UNIVERSITÀ DI PISA

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RELAP5 Applications at GRNSPG-NINE: Thirty Years of Activities

A. Petruzzi, M. Cherubini, (M.Lanfredini) (UNIPI-NINE) F. D’Auria (UNIPI)

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 2/27

Contents

● Introduction and overview on the activities

● Recent participation to International Benchmark Activities

● ITF, Research Reactor and NPP calculations

● Specific application of Relap5: ISP-42 – PANDA Facility

● Example of NPP calculations (safety analyses)

o VVER-1000, CANDU

● Investigation on Relap5\CFX coupling

● Conclusions

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 3/27

Introduction

● Main contributes in the TH-SYS code area

o Code Assessment (internally / within International programs)

On-Going benchmarks : Oskarshamn-2, PKL-III H2.2 run2, ATLAS A5.1, EBR-II

o Accuracy quantification

Code Assessment (FFTBM)

Database for deriving the Uncertainty Database (CIAU uncertainty method)

o Characterization of transient scenarios in NPP

Design evaluation

Licensing of NPP (BEPU)

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 4/27

Introduction

● List of Experimental Facilities and Test Analyzed (not Exhaustive List)

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 5/27

Introduction

● List of Experimental Facilities and Test Analyzed (not Exhaustive List)

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 6/27

Introduction

● List of Code Applications for NPP (not Exhaustive List)

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 7/27

Oskarshamn-2 benchmark

● Oskarshamn-2 OECD Benchmark: February 25, 1999 stability event o Loss of FW pre-heating & Control System failure: High FW flow, low temp, no SCRAM o Power and flow control system interaction: low flow, high power

● Nodalization Scheme (Draft)

STEAM DOME

DRYER ZONE

SEPARATOR

STAND PIPES

UPPER PLENUM

CORE OUTLET

CORE

CORE INLET

LOWER PLENUM

DOWNCOMER

BYPASSSTEAM LINE

FEED WATER

RECIRCULATION LOOP

CORE BYPASS

GUIDE TUBES1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

1

1

2

7

1

1 1 1

6 6 6

SL

FW

x 2 x 2 444

109

x 2 x 2

109

5

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 8/27

Oskarshamn-2 benchmark

● Oskarshamn-2: Core

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

7

101 102 103 114

115

209208207196

195

694

Downcomer

Core bypass

Core channels

* * * * * * * * RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 * * * * * * * *

* * * * * * RE 0 RE 0 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 RE 0 RE 0 * * * * * *

* * * * RE 0 RE 0 1 3 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 3 RE 0 RE 0 * * * *

* * RE 0 RE 0 1 3 1 2 1 1 3 1 1 1 2 1 2 1 1 1 2 1 2 1 2 1 2 1 2 1 1 1 2 1 1 1 1 2 1 3 RE 0 RE 0 * *

RE 0 RE 0 1 3 1 2 2 1 2 1 1 1 3 1 4 1 1 1 3 1 1 1 4 1 3 1 1 1 4 1 1 1 1 1 2 1 2 1 1 2 1 3 RE 0 RE 0

RE 0 1 3 1 2 2 1 2 1 1 1 4 1 2 1 1 1 3 1 2 1 3 1 1 1 1 1 3 1 1 1 3 1 4 1 1 1 2 1 2 1 1 2 1 3 RE 0

RE 0 1 3 1 2 2 1 1 1 4 1 3 1 1 1 1 1 2 1 3 1 1 1 3 1 3 1 1 1 2 1 1 1 3 1 4 1 1 1 3 1 1 2 1 3 RE 0

RE 0 1 3 1 2 1 1 2 1 3 1 1 1 4 1 2 1 2 1 2 1 2 1 2 1 2 1 1 1 1 1 3 1 1 1 2 1 3 1 2 1 1 2 1 3 RE 0

RE 0 1 3 1 2 4 1 4 1 1 1 3 1 1 1 3 1 2 1 2 1 2 1 3 1 3 1 1 1 3 1 1 1 3 1 1 1 4 1 2 1 1 2 1 3 RE 0

RE 0 1 3 1 2 4 1 1 1 3 1 2 1 3 1 1 1 1 1 1 1 3 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 1 1 2 1 1 2 1 3 RE 0

