Bachmann, C.

Balazs Bajari, J.

Bongiovi, G.

Chiovaro, P.

D’Amico, S.

Federici, G.

Gliss, C.

Graziosi, G.

Moscato, I.

Narcisi, V.

Quartararo, A.

Rossetti, C.

Santucci, A.

Spagnuolo, G. A.

Tarallo, A.

Terranova, N.

Vallone, E.

English

KITopen

2 bar taken as VV design limitRupture disks andbleed valvesCollection tanks CondensersSteam ductSteaminlet fromVVVVPSS integrationABSTRACTThe design of the primary heat transport systems is dependent on a multitude of requirements and constraints. Primarily, the thermal energy that is deposited in the first wall, blanket, divertor and limiters must be removed and transferred to the power conversion system at sufficiently high temperatures to achieve economically attractive efficiency. Additionally, the heat transport systems must provide a reliable barrier against radioactivity releases and be designed to ensure integrity throughout the plant lifetime. As such, safety considerations are critical from the early phases of the heat transport system’s design as the minimisation of radiation exposure and plant activity levels must be pursued. The system design must cope with the contamination of the cooling water with activated products, and the transportation of these radiation sources outside the primary shielding by the coolant circulation. These activated products include strong gamma and neutron emitters. Finally, the significant operating temperature and pressure of the coolant results in high energy stored within the system. The integration concepts adopted to safely operate water coolant systems in a nuclear fusion device are outlined below. The design principles of EU-DEMO adopt the approach implemented in fission power plants, where the entire coolant system is integrated in building areas with massive concrete shielding and segregated from other plant systems. Furthermore, the building is adapted to withstand the consequences of an accidental release through the integration of a pressure suppression system. Finally, the coolant system is equipped with purification systems to prevent the accumulation of tritium and activation products.I. Moscatoa*, C. Bachmanna, J.B. Bajaria, G. Bongiovìb, P. Chiovarob, S. D’Amicoa, G. Federicia, C. Glissa, G. Graziosia, V. Narcisic, A. Quartararob, C. Rossettid, A. Santuccic, G.A. Spagnuoloa, A. Tarallod, N. Terranovac, E. VallonebaFusion Technology Department – Programme Management Unit, EUROfusion Consortium, Boltzmannstraße 2, 85748 Garching, GERMANYbDepartment of Engineering, University of Palermo, Viale delle Scienze, Ed. 6, 90128 Palermo, ItalycENEA, FSN Department, Via Enrico Fermi 45, 00044, Frascati, Rome, ItalydCREATE Consortium, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli, ItalyIvo.Moscato@euro-fusion.orgDesign and integration of Tokamak Coolant Systems based on water technology in the EU-DEMOConclusion and outlookAs result of the recent EUROfusion activities, requirements and constraints with the highest impact on PHTSs’ integration within the tokamak building were identified. Relevant quantities associated to the main hazards implying systems operation were assessed as well. Analyses on PHTSs response during off-normal and accidental events are ongoing to assess design and safety implications of the engineering solutions that are currently under investigations.The DEMO Tokamak Coolant SystemsSuppression of pressure build-up during LOCA eventsRadioactive contamination of water drives the integration in the building and systems design approach.Separate heat removal systems operating at different pressure and temperature levels are utilized for:1) Breeding Blanket2) Divertor Cassette and Limiters Shield Block3) Divertor and Limiters Plasma Facing Components4) Vacuum Vessel5) Other auxiliaries (e.g., shield plugs, add. heating)The first three sources integrated into energy conversion chain being judged economically attractive. Heat from divertor and limiters exploited to preheat feedwater system. Thermal power from other sources is wasted.Main water activity[kBq g-1]DEMO – 2000 MW fusion power NPPBB PHTSDivertor CB & Limiter SB PHTSPFCs PHTSAP600 (1933 MWth)16N 4.38·106 4.46·106 8.40·105 6.03·10317N 