Petten, Netherlands, 26 February, 2013 Kaspar Kööp, Marti Jeltsov Division of Nuclear Power Safety Royal Institute of Technology (KTH) Stockholm, Sweden Analyses of representative DEC events of the ETDR LEADER WP5 MEETING, Petten – 26 th of February 2013
LEADER WP5 MEETING, Petten – 26 th of February 2013. Analyses of representative DEC events of the ETDR. Kaspar Kööp, Marti Jeltsov Division of Nuclear Power Safety Royal Institute of Technology (KTH) Stockholm, Sweden. ETDR – ALFRED description. Pool-type 300 MWth - PowerPoint PPT Presentation
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Petten, Netherlands, 26 February, 2013
Kaspar Kööp, Marti JeltsovDivision of Nuclear Power Safety
Royal Institute of Technology (KTH) Stockholm, Sweden
Analyses of representative DEC events
of the ETDR
LEADER WP5 MEETING, Petten – 26th of February 2013
Slide 2Petten, Netherlands, 26 February, 2013
• Pool-type• 300 MWth• Core pressure drop 1 bar• Temperature
– Core inlet 400 C– Core outlet 480 C
• Coolant velocity– Average 2 m/s– Maximum 3 m/s
• Lead void effect at EOC (only the fuel zones)– +2 $
ETDR – ALFRED description
Slide 3Petten, Netherlands, 26 February, 2013
• T-DEC1 – complete loss of forced flow + SCRAM fail
• T-DEC4 – complete loss of forced flow, complete loss of SCS, DHR system operating
KTH contribution
Slide 4Petten, Netherlands, 26 February, 2013
T-DEC1&4 RELAP5 model
Feedwater
Steam521-8
531-8
551-8 561-8
151-
8
Feedwater
Steam521-8
531-8
551-8 561-8
151-
8
841- 4
851- 8441-8
801- 4
811-4831-4
815
401-8
841- 4
-
801- 4
811-4831-4
815
841- 4
-
801- 4
811-4831-4
815
611- 8
841- 4
-
801- 4
811-4831-4
815
611-
711-
731-
741- 4
751- 8
761- 4
621- 4
641- 4
771
781- 8
601- 4
661- 4
611-
711- 8
731- 8
741- 4
751-
761- 4
621- 4
641- 4
771-8
781-
601- 4
661- 4
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781
601- 4
661- 4
841- 8
-
801- 4
811-4831-4
815
841-
-
801- 8
811-8831-8
815
611-
841-
-
801-
811-831-
411-8
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771
781
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
601- 8
661- 8
611-
711-
731-
741- 8
751-
761- 8
621- 8
641- 8
841- 4
851- 8441-8
801- 4
811-4831-4
815
401-8
841- 4
-
801- 4
811-4831-4
815
841- 4
-
801- 4
811-4831-4
815
611- 8
841- 4
-
801- 4
811-4831-4
815
611-
711-
731-
741- 4
751- 8
761- 4
621- 4
641- 4
771
781- 8
601- 4
661- 4
611-
711- 8
731- 8
741- 4
751-
761- 4
621- 4
641- 4
771-8
781-
601- 4
661- 4
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781
601- 4
661- 4
841- 8
-
801- 4
811-4831-4
815
841-
-
801- 8
811-8831-8
815
611-
841-
-
801-
811-831-
411-8
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771
781
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
601- 8
661- 8
611-
711-
731-
741- 8
751-
761- 8
621- 8
641- 8
ALFRED Nodalization scheme with RELAP5
8 SGs
8 Secondary loops Primary circuit
8 IC loops
Steam line
Feedwater line
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
Feedwater
Steam521-8
531-8
551-8 561-8
151-
8
Feedwater
Steam521-8
531-8
551-8 561-8
151-
8
841- 4
851- 8441-8
801- 4
811-4831-4
815
401-8
841- 4
-
801- 4
811-4831-4
815
841- 4
-
801- 4
811-4831-4
815
611- 8
841- 4
-
801- 4
811-4831-4
815
611-
711-
731-
741- 4
751- 8
761- 4
621- 4
641- 4
771
781- 8
601- 4
661- 4
611-
711- 8
731- 8
741- 4
751-
761- 4
621- 4
