VVER core catcher

Analytical and Experimental Studies Analytical and Experimental Studies for Core Catcherfor Core Catcher DevelopmentDevelopment

Yu. ZvonarevNRC “Kurchatov Institute”

Seminar with Vietnamese expertsMoscow, NRC “Kurchatov Institute”, December 9, 2013

22

The Safety ConceptThe Safety Concept

• Severe accident analysis

• Severe accident management

• Core catcher application

33

ScientificScientific Background Background of Severe Accident Measures Procedures Development:of Severe Accident Measures Procedures Development:

RASPLAV (1994-2000) and MASCA (2000-2006) OECD Projects

List of participants:The Association Vincotte Nuclear, jointly with Tractebel S.A., BelgiumThe Atomic Energy of Canada Limited, CanadaThe Fortum Nuclear Services Ltd, jointly with Valtion Teknillinen Tutkimuskeskus and Säteilyturvakeskus, FinlandThe Institut de Radioprotection et de Sûreté Nucléaire, FranceThe Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH, GermanyThe KFKI Atomic Energy Research Institute, HungaryThe Nuclear Power Engineering Corporation, JapanThe Korea Atomic Energy Research Institute, Korea

The Nuclear Regulatory Authority of the Slovac Republic, Slovakia The Consejo de Seguridad Nuclear, SpainThe Statens Kärnkraftinspektion, SwedenThe Paul Scherrer Institute, SwitzerlandThe United States Nuclear Regulatory Commission, USAThe Russian Federation Ministry of Atomic Energy, jointly with theFederal Nuclear and Radiation Safety Authority of Russia, and theNational Research Centre «Kurchatov Institute», Russia

44

Study of Melt Stratification and Distribution of Major Species (U , Zr, O, Fe(SS)) between layers in Inert

Atmosphere at Large Iron (SS) to Corium Ratio

Test conditions: Inert atmosphere Two basic corium compositions: C-32

and C-70 with U/Zr = 1.2 and U/Zr=0.9

Small scale STFM facility with the loaded mass about 0.5 kg; Middle scale RASPLAV-3 facility with the loaded mass of

about 2 kg;

Objective:To obtain quantitative and qualitative characteristics of uranium, zirconium and steel components partitioning between different phases.

Activity: Technology development; Facility modernization; Test preparation and performance; Post-test examinations.

STFM

RASPLAV-3

Facilities:

55

Study of Control Rod Materials Effects on Interaction and Distribution of Major Species

(U , Zr, O, Fe(SS)) in Inert Atmosphere

The effects of the following absorbing materials are studied: Boron carbide (Matrix 2.1), silver-indium-cadmium (Matrix 2.2) and boron

oxide (Matrix 2.3)

Objective: to extend the thermodynamic database including additional structural materials

Test conditions Inert atmosphere Two basic corium compositions: C-32 and C-70 with FP simulants in some

tests U/Zrratio=1.2

STFM-B KORPUS-M

66

RASPLAV ProjectRASPLAV ProjectMajor Objective: Extend knowledge base to determine specific

features of prototypic corium molten pool

Scope of Work: Separate effect corium tests, Material properties, Supporting salt tests, Confirmatory large-scale integral tests, Code development

RASPLAV-AW-200 Test Matrix

RASPLAV-AW-200 Facility

AW-1 AW-2 AW-3 AW-4 Corium composition C-22 C-22 C-100 C-32 Corium loading 198 kg 198 kg 195 kg 200 kg Peak heat flux to the test wall 130 kW/m2 280

kW/m2 90 kW/m2 180 kW/m2

Molten volume 70% 72% 60% 76%

Specific features Stratification of the

melt into two immiscible layers

Additives: FeO: 2.4 kg La2O3: 3.5 kg

No carbon

77

The MASCA Project Findings

Low iron to corium ratioLow corium oxidation degree

High iron to corium ratioHigh corium oxidation degree

Low iron to corium ratioMedium corium oxidation

degree

Molten steel extracts some metallic uranium and zirconium from sub-oxidized corium

ρmet> ρoxide ρmet~ ρoxide ρmet< ρoxide

OxideOxide

Metal bodyMetal body

OxideOxide


OxideOxide


Core Catcher Basic Functions

• Localization into the core catcher vessel of liquid and solid components of the corium, fragments of the core and reactor structural materials;

• The transfer of heat from the corium to the cooling water and the guaranteed cooling of the corium melt;

• Providing subcritical state of the corium;• Prevention of steam explosion;• Minimizing of fission products release from corium into

containment;• Minimizing of hydrogen generation.