RE 0 1 3 1 2 1 1 2 1 1 1 3 1 1 1 3 1 2 1 3 1 2 1 2 1 3 1 3 1 2 1 2 1 3 1 1 1 3 1 2 1 1 2 1 3 RE 0

RE 0 1 3 1 2 1 1 4 1 1 1 3 1 1 1 3 1 3 1 2 1 2 1 2 1 2 1 2 1 1 1 1 1 1 1 3 1 1 1 2 1 1 2 1 3 RE 0

RE 0 1 3 1 2 2 1 1 1 3 1 1 1 1 1 1 1 2 1 2 1 2 1 2 1 2 1 3 1 3 1 1 1 3 1 1 1 4 1 1 1 1 2 1 3 RE 0

RE 0 1 3 1 2 2 1 3 1 1 1 3 1 2 1 2 1 3 1 3 1 2 1 2 1 3 1 2 1 3 1 1 1 3 1 1 1 2 1 1 1 1 2 1 3 RE 0

RE 0 1 3 1 2 2 1 1 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 3 1 1 1 1 1 1 1 3 1 2 1 3 1 1 1 4 1 1 2 1 3 RE 0

RE 0 1 3 1 2 2 1 4 1 1 1 3 1 1 1 3 1 1 1 3 1 3 1 2 1 2 1 2 1 3 1 1 1 3 1 1 1 4 1 4 1 1 2 1 3 RE 0

RE 0 1 3 1 2 2 1 3 1 2 1 1 1 3 1 1 1 1 1 2 1 2 1 2 1 2 1 2 1 2 1 4 1 1 1 3 1 2 1 1 1 1 2 1 3 RE 0

RE 0 1 3 1 2 3 1 1 1 4 1 3 1 1 1 2 1 1 1 3 1 3 1 1 1 3 1 2 1 1 1 1 1 3 1 4 1 1 1 2 1 1 2 1 3 RE 0

RE 0 1 3 1 2 2 1 2 1 1 1 4 1 3 1 1 1 3 1 1 1 1 1 3 1 2 1 3 1 1 1 2 1 4 1 1 1 2 1 2 1 1 2 1 3 RE 0

RE 0 RE 0 1 3 1 2 2 1 2 1 1 1 1 1 4 1 1 1 3 1 4 1 1 1 3 1 1 1 4 1 3 1 1 1 2 1 2 1 1 2 1 3 RE 0 RE 0

* * RE 0 RE 0 1 3 1 2 1 1 2 1 1 1 2 1 2 1 2 1 2 1 2 1 1 1 2 1 2 1 1 1 3 1 1 1 1 2 1 3 RE 0 RE 0 * *

* * * * RE 0 RE 0 1 3 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 3 RE 0 RE 0 * * * *

* * * * * * RE 0 RE 0 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 RE 0 RE 0 * * * * * *

* * * * * * * * RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 RE 0 * * * * * * * *

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 9/27

Oskarshamn-2 benchmark

● Considerable use of code resources

o ≈800 1D components ≈ 13500 volumes

≈ 14500 junctions

o Possible use of 3D components

o Detailed thermal model ≈ 11100 active heat structures

(about 20000 nodes)

o Detailed 3D NK model (limitation embedded in NESTLE exists) Careful description of TH feedback

● Opportunity to investigate the coupling via PVMEXEC (NPP calculation)

o TH-TH (semi-implicit scheme)

o TH-3DNK

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 10/27

ATLAS benchmark

● Within the OECD-ATLAS project - Under OECD/NEA working group

● UNIPI-NINE asked for coordination (together with the OA [KAERI]) of a benchmark

● UNIPI-NINE nodalization qualification methodology adopted

● UNIPI-NINE interact with the OA during the design of the test

● Selected test

o ATLAS A5.1 (Counterpart with LSTF SB-CL-32) - 1% SBLOCA

o Operator action – SS depressurization

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 11/27

ATLAS benchmark

● UNIPI-NINE involved in previous ATLAS OECD based project: ISP-50

o Participated to both blind and open phases

o Adoption of FFT-BM

● RELAP5/MOD3.3 nodalization features:

o Fictitious 3D approach

o Slice approach

o Both loops represented

o Heat losses simulation

● RELAP5-3D nodalization adopted to simulate A5.1 is actually under development (based on the one adopted for the ISP-50)

o Main improvement interests the secondary side

o Use of MULTID component

ATLAS DC instrumentation is capable to capture 3D phenomena

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 12/27

ATLAS benchmark

4 downward pipes covering 90° linked by MULTIPLE JUNCTION (not represented) BRANCH in correspondence of connections with CL and DVI line

