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Structure-phase investigation Structure-phase investigation and mechanical properties of and mechanical properties of Zr-1%Nb alloy claddings after Zr-1%Nb alloy claddings after LOCA tests on PARAMETR LOCA tests on PARAMETR

facility under 1400 facility under 1400 °C°C

FSUE SRI SIA «LUCH»

Gukov M.Yu., Deniskin V.P., Ignatjev D.N., Konstantinov V.S., Nalivaev V.I., Fedik I.I.FSUE “SRI SIA LUCH”

Nechaeva O.A., Novikov V.V., Salatov A.V., Fedotov P.V.FSUE VNIINM

Semishkin V.P.FSUE EDB “Gidropress”

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ContentContent

1. Experimental Facility:Design and basis Technical Parameters

2. Experimetal Results of Tests under the Quench Conditions at different Temperatures:

- 1-st Test (FA1) – 900 °C - 2-nd Test (FA2) – 1200 °C- 3-d Test (FA3) – 1400 °C

3. Material researches CONCLUSIONSCONCLUSIONS

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Heated rod Unheated rod Test Bundle

Test InstrumentationTest InstrumentationTest Bundle SpecificationTest Bundle Specification

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Experimental FacilityExperimental Facility

Functional DiagramFunctional Diagram

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Basis parametersBasis parameters of testsof tests

Quench temperature, °C

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Appearance of claddings after tests of Appearance of claddings after tests of FA1FA1 and FA2and FA2

Fuel Assembly #1Fuel Assembly #1

Fuel Assembly #2Fuel Assembly #2

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Вход пара

Залив снизу

Appearance of FA3 after testsAppearance of FA3 after tests

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1

2

3

1 2

3 4

TTcladdingscladdings=1=100000 °0 °СС TTcladdingscladdings=1=120200 °0 °СС

TTcladdingscladdings=1=140400 °0 °СС TTcladdings claddings >>22000000 °°СС

Input of steamInput of steam

Embayment from Embayment from belowbelow

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Appearance of external surface of FA1 Appearance of external surface of FA1

and FA2 deformed claddingsand FA2 deformed claddings

Multilayer oxide film on external cladding surface (FA2)

Profile of oxide film rupture in a zone of maximal deformation of claddings (FA1)

State of an external surface of State of an external surface of strainedstrained claddings claddings (FA1, FA2) (FA1, FA2)

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Maximum valuations of structural Maximum valuations of structural

parameters of claddings FA1-3parameters of claddings FA1-3

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Change of Change of - Zr (O) layer thickness - Zr (O) layer thickness depending depending

onon ECR value ECR value (FA1–3)FA1–3)

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Change of structural-phase parameters and Change of structural-phase parameters and – Zr failure type depending on ECR value – Zr failure type depending on ECR value

(FA 1 – 3)(FA 1 – 3)

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Change of ECR on azimuth of claddings Change of ECR on azimuth of claddings depressurization zonedepressurization zone

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Character of ZrOCharacter of ZrO22 and and αα-Zr(O)-Zr(O)

layers failurelayers failure

ZrOZrO2 2 ((x1600)x1600) αα-Zr(O) (x3000)-Zr(O) (x3000)

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Change of Change of – Zr layer failure character under – Zr layer failure character under

mechanical tests of samplesmechanical tests of samples

FA1 (x2000) FA2 (x2000) FA3 (x2000)

Ductile Quasi-brittle Brittle

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Strength Strength propertiesproperties of claddings in a of claddings in a transverse direction depending on ECR valuetransverse direction depending on ECR value

(FA 1 – 3) FA 1 – 3)

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Microhardness Microhardness level at which level at which spreading of the spreading of the crack, arisen in crack, arisen in brittle brittle αα-Zr (O) -Zr (O) layer, was layer, was complicated due to complicated due to enough enough high fracture high fracture toughness of toughness of αα '-Zr '-Zr layerlayer

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““Constructive strength” of unstrained and Constructive strength” of unstrained and depressurized claddings of FA1 and FA2 depressurized claddings of FA1 and FA2

under tensionunder tension

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Change of microhardness on azimuth of Change of microhardness on azimuth of claddings rupture zone (FA1, FA2)claddings rupture zone (FA1, FA2)

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• It was experimentally shown, that quenching of It was experimentally shown, that quenching of bundles at temperatures 900 C (FA1) and 1200 C bundles at temperatures 900 C (FA1) and 1200 C (FA2) did not result in the claddings fragmentation, (FA2) did not result in the claddings fragmentation, and the residual resource of mechanical properties and the residual resource of mechanical properties was sufficient for its subsequent dismantling and was sufficient for its subsequent dismantling and transportation. transportation.

• The increase of bundle temperature up to 1400°The increase of bundle temperature up to 1400°СС (FA3) before quenching resulted in the claddings (FA3) before quenching resulted in the claddings fragmentation.fragmentation.

• The faultiest zone ofThe faultiest zone of the claddings of FA1 and FA2 the claddings of FA1 and FA2 was the rupture zone due to the thinning of the was the rupture zone due to the thinning of the cladding under the peripheral deformation and its cladding under the peripheral deformation and its double-side oxidation.double-side oxidation.

CONCLUSIONSCONCLUSIONS

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• Non-monotonic character of changing strength Non-monotonic character of changing strength characteristics of the claddings was established characteristics of the claddings was established depending on their oxidation level. Increase in a depending on their oxidation level. Increase in a yield stress in a transverse direction decrease in yield stress in a transverse direction decrease in plasticity to a zero value was observed up to ECR plasticity to a zero value was observed up to ECR value of ~ 8 - 9 %. The further oxidation of the value of ~ 8 - 9 %. The further oxidation of the claddings resulted in reducing strength.claddings resulted in reducing strength.

• Based on electron-microscopic researches change Based on electron-microscopic researches change of of –Zr layer failure character was established –Zr layer failure character was established depending on its structural – phase state determined depending on its structural – phase state determined by ECR value:by ECR value: