SPES3 Facility RELAP5 Sensitivity Analyses on the Containment System for Design Review

Table 1

Characteristics of the SPES3 cases.

SPES3 cases	Characteristicseffect for mass	Results
SPES3-97	Containment volume ~110% of IRIS volume; DW wall thickness 25 mm for 2 MPa design pressure; Containment metal wall initial temperature 48.9°C.	Starting point for sensitivity analyses.
Sensitivity on the DW inner surface insulation
SPES3-94	1 mm Teflon on the DW inner surface	Little improvements in containment pressure, limited to the early phase of transient.
SPES3-100	DW volume correctly scaled on IRIS volume.; 1.5 mm Rescor 902 Aluminium Silicate layer on the DW inner surface	Little improvements in containment pressure. Negative effect for mass addition.
SPES3-103	DW volume correctly scaled on IRIS volume.; 3 mm Rescor 902 Aluminium Silicate layer on DW inner surface	Little improvements in containment pressure. Negative effect for mass addition.
Sensitivity on the containment volume
SPES3-99	DW volume correctly scaled on IRIS volume	Little improvements in containment pressure.
SPES3-106	DW volume scaled 1 : 150 on IRIS volume	Little improvements in containment pressure, limited to the early phase of transient. Modelling due to a component simulation with a different scaling factor.
SPES3-107	Equivalent to SPES3-99 with corrected minor input mistakes
Sensitivity on the containment metal structure
SPES3-104	DW wall thickness 15 mm for 1.5 MPa design pressure	Improvement of containment pressure, but not sufficient.
SPES3-105	DW wall thickness 10 mm (equivalent to 1 : 100 IRIS DW mass distributed on SPES3 surface)	Further improvement of containment pressure, but not sufficient.
SPES3-108	DW heat structure directly scaled 1 : 100 in terms of mass and surface (a one-hundredth slice of IRIS structure attributed to SPES3). DW wall material as in IRIS	Improvement of containment pressure response in early phase of the transient, due to DW surface reduction impact. No improvement in later phases, due to other SPES3 containment structures, not simulated in IRIS.
SPES3-111	DW heat structure initial temperature from 48.9°C to 84°C	Heat structure preheating compensates for the extra mass. Containment pressure response not sufficiently improved as other containment heat structures are non-preheated.
SPES3-112	PSS wall eliminated	Containment pressure response improved.
SPES3-115	All containment tanks volume resized to scale IRIS 1 : 100. Thickness reduced to resist 1.5 MPa design pressure. Air space metal structure initial temperature 84°C.; PSS main vent pipe no additional restriction.; LGMS to DVI line calibrated orifice from 4 mm to 3.2 mm.; ADS stage I ST calibrated orifice from 7.019 mm to 5.637 mm.; ADS stage I DT calibrated orifice from 9.927 mm to 7.973 mm.; EHRS-A and B CL calibrated orifice from 6 mm to 5 mm.; EHRS-C CL calibrated orifice from 12 mm to 8.5 mm	Containment pressure similar in SPES3 and IRIS.; ADS stage I mass flow correctly reproducing IRIS.; LGMS to DVI line and EHRS CL mass flow not correctly reproduced.
SPES3-119	Containment volume scaled 1 : 100 on IRIS.; DW heat structure directly scaled 1 : 100 in terms of mass and surface.; PSS, LGMS, RC thickness 1 mm (to get closer to IRIS nonsimulated structure); LGMS to DVI line calibrated orifice from 2.3 mm to 2.5 mm.; PSS vent pipe extension orifice from 5.2 to 7.3 mm.; RC to DVI line additional calibrated orifice of 1 mm (original valve D = 10.7 mm); EHRS-C CL calibrated orifice from 6.7 mm to 7 mm	Containment pressure very similar in SPES3 and IRIS.Great importance of correct heat structure simulation.
SPES3-122	As SPES3-120.; Containment heat structure initial temperature 48.9°C.	For comparison with SPES3-120 to quantify the heat structure preheating influence.
SPES3-132	As SPES3-130.; EHRS-A and B tube 2% additional surface thermally insulated with Teflon (originally 0.6 tubes out of 3 insulated to scale 1 : 100 240 IRIS tubes).; EHRS-C 0.2 tubes out of 5 insulated to scale 1 : 100 480 IRIS tubes. Additional 2% tube surface thermally insulated with Teflon	EHRS tube heat transfer surface reduced to correctly simulate IRIS surface.
Sensitivity on the containment piping pressure drops
SPES3-109	PSS main vent pipe resizing from 2.5^′′ to 2^′′ Sch. 40.; PSS vent pipe extension resizing from 3/4^′′ to 1/2^′′ Sch. 40	PSS to DW mass flow closer to IRIS one.
SPES3-110	PSS main vent pipe additional restriction at the check valve (𝐷orifice 14.19 mm)	Only early steep but limited containment pressure increase.
SPES3-118	Containment volume scaled 1 : 100 on IRIS.; LGMS to DVI line calibrated orifice from 3.2 mm to 2.3 mm.; EHRS-C CL calibrated orifice from 8.5 mm to 6.5 mm.; PSS vent pipe extension additional restriction (𝐷orifice 5.2 mm).; Containment heat structure initial temperature 48.9°C	Attempt to match IRIS injection mass flows.
SPES3-120	Containment volume scaled 1 : 100 on IRIS.; Thickness to resist 1.5 MPa design pressure.; Air space metal structure initial temperature 84°C. QT initial temperature 48.9°C.; LGMS to DVI line calibrated orifice from 2.3 mm to 2.5 mm	IRIS injection mass flow reproduced, but different pressure drops in the pipes.
SPES3-124	PSS main vent pipe resizing from 2^′′ to 2.5^′′ Sch. 40; PSS vent pipe extension resizing from 1/2^′′ to 1^′′ Sch. 40; LGMS to DVI line calibrated orifice from 2.5 mm to 3.6 mm.; PSS vent pipe extension orifice from 7.3 to 19 mm.; PSS vent pipe extension connection to DW elevation decrease of 1.5 m to match IRIS.; PSS sparger elevation decrease of 0.25 m to match IRIS.; PSS bottom modelled with a branch.; Containment air space metal structure initial temperature 84°C, water space 48.9°C	Mass flow determined by actual piping pressure drops as in IRIS.Containment pressure response qualitatively and quantitatively close to IRIS.; The PSS bottom modelling did not affect the PSS vent pipe emptying mode.
SPES3-127	As SPES3-124; PSS bottom modelled with three branches.	The PSS bottom modelling did not strongly affect the PSS vent pipe emptying mode.
SPES3-130	As SPES3-127; RWST top pipe introduction for connection to atmosphere.	Reduced loss of mass at RWST top due to dry air and water contact.
SPES3-135	AS SPES3-132; Completely reviewed the EHRS circuits and RWST model: EHRS-A and B tube 4% surface thermally insulated with Teflon other than the originally insulated 0.6 tubes.; EHRS-C 4% surface thermally insulated other than the originally insulated 0.2 tubes.; EHRS-A and B HL resized from 2^′′ to 1.25^′′ Sch. 80.; EHRS-A and B CL resized from 1.25^′′ to 1.5^′′ Sch. 80.; EHRS-C HL resized from 2.5^′′ to 2^′′Sch. 80.; EHRS-C CL resized from 1.5^′′to 3^′′ Sch. 80.; HL-A and B additional orifice D = 17 mm.; HL-C additional orifice D = 24 mm.; CL-A and B orifice resized from 5 mm to 5.9 mm.; CL-C orifice resized from 7 mm to 8.3 mm.; EHRS tube heat structure fouling factor set to 2.9 left and 2.77 right (original values 2.725 left, 3.54284 right) [13].; RWST-AB and C rising slice area resized from 0.491 m^2 to 0.119167 m^2; recirculation slice resized from 1.217 m^2 to 1.601169 m^2 [13].; RWST-AB and C slice side junction area from 0.151 m^2 to 0.135 m^2 [13].	The complete revision of the EHRS piping and heat exchanger parameters led to matching transferred energy.
SPES3-146	As SPES3-135.; PSS vent pipe extension orifice from 19 mm to 17.5 mm.; SG tube inlet orifice from 12.5 mm to 11.7 mm	Good similarity between SPES3 and IRIS; BASE CASE for FSA final application.