THAI experimental research on hydrogen risk and source term related safety systems

Abstract

In the defense-in-depth concept employed for the safety of nuclear installations, maintaining integrity of containment as the last barrier is of high importance to limit the release of radioactivity to the environment in case of a severe accident. The active and passive safety systems implemented in containments of light water reactors (LWRs) are designed to limit the consequences of such accidents. Assessing the performance and reliability of such systems under accident conditions is critical to the safety of nuclear installations.

In the aftermath of the Fukushima accident, there has been focus on re-examining the existing safety systems to demonstrate their capabilities for a broader range of boundary conditions comprising both the early as well as the late phases of an accident. In addition to the performance testing of safety systems, their interaction with containment atmosphere needs detailed investigations to evaluate the effects of operation of safety systems on H₂ risk and fission product (FP) behavior in containment, which may ultimately have an impact on the source term to the environment.

In this context, an extensive containment safety related experimental research has been conducted in a thermal-hydraulics, hydrogen, aerosols, and iodine test facility (THAI, 60 m³, single vessel)/(THAI⁺, 80 m³, two interconnected vessels). Related to the subject of this paper, experimental investigations covered performance testing of various safety and mitigation systems, i.e., containment spray, passive autocatalytic recombiner (PAR), pressure suppression pool (water pools), and effects of their operation on H₂ risk and in-containment FP behavior. The experimental results have provided a better phenomenological understanding and database for validation and further improvement of a safety analysis tool based on computation fluid dynamic (CFD) and lumped parameter (LP) modeling approach. This paper summarizes the main insights obtained from the aforesaid THAI experimental research covering safety systems installed in containments of LWRs. The relevance of experimental outcomes for reactor safety purpose is also discussed.

Graphical abstract

Keywords

severe accident / containment / safety / mitigation / H₂ risk / source term

References

[1] International Atomic Energy Agency. Developments in the analysis and management of combustible gases in severe accidents in water cooled reactors following the Fukushima Daiichi accident. Report: IAEA-TECDOC-1939, 2020

[2] NEA. CSNI/WGAMA source term workshop 2019. Report: NEA/CSNI/R (2020)4, 2020

[3] Cheng X, Wielenberg A, Hampel U, Summary of 3rd Sino-German symposium on fundamentals of advanced nuclear safety technology. Kerntechnik, 2020, 85(2): 131–135

[4] Bentaib A. SAMHYCO-NET overview. In: Proceedings of the International Workshop on Hydrogen Safety for Nuclear Power Plants 2019, Fontenay-aux-Roses, 2019

[5] Gupta S, Herranz L E, Van Dorsselaere J. Integration of pool scrubbing research to enhance Source Term calculations. In: Proceedings of 8th European Review Meeting of Severe Accident Research (ERMSAR) 2017, Warsaw, Poland, 2017

[6] Herranz L E, Bentaib A, Gabrielli F, NUGENIA/TA2 achievements in severe accidents research (2015–2020). Journal of Nuclear España, 2020, 2020: 1–6

[7] Gupta S, Schmidt E, von Laufenberg B, THAI test facility for experimental research on hydrogen and fission product behaviour in light water reactor containments. Nuclear Engineering and Design, 2015, 294: 183–201

[8] Kanzleiter T, Ahrens G, Fischer K, Experimental facility and program for the investigation of open questions on fission product behaviour in the containment, Part 1: test facility and thermal-hydraulic experiments. Report N: 150 1218–S1, 2003

[9] Funke F, Greger G U, Langrock G, Experimental facility and program for the investigation of open questions on fission product behaviour in the containment, Part 2: iodine experiments. Report Nr. 150 1218–S2, 2004

[10] Kanzleiter T F, Ahrens G, Fischer K, Experimental facility and program for the investigation of open questions on fission product behaviour in the containment, ThAI Phase II, Part 1: test facility, thermal-hydraulic and aerosol experiments. Report N: 150 1272–S1, 2007

[11] Funke F, Langrock G, Kanzleiter T, Experimental facility and program for the investigation of open questions on fission product behaviour in the containment, ThAI Phase II, Part 2: iodine experiments. Report N: NTR-G/2007/de/0233A, 2006

