Thermal desorption of helium from reactor steel

Abstract

Thermal desorption was used to study the behavioral particulars of the ion-implanted at 20 and 650°C helium in reactor ferrite-martensite austenitic steel. It is established that compared with the thermal desorption spectrum of EP-450 and Euroffer-97 steel the temperature interval for helium release from dispersion-hardened EP-450 and Eurofer 97 steels is wider for helium implantation at room temperature and especially at 650°C. In steel hardened by disperse oxides Y 2 O 3 , a substantial amount of helium is released at high temperatures after the main maximum in the thermal desorption spectrum as a result of the formation at the incoherent particle-matrix boundary of bubbles with high bonding energy with particles. In contrast to the ferrite-martensite steel irradiated in the temper state, the thermal desorption spectrum of EK-164 austenitic steel is more complex because of the multiple stage helium release due to the structural defects introduced by cold deformation.Many different makes of reactor steel have now been developed, including steels containing aside from chromium and nickel up to three or more alloying elements. Until recently, this development work was conducted in the direction of developing or improving austenitic steels. For fast reactors, steel as a material for fuel-element cladding is characteristically used in the following sequence: Kh18N9T → Kh18N10T → Kh16N15MZB (EI-847) → Kh16N15M3BR (EP-172) → → Kh16N15M2G2TFR (ChS-68) → 07Kh16N19M2G2BTFPR (EK-164). As one can see, the work proceeded in the direction of increasing nickel content and complicating its composition in order to increase the high-temperature strength and radiation resistance. Since for the nuclear fuel burnup of about 12% h.a. attained up to now the main cladding steel ChS-68 no longer satisfies the radiation resistance requirements, first and foremost, radiation swelling, the possibility of using in BN-800 austenitic steel EK-164 with elevated nickel content and more complicated compositions than ChS-68 steel is under investigation.In addition, in the last few decades intense development and research work has been done on chromium-based steels with bcc crystal lattice, since swelling of such steel is appreciably weaker than in austenitic steels (Table 1) [1]. In connection with the main drawback of chromium steel -its low high-temperature strength under conditions characteristic for fastreactor cores, increasing attention is going