Break device: Part of DVI line TRPVLV TMDPVOL constant pressure

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 13/27

ATLAS benchmark

● Core

o 4 upward pipes (14 subvolumes) covering 90° linked by MULTIPLE JUNCTION (not shown)

● LP & UP follow the same approach

● UH unique BRANCH

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 14/27

ATLAS benchmark

● Both loops nodalized

● SG UT represented by 3 equivalent pipes

● PRZ level and pressure control used for initialization purpose only

● SS nodalization includes

o SG Downcomer

o SG Riser

o Economizer

o Two FW connections

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 15/27

ATLAS benchmark

● SIT and ECCS line fully nodalized

o Accumulator

o TIME DEPENDENT JUNCTION

DC-UH bypass

DC-HL bypass ● DC-HL bypass (two paths)

● DC-UH bypass (two paths)

● Core Guide Tube bypass (five paths)

● Core-UP bypass (four paths)

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 16/27

ATLAS benchmark

-500. 0 500. 1000. 1500. 2000. 2500. 3000.

Time (s)

0

.2

.4

.6

.8

1

1.2

1.4

1.6

x 10 7

Pre

ss

ure

(P

a)

WinGraf 4.1 - 05-17-2010

XXX ISP-50-ExpData-Final P-PRZ

X X

X

X

X

XX X X X X X X X X X X X X

YYY AtlasT-03 p341100000

Y

Y

Y

Y

Y

YY Y Y Y Y Y Y Y Y Y Y Y Y

Primary side pressure (Blind and Open calculation)

Break mass flow rate (Blind and Open calculation)

● ISP-50 Selected results: comparison between Blind and open Phases

o ISP-50 used to qualify the (improved) nodalization at “on-Transient” level

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 17/27

PKL III H2.2 run2 benchmark

● UNIPI involved in several OECD/NEA PKL project benchmarks

o Benchmark coordinator

o Participated to both blind and open phases (TRACE, RELAP5, CATHARE)

● Test H2.2 - Station-Blackout

o Station-Blackout AM based on CET measurement Secondary-side Depressurization (SDE)

Primary side Depressurization (PDE)

Mobile Pump (SS) & Emergency RHRS pump (PS)

● RELAP5-3D nodalization features (under improvement)

o Fictitious 3D approach (UP)

o Slice approach

o Four loops represented

o Heat losses simulation

o Detailed modelling of PRZ and SGs (7 UT bundles)

● H2.1 and H2.2 run 1 (and the conditioning phases)will be investigated by UNIPI-NINE to qualify the nodalization

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 18/27

PKL III H2.2 run2 benchmark

● H2.2 run2 benchmark involves more than 15 participants

● Time schedule

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 19/27

PKL III H2.2 run2 benchmark

● Adoption of UNIPI-NINE nodalization qualification methodology

● Special focus put on

o CET and PCT behavior

o PRZ behavior (PRZ RV&SV)

o Accumulator behavior

o Loop seal behaviour

o SG behavior (N2 presence)

PRZ RV&SV closure after PDE in H2.2 run2

● UNIPI suggested improvements of the test specification

o Radial core power distribution

o Additional measurements to investigate the ACC behavior

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 20/27

EBR-II benchmark

● Heterogeneity in the reactor core

o 10 types of assemblies modelled

● Sodium Tank (open pool type reactor with immersed components)

o “Fictitious 3D” approach

o Use of MULTID (turbulent shear stress)

● UNIPI-NINE qualification methodology adopted in the benchmark

● SHRT-17 (1984)

o Protected Loss of Flow Test (PLOFT)

o Simultaneous trip of sodium pumps and control rod scram (@ full power)

o Demonstrated effectiveness of natural circulation cooling characteristics to remove residual heat and keep core cooled during accident

Temperature rose to high, but acceptable levels

Thermal expansion and thermal inertia of sodium effective in protecting reactor from potentially adverse consequence from PLOF

o Coupling of thermal hydraulic phenomena in core and primary loop created challenging benchmark problem

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 21/27

EBR-II benchmark

580

600

620

640

660

680

700

720

740

760

780

0 100 200 300 400 500 600 700 800 900 1,000

Tem

pe

ratu

re (K

)

Time (seconds)

Outlet and IHX Temperatures

Z-Pipe Inlet

IHX Primary Inlet

IHX Intermediate Outlet

600

620

640

660

680

700

720

740

760

780

0 100 200 300 400 500 600 700 800 900

Tem

pe

ratu

re (K

)

Time (seconds)

XX09 Coolant Outlet, and Thimble Annulus Thermocouples

Coolant Outlet (OTC-01) -15

Thimble Annulus (ATC-A1) -15

● Several sensitivities carried out to

address selected issues. E.g.:

o Power supplied also above and below the active part of the core (Gamma heating)

o Axial power distribution (as in SHRT-45)

621

622

623

624

625

626

627

628

629

630

631

632

633

0 100 200 300 400 500 600 700 800 900

Tem

pe

ratu

re (K

)

Time (s)

Upper Flowmeter TC

Phase-2A

Sens-1

Sens-2

Sens-3

Sens-4

600

650

700

750

800

850

900

950

0 100 200 300 400 500 600 700 800 900

Tem

pe

ratu

re (K

)

Time (s)

Mid Core (MTC-20)

Phase-2A

Sens-1

Sens-2

Sens-3

Sens-4

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 22/27

ISP-42: PANDA facility

● Application to Containment: ISP-42 in PANDA Facility - (Passive Systems) o Phase A: Passive Containment Cooling System (PCC) Start-Up o Phase B: Gravity-Driven Cooling System (GDCS) Discharge o Phase C: Long-Term Passive Decay Heat Removal o Phase D: Overload at Pure-Steam Conditions o Phase E: Release of Hidden Air o Phase F: Release of Light Gas in RPV

Relap5

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 23/27

NPP analyses: VVER-1000

● Several scenarios investigated VVER-1000 (e.g. LB-LOCA, MCP trip, MSLB, LOFW)

● Investigation and optimization of AM procedure to cope with SBO

o Depressurization of SS (SDE) and PS (PDE)

o Development of a methodology for AM procedure optimization

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 24/27

NPP analyses: CANDU

● LOFW scenario (Nov. 1993) in Darlington Nuclear Generating Station (CANDU)

● Accurate modeling of o Channel end-fitting

o Process control system

o Emergency control system

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 25/27

TH-SYS\CFD coupling

● Relap5-3D\CFX coupling: file dumping approach

o Development of PERL and FORTRAN routines to allows and coordinate the data exchange

o Development of a GUI

● Two different coupling schemes investigated o Explicit o Semi-implicit

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 26/27

TH-SYS\CFD coupling

● NACIE Facility – Test ID: 303

● Natural circulation (LBE loop) o Power: 21,5 kW (5 min ramp)

o Average fluid temp: 300-350°C

o Gas lift circ. NC (@ 21000s)

o Active heat sink

● MP101 not fully reliable ● Improvement of the BIC

and (coupled) models

Preliminary results

1 m

International RELAP5 User Seminar – Idaho Falls, ID – August 10-14, 2015 27/27

Conclusions

● Summary of the experience gained on RELAP5 code at UNIPI-NINE

● Simulation of several ITF and SETF, different NPP design and scenarios

o ITF simulating PWR and VVER

o SETF: e.g. sub-channels analyses and containment behavior

o Different NPP design: HWR, PHWR, BWR, VVER, RMBK

o Different framework: Benchmarks, Safety Support Analysis, Licensing

o LOCA and Non-LOCA scenarios

● Qualitative and quantitative accuracy evaluation

● Consolidation of procedure for nodalization development and qualification

o Qualified results for Safety Analyses in Licensing (BEPU)

Strong bases on code use are the starting point for new challenges ( BEPU, coupling, …)