[12] Kanzleiter T, Fischer K, Langer G, Test program on fission product and hydrogen behaviour in containment, THAI-III-National-1. Report N: 1501325-III-N1, 2009

[13] Gupta S, Balewski B, Freitag M, Experimental program on source-term relevant phenomena in the containment and for further development and validation of models-THAI IV. Report N: 1501361-FR, 2013

[14] Gupta S, Freitag M, Schmidt E, Single- and multi-compartment tests on fission- product and hydrogen behaviour in the containment-THAI-V. Report N: 1501455-FR, 2017

[15] Gupta S, Poss G, Freitag M, Experimental investigations on fission-product retention and hydrogen mitigation for design-basis and severe accidents in the containment-THAI VI. Report N: 1501547-FR, 2019.

[16] Gupta S, Poss G, Freitag M, Experimental investigations on fission-product retention and hydrogen mitigation for design-basis and severe accidents in the containment-THAI VI-b. Report Nr. 1501594-FR, 2021.

[17] OECD/NEA THAI Project. Hydrogen and fission product issues relevant for containment safety assessment under severe accident conditions. OECD/NEA THAI Project Final Report NEA/CSNI/R(2010)3, 2010

[18] OECD/NEA THAI-2 Project. Aerosol and iodine issues, and hydrogen mitigation under accidental conditions in water cooled reactors. Thermal-hydraulics, Hydrogen, Aerosols and Iodine (THAI-2) Project Final Report: NEA/CSNI/R(2016)8, 2016

[19] Gupta S, Poss G, Freitag M, Fission product behaviour, hydrogen mitigation, and hydrogen combustion in water cooled reactors under severe accident conditions. OECD/NEA THAI-3 Project Final Report: 1501516-FR-1, 2020

[20] Nuclear Energy Agency. THAI experiments on mitigation measures, and source term issues to support analysis and further improvement of severe accident management measures (THEMIS) project. 2021–6-4, available at website of NEA

[21] Gupta S, von Laufenberg B, Freitag M, Instrumentation for LWR containment experiments under accident conditions. In: Proceedings of Specialist Workshop on Advanced Instrumentation and Measurement Techniques for Nuclear Reactor Thermal Hydraulics (SWINTH-2016), Livorno, Italy, 2016

[22] Freitag M, von Laufenberg B, Colombet M, Challenges and uncertainties in providing validation data for fission product transport modelling. In: Proceedings of ANS Best Estimate Plus Uncertainty International Conference (BEPU 2018), Lucca, Italy, 2018

[23] Freitag M, von Laufenberg B, Poss G. Development and application of an online spectroscopy based gas concentration measurement system applicable for gaseous iodine and steam concentration. In: Proceedings of OECD/NEA Specialist Workshop on Advanced Measurement Method and Instrumentation for Enhancing Severe Accident Management in an NPP addressing Emergency, Stabilization and Long-term Recovery Phase (SAMMI), 2020

[24] Schwarz S, Fischer K, Bentaib A, Benchmark on hydrogen distribution in a containment based on the OECD-NEA THAI HM-2 experiment. Nuclear Technology, 2011, 175(3): 594–603

[25] Allelein H J, Fischer K, Vendel J, International standard problem ISP-47 on containment thermal hydraulic. Report: NEA/CSNI/R(2007)10, 2007

[26] Freitag M, Schmidt E, Gupta S, Simulation benchmark based on THAI-experiment on dissolution of a steam stratification by natural convection. Nuclear Engineering and Design, 2016, 299: 37–45

[27] Freitag M, Kljenak I, Jankowski T, Benchmark exercise TH-27 on natural convection with steam injection and condensation inside the extended THAI facility. Annals of Nuclear Energy, 2018, 116: 90–104

[28] Gupta S, Freitag M, Liang Z, Main outcomes and lessons learned from THAI passive autocatalytic recombiner experimental research and related model development work. In: Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17), Xi’an, China, 2017

[29] NEA. ISP-49 on hydrogen combustion 2012. Report. Nuclear Safety NEA/CSNI/R(2011)9, 2011

[30] Weber G, Bosland L, Funke F, ASTEC, COCOSYS, and LIRIC interpretation of the iodine behaviour in the large-scale THAI test Iod-9. In: Proceedings of 17th International Conference on Nuclear Engineering, Brussels, Belgium, 2010: 519–531