88

99

Main Technical Decisions for Core Catcher Development

• The choice of "crucible" type of core catcher design for melt localization and cooling by water;

• The application of double-layer wall for core catcher vessel to prevent its destruction due to thermal stress;

• The use of sacrificial materials from iron oxide and aluminum oxide to reduce:- the molten corium temperature and the volume density of decay heat release - minimizing of fission products release from corium;- minimizing of hydrogen generation;

• Adding to the sacrificial materials a gadolinium oxide to provide subcritical state of the corium.

Design of the Core Catcher for VVER-1200Design of the Core Catcher for VVER-1200

1 ‑ reactor vessel ; 2 ‑ bottom plate; 3 ‑ console truss; 4 ‑ technological corridor; 5 ‑ core catcher vessel; 6 ‑ reactor cavity; 7‑11 - cassettes with sacrificial materials;

12 ‑ thermal protection; 13 – service platform; 14 ‑ ventilating corridor.

1111

Core Catcher Vessel Filled Core Catcher Vessel Filled by the Cassettes with Sacrificial Materialsby the Cassettes with Sacrificial Materials

1212

Core Catcher Cassette with Sacrificial Materials Core Catcher Cassette with Sacrificial Materials (4-th Layer)(4-th Layer)

1313

Sacrificial material brick in the form of a triangular prism

Sacrificial material composition: Fe2O3 (65-70%), Al2O3 (28-30%), Gd2O3 (0.15%), SiO2 7%

Manufacturing technology: dosage; mixing; pressing; sintering.

Appearance of theAppearance of the Brick of a Sacrificial MaterialBrick of a Sacrificial Material

213

50

1414

Sacrificial Material SelectionSacrificial Material Selection

Stage 1: Preliminary selection of oxidic material Stage 2: Experimental examination of corium and

sacrificial materials phase properties Stage 3: Experimental study of corium Interactions with

sacrificial materials

Main Stages of Work

1515

Sacrificial Material SelectionSacrificial Material SelectionStage 1: Preliminary Selection of Oxidic Material

Basic Properties of Considered Oxides

Oxide Density (g/cm3)

Melting temperature

(оC)

Boiling temperature

(оС)

Melting heat

(kJ/kg)

Heat capacity at

300 K (kJ/(g·K))

Heat conductivity

at 300 K (W/(m·K))

α-Al2O3 3.97 2046 3696 1108 0.775 25 B2O3 1.84 450 2074 353 0.902 - BаO 5.72 1923 3050 376 0.306 - CaO 3.37 2777 3632 1344 0.749 15 Cr2O3 5.21 2234 3051 689 0.843 - (FeO)* 5.7 1374 3079 437 0.695 - Fe3O4 5.18 1597 decomposed - 0.651 ~5 Fe2O3 5.25 1457 decomposed - 0.650 ~5 MgO 3.58 2825 3115 1921 0.923 36

Nb2O5 4.95 1490 3397 389 0.497 - α-SiO2 2.65 1610 2857 186 0.969 1.0 α-TiO2 3.84 1868 2927 838 0.690 6.53 V2O5 3.36 680 2052 358 0.703 4.4 Y2O3 4.84 2430 4027 372 0.454 6.28

Analyzed reference properties of the selected materials taking into account functional

requirements (including cost) allowed to reduce this list and to choose as the main sacrificial materials (SM) Fe2O3 and Al2O3.

1616


Objectives:• Evaluation of SM compositions with lowest solidus temperatures.• Estimation of gas release.• Assessment of minimum oxide density to provide corium layers inversion

(oxide layer – the upper one).Experimental program:• Two facilities in Russia : STF (NRC KI) and RASPLAV-2 (NITI).• Induction heating of W acceptor, radiation heating of the sample.• Specimens with corium C-30, C-100 and different composition of Fe2O3 +

Al2O3 + SiO2+ Cr2O3 sacrifice material (SM).• Temperature measurements of sample melting (liquidus) and corium

spreading.• Gas release measurements.• 36 experiments were performed in NRC KI and NITI.

Stage 2: Experimental Examination of Corium + SM Phase Properties

1717


Objectives:• Measurement of interaction rate.• Detection of potential oxygen release.• Assessment of optimal Fe2O3 content.

