Refine your search:     
Report No.
 - 
Search Results: Records 1-15 displayed on this page of 15
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Development of fission product chemistry database ECUME for the LWR severe accident

Miwa, Shuhei; Miyahara, Naoya; Nakajima, Kunihisa; Nishioka, Shunichiro; Suzuki, Eriko; Horiguchi, Naoki; Liu, J.; Miradji, F.; Imoto, Jumpei; Mohamad, B. A.; et al.

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05

We constructed the first version of fission product (FP) chemistry database named ECUME for LWR severe accident. The first version of ECUME is equipped with dataset of the chemical reactions and their kinetics constants for the reactions of cesium(Cs)-iodine(I)-boron(B)-molybdenum(Mo)-oxygen(O)-hydrogen(H) system in gas phase, the elemental model for the high temperature chemical reaction of Cs with stainless steel, and thermodynamic data for CsBO$$_{2}$$ vapor species and solids of Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$ and CsFeSiO$$_{4}$$. The ECUME will provide more accurate estimation of Cs distribution due to the evaluation of effects of interaction with BWR control material B and stainless steel on Cs behavior in the Fukushima Daiichi Nuclear Power Station.

Journal Articles

Effects of $$gamma$$-ray irradiation on the high temperature oxidation of austenitic stainless steel in supercritical water

Nakahara, Yukio; Yamamoto, Masahiro; Karasawa, Hidetoshi*; Kiuchi, Kiyoshi; Katsumura, Yosuke*

Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10

Three types of commercial-grade austenitic stainless steel, Type 304L, Type 316L, and Type 310S, were immersed in deaerated supercritical water (SCW) of 25 MPa, 550 $$^{circ}$$C with $$gamma$$-ray irradiation for 1000 hours in total. Absorbed dose rates in SCW are estimated at 5-15 kGy h$$^{-1}$$. High temperature oxidation experiments resulted in the formation of two-layer oxide film in which the outer layer is porous iron oxide and the inner layer is dense iron-chromium-nickel oxide. Rate constants of parabolic rate law in net weight gains of Type 304L SS and Type 310S SS are decreased as the $$gamma$$-ray exposure rate is increased. The net weight gain of $$gamma$$-ray irradiated Type 316L SS is sharply fluctuating and decreasing, because the flaking of the outer layer occurred. Hematite is formed in the outer layer on all irradiated samples of examined alloys. The concentration of chromium on the surface is increased by $$gamma$$-ray irradiation. A chromium-rich part in the inner layer accompanying a nickel-rich part in the metal is formed along to the oxide/metal interface of $$gamma$$-ray irradiated Type 304L SS, non-irradiated and $$gamma$$-ray irradiated Type 316L SS.

Oral presentation

Effect of $$gamma$$ ray irradiation on the corrosion of stainless steel in supercritical water

Nakahara, Yukio; Karasawa, Hidetoshi*; Yamamoto, Masahiro; Kiuchi, Kiyoshi; Katsumura, Yosuke*

no journal, , 

A supercritical water-cooled nuclear reactor (SCWR) has been under review as one of advanced reactors. Corrosion tests of several types of stainless steel in supercritical water (25MPa, 400$$sim$$500$$^{circ}$$C) were executed under $$gamma$$ ray irradiation in order to clarify the effect of $$gamma$$ ray on the corrosion. The results of the tests shows that the corrosion of stainless steel was progressed by the growth and degradation of surface oxide film, the dependence of the parabolic rate law constant on temperature can be fit with Arrhenius' equation, $$gamma$$ ray irradiation changed the property of surface oxide film.

Oral presentation

Influence of $$gamma$$ ray irradiation on surface film structures of stainless steels created in super critical water environment

Yamamoto, Masahiro; Nakahara, Yukio; Karasawa, Hidetoshi*; Katsumura, Yosuke*

no journal, , 

Super critical water cooling reactor (SCWR), which has higher energy efficiency than existent reactor, has been planned and examined. To realize the SCWR system, it is important to ensure the reliabilities of the materials used in the super critical condition. Some types of stainless steels were immersed in super critical water with $$gamma$$-ray irradiated condition. After the test, the surface films of stainless steels were analyzed. It was found that hematite (Fe$$_{2}$$O$$_{3}$$) was formed on the surface of oxide film with $$gamma$$-ray irradiation. Contrastingly, complex oxide including Cr and Ni was formed on the surface without $$gamma$$-ray irradiation.

