Modelling and simulant experiments of severe accident phenomena (MOSES): Experiments on dryout heatflux in volumetrically heated granular particle bed with the STYX facility

Stefan Holmström, Pekka Pankakoski, Ensio Hosio, Ilona Lindholm, Jaakko Miettinen, Risto Sairanen, H. Sjöval

    Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional

    Abstract

    Core debris coolability in the containment is studied to verify the severe accident management strategy adapted in Olkiluoto BWRs. The molten core material discharged from the failed reactor pressure vessel falls into a several meters deep water pool in the Olkiluoto containment. It is most likely, that the melt will fragment on its way down in the subcooled water pool and form a self-heating particle debris bed on the pedestal floor. The coolability of this particle bed is the key question to be answered. The problem of particle bed coolability has been approached first by defining the representative particle size distribution for Olkiluoto plant [1]. The mass-averaged particle size of this distribution was determined to be 3.46 mm with the particle size ranging from 0.25 mm to 11 mm. The particles formed in melt-coolant interaction tests were generally non-spherical. Second, a literature review on existing debris bed coolability experiments was carried out [3]. An extensive dryout heat flux database exists for beds of single-sized, spherical particles. Some data is available for homogeneously mixed or stratified beds with particles having a narrow size distribution from POMECO tests [4], and for homogeneous and stratified beds with wider particle size range from DCC tests [5],[6]. However, the particle shape may have been more uniform in the POMECO tests (natural sand) and DCC tests (UO2 particles) than resulted e.g. FARO experiments and MACE tests with formation of particulate. The available calculational models were sensitive to the particle size and bed porosity, yielding results from easily coolable to non-coolable situation with a relatively small parameter range. Most of the measured data and all the calculational models suggested that a bed with average particle size of 3.5 mm would have a dryout heat flux close to 1 MW/m2 and thus would be easily coolable. For investigating of the effects of Olkiluoto specific particle bed characteristics on dryout heat flux an own simulant material test facility, STYX-1 [2] was constructed at VTT as a combined effort between VTT Industrial Systems and VTT Processes. The particles in STYX bed follow the representative size distribution constructed for Olkiluoto case and the shape of particles is irregular. The bed depth is determined to be the same as expected in Olkiluoto plant if the whole corium inventory would spread uniformly on pedestal floor. VTT Industrial Systems designed and built a test rig capable of heating a pressurised test bed immersed in water to a heat flux up to 1 MW/m2 and run the tests. The resulting power and temperature distribution data is utilised by VTT Processes to model and assess the coolability concepts related to severe accident management in the Olkiluoto BWR.
    Original languageEnglish
    Title of host publicationFINNUS: The Finnish Research Programme on Nuclear Power Plant Safety 1999-2002
    Subtitle of host publicationFinal Report
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Pages187-195
    ISBN (Electronic)951-38-6086-8
    ISBN (Print)951-38-6085-X
    Publication statusPublished - 2002
    MoE publication typeNot Eligible

    Publication series

    SeriesVTT Tiedotteita - Research Notes
    Number2164
    ISSN1235-0605

    Fingerprint

    accident
    modeling
    particle size
    experiment
    heat flux
    containment
    particle
    test
    melt
    heating
    literature review
    vessel
    deep water
    porosity
    water
    sand

