1. Influence of neutron irradiation parameters on swelling and mechanical properties of stainless steels - materials of BN-350 fuel assembly ducts O.P.Maksimkin, M.N.Gusev, K.V.Tsai, O.G.Romanenko, L.G.Turubarova, N.S.Silnyagina, O.V.Tivanova Almaty, Kazakhstan Republic, 2005 Laboratory of the materials physical-mechanical properties investigations, maksimkin@inp.kzmaksimkin@inp.kz

2. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Report contents Mechanical properties of investigated steels Influence of damage dose rate on microstructure and swelling of investigated steels. Peculiarities of plastic deformation of highly irradiated materials.

3. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Investigated materials 08Cr16Ni11Mo3 12Cr18Ni10Ti поток нейтроно в Т, о С 280450 Object of investigation – hexagonal shroud of fuel assemblies Sample’s sizes: 20  2  0.3mm. Neutron flux

4. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Irradiation condition for investigated steels Assembly, mark. 08Cr16Ni11Mo3 N-214(2) 08Cr16Ni11Mo3 V-300 08Cr16Ni11Mo3 V-337 12Cr18Ni10Ti, N-214(1) 0 Dose, dpa [T,C]15.6 [337°]17.1 [354°] Damage rate, dpa/s 4.8  10 -8 1.6  10 -7 +500 Dose, dpa [T,C]-11.0 [346°]12.1 [354°]7.1 [309°] Damage rate, dpa/s 2.0  10 -7 2.6  10 -7 2.2  10 -7 -500 Dose, dpa [T,C]7.08 [309°]10.8 [302°]11.9 [305°] Damage rate, dpa/s 2.2  10 -8 1.9  10 -7 2.6  10 -7 -900 Dose, dpa [T,C]1.27 [281°] Damage rate, dpa/s 4  10 -9 - 1200 Dose, dpa [T,C]0.25 [280°] Damage rate, dpa/s 8  10 -10

5. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Experimental equipment and investigation techniques  Uniaxial tensile mechanical test. (definition of  02  В,  full ).  Transmission and scanning electron microscopy (concentration and morphology of radiation defects, swelling value).  Metallography and microhardness measurement.  Magnitometry and optical extensometry.

6. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Influence of irradiation on mechanical properties of 08Cr16Ni11Mo3 steel BB  02

7. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Correlation between yield stress and microhardness

8. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Changes in density of irradiated 08Cr16Ni11Mo3 steel

9. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Swelling of irradiated 08Cr16Ni11Mo3 steel

10. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Voids in irradiated 08Cr16Ni11Mo3 steel N-214, «-900», 1.27 dpa., 4  10 -9 dpa/s N-214(2), «-500», 7.08 dpa. 2.2  10 -8 N-214(2), «0», 15.6 dpa. 2.2  10 -8 dpa/sТВС «V-337», 11.9 dpa, 2.6  10 -7 dpa/s

11. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Voids in irradiated 12Cr18Ni10Ti, assembly N-214(1) 50 nm Dose 0.67 dpa, Dose rate 0,12  10 -8 dpa/s, T irr = 281°С

12. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Influence of dose rate on yield stress of 08Cr16Ni11Mo3

13. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Peculiarities of plastic deformation and fracture of high irradiated samples SEM image of fracture surface for specimen from «-1200mm» mark (08Cr16Ni11Mo3 steel). The deformation relief develops in zone of localized deformation

14. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Method of mark extensometry for miniature irradiated samples

15. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Distribution of strains and stresses on on deformed sample of 08Cr16Ni11Mo3 steel σ ист, кг/мм 2 Рабочая длина образца ε, % Рабочая длина образца V-337, -500.

16. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Engineering curves and dependences “true stress – conditional strain” Unirradiated steel Irradiated (V-337, -500) «true» curves

17. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Relationship between true stress and true strain for irradiated 08Cr16Ni11Mo3 steel 

18. Laboratory of the materials physical-mechanical properties investigations, INP NNC RK Conclusion The changes in structure and mechanical properties of 08Cr16Ni11Mo3 and 12Cr18Ni10Ti steels – as materials of spent fuel assemblies of BN-350 reactor – irradiated up to damage doses 0.25 – 15.6 dpa at dose rate from 8  10 -10 to 2.6  10 - 7 dpa/s were investigated. It was found that the dose rate is one of important factors influencing on void formation and development as well as on formation of mechanical properties of investigated materials. The void formation at low dose rates and low damage doses (1.27 dpa for 08Cr16Ni11Mo3 steel and 0.67 dpa for 12Cr18Ni10Ti steel) was observed. The method of mark extensometry was proposed and applied for investigation of peculiarities of plastic deformation of miniature specimens irradiated at various dose rates. It was shown that relation between true stresses and true strains at localized deformation of high irradiated steel samples can be described by equation  =k  0.5 +  0.