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

NameVTT Tiedotteita - Research Notes
PublisherVTT
Number2164
ISSN (Print)1235-0605
ISSN (Electronic)1455-0865

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).
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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).