1. UNIVERSITÀ DI PISA GRUPPO DI RICERCA NUCLEARE – SAN PIERO A GRADO (GRNSPG) Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar September 20-23, 2010 West Yellowstone, Montana September 20-23, 2010 Title3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code AuthorsA. Del Nevo, C. Parisi, F. D'Auria Revision/Date020 09 2010

2. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 List of content  INTRODUCTORY REMARKS  MASLWR ITF FACILITY  OBJECTIVE OF THE ACTIVITY  NODALIZATIONS DEVELOPED  QUALIFICATION OF THE NODALIZATION  THE EXPERIMENTAL DATA  SIMULATIONS OF MASLWR TESTS 002 AND 003A  IAEA ICSP ON MASLWR  CONCLUSIVE REMARKS 2/23

3. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Introductory remarks  S. M. Modro, J. E. Fisher, K. D. Weaver, J. N. Reyes Jr., J. T. Groome, P. Babka, T. M. Carlson, Multi-Application Small Light Water Reactor Final Report, INEEL/EXT-04-01626, December 2003  The Multi-Application Small Light Water Reactor (MASLWR) project was conducted under the auspices of the Nuclear Energy Research Initiative (NERI) of the U.S. Department of Energy (DOE).  Objectives were:  to develop the conceptual design for a safe and economic small, natural circulation light water reactor,  to address the economic and safety attributes of the concept, and  to demonstrate the technical feasibility by testing in an integral test facility 3/23

4. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Introductory remarks  Features of the concept design:  The reactor core and the SGtube bundles inside the vessel  No main primary system piping  Buoyancy forces driving head for primary coolant flow  RPV inside a steel containment vessel filled with water  passive ultimate heat sink 4/23  5 years for refueling and maintenance performed by removing the entire module  Test prgram with ITF (MASLWR) has been executed at Oregon State University (OSU)

5. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Introductory remarks  Nuscale Power formed in 2007 with tech-transfer agreement from OSU and privately funded  NuScale technology developed and tested by Oregon State University, based on OSU, INL and Nexant (Bechtel) DOE NERI program for MASLWR  NuScale Power is commercializing a 45 MWe natural circulation PWR module that can be scaled to meet customer requirements of virtually any size  Base Design is a 12-Module, 540 MWe plant  Designed to meet NuScale Customer Advisory Board  Utility Requirements for near-term deployment in the USA  Seeking US-NRC Design Certification  NuScale Project Organization 5/23

6. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Oregon State University MASLWR ITF  Integral test facility  Scaling  1:3 length  1:254.7 volume  1:1 time scale  Characteristics  Full pressure (11.4 MPa)  Full temperature (590 K)  Fuel rods eclectically heated  Maximum power 398 kW (7.1 kW per 56 rods) 6/23

7. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Oregon State University MASLWR ITF  It simulates  the primary system  the secondary system  the containment system  the water pool 7/23 Containment Water pool Primary systemDetails of the helical-coils SG

8. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Oregon State University MASLWR ITF  Four tests are documented (full set of experimental data not available)  OSU-MASLWR-001: Inadvertent actuation of 1 submerged ADS valve  OSU-MASLWR-002 & 003A: Natural circulation with core power up to 210kW (used to set up the nodalizations for ICSP participation)  OSU-MASLWR-003B: Inadvertent high containment ADS vent line actuation 8/23

9. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. Use of RELAP5-3D at GRNSPG/UNIPI 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Objective of the activity  GRNSPG participation in the IAEA International Collaborative Standard Problem (ICSP) on Integral PWR Design Natural Circulation Flow Stability and Thermo-hydraulic Coupling of Containment and Primary System during Accidents  Validation of RELAP5-3D v2.4.2 applicability in modeling integral PWR  Explore thermal-hydraulic and modeling challenges for new small design PWR  3D vs. 1D modeling (in SPF & TPF conditions)  Assessment/accuracy of current TH/SYS (i.e. RELAP5-3D v2.4.2) performance in predicting  HEX in helical coils SG  Choked flow & coupled containment pressurization  NC flow instabilities at reduced mass inventories  Condensation 9/23

10. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Nodalizations developed General features of the nodalizations  Two independent nodalizations were set up  1D nodalization, which can be run with RELAP5-3D v2.4.2, RELAP5/Mod3.3 (and TRACE code) and 3D nodalization by RELAP5-3D v2.4.2  All relevant parts of the MASLWR ITF are modeled  3 equivalent SG helical-coil tubes (1 for each tube group length)  1 equivalent SG helical-coil tube  The maximum pipe node to node length ratio adopted is 1.2  Sliced nodalization approach  HF option activated  chocked flow  Absolute and relative elevations maintained as in facility description  MULTID components (3D nodalization)  3D momentum equations used 10/23

11. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Nodalizations developed: 1D nodalization  1D nodalization, which can be run with RELAP5/Mod3.3 (and TRACE code)  Reactor coolant system (3 pipe and 2 branch)  41 axial nodes  Secondary system (2 tmdpvol, 1 tmdpjun, 2 vlv, 2 branch, 3 pipe)  High pressure containment vessel (3 pipe, 2 branch, 1 vlv, 1 tmdpjun)  48 axial nodes  Cooling pool vessel (2 pipe and 2 branch)  56 axial nodes  Automatic depressurization systems  Blowdown lines (2 pipe, 2 vlv, 1 branch)  Vent lines (2 pipe, 2 vlv, 1 branch)  Sump return lines (2 pipe, 2 vlv, 1 branch) 11/23

12. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Nodalizations developed: 3D nodalization RELAP5-3D COMPONENTS  REACTOR COOLANT SYSTEM  1 MULTID COMPONENT  SECONDARY SYSTEM  2 TMDPVOL, 1 TMDPJUN, 2 VLV, 2 BRANCH, 5 PIPE  HIGH PRESSURE CONTAINMENT VESSEL  1 MULTID COMPONENT, 1 PIPE, 1 VLV, 1 TMDPJUN  COOLING POOL VESSEL  1 MULTID COMPONENT  AUTOMATIC DEPRESSURIZATION SYSTEMS 1.BLOWDOWN LINES (2 PIPE, 2 VLV, 1 BRANCH) 2.VENT LINES (2 PIPE, 2 VLV, 1 BRANCH) 3.SUMP RETURN LIENS (2 PIPE, 2 VLV, 1 BRANCH) 12/23

13. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Nodalizations developed: 3D nodalization  REACTOR COOLANT SYSTEM ( MULTID)  2 radial; 8 azimuthal, 42 axial  672 volumes Leaning MULTIDLeaning TOWER 13/23

14. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Nodalizations developed: 3D nodalization HL REGION (w/ area reduction) UPUP SUMP RETURN (340) UPUP HL REGION (reduced area) PRZ UP SG UP SGSG CL CORE REGION UPUP DC CL DC UP UPUP FW inlet (210-220-230) SL outlet (210-220-230) ADS VENT (300) BLOWDOWN (320) PRZ plate Grid wires Upper grid wires Core flow plate Sect. A-A A A Heaters 3 parallel pipes 14/23

15. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010  HPC ( MULTID)  2 r adial; 4 azimuthal, 48 axial  384 volumes  CPV (MULTID)  1 radial; 4 azimuthal, 56 axial  224 volumes Nodalizations developed: 3D nodalization RUPTURE DISK (410) SUMP RETURN (340) BLOWDOWN (320) ADS VENT (300) HPC CPV 15/23

16. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010  NC tests (002 and 003A) with core power up to 210kW  Results provided during the 1 st ISCP meeting at OSU 15-18 March 2010 Nodalization qualification: the experimental data 16/23 ΔT across the core presented by B. Woods: Test 002 Specifications according with INEEL/EXT-04-01626, Dec. 2003 ΔT across the core presented by B. Woods: Test 003A

17. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Nodalization qualification: simulations of MASLWR Tests 002 and 003A 17/23 Power

18. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Nodalization qualification: simulations of MASLWR Tests 002 and 003A Δ T across the core vs time 18/23

19. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Nodalization qualification: simulations of MASLWR Tests 002 and 003A 19/23 core volumetric flow rate vs time

20. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Nodalization qualification: simulations of MASLWR Tests 002 and 003A 20/23 SG outlet coolant temperature secondary side

21. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 IAEA ICSP on MASLWR  The ICSP is divided into two separate tests.  The first test involves a stepwise reduction in primary coolant volumetric inventory in the MASLWR test facility while operating at decay power. 21/23 B. G. Woods, M. R. Galvin, C. J. Bowser, Problem Specification for the IAEA International Collaborative Standard Problem on Integral PWR Design Natural Circulation Flow Stability and Thermo-hydraulic Coupling of Containment and Primary System during Accidents, OSU-ICSP-10001, Augusto 2010

22. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. 3D nodalization performances of MASLWR ITF by RELA5-3D©v2.4.2 code 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 IAEA ICSP on MASLWR  The ICSP is divided into two separate tests (cont’ed)  The second test involves a loss of FW transient with subsequent ADS blowdown and long term cooling. 22/23 B. G. Woods, M. R. Galvin, C. J. Bowser, Problem Specification for the IAEA International Collaborative Standard Problem on Integral PWR Design Natural Circulation Flow Stability and Thermo-hydraulic Coupling of Containment and Primary System during Accidents, OSU-ICSP-10001, Augusto 2010

23. Gruppo Ricerca Nucleare San Piero a Grado Any reproduction, alteration, transmission to any third party or publication in whole or in part of this document and/or its content is prohibited unless the University of Pisa – San Piero a Grado Nuclear Research Group has provided its prior and written consent. This document and any information it contains shall not be used for any other purpose than the one for which they were provided. Legal action may be taken against any infringer and/or any person breaching the aforementioned obligations. Use of RELAP5-3D at GRNSPG/UNIPI 2010 RELAP5 International User’s Seminar West Yellowstone, Montana – September 20-23, 2010 Conclusive remarks  The nodalization is developed and set up and ready for the participation in the ICSP (submission of the pre-test results by the end of December 2010)  GRNSPG/UNIPI will participate with RELALP5-3D v2.4.2  RELAP5/Mod3.3 and TRACE code might be used depending upon the working resources  Performances of the code RELAP5-3D v2.4.2 are presented  The activity is still in progress 23/23