    Cite this

    Holmström, S., Pankakoski, P., Hosio, E., Lindholm, I., Miettinen, J., Sairanen, R., & Sjöval, H. (2002). Modelling and simulant experiments of severe accident phenomena (MOSES): Experiments on dryout heatflux in volumetrically heated granular particle bed with the STYX facility. In FINNUS: The Finnish Research Programme on Nuclear Power Plant Safety 1999-2002: Final Report (pp. 187-195). Espoo: VTT Technical Research Centre of Finland. VTT Tiedotteita - Research Notes, No. 2164
    Holmström, Stefan ; Pankakoski, Pekka ; Hosio, Ensio ; Lindholm, Ilona ; Miettinen, Jaakko ; Sairanen, Risto ; Sjöval, H. / Modelling and simulant experiments of severe accident phenomena (MOSES) : Experiments on dryout heatflux in volumetrically heated granular particle bed with the STYX facility. FINNUS: The Finnish Research Programme on Nuclear Power Plant Safety 1999-2002: Final Report. Espoo : VTT Technical Research Centre of Finland, 2002. pp. 187-195 (VTT Tiedotteita - Research Notes; No. 2164).
    @inbook{da58f770619244beb6f0e72eac3571a4,
    title = "Modelling and simulant experiments of severe accident phenomena (MOSES): Experiments on dryout heatflux in volumetrically heated granular particle bed with the STYX facility",
    abstract = "Core debris coolability in the containment is studied to verify the severe accident management strategy adapted in Olkiluoto BWRs. The molten core material discharged from the failed reactor pressure vessel falls into a several meters deep water pool in the Olkiluoto containment. It is most likely, that the melt will fragment on its way down in the subcooled water pool and form a self-heating particle debris bed on the pedestal floor. The coolability of this particle bed is the key question to be answered. The problem of particle bed coolability has been approached first by defining the representative particle size distribution for Olkiluoto plant [1]. The mass-averaged particle size of this distribution was determined to be 3.46 mm with the particle size ranging from 0.25 mm to 11 mm. The particles formed in melt-coolant interaction tests were generally non-spherical. Second, a literature review on existing debris bed coolability experiments was carried out [3]. An extensive dryout heat flux database exists for beds of single-sized, spherical particles. Some data is available for homogeneously mixed or stratified beds with particles having a narrow size distribution from POMECO tests [4], and for homogeneous and stratified beds with wider particle size range from DCC tests [5],[6]. However, the particle shape may have been more uniform in the POMECO tests (natural sand) and DCC tests (UO2 particles) than resulted e.g. FARO experiments and MACE tests with formation of particulate. The available calculational models were sensitive to the particle size and bed porosity, yielding results from easily coolable to non-coolable situation with a relatively small parameter range. Most of the measured data and all the calculational models suggested that a bed with average particle size of 3.5 mm would have a dryout heat flux close to 1 MW/m2 and thus would be easily coolable. For investigating of the effects of Olkiluoto specific particle bed characteristics on dryout heat flux an own simulant material test facility, STYX-1 [2] was constructed at VTT as a combined effort between VTT Industrial Systems and VTT Processes. The particles in STYX bed follow the representative size distribution constructed for Olkiluoto case and the shape of particles is irregular. The bed depth is determined to be the same as expected in Olkiluoto plant if the whole corium inventory would spread uniformly on pedestal floor. VTT Industrial Systems designed and built a test rig capable of heating a pressurised test bed immersed in water to a heat flux up to 1 MW/m2 and run the tests. The resulting power and temperature distribution data is utilised by VTT Processes to model and assess the coolability concepts related to severe accident management in the Olkiluoto BWR.",
    author = "Stefan Holmstr{\"o}m and Pekka Pankakoski and Ensio Hosio and Ilona Lindholm and Jaakko Miettinen and Risto Sairanen and H. Sj{\"o}val",
    year = "2002",
    language = "English",
    isbn = "951-38-6085-X",
    series = "VTT Tiedotteita - Research Notes",
    publisher = "VTT Technical Research Centre of Finland",
    number = "2164",
    pages = "187--195",
    booktitle = "FINNUS: The Finnish Research Programme on Nuclear Power Plant Safety 1999-2002",
    address = "Finland",

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    Holmström, S, Pankakoski, P, Hosio, E, Lindholm, I, Miettinen, J, Sairanen, R & Sjöval, H 2002, Modelling and simulant experiments of severe accident phenomena (MOSES): Experiments on dryout heatflux in volumetrically heated granular particle bed with the STYX facility. in FINNUS: The Finnish Research Programme on Nuclear Power Plant Safety 1999-2002: Final Report. VTT Technical Research Centre of Finland, Espoo, VTT Tiedotteita - Research Notes, no. 2164, pp. 187-195.

    Modelling and simulant experiments of severe accident phenomena (MOSES) : Experiments on dryout heatflux in volumetrically heated granular particle bed with the STYX facility. / Holmström, Stefan; Pankakoski, Pekka; Hosio, Ensio; Lindholm, Ilona; Miettinen, Jaakko; Sairanen, Risto; Sjöval, H.

    FINNUS: The Finnish Research Programme on Nuclear Power Plant Safety 1999-2002: Final Report. Espoo : VTT Technical Research Centre of Finland, 2002. p. 187-195 (VTT Tiedotteita - Research Notes; No. 2164).

    Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional

    TY - CHAP

    T1 - Modelling and simulant experiments of severe accident phenomena (MOSES)

    T2 - Experiments on dryout heatflux in volumetrically heated granular particle bed with the STYX facility

    AU - Holmström, Stefan

    AU - Pankakoski, Pekka

    AU - Hosio, Ensio

    AU - Lindholm, Ilona

    AU - Miettinen, Jaakko

    AU - Sairanen, Risto

    AU - Sjöval, H.

