Main Insights and Perspectives of Pool scrubbing Research: Examples of THAI and NUGENIA/IPRESCA Sanjeev GmbH, Germany gupta@becker-technologies.com February 28 th, 2017
Pool scrubbing - Introduction Definition Absorption of radioactive particles and vapours in water pools when carried through by gases Decontamination Factor (DF) DF m m Meaningful limit DF 1 out DF not suitable concept for re-entrainment in Relevance - Source-term mitigation by fission product retention - Importance: water cooled reactor (e.g. BWR, PWR, CANDU), Gen. IV concepts of SMR - Improving SAM measures, e.g. time, capacity and duration for FCVS operation 2
Pool scrubbing Specific issues Relevant scenario or specific phenomena Selection of relevant scenario for pool scrubbing tests under severe accident conditions (e.g. suppression pool, MCCI, SGTR, FCVS) PIRT needed Experimental database Detailed models available in literature but sparse experimental data for systematic validation of pool scrubbing models/codes Sparse data on pool hydrodynamics (e.g. bubble dynamics, bubble gas circulation effect, water circulation flow ) Lack of information about the presence or concentration of surfactants/impurities in real plants under normal or accident conditions Sparse data involving realistic aerosols/ iodine (e.g. particle size, concentration, constituent) Experimental hardware Challenging conditions (e.g. pressure, temperature, steam) for aerosol generation hardware and measurement techniques Change of particle size between inlet and outlet is largely unknown; effect is suppressed in noncondensing tests with monodisperse aerosol 3
Pool scrubbing: experimental needs Calculated DF Example: SPARC- 98B Validation of aerosol DF calculation Calculation underestimates measured DF BUT model is not capable of predicting high DFs (relevant in FCVS) 81 experiments: 63 EPRI series 3 14 Poseidon 4 Ciemat Note: Log scale Range 1 to 7000 Measured DF 4
Pool scrubbing Further R&D needs Relevant parameters for pool scrubbing experiments Aerosol/vapours and carrier gas properties Injection geometry Water pool hydrodynamics (e.g. bubble dynamics) Chemical boundary conditions in water pool Results independence from test facility specific features should be confirmed Need for international co-operation; Generic pool scrubbing database for common use Benchmarking/assessment of pool scrubbing codes (models) Benchmarking of aerosol measurement techniques Perspectives (examples) THAI NUEGNIA/IPRESCA 5
THAI pool scrubbing relevant database THAI+ test facility Thermal-hydraulics, Hydrogen, Aerosols, and Iodine Experimental investigations to mimic generic two-room system in containments with different but coupled thermal-hydraulics P/T: 1.4 MPa / 180 C Stainless steel 22 mm walls Configurable sub-compartments Pressure resistant for H 2 -deflagrations Licensed for use of radiotracer I 123 6
THAI pool scrubbing relevant activities Aerosol hardware Development/adaption of aerosol generation devices and measurement techniques Experimental database Experiments on water pool hydrodynamics Iodine mass transfer from water pool Aerosol (soluble/insoluble) re-entrainment tests Aerosol DF measurement Aerosol test loop for development/qualification of aerosol generators/measurement techniques Acknowledgement: AREVA GmbH 7
THAI pool scrubbing relevant activities Aerosol generators and measurement techniques Well defined aerosol particle size spectrum (MMD: ~ 1 µm, GSD : 2) Different generation devices for the test aerosol (soluble/insoluble) Operational conditions: high pressure/temperature (10 bar, 200 C) and steam atmosphere Ag aerosol MMD: 1.2 µm GSD: 2 Aerosol generator for non-soluble powders ( e.g. SnO 2, Ag) 8
Aerosol re-entrainment THAI tests Aerosol re-entrainment Release of pre-accumulated aerosols in a water pool Weak but long lasting late phase source-term Released aerosol characteristics (e.g. particle size, concentration) relevant information for FCVS operation Relevant parameters for THAI tests Gas injection geometry: Blowdown pipe (DN 100) & Sinter metal pipe (pore size: 100 µm) System thermal-hydraulics (pressure, temperature) Aerosol types (soluble, insoluble) Flow regimes (bubbly churn turbulent ) Pool hydrodynamics (e.g. bubble dynamics) Potential parameters for future THAI tests Pool chemical boundary conditions (e.g. surfactants) Aerosol re-entrainment by depressurization induced boiling 9
Aerosol re-entrainment THAI tests THAI data application: development/validation of RUB re-entrainment model Source: RUB Bochum, pool scrubbing information exchange meeting, May 14th, 2014, Eschborn, Germany Current status: Model for soluble aerosols under bubbly flow regime implemented in GRS code COCOSYS Work in progress Extension of re-entrainmenment model to insoluble aerosols (RUB Bochum) Extension of re-entrainment model for soluble aerosols to churn turbulent flow regime (University of Luxembourg) 10
THAI database relevant for pool scrubbing Bubble dynamics (without aerosol) THAI national project WH 7-15 (performed) Bubble dynamics, Aerosol re-entrainment THAI national /OECD-THAI projects TH14-17, TH25 (performed) WH24 (ongoing) & WH28 (planned) Bubble dynamics, DF measurement THAI national project WH25 27 (planned) Downcomer pipe (DN 100) Sinter metal pipe (pore size: 100 µm) Soluble and insoluble aerosols Downcomer pipe (DN 100) Soluble and insoluble aerosols tests using downcomer pipe (DN 100) pool temperature, gas mass flow rate, air or air/steam mixture, system pressure submergence depth 11
IPRESCA Introduction IPRESCA: Integration of Pool scrubbing Research to Enhance Source-term CAlculations Framework: NUGENIA Technical Area 2/SARNET (Severe Accident) Sub Technical Area 2.4 (Source-term) Project duration: 4 years In-kind project: currently no external funding is foreseen. Partners are expected to join the project with in-kind contributions Kick-off meeting for IPRESCA combined with an international workshop on pool scrubbing is planned on June 21-22, 2017 in Frankfurt. 12