Experimental program:• Two facilities in Russia : KORPUS (NRC KI) and RASPLAV-2 (NITI).• Induction heating in cold crucible.• Specimens with corium C-32, C-100 and different composition of Fe2O3 +

Al2O3 + concrete + Gr2O3 sacrifice material (SM).• 7 experiments were performed in NRC KI and NITI.

Stage 3: Experimental Study of Corium Interactions with Sacrificial Materials

1818


1. Equimolar compound allows effective binding of active Zr in corium.2. Decrease of hematite content from 100% led to excluding of potentially

dangerous release of free oxygen.3. Application of Fe2O3 + Al2O3 compound excluded the recovery of

Al2O3 and subsequent gas release of highly volatile AlO2 from corium.4. Experiments confirmed low melting temperatures during eutectic

interaction between corium and sacrificial material.5. Mutual dissolution of corium and sacrificial material can be realized

with high rates, sufficient for effective corium temperature decrease.6. Theoretical and experimental examinations allowed to recommend the

following composition for sacrificial material: Fe2O3 (65-70%), Al2O3 (28-30%), Gd2O3 (0.15%), SiO2 7%

Results

List of Patents on Core Catcher Design List of Patents on Core Catcher Design and Sacrificial Materialand Sacrificial Material

1. Gusarov V.V., Khabensky V.B., Bechta S.V., Granovsky V.S., Almjashev V.I., Krushinov E.V., Vitol S.A., Sergeev E.D., Petrov V.V., Tikhomirov V.A., Migal V.P., Mozherin V.A., Sakulin V.Ya., Novikov A.N., Salagina G.N., Shtern E.A. Oxide material for a molten-core catcher of a nuclear reactor // China Patent ZL 02807587.0. Published July 13 2005.

2. Хабенский В.Б., Грановский В.С., Бешта С.В., Сидоров А.С., Носенко Г.Е., Клейменова Г.И., Сергеев Е.Д., Тихомиров В.А., Петров В.В., Замятин О.Н., Нечаев А.К., Онуфриенко С.В., Кухтевич И.В., Безлепкин В.В., Гусаров В.В., Беркович В.М., Клоницкий М.Л., Копытов И.И. Система локализации и охлаждения кориума аварийного ядерного реактора водо-водяного типа // Патент РФ № 2253914. Приоритет от 18.08.2003. Дата публикации – 27.02.2005.

3. Павлова Е.А., Сидоров А.С., Соловейчик Э.Я., Тихомиров В.А., Удалов Ю.П., Федоров Н.Ф. Керамический материал для ловушки расплава активной зоны атомного реактора // Евразийский патент № 003961, Дата публикации: 30.10.2003.

4. Бешта С.В., Витоль С.А., Миселев В.М., Павлова Е.А., Сидоров А.С., Судакас Л.Г., Удалов Ю.П., Федоров Н.Ф., Хабенский В.Б. Бетон для ловушки расплава активной зоны атомного реактора // Патент РФ № 2214980, Дата публикации: 27.10.2003.

5. Бешта С.В., Витоль С.А., Миселев В.М., Павлова Е.А., Сидоров А.С., Судакас Л.Г., Удалов Ю.П., Федоров Н.Ф., Хабенский В.Б. Цемент для ловушки расплава активной зоны атомного реактора // Патент РФ № 2215340, Дата публикации: 27.10.2003.

6. Gusarov V.V., Khabensky V.B., Beshta S.V., Granovsky V.S., Almyashev V.I., Krushinov E.V., Vitol S.A., Sergeev E.D., Petrov V.V., Tikhomirov V.A., Migal V.P., Mozherin V.A., Sakulin V.Ya., Novikov A.N., Salagina G.N., Shtern E.A. Oxide material for a molten-core catcher of a nuclear reactor // PCT patent WO 03/032326. Priority Apr. 2, 2002. Patented Apr. 17, 2003.

7. Gusarov V.V., Khabensky V.B., Beshta S.V., Granovsky V.S., Almyashev V.I., Krushinov E.V., Vitol S.A., Sergeev E.D., Petrov V.V., Tikhomirov V.A., Migal V.P., Mozherin V.A., Sakulin V.Ya., Novikov A.N., Salagina G.N., Shtern E.A. Oxide material for a molten-core catcher of a nuclear reactor // PCT patent WO 03/032325. Priority Apr. 2, 2002. Patented Apr. 17, 2003.