6.06·102 3.78·102 1.17·102 1.773H ≤7.40·104 <3.70·104 <7.40·104 1.3·102 **In CANDU 6 the 3H concentration in HTS is typically limited to ≤9.25·104 kBq g-1Secondary shielding requirements:• 16N specific activity ~700 times higher than NPPs• Secondary shielding in fission plants ~0.8-1.2 m• Thicker walls to keep similar dose levels (+50 cm)Water chemistry and purification:• Tight control of water chemistry (pH, H2, low halides contents,etc.) to minimize corrosion issue and radiation field• Purification half-life up to 60 min to effectively removecorrosion products and ensure high water purity• Dedicated active detritiation system for coolant based on waterdistillation technologyPrimary Heat Transport SystemBreeding BlanketDivertor cassette & Limiters shieldDivertor & LimiterPFCsVacuum VesselNominal thermal-power [MW] 1900 230 240 11Primary water volume [m3] ≈620 ≈150 ≈170 ≈600Primary temperature (ave) [°C] 311.5195(311.5)*133 50Primary pressure [MPa] 15.53.5(15.5)*5.0 1.4Stored water energy [GJ] 530 100(140)*76(90)**75(365)***An option with divertor cassette and limiters shield blocks at high temperature/pressure is being investigated**Conditions refer to water baking at 180 °CPalpha403 MWPfusion2000 MWPneutrons1597 MWPaux50 MWPalpha+aux453 MWPCore rad302 MWPSOL151 MWPSOL rad106 MWPcharged45 MWBreeding Blanket1872 MWOther ports for auxiliaries62 MWVacuum Vessel8 MWE-mult. 1.191Pvolumetric1902 MWLimiters114 MWDivertor299 MWVV coolant11 MWFW coolant706-743 MWBZ coolant1126-1163 MW~92-95% ~5-8% PFCs coolant80 MWSB coolant34 MWTargets coolant115 MWCassette coolant184 MWAuxiliaries coolant(s)62 MW2 MW Total depositedpower1 MW Total power to coolantsPvolumetric+Palpha+aux = 2355 MW=Long-term CRUDdeposit specific activity[kBq gcrud−1 ]DEMO NPPBB PHTSAP600 (1933 MWth)58Co 7.89·104 4.44·10560Co 1.61·105 2.22·10559Fe 2.22·104 1.85·10454Mn 1.31·106 5.18·104• Special provision to minimize and collect leakage from flanged mechanical joints, valve stems, pump shaft glands• Leakage detections devices together with vapour andliquid water recovery systems keep under controlradioactive discharge from stackOnly tritium permeation with no SGs leakage.Limit for nuclearclassification ofthe BOP System.PCS tritium concentration vs SGs leakageRadiation protection approachDEMO is equipped with pressure suppression systems to manage both In- and Ex-Vessel LOCAs.• 4 steam generators and 6 main heat exchangers• 10 main coolantpumps• > 18 km of pipework with diameter up to DN 600, 53 mm thick• ≈ 40 MW of required power (<2% thermal power)Tokamk Building pressure suppression system• Rooms housing the cooling systems are about 105 m3. However this expansion volume alone is not sufficient to keep pressure below 2.5 bar(a) following a large Ex-VV LOCA. • Suppression pool with 1700 m3 cold water and spray systems are being integrated into the containment to mitigate pressure build-up and not to challenge the structural integrity of the second confinement barrier.Vacuum Vessel Pressure Suppression System• Sized to accept the full discharge of water from the PHTS with the largest stored energy. Double-ended guillotine break of the largest feeder, DN200, considered as Design Basis Accident. • Fully-passive safety features: natural circulation, and boiling and condensation phenomena are exploited.• 6 rupture disks, 1 m each, for large LOCAs, and bleed valvessized to handle small leaks, placed in dedicated area at L2.• 11 m2 steel-lined duct connects L2 to B3 level• Condensers heat transfer area ≥ 20000 m2• Inventory of water in the main pool ≥ 3500 m3• Target for DBA: peak pressure in the VV ≤1.5 bar(a)Expansion area fornon-condensable airTokamak buildingcontainment wallPart of secondaryshieldingSecondaryshield wallsBioshieldIn-Vessel LOCAEx-Vessel LOCAAll PHTSs sized to extractthe estimated heat inputsfrom volumetric andsurface loads plus margins

Design and integration of Tokamak Coolant Systems based on water technology in the EU DEMO

https://publikationen.bibliothek.kit.edu/1000167415/152040622

Design and integration of Tokamak Coolant Systems based on water technology in the EU DEMO

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