IPRESCA NUGENIA Label 13
IPRESCA Objectives Overall Aim Integration of international research activities related to pool scrubbing by providing support in: Experimental research to broaden the current knowledge and database Analytical research to facilitate systematic validation and model enhancement of the existing pool scrubbing models/codes to facilitate implementation of new/improved models or stand-alone pool scrubbing codes into system codes (e.g. ASTEC, COCOSYS, MELCOR) Other related national/international programs OECD: THAI-3, SAREF EC: PASSAM,CESAM National: THAI-VI (in preparation, 2017-2019), SAAB (RWTH/JÜLICH) Others: ongoing national activities in Japan, Korea, China etc 14
Confirmation of interest to join IPRESCA 15 countries, 34 organizations brings together experimentalists, code developers & code users [China] SNPSDC, CIAE, HEU, SJTU [Czech Republic] UJV [France] IRSN [Finland] VTT [Germany] AREVA,, GRS, FZJ/ RWTH Aachen, RUB, KIT, Mannheim University, HZDR [India] BARC, IITK, IITB [Italy] NINE, Politecnico di Milano [Japan] CRIEPI, JAEA, IAE [Korea] KAERI, KINS, KHNP [Lithuania] Lithuanian Energy Institute [Luxembourg] University of Luxembourg [Spain] CIEMAT [Slovenia] Jozef Stefan Institute [Switzerland] PSI [USA] NRC, University of Missouri, Purdue University 15
IPRESCA - Resources Experimental Test facilities with size ranging from lab scale (~ 1 m 3 ) to large scale (> 60 m 3 ); Analytical Fission product: specific pool scrubbing models (e.g. SPARC versions using different models/empirical correlations) applied in different system codes, e.g. ASTEC, COCOSYS, MELCOR, for reactor application; Thermal-hydraulic: computer codes based on lumped parameter or computational fluid dynamics approaches for detailed investigations on water pool hydrodynamics, e.g. bubble dynamics; Academic Involving PhD, Master and Graduate students, to focus on specific experimental and analytical activities. 16
IPRESCA Orgnisational structure Co-ordinator/ Management Board Critical (experimental/analytical) Assessment of Background (CAB) Reference testing (RT) Innovation in Pool Scrubbing (IPS) Model Enhancement and Simulations (MES) 17
WP1: Critical Assessment of Background (CAB) Pool Scrubbing scenario s high complexity of pool scrubbing phenomena and related thermal-hydraulic conditions, e.g. aerosol retention in the suppression pool in a BWR by injection through spargers or downcomer pipes, in the pressurizer relief tank in a PWR by injection through spargers, in Steam Generator Tube Rupture (SGTR) scenarios with tube rupture covered with water, in a water pool in case of wet scrubber based FCVS, and in a containment water pool covering a melt pool (after RPV failure) in the containment. Preparation of a PIRT table for identification/prioritization of representative phenomena for pool scrubbing 18
WP1: Critical Assessment of Background (CAB) Experimental work Applicability of experimental results for relevant processes in plants Experimental technology including aerosol generation Measurement devices, mainly for aerosols and bubble measurements Needs for further experimental research or improvements in new experiments Analytical work Analytical aerosol pool scrubbing models available and application range for different plants and phenomena Intention for improvement of current models or need to develop new ones (simplified, mechanistic for some phenomena, etc.) Identification of experimental needs (e.g required details on measurement data) 19
Injection zone Bubble Surface zone WP1: Critical Assessment of Background (CAB) Pool scrubbing phenomena and research framework (Example) Bubble breakup Droplet generation Droplet release to atmosphere Dissolved mass in droplets Insoluble mass carried with droplets Aerosol release from bubble gas Hydrodynamics Aerosol behavior Experiment Modeling Experiment Modeling Bubble column geometry Bubble rising velocity Pool recirculation flow Bubble gas thermodynamics Aerosol removal inside bubbles rising zone Bubble size distribution Primary injection: Downcomer Horizontal vent Quencher Orifice Formation of primary bubbles Decay of primary bubbles Initial bubble size distribution after decay Pool flow due to gas injection Aerosol removal during primary bubble formation Aerosol removal in primary bubbles Aerosol removal during decay of primary bubbles Primary bubble gas thermodynamics Aerosol release via pool bypass 20
WP-2 (RT) & WP-3 (IPS) WP-2: Reference testing Inter-comparison of simplified pool scrubbing tests from different test facilities Identify facility-specific features which might have biasing impact upon measured DF WP-3: Innovation in pool scrubbing New experiments link to WP1 & WP2 Instrument benchmarking: inter-comparison of aerosol measuring devices and procedures BT- Aerosol Test Loop (BT-ATL) 21
WP-4 Model Enhancement and Simulation Evaluation of relevant models Quantification of modelling uncertainties, identification of potential weaknesses in test data and/or models Improvement, simplification or replacement of models if needed Code benchmarking to assess contribution of individual sub-models in calculating the decontamination factors Overall aim: MES activity should go beyond the application of complex pool scrubbing codes in a black-box fashion, but instead should clarify the contribution of individual sub-models in calculating the decontamination factors. 22
Kick-off meeting IPRESCA Kick-off meeting & International workshop on Pool Scrubbing 21 22 June 2017, Frankfurt, Germany 23
ACKNOWLEDGMENTS German Federal Ministry for Economic Affairs and Energy (BMWi) which financially supports the THAI research programs. The sponsorship by the countries of the OECD/NEA THAI-3 project partners is gratefully acknowledged.