8. Гусаров В.В., Альмяшев В.И., Столярова В.Л., Хабенский В.Б., Бешта С.В., Грановский В.С., Анискевич Ю.Н., Крушинов Е.В., Витоль С.А., Саенко И.В., Сергеев Е.Д., Петров В.В., Тихомиров В.А., Мигаль В.П., Можжерин В.А., Сакулин В.Я., Новиков А.Н., Салагина Г.Н., Штерн Е.А. Оксидный материал ловушки расплава активной зоны ядерного реактора // Патент РФ № 2212719. Приоритет от 12.10.2001. Дата публикации – 20.06.2003.

9. Гусаров В.В., Альмяшев В.И., Саенко И.В., Бешта С.В., Грановский В.С., Хабенский В.Б., Мигаль В.П., Можжерин В.А., Сакулин В.Я., Новиков А.Н., Салагина Г.Н., Штерн Е.А. Способ получения керамических материалов для ловушки расплава активной зоны ядерного реактора, содержащих оксиды железа, алюминия и диоксид кремния // Патент РФ № 2206930. Приоритет от 02.04.2002. Дата публикации – 20.06.2003.

10. Gusarov V.V., Khabensky V.B., Beshta S.V., Granovsky V.S., Almyashev V.I., Krushinov E.V., Vitol S.A., Sergeev E.D., Petrov V.V., Tikhomirov V.A., Bezlepkin V.V., Kukhtevich I.V., Aniskevich Yu.N., Sayenko I.V., Stolyarova V.L., Migal V.P., Mozherin V.A., Sakulin V.Ya., Novikov A.N., Salagina G.N., Shtern E.A., Asmolov V.G., Abalin S.S., Degaltzev Yu.G., Zagryazkin V.N. Oxide material for a molten-core catcher of a nuclear reactor // PCT patent WO 02/080188. Priority Apr. 2, 2002. Patented Nov. 21, 2002.



13. Gusarov V.V., Khabensky V.B., Beshta S.V., Granovsky V.S., Almyashev V.I., Krushinov E.V., Vitol S.A., Sergeev E.D., Petrov V.V., Tikhomirov V.A., Bezlepkin V.V., Kukhtevich I.V., Aniskevich Yu.N., Sayenko I.V., Stolyarova V.L., Migal V.P., Mozherin V.A., Sakulin V.Ya., Novikov A.N., Salagina G.N., Shtern E.A., Asmolov V.G., Abalin S.S., Degaltzev Yu.G., Zagryazkin V.N. Oxide material for a molten-core catcher of a nuclear reactor // PCT patent WO 02/080188. Priority Apr. 2, 2002. Patented Nov. 21, 2002.

14. Гусаров В.В., Бешта С.В., Хабенский В.Б., Грановский В.С., Саенко И.В., Безлепкин В.В., Кухтевич И.В., Можжерин В.А., Мигаль В.П., Сакулин В.Я., Новиков А.Н., Салагина Г.Н., Штерн Е.А. Шихта для получения материала, обеспечивающего локализацию расплава активной зоны ядерных реакторов // Патент РФ № 2178924. Приоритет от 02.04.2001. Дата публикации – 27.01.2002.

15. Силин В.А.; Вознесенский В.А.; Малышенко С.П.; Митькин В.В.; Осадчий А.И.; Пономарев-Степной Н.Н.; Столяревский А.Я. Устройство для улавливания расплавленных материалов из ядерного реактора // Патент № 2164043, Дата подачи заявки: 04.08.1999, Дата публикации: 10.03.2001.

16. Сидоров А.С., Носенко Г.Е., Розенберг Ю.С., Максимов Ю.Н., Рогов М.Ф., Логвинов С.А. Ловушка активной зоны ядерного реактора // Патент № 2100854. Патентообладатель: «ОКБ Гидропресс».

2020

2-D axial symmetric conductivity

Volumetric heat decay

Melting of the sacrificial material and mixing with the corium

Thermal ablation of the concrete

Chemical reactions between the sacrificial materials and the corium

Molten pool formation and stratification

Convective heat transfer between the layers of the molten materials

Crust formation

Radiation heat transfer from the upper surface of the molten pull

External water cooling of the core catcher vessel

HEFEST-ULR CodeHEFEST-ULR Code

Modeled thermal physics and physical chemical processes:

2121

Modeled processesModeled processes: : chemical reactionschemical reactionsOn the melt front:Zr oxidation:Zr + 2H2O = ZrO2 + 2H2 + QFe2O3 + 1.5Zr = 2Fe + 1.5ZrO2 + Q

