the system pressure of 3.8 kg/cmg of the hot leg piping in secondary circuit of the actual plant was applied, and sodium was spilled. Spill duration was approximately 13 minutes. The test results showed that the integrity of the insulation structure around the piping will not be broken by a Na Pressure and combustion heat during an accident, therefore, the spray leakage of Na can be fully prevented. Moreover, burning rate of Na during leakage was approximately 4% of the flow rate of the Na leak. Compared to about 30% obtained from the spray combustion test conducted previously using a spray nozzle, the combustion following a realistic Na Leak from the actual piping is found to be milder than that of spray combustion.

Discussion on technology for preventing sodium combustion in the dismantling of a large sodium tank

Hayakawa, Masato; Yoshida, Eiichi; Shimoyama, Kazuhito; Miyakoshi, Hiroyuki

no journal, , 

no abstracts in English

Melting behavior of sodium peroxide produced by sodium fire

Kikuchi, Shin; Koga, Nobuyoshi*

no journal, , 

Sodium peroxide is one of the reaction products of sodium fire, which occurs by the reaction between liquid sodium and oxygen. Melting and evaporation behavior of these sodium oxides are key elements for evaluating plant safety and structural integrity of sodium-cooled fast reactor in relation to the influence on the ambient temperature in case of sodium fire. However, the phase change behavior of sodium oxides is not well revealed because of the experimental difficulties due to high temperature environment and significant chemical reactivity of sodium oxides. In this study, the melting behavior of sodium peroxide was investigated using differential scanning calorimetry (DSC). After careful temperature and energy calibrations of the DSC instrument, enthalpies of sodium peroxide transition and melting were obtained for validating the sodium fire analysis code.

Development of advanced reactor knowledge- and AI-aided design integration approach through the whole plant lifecycle, ARKADIA, 12; Design optimization of containment vessel by ARKADIA-Safety

Uchibori, Akihiro; Okano, Yasushi; Takata, Takashi*

no journal, , 

The evaluation tool, ARKADIA-Safety, has been developed to optimize a design considering safety and economy for advanced reactors such as sodium-cooled fast reactors. In this study, safety assessment for containment vessel during a sodium leak accident was performed to construct a design optimization process. The applied numerical method and evaluation process successfully provided some design conditions which meet the safety criteria and be excellent at economy.