Oral presentation

Effects of $$gamma$$-ray irradiation on the high temperature oxidation of stainless steel in supercritical water

Nakahara, Yukio; Yamamoto, Masahiro; Kato, Chiaki; Kiuchi, Kiyoshi; Karasawa, Hidetoshi*; Katsumura, Yosuke*

no journal, , 

Corrosion experiments of stainless steel (SS) in supercritical water (SCW) have done with a flowing SCW loop including a $$gamma$$-ray irradiated autoclave. Three types of commercial-grade austenitic SS, Type 304L, Type 316L, and Type 310S, were examined. The condition of SCW was adjusted to the core environment of a SCW reactor system. Test samples of the SS were immersed in deaerated pure SCW (25 MPa, 550 $$^{circ}$$C). Feed water was circulated at a flow rate of 4 L h$$^{-1}$$. Absorbed dose rates near the surface of the test samples in SCW were estimated at 5-15 kGy h$$^{-1}$$. The time dependence of net weight gains followed parabolic rate law except $$gamma$$-ray irradiated Type 316L SS. The net weight gains of $$gamma$$-ray irradiated Type 304L SS and Type 310S SS were larger than those of the non-irradiated. Rate constants of parabolic rate law in net weight gains of Type 304L SS and Type 310S SS were decreased as the $$gamma$$-ray exposure rate was increased. The net weight gain of $$gamma$$-ray irradiated Type 316L SS was fluctuating and decreasing widely, because the exfoliation of the surface oxide occurred. On the surface of all the samples, the formation of two-layer oxide film in which the outer layer was porous iron oxide and the inner layer was dense iron-chromium-nickel oxide occurred. Iron oxide in the outer layer was magnetite (Fe$$_{3}$$O$$_{4}$$) with non-irradiated samples. Hematite ($$alpha$$-Fe$$_{2}$$O$$_{3}$$) was additionally formed in the outer layer with $$gamma$$-ray irradiated samples. A chromium-rich part in the inner layer was formed along to the oxide/metal interface of $$gamma$$-ray irradiated Type 304L SS.

Oral presentation

Investigation of in-reactor cesium chemical behavior in TEPCO's Fukushima Daiichi Nuclear Power Station accident, 1; Cesium chemistry team formation and research plan

Mizokami, Shinya; Osaka, Masahiko; Ito, Kenichi*; Karasawa, Hidetoshi*; Honda, Takeshi*

no journal, , 

Overview of the activity conducted in the project (Upgrading level of grasping state inside reactor) by cesium chemistry team will be introduced as a start point of the series presentation.

Oral presentation

Development of long term FP behavior analysis method for TEPCO's Fukushima Daiichi Nuclear Power Plants

Kino, Chiaki*; Karasawa, Hidetoshi*; Uchida, Shunsuke*; Nishioka, Shunichiro; Osaka, Masahiko

no journal, , 

Analysis of the long-term transport behavior of fission products (FP) is important for decommissioning of Fukushima-Daiichi Nuclear Power Station, "Decommissioning analysis code" which can analyze thermal-hydraulic and FP behavior for 10 years after the severe accident has been developed based on SAMPSON code. As the results of test analysis for 2 months after SA, Cs concentration in the wet-well (W/W) decreased slower than that in the case of consideration only with treatment of contaminated water. This result indicates a possible long-term contribution of accumulated Cs in W/W as the Cs contamination source.

Oral presentation

Present status and evaluation methods of contaminated water

Kino, Chiaki*; Karasawa, Hidetoshi*; Uchida, Shunsuke*; Nishioka, Shunichiro; Osaka, Masahiko

no journal, , 

To evaluate the remigration behavior of FP through the aqueous phase in FDNPS for a long term, an analysis methodology of contaminated water was developed based on SAMPSON code. The test analysis result for cesium concentration in the contaminated water in FDNPS unit 1 for 1 year, with the consideration of cesium release from the fuel debris to the aqueous phase had a good agreement with the actual measured cesium concentration.

Oral presentation

Fission product chemistry database ECUME

Imoto, Jumpei; Miwa, Shuhei; Miyahara, Naoya; Nakajima, Kunihisa; Nishioka, Shunichiro; Suzuki, Eriko; Horiguchi, Naoki; Liu, J.; Miradji, F.; Mohamad, A.; et al.

no journal, , 

Fission product (FP) chemistry database ECUME (Effective Chemistry database of fission products Under Multiphase rEaction) consists of three kinds of datasets: CRK (dataset for Chemical Reaction Kinetics), EM (Elemental Model set) and TD (ThermoDynamic dataset). The present ECUME is equipped with the CRK for the reaction of Cs-I-B-Mo-O-H system in gas phase, the EM for the Cs chemical reaction with stainless steel (SS) (Cs chemisorption onto SS) and the TD for CsBO$$_{2}$$ vapor species and solid Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$ and CsFeSiO$$_{4}$$. The Cs chemisorption behavior model has successfully reproduced the effects of CsOH vapor concentration in gas phase and Si content in SS on the Cs chemisorption behavior which were not able to be considered by the existing model. The ECUME are expected to contribute to more accurate evaluation of FP distribution in Fukushima Daiichi Nuclear Power Station.