Cr and Ni oxidation:Сr + 1.5H2O = 0.5Сr2O3 + 1.5H2 + QNi + H2O = NiO + H2 + QFe2O3 + 2Cr = 2Fe + Cr2O3 + QFe2O3 + Ni = 2FeO + NiO + Q

Hematite restoration:Fe2O3 = 2FeO + 0.5O2 – Q

Fe oxidation:Fe + 0.5O2 = FeO + Q Fe + H2O = FeO + H2 + Q

In the molten pool volume:

Zr oxidation:FeO + 0.5 Zr = Fe + 0.5ZrO2 +QZr + O2 = ZrO2 + Q

Cr oxidation:Cr + O2 = Cr2O3 + Q

Ni oxidation:Ni + 0,5 O2 = NiO + Q

Heat generation Q is taken in the account in the total energy balance

2222

HEFEST-ULR code verificationHEFEST-ULR code verification

Basis for verification Verified models

The analytical decision of a problem of Stefana

Propagation of the melting front

Salt experiments of RASPLAV project(NRC KI)

Convective heat exchange in the conditions of crust formation on a cooled wall

Experiments of series AW-200 of RASPLAV project(NRC KI)

Dynamics of the molten pool formation in a natural corium

Experiments of series SACR of RASPLAV project (NITI)

Corium interaction with sacrificial materials

2323

HEFEST-ULR code verification against analytical testsHEFEST-ULR code verification against analytical testsMelt front propagation

Case of the low heat conductivity of phases

Thin line – analytical solutionThick line – calculation on the HEFEST-ULR code

Case of the high heat conductivity of phases

Thin line – analytical solutionThick line – calculation on the HEFEST-ULR code

0,00 0,04 0,08 0,12 0,16 0,201000

1100

1200

1300

1400

1500

1600

1700

1800

Расстояние, м

0.400E+01 0.160E+02 0.360E+02 0.640E+02 0.100E+03 0.144E+03 0.196E+03 0.256E+03 0.324E+03 0.400E+03

0,00 0,05 0,10 0,15 0,20 0,25 0,30 0,35 0,40 0,45 0,50 0,55 0,601000

1100

1200

1300

1400

1500

1600

1700

1800

Расстояние, м

0.100E+03 0.400E+03 0.900E+03 0.160E+04 0.250E+04 0.360E+04 0.490E+04 0.640E+04 0.810E+04 0.100E+05

2424

HEFEST-ULR code verification against RASPLAV salt testsHEFEST-ULR code verification against RASPLAV salt tests

Temperatures of the internal and external wall surfaces

Heat flux change along the wall

0 10 20 30 40 50 60 70 80 90

400

410

420

430

440

450

460

470 T_exp_наруж T_exp_внутр T_calc_наруж T_calc_внутр

Тем

пера

тура

, о С

Угол от вертикали, град

0 10 20 30 40 50 60 70 80 900,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

2,2

2,4 Эксперимент Расчёт

Норм

иров

анны

й по

ток

тепл

а, q

/qe

Угол от вертикали, град

2525

HEFEST-ULR code verification against RASPLAV AW-200HEFEST-ULR code verification against RASPLAV AW-200 testtest

Temperature of the graphite heater in experiment AW2001

Temperature of the wall and corium in experiment AW2001

0 10000 20000 30000 40000 500000

400

800

1200

1600

2000

2400

2800

Тем

пера

тура

, С

Время, с

Графитовый нагреватель пирометр

0 10000 20000 30000 40000 50000 60000 700000

400

800

1200

1600

2000

2400

2800

Тем

пера

тура

, С

Время, с

Кориум-расчёт Кориум-пирометр Сталь-расчёт Сталь-термопара

2626

HEFEST-ULR code verification against SACRHEFEST-ULR code verification against SACR-7-7 testtest

Model of chemical reactions

Corium С-32:

76 % UO2 + 9 % ZrO2 + 15 % Zr

Sacrificial Materials:

85 % Fe2O3 + 15 % Аl2О3

Initial composition

2727

Composition after interaction

Calculation

61 % UO2 + 24 % ZrO2 + 2 % Zr + 0 % FeO + 3 % Al2O3 +10 % Fe

Experimental data

65 % UO2 + 20 % ZrO2 + 2 % Zr + 0 % FeO + 3 % Al2O3 +10 % Fe

HEFEST-ULR code verification against SACRHEFEST-ULR code verification against SACR-7-7 testtest

Model of chemical reactions

2828

The Certificate of the State Registration The Certificate of the State Registration of the GEFEST-ULR Codeof the GEFEST-ULR Code

2929

Analysis of overall performance of the core catcherAnalysis of overall performance of the core catcher for VVER-1200for VVER-1200

Simulation of physical chemical processes in the core catcher during severe accident on a VVER-1200 with help of HEFEST-ULR code.