[31] Funke F, Langrock G, Kanzleiter T, Iodine oxides in large-scale THAI tests. Nuclear Engineering and Design, 2012, 245: 206–222

[32] Weber G, Herranz L E, Bendiab M, Thermal-hydraulic-iodine chemistry coupling: insights gained from the SARNET benchmark on the THAI experiments Iod-11 and Iod-12. Nuclear Engineering and Design, 2013, 265: 95–107

[33] Gupta S, Funke F, Langrock G, THAI experiments on volatility, distribution and transport behaviour of iodine and fission products in the containment. International Iodine Workshop Summary Report Nuclear Safety. NEA/CSNI/R(2016)5, 2016

[34] Funke F, Gupta S, Weber G, Interaction of gaseous I₂ with painted surfaces and aerosols in large-scale THAI tests. International Iodine Workshop Summary Report Nuclear Safety NEA/CSNI/R(2016)5, 2016

[35] Weber G, Funke F, Klein-Hessling W, Iodine and silver wash-down modelling in COCOSYS-AIM by use of THAI results. International Iodine Workshop Summary Report Nuclear Safety NEA/CSNI/R(2016)5, 2016

[36] Wang F, Cheng X, Gupta S. COCOSYS analysis on aerosol wash-down of THAI-AW3 experiment and generic containment. Annals of Nuclear Energy, 2021, 153: 108076

[37] Gupta S, Schmidt E, Freitag M, Experimental investigations on containment spray performance under severe accident conditions. In: Proceedings of 8th European Review Meeting on Severe Accident Research (ERMSAR), Warsaw, Poland, 2017

[38] Freitag M, Gupta S, Beck S, Experimental and analytical investigations of aerosol processes—wash-out and wash-down. Nuclear Science and Engineering, 2019, 193(1−2): 198–210

[39] Kühnel A, Fischer K, Langer G. Test TH-19 in the THAI facility on the performance of spray systems. Report: BT-70084–1, 2006

[40] Gupta S, Langer G. Experimental research on hydrogen deflagration in multi-compartment geometry and application to nuclear reactor conditions. Nuclear Engineering and Design, 2019, 343: 103–137

[41] Freitag M, von Laufenberg B, Colombet M, Measurements of the impact of carbon monoxide on the performance of passive autocatalytic recombiners at containment-typical conditions in the THAI facility. Annals of Nuclear Energy, 2020, 141: 107356

[42] Cheng L, Woo K S, Ishii M, Suppression pool mixing and condensation tests in PUMA facility. In: Proceedings of 14th International Conference on Nuclear Engineering, Miami, USA, 2008

[43] Laine J, Puustinen M. Thermal stratification experiments with the condensation pool test rig. Report: NKS-117 ISBN 87–7893–178–9, 2006

[44] Balewski B, Gupta S, Fischer K. Water flow with bubble columns-Boiling Water Reactor experiments WH-7 to WH-15. Technical Report: 1501361-WH-7–15-FB/TR, 2011

[45] Paul D D, Flanigan L J, Cunnane, J C, Radionuclide scrubbing in water pools. Report: EPRI NP-4154-L, 1991

[46] Ouallal M, Leyer S, Gupta S. Literature survey of droplet entrainment from water pools. Nuclear Engineering and Design, 2021, 379: 111188

[47] Schmidt E W, Gupta S, Freitag M, Wet resuspension of insoluble material from a boiling sump. In: Proceedings of the International Conference on Nuclear Engineering: ICONE, Chiba, Japan, 2015

[48] Bunz H, Koyro M, Propheter B, Resuspension of fission products from sump water. Final Report: EUR 14635 EN, 1992

[49] Cosandey J O, von Rohr P R. Entrainment of soluble and non soluble tracers from a boiling water surface. Nuclear Engineering and Design, 2001, 208(1): 87–97

[50] Freitag M, Schmidt E, Colombet M, Aerosol retention in water pools-Pool Scrubbing. Technical Report: 1501547-FB/TR-WH25–27, 2018

RIGHTS & PERMISSIONS

Higher Education Press