641- 4
771-8
781-
601- 4
661- 4
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781
601- 4
661- 4
841- 8
-
801- 4
811-4831-4
815
841-
-
801- 8
811-8831-8
815
611-
841-
-
801-
811-831-
411-8
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771
781
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
601- 8
661- 8
611-
711-
731-
741- 8
751-
761- 8
621- 8
641- 8
841- 4
851- 8441-8
801- 4
811-4831-4
815
401-8
841- 4
-
801- 4
811-4831-4
815
841- 4
-
801- 4
811-4831-4
815
611- 8
841- 4
-
801- 4
811-4831-4
815
611-
711-
731-
741- 4
751- 8
761- 4
621- 4
641- 4
771
781- 8
601- 4
661- 4
611-
711- 8
731- 8
741- 4
751-
761- 4
621- 4
641- 4
771-8
781-
601- 4
661- 4
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781
601- 4
661- 4
841- 8
-
801- 4
811-4831-4
815
841-
-
801- 8
811-8831-8
815
611-
841-
-
801-
811-831-
411-8
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771
781
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
601- 8
661- 8
611-
711-
731-
741- 8
751-
761- 8
621- 8
641- 8
ALFRED Nodalization scheme with RELAP5
8 SGs
8 Secondary loops Primary circuit
8 IC loops
Steam line
Feedwater line
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
Slide 5Petten, Netherlands, 26 February, 2013
• T-DEC1 – complete loss of forced flow + SCRAM fail• Pumps are tripped at 0s• Secondary side is operational, IC valves closed
T-DEC1 – Description
Slide 6Petten, Netherlands, 26 February, 2013
T-DEC1 - loss of 8 pumps
Slide 7Petten, Netherlands, 26 February, 2013
T-DEC1 - loss of 8 pumps
Slide 8Petten, Netherlands, 26 February, 2013
T-DEC1 - loss of 8 pumps
Slide 9Petten, Netherlands, 26 February, 2013
T-DEC1 - loss of 8 pumps
Slide 10Petten, Netherlands, 26 February, 2013
• T-DEC4 – complete loss of forced flow + complete loss of secondary cooling system + SCRAM fail
• Pumps and SCS are tripped at 0s, IC valves opened at 1s
T-DEC4 – Description
Slide 11Petten, Netherlands, 26 February, 2013
T-DEC4 – loss of flow + loss of SCS + IC valves open
Slide 12Petten, Netherlands, 26 February, 2013
T-DEC4 – loss of flow + loss of SCS + IC valves open
Slide 13Petten, Netherlands, 26 February, 2013
T-DEC4 – loss of flow + loss of SCS + IC valves open
Slide 14Petten, Netherlands, 26 February, 2013
T-DEC4 – loss of flow + loss of SCS + IC valves open
Slide 15Petten, Netherlands, 26 February, 2013
T-DEC1&4 RELAP5 model
Feedwater
Steam521-8
531-8
551-8 561-8
151-
8
Feedwater
Steam521-8
531-8
551-8 561-8
151-
8
841- 4
851- 8441-8
801- 4
811-4831-4
815
401-8
841- 4
-
801- 4
811-4831-4
815
841- 4
-
801- 4
811-4831-4
815
611- 8
841- 4
-
801- 4
811-4831-4
815
611-
711-
731-
741- 4
751- 8
761- 4
621- 4
641- 4
771
781- 8
601- 4
661- 4
611-
711- 8
731- 8
741- 4
751-
761- 4
621- 4
641- 4
771-8
781-
601- 4
661- 4
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781
601- 4
661- 4
841- 8
-
801- 4
811-4831-4
815
841-
-
801- 8
811-8831-8
815
611-
841-
-
801-
811-831-
411-8
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771
781
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
601- 8
661- 8
611-
711-
731-
741- 8
751-
761- 8
621- 8
641- 8
841- 4
851- 8441-8
801- 4
811-4831-4
815
401-8
841- 4
-
801- 4
811-4831-4
815
841- 4
-
801- 4
811-4831-4
815
611- 8
841- 4
-
801- 4
811-4831-4
815
611-
711-
731-
741- 4
751- 8
761- 4
621- 4
641- 4
771
781- 8
601- 4