Severe accident scenario: Large Break LOCA with simultaneous station blackout.

Main assumptions: Double-ended rupture of a RCS D = 850 mm; No operator actions.

Break location: Cold leg of the RCS loop on the reactor inlet.

3030

Input data: Mass of the sacrificial materials in the core catcherInput data: Mass of the sacrificial materials in the core catcher

Material Mass

Iron oxide, ton

66

Aluminum oxide, ton

28

Concrete, ton

8

Steel, ton 64

Free volume, m3

35

3131

Calculation results:Calculation results: Corium behavior in the core catcherCorium behavior in the core catcher

9 minutes From the onset of the first corium portion (75 tons) pouring into core catcher

47 minutes The front of corium pool is achieved of internal wall of

core catcher vessel

5 hours Propagation of the front of

corium pool in radial direction is stopped

In the initial phase In the long term

Calculation resultsCalculation results:: Corium temperature in the Core Catcher Corium temperature in the Core Catcher

0 0 .2 0 .4 0 .6 0 .8 1 1 .2 1 .4 1 .6 1 .8 2

В р е м я (ч а с )

1 8 0 0

2 0 0 0

2 2 0 0

2 4 0 0

2 6 0 0

2 8 0 0

3 0 0 0

Тем

пер

атур

а (К

) С м еш а н н ы й р а сп л а вМ ета л л и ч еск а я ф а заО к си дн а я ф а за

0 0 .5 1 1 .5 2 2 .5 3 3 .5 4 4 .5 5

В р е м я (с у т к и )

1 8 0 0

2 0 0 0

2 2 0 0

2 4 0 0

2 6 0 0

2 8 0 0

3 0 0 0

Тем

пер

атур

а (К

) С м еш а н н ы й р а сп л а вМ етал л и ч еск а я ф азаО к си дн а я ф а за

Mixed coriumMetal phase

Oxide phase

Mixed coriumMetal phase

Oxide phase

Time, hour Time, day

Tem

pera

ture

, K

Tem

pera

ture

, K

Tem

pera

ture

, K

Tem

pera

ture

, K

Evolution versus time Changing along a height

Calculation resultsCalculation results:: Maximum heat flux on external surface Maximum heat flux on external surface of the core catcher vessel of the core catcher vessel

0 2 0 4 0 6 0 8 0 1 0 0 1 2 0

В ре м я (ч ас )

0

0 .2

0 .4

0 .6

0 .8

1

1 .2

q (М

Вт/

м2 )

Критический тепловой поток

0 0 .2 0 .4 0 .6 0 .8 1 1 .2

q (М В т /м 2)

0

0 .5

1

1 .5

2

2 .5

3

3 .5

4

4 .5

5

Вы

сота

(м)

Критический тепловой

потокCritical flux

Time, hour

Critical flux

Hei

ght,

m

3434

Calculation resultsCalculation results:: Hydrogen generationHydrogen generation

Ex-vessel stage of the accident: Melt localization in the core catcher

NPP projectIn-vessel

phase (kg)

Ex-vessel

phase (kg)

Total(kg)

Without core catcher 470 1600 2070

With core catcher 470 98 ~ 570

Hydrogen generation fromcore catcher

Core catcher application for severe accident management removes a sharpness of a hydrogen hazard during ex-vessel stage of the accident

Hydrogen generation during in-vessel phase of the accident, first 24 hours

of the ex-vessel phase and total hydrogen generation on NPP with

and without of the core catcher

0 1 2 3 4 50

1 5 0

0 1 2 3 4 5В р ем я , су т

Мас

сакг,

30

60

90

1 2 0

Time, day

Mas

s, k

g

3535

SummarySummary

Application in modern projects of NPP with VVER the big capacity as one of means core catcher, specially provided for severe accident management, provides safety increase.

Safety increase is reached by means of exception of release of liquid and firm radioactive materials from core catcher, reduction of quantity of generated hydrogen.

The key role in working out core catcher is played by a choice and optimization of composition of sacrificial material placed in core catcher vessel.

On an example of the settlement analysis of behavior of a corium in core catcher for VVER-1200 it is shown that core catcher effectively carries out the functions on localization and long-term cooling of a corium.

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Core Catcher montage on NVO NPP with VVER-1200