    PY - 2002

    Y1 - 2002

    N2 - Core debris coolability in the containment is studied to verify the severe accident management strategy adapted in Olkiluoto BWRs. The molten core material discharged from the failed reactor pressure vessel falls into a several meters deep water pool in the Olkiluoto containment. It is most likely, that the melt will fragment on its way down in the subcooled water pool and form a self-heating particle debris bed on the pedestal floor. The coolability of this particle bed is the key question to be answered. The problem of particle bed coolability has been approached first by defining the representative particle size distribution for Olkiluoto plant [1]. The mass-averaged particle size of this distribution was determined to be 3.46 mm with the particle size ranging from 0.25 mm to 11 mm. The particles formed in melt-coolant interaction tests were generally non-spherical. Second, a literature review on existing debris bed coolability experiments was carried out [3]. An extensive dryout heat flux database exists for beds of single-sized, spherical particles. Some data is available for homogeneously mixed or stratified beds with particles having a narrow size distribution from POMECO tests [4], and for homogeneous and stratified beds with wider particle size range from DCC tests [5],[6]. However, the particle shape may have been more uniform in the POMECO tests (natural sand) and DCC tests (UO2 particles) than resulted e.g. FARO experiments and MACE tests with formation of particulate. The available calculational models were sensitive to the particle size and bed porosity, yielding results from easily coolable to non-coolable situation with a relatively small parameter range. Most of the measured data and all the calculational models suggested that a bed with average particle size of 3.5 mm would have a dryout heat flux close to 1 MW/m2 and thus would be easily coolable. For investigating of the effects of Olkiluoto specific particle bed characteristics on dryout heat flux an own simulant material test facility, STYX-1 [2] was constructed at VTT as a combined effort between VTT Industrial Systems and VTT Processes. The particles in STYX bed follow the representative size distribution constructed for Olkiluoto case and the shape of particles is irregular. The bed depth is determined to be the same as expected in Olkiluoto plant if the whole corium inventory would spread uniformly on pedestal floor. VTT Industrial Systems designed and built a test rig capable of heating a pressurised test bed immersed in water to a heat flux up to 1 MW/m2 and run the tests. The resulting power and temperature distribution data is utilised by VTT Processes to model and assess the coolability concepts related to severe accident management in the Olkiluoto BWR.

    AB - Core debris coolability in the containment is studied to verify the severe accident management strategy adapted in Olkiluoto BWRs. The molten core material discharged from the failed reactor pressure vessel falls into a several meters deep water pool in the Olkiluoto containment. It is most likely, that the melt will fragment on its way down in the subcooled water pool and form a self-heating particle debris bed on the pedestal floor. The coolability of this particle bed is the key question to be answered. The problem of particle bed coolability has been approached first by defining the representative particle size distribution for Olkiluoto plant [1]. The mass-averaged particle size of this distribution was determined to be 3.46 mm with the particle size ranging from 0.25 mm to 11 mm. The particles formed in melt-coolant interaction tests were generally non-spherical. Second, a literature review on existing debris bed coolability experiments was carried out [3]. An extensive dryout heat flux database exists for beds of single-sized, spherical particles. Some data is available for homogeneously mixed or stratified beds with particles having a narrow size distribution from POMECO tests [4], and for homogeneous and stratified beds with wider particle size range from DCC tests [5],[6]. However, the particle shape may have been more uniform in the POMECO tests (natural sand) and DCC tests (UO2 particles) than resulted e.g. FARO experiments and MACE tests with formation of particulate. The available calculational models were sensitive to the particle size and bed porosity, yielding results from easily coolable to non-coolable situation with a relatively small parameter range. Most of the measured data and all the calculational models suggested that a bed with average particle size of 3.5 mm would have a dryout heat flux close to 1 MW/m2 and thus would be easily coolable. For investigating of the effects of Olkiluoto specific particle bed characteristics on dryout heat flux an own simulant material test facility, STYX-1 [2] was constructed at VTT as a combined effort between VTT Industrial Systems and VTT Processes. The particles in STYX bed follow the representative size distribution constructed for Olkiluoto case and the shape of particles is irregular. The bed depth is determined to be the same as expected in Olkiluoto plant if the whole corium inventory would spread uniformly on pedestal floor. VTT Industrial Systems designed and built a test rig capable of heating a pressurised test bed immersed in water to a heat flux up to 1 MW/m2 and run the tests. The resulting power and temperature distribution data is utilised by VTT Processes to model and assess the coolability concepts related to severe accident management in the Olkiluoto BWR.

    M3 - Chapter or book article

    SN - 951-38-6085-X

    T3 - VTT Tiedotteita - Research Notes

    SP - 187

    EP - 195

    BT - FINNUS: The Finnish Research Programme on Nuclear Power Plant Safety 1999-2002

    PB - VTT Technical Research Centre of Finland

    CY - Espoo

    ER -

    Holmström S, Pankakoski P, Hosio E, Lindholm I, Miettinen J, Sairanen R et al. Modelling and simulant experiments of severe accident phenomena (MOSES): Experiments on dryout heatflux in volumetrically heated granular particle bed with the STYX facility. In FINNUS: The Finnish Research Programme on Nuclear Power Plant Safety 1999-2002: Final Report. Espoo: VTT Technical Research Centre of Finland. 2002. p. 187-195. (VTT Tiedotteita - Research Notes; No. 2164).