661- 4
611-
711- 8
731- 8
741- 4
751-
761- 4
621- 4
641- 4
771-8
781-
601- 4
661- 4
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781
601- 4
661- 4
841- 8
-
801- 4
811-4831-4
815
841-
-
801- 8
811-8831-8
815
611-
841-
-
801-
811-831-
411-8
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771
781
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
601- 8
661- 8
611-
711-
731-
741- 8
751-
761- 8
621- 8
641- 8
ALFRED Nodalization scheme with RELAP5
8 SGs
8 Secondary loops Primary circuit
8 IC loops
Steam line
Feedwater line
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
Feedwater
Steam521-8
531-8
551-8 561-8
151-
8
Feedwater
Steam521-8
531-8
551-8 561-8
151-
8
841- 4
851- 8441-8
801- 4
811-4831-4
815
401-8
841- 4
-
801- 4
811-4831-4
815
841- 4
-
801- 4
811-4831-4
815
611- 8
841- 4
-
801- 4
811-4831-4
815
611-
711-
731-
741- 4
751- 8
761- 4
621- 4
641- 4
771
781- 8
601- 4
661- 4
611-
711- 8
731- 8
741- 4
751-
761- 4
621- 4
641- 4
771-8
781-
601- 4
661- 4
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781
601- 4
661- 4
841- 8
-
801- 4
811-4831-4
815
841-
-
801- 8
811-8831-8
815
611-
841-
-
801-
811-831-
411-8
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771
781
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
601- 8
661- 8
611-
711-
731-
741- 8
751-
761- 8
621- 8
641- 8
841- 4
851- 8441-8
801- 4
811-4831-4
815
401-8
841- 4
-
801- 4
811-4831-4
815
841- 4
-
801- 4
811-4831-4
815
611- 8
841- 4
-
801- 4
811-4831-4
815
611-
711-
731-
741- 4
751- 8
761- 4
621- 4
641- 4
771
781- 8
601- 4
661- 4
611-
711- 8
731- 8
741- 4
751-
761- 4
621- 4
641- 4
771-8
781-
601- 4
661- 4
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781
601- 4
661- 4
841- 8
-
801- 4
811-4831-4
815
841-
-
801- 8
811-8831-8
815
611-
841-
-
801-
811-831-
411-8
611-
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771
781
711-
731-
741- 4
751-
761- 4
621- 4
641- 4
771-
781-
601- 8
661- 8
611-
711-
731-
741- 8
751-
761- 8
621- 8
641- 8
ALFRED Nodalization scheme with RELAP5
8 SGs
8 Secondary loops Primary circuit
8 IC loops
Steam line
Feedwater line
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
100
101102109
110
115
060061-8 070
050
020
200 151-8
121-8
131-8
141-8
220
230
210
Slide 16Petten, Netherlands, 26 February, 2013
T-DEC4 with 1 working pump
Slide 17Petten, Netherlands, 26 February, 2013
T-DEC4 with 1 working pump
Slide 18Petten, Netherlands, 26 February, 2013
T-DEC4 with 1 working pump
Slide 19Petten, Netherlands, 26 February, 2013
• TR-4 – a transient event due to reactivity insertion (enveloping SGTR, flow blockage, core compaction)
KTH contribution
Slide 20Petten, Netherlands, 26 February, 2013
• TR-4 – a transient event due to reactivity insertion (enveloping SGTR, flow blockage, core compaction)
Steam Generator Tube Leakage (SGTL) is assumed to be the cause for reactivity insertion (voiding of part of active region• We address the task on the transport of bubbles that have
leaked in the SG to the primary coolant flow• Reactor is at hot full power (HFP)• Actions:
– First thermal-hydraulic part (CFD analysis of bubble transport)– Neutronic part (SERPENT code to look at the consequences of different
local core voiding that are typical for SG leakage)
TR-4 – Description
Slide 21Petten, Netherlands, 26 February, 2013