Oral presentation

Development of fission product chemistry database ECUME for improved source term estimation method, 1; Dataset for chemical reaction kinetics

Miwa, Shuhei; Horiguchi, Naoki; Miyahara, Naoya*; Nakajima, Kunihisa; Suzuki, Eriko; Imoto, Jumpei; Liu, J.; Karasawa, Hidetoshi; Osaka, Masahiko

no journal, , 

We developed the fission product chemistry database named ECUME ($$underline{E}$$ffective $$underline{C}$$hemistry database of fission products $$underline{U}$$nder $$underline{M}$$ultiphase r$$underline{E}$$action) for the LWR severe accident. The dataset for chemical reaction kinetics of ECUME consists of main chemical reactions and their effective chemical reaction kinetic constants. This dataset has the advantages in kinetics evaluation of the effects of molybdenum and BWR control material boron on cesium and iodine chemistry. This can improve prediction accuracy of chemical forms and their fraction in lower temperature region such as a primary containment vessel and a reactor building.

Oral presentation

Development of fission product chemistry database ECUME for improved source term estimation method, 2; Elemental model set

Suzuki, Eriko; Nakajima, Kunihisa; Nishioka, Shunichiro*; Miwa, Shuhei; Horiguchi, Naoki; Imoto, Jumpei; Liu, J.; Karasawa, Hidetoshi; Osaka, Masahiko

no journal, , 

The elemental model set (EM) of ECUME consists of improved models which can be directly incorporated into the present severe accident analysis codes. The models of EM has advantages in considering various chemical conditions. The improved model for cesium (Cs) chemisorption has successfully reproduced the effects of Cs vapor concentration in gas phase and silicon content in stainless steel on the Cs chemisorption behavior. This improved model can contribute to more accurate estimation of Cs distribution in a high temperature area.

Oral presentation

Development of fission product chemistry database ECUME for improved source term estimation method, 3; Thermodynamic dataset

Nakajima, Kunihisa; Suzuki, Eriko; Nishioka, Shunichiro*; Miwa, Shuhei; Horiguchi, Naoki; Imoto, Jumpei; Liu, J.; Karasawa, Hidetoshi; Osaka, Masahiko

no journal, , 

Thermodynamic data of cesium compounds with boron and silicon are included in the thermodynamic dataset (TM) of ECUME. Chemical forms and fractions of cesium compounds formed in high temperature regions of nuclear reactors and revaporization amount of Cs chemisorbed onto stainless steel can be more accurately estimated by using the TM of ECUME. Incorporation of ECUME into severe accident analysis codes can cope with chemical behaviors of FPs influencing their release and transport behaviors and can be expected to improve source term estimations.

Oral presentation

Evaluation of short and long-term behavior of radioactive nuclides distributed in Fukushima Daiichi NPP, 1; Primary procedures for evaluation of short and long-term radioactive nuclide behavior

Uchida, Shunsuke*; Karasawa, Hidetoshi*; Kino, Chiaki*; Naito, Masanori*; Osaka, Masahiko

no journal, , 

Development of analysis code of FP behavior both for short and long terms after severe accident is conduced. A risk analysis method for workers' radiation and FP release is proposed based on the evaluation result for FP distribution during 10 years after the accident.

Oral presentation

Evaluation of short and long-term behavior of radioactive nuclides distributed in Fukushima Daiichi NPP, 2; Major subjects for evaluation of short and long-term radioactive nuclide behavior after severe accident

Karasawa, Hidetoshi*; Uchida, Shunsuke*; Kino, Chiaki*; Naito, Masanori*; Osaka, Masahiko

no journal, , 

FPs that can have impact on the fuel-debris retrieval are selected and amount and radioactivities are evaluated based on FP distribution inside containment predicted by SA analysis code.

Oral presentation

Evaluation of short and long-term behavior of radioactive nuclides distributed in Fukushima Daiichi NPP, 3; Phenomenologically estimation of dose rate in a building based on an accident scenario investigation (Unit-1)

Kino, Chiaki*; Karasawa, Hidetoshi*; Uchida, Shunsuke*; Naito, Masanori*; Osaka, Masahiko

no journal, , 

FP distribution in 1F was phenomenologically evaluated in views of accident scenario. Possible retention of chemisorbed Cs in the separator etc. was implied.

15 (Records 1-15 displayed on this page)
  • 1