Structure-phase investigation and mechanical properties of Zr-1%Nb alloy claddings after LOCA tests on PARAMETR facility under 1400 °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”

2 Content 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 CONCLUSIONS

3 Heated rodUnheated rodTest Bundle Test Instrumentation Test Bundle Specification

4 Experimental Facility Functional Diagram

5 Basis parametersof tests Basis parameters of tests Quench temperature, °C

6 Appearance of claddings after tests of FA1 and FA2 Fuel Assembly #1 Fuel Assembly #2

7 Вход пара Залив снизу Appearance of FA3 after tests T claddings =1000 °С T claddings =1200 °С T claddings =1400 °С T claddings >2000 °С Input of steam Embayment from below

8 Appearance of external surface of FA1 and 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 strained claddings (FA1, FA2)

9 Maximum valuations of structural parameters of claddings FA1-3

10 Change of  - Zr (O) layer thickness depending on ECR valueFA1–3) Change of  - Zr (O) layer thickness depending on ECR value (FA1–3)

11 Change of structural-phase parameters and  – Zr failure type depending on ECR value (FA 1 – 3)

12 Change of ECR on azimuth of claddings depressurization zone

13 Character of ZrO 2 and α-Zr(O) layers failure ZrO 2 (x1600) α-Zr(O) (x3000)

14 Change of  – Zr layer failure character under mechanical tests of samples FA1 (x2000)FA2 (x2000)FA3 (x2000) DuctileQuasi-brittleBrittle

15 Strength properties of claddings in a transverse direction depending on ECR value FA 1 – 3) Strength properties of claddings in a transverse direction depending on ECR value (FA 1 – 3)

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

17 “Constructive strength” of unstrained and depressurized claddings of FA1 and FA2 under tension

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

19 It was experimentally shown, that quenching of bundles at temperatures 900 C (FA1) and 1200 C (FA2) did not result in the claddings fragmentation, and the residual resource of mechanical properties was sufficient for its subsequent dismantling and transportation.It was experimentally shown, that quenching of bundles at temperatures 900 C (FA1) and 1200 C (FA2) did not result in the claddings fragmentation, and the residual resource of mechanical properties was sufficient for its subsequent dismantling and transportation. The increase of bundle temperature up to 1400°С (FA3) before quenching resulted in the claddings fragmentation.The increase of bundle temperature up to 1400°С (FA3) before quenching resulted in the claddings fragmentation. The faultiest zone of the claddings of FA1 and FA2 was the rupture zone due to the thinning of the cladding under the peripheral deformation and its double-side oxidation.The faultiest zone of the claddings of FA1 and FA2 was the rupture zone due to the thinning of the cladding under the peripheral deformation and its double-side oxidation. CONCLUSIONS

20 Non-monotonic character of changing strength characteristics of the claddings was established depending on their oxidation level. Increase in a yield stress in a transverse direction decrease in plasticity to a zero value was observed up to ECR value of ~ %. The further oxidation of the claddings resulted in reducing strength.Non-monotonic character of changing strength characteristics of the claddings was established depending on their oxidation level. Increase in a yield stress in a transverse direction decrease in plasticity to a zero value was observed up to ECR value of ~ %. The further oxidation of the claddings resulted in reducing strength. Based on electron-microscopic researches change of  –Zr layer failure character was established depending on its structural – phase state determined by ECR value:Based on electron-microscopic researches change of  –Zr layer failure character was established depending on its structural – phase state determined by ECR value: