ENSA (Grup SEPI) Fabricatin Thermal Test. Methdlgy fr a Safe Cask Thermal Perfrmance IAEA Internatinal Cnference n the Management f Spent Fuel frm Nuclear Pwer Reactrs An Integrated Apprach t the Back-End f the Fuel Cycle Vienna, Austria. 15-19 June 2015 David Garrid Queved Design & Licensing Manager. Spent Fuel Cask Div. Equips Nucleares, S.A.
Outline Intrductin Thermal Test Analytical Mdel Fabricatin Thermal Test Results and Cnclusins
Intrductin Thermal is ne f the Safety Related Functins f a Spent Fuel Strage and/r Transprtatin Cask Cask Thermal Perfrmance shall be assured bth in nrmal and accident cnditins. Cnfirmatry tests are required (but nt mandatry) in the transprt regulatins fr HAC and may be required (lw pririty) fr strage Traditinally, the thermal behavir relies n analyses due t the difficulties f the thermal tests, althugh.. Many regulatrs require, as part f the licensing prcess, a fabricatin thermal test n the first unit manufactured Gals: 1) mdel validatin, and 2) thermal perfrmance
Thermal Test Analytical Mdel Mdel validatin is the first gal f this methdlgy Finite Element Mdel (FEM) f the cask is used in the analysis, which intends t simulate the real behavir f a laded (heaters) cask during the fabricatin thermal test Different assumptins, engineering appraches, bundary cnditins and material prperties used fr cask licensing thermal evaluatin are applied in this analysis and will be cnfirmed and validated with the subsequent fabricatin thermal test
Finite Element Mdel Descriptin A few differences are being cnsidered t adjust the mdel t the cask thermal test cnfiguratin Cask inner and uter lids are replaced by a single lid Trunnins are nt mdelled Fuel Assembly equivalent material is replaced by the electrical heaters equivalent material Material prperties are taken frm the ASME Cde ENSA - ENUN 52B Dual Purpse Cask
Finite Element Mdel Descriptin (cnt d) Simulatin f cask decay heat is based n electrical heaters n every basket psitin (52 fr this particular case ENSA - ENUN 52B Dual Purpse Cask) Methdlgy fr equivalent material f electrical heaters the same as fr the fuel assembly equivalent material prperties (Arpaci, V.S and SAND90-2406) Radial and axial thermal cnductivity, density and specific heat are btained with this methdlgy t use in the mdel
Finite Element Mdel Descriptin (cnt d) Figures are nt scaled Fuel assembly axial thermal prfile vs. electrical heater axial thermal prfile (difficulties, tp and bttm temperatures) Bundary cnditins are imprtant in this evaluatin Ambient temperature during thermal test (sensitivity analysis) Heat transfer mechanisms inside the cask, cnductin and radiatin and utside the cask, cnvectin and radiatin View factrs fr external radiatin are adjusted t simulate fabricatin test cnditins Slar radiatin is nt cnsidered (test inside the fabricatin shp building)
Finite Element Mdel Descriptin (cnt d) Results f the analysis and test shall be cmpared with the licensing results (quasi-static), s a criterin fr the thermal equilibrium shall be established Transient analysis is perfrmed t btain the duratin f the test until the thermal equilibrium is reached
Thermal Test Analytical Mdel. Results The quasi-static thermal test analysis prvides the temperatures alng the cask ( key lcatins ) fr different ambient temperatures Temperatures are required t be higher than thse btained in the test (cnservatisms in the analysis) Thermcuple Lcatin Ambient Temperature ( C) 21 24 27 40.1 Nrmal Cnditin Mid-plane Inner (EHOS) 1 143.6 146.0 148.4 158.9 169.9 Bttm Inner Cask Bdy 58.5 61.2 63.8 75.4 78.9 Mid-plane Outer Cask Surface 54.4 57.1 59.7 71.2 77.4 Bttm Outer Cask Surface 49.1 51.7 54.4 66.0 71.6 [1] EHOS = Electrical Heater Outer Surface
Fabricatin Thermal Test Test t validate analytical methdlgy Assumptins in the mdel Bundary cnditins Material prperties Level f cnservatisms Test t cnfirm apprpriate cask thermal perfrmance The mre yu knw the better yu understand Having the chance t d s, it is always a gd practice t carry ut test befre peratin, when feasible, t demnstrate safety related respnse f a new cask design
Cask Preparatin fr Thermal Test First unit manufactured f every new cask design Test will be representing the nrmal cnditin f Strage Thermal test is ne f the latest activities f the cask fabricatin schedule, s the cask shall be in final cnditin Only final helium leak test is t be dne after thermal test and befre delivery All previus QA inspectins cnfirm the cmpliance with design and fabricatin requirements
TP13TP14 TP3 TP4 TP-B TP11TP12 TP-F TP9 TP10TP-E TP5 TP6 TP-C TP7 TP1 TP2 TP8 TP-D TP-A Cask Preparatin fr Thermal Test (cnt d) Fifty-tw (52) electrical heaters t simulate the maximum design thermal decay heat TP-B TP-A These heaters are intercnnected in fur grups, and each grup is cnnected t an independent pwer statin TP-E TP-F TP2 TP10 TP12 TP4 TP-C TP-D TP6 TP8 TP1 Temperature is recrded in key lcatins f the cask bdy, basket and heaters using calibrated type K thermcuples TP9 TP5 TP11 TP7 TP3 TP14 TP13
Cask Preparatin fr Thermal Test (cnt d) Design f the thermal test lid is a challenge Same r almst same equivalent thermal cnductivity Allw the instrumentatin cming ut frm the inner cask cavity, while maintaining Leak tightness fr vacuum and inert gas filling (helium) Maintain test pressure during the test duratin
Results and Cnclusins After 73 h (76 h were predicted in the transient analysis) the thermal equilibrium criterin was reached Small leakage every 12 h was detected and refilled was required Temperature n every thermcuple was cntinuusly registered RESULTS (Temperature in C) TC Thermal Test Analytical Mdel ΔT TP1 76.8 93.5 16.7 TP2 114.3 146 31.7 TP3 69.9 87.1 17.2 TP4 104.3 128.8 24.5 TP5 52.9 61.2 8.3 TP6 60.4 68.3 7.9 TP7 46.5 52.6 6.1 TP8 51 57.1 6.1 TP9 56.2 64.9 8.7 TP10 68.1 76.2 8.1 TP11 45.8 51.7 5.9 TP12 51 55.2 4.2 TP13 59.5 66.4 6.9 TP14 61.9 68 6.1
Results and Cnclusins (cnt d) Calculated temperatures in all key lcatins are higher than temperatures frm the thermal test Assumptins and engineering appraches taken in the analytical mdel are cnservative, prviding enugh cnfident n analytical evaluatins when test are nt pssible Temperatures frm the calculatin and frm the test are in the same rder f magnitude. Gd crrelatin exists between bth results The abve mentined cnfirms the tw gals f this methdlgy: a) mdel validatin, and b) cask thermal perfrmance
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