• ALFRED – Advanced Lead Fast Reactor European Demonstrator• Power – 125 MWel (300 MWth, ~41% efficiency)• 8 steam generators with 8 axial pumps• 2 independent DHRs using SG tubes
ALFRED design
Slide 22Petten, Netherlands, 26 February, 2013
• Core – submerged in the bottom middle part of the pool• 8 SGs – located inside the primary circuit radially
around the core• One co-axial pump per SG• High P secondary vs low P primary system
• SG tube rupture and leakage events in PWRs suggest that it can be a concern in LFRs
• Risk of core voiding in case of SGTL due to:– Proximity of SGs to core– Nature (shape) of the flow path– Leak-Before-Break (LBB) (< liter/day in PWRs)
• SGTL can hinder licensing due to:– Potential severe consequences (core damage)– Lack of operational experience (uncertainty in frequency
of SGTL)
Motivation
Slide 23Petten, Netherlands, 26 February, 2013
Objectives• To assess the risk related to SGTL
• To identify the scenarios of core voiding
• To quantify the likelyhood that a steam bubble is transported from a SG to the core– Identify the uncertainties in SGTL– Quantifiy these uncertainties
• To estimate void accumulation rates in the core
• To estimate the consequent effect to power (or to neutron flux) with a neutronic code
Slide 24Petten, Netherlands, 26 February, 2013
• SGT leakage is considered during normal operation• If steam bubbles are dragged to the core then there are 3 distinct
scenarios of safety concern:a) Homogeneous voiding of the coolant (continuous leak, small bubbles)b) Bubbles stuck in spacers (mid-size bubbles)c) Slugs of void entering the core (formed in stagnation zones)
Depending on the scenario...– RIA– Local damage (burn-out) of the fuel– Overpressurization of the vessel
...can happen.
Scenarios
Slide 25Petten, Netherlands, 26 February, 2013
• Aleatory and epistemic uncertainties assessed in the SGTL scenarios and phenomenology:
Crack size and morphology Bubble size distribution Leak rate through the crack Bubble drag correlation
• Bubble size distribution
• Leak rate depends on crack size, morphology and pressure differences between two sides– ”Leak-before-break”
Uncertainties
K. Terasaka et al. (2011) A. V. Beznosov et al. (2005)
Slide 26Petten, Netherlands, 26 February, 2013
Non-linear drag coefficientm, , as a function of bubble diameter
Validation is done by comparing with predictions from Stokes and Mendelsons law
Bubbles were modeled:• As Lagrangian particles• Constant density• Drag coefficient• With/without turbulent dispersion
Tomiyama et al. correlation chosen:
Drag coefficient
0 1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
bubble diameter [mm]
velo
city
[m/s
]
Stokes lawMendelsons eq. for PbMori et al. data for Hg
0 1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
bubble diameter [mm]
velo
city
[m/s
]
Stokes lawMendelson eq.Schiller-NaumannModif. Schiller-NaumannRodrigueTomiyama et al.
Slide 27Petten, Netherlands, 26 February, 2013
Bubbles are injected at - 3 different height levels in SG (bottom, middle, top) - at the exit of the core - at the pump outlet
to estimate probabilities:P1 – that bubble enters coreP2 – that bubble proceeds to pumpP3 – that bubble stays in the primary loop
Steam accumulation rate in the primary system:
and in the core (assumed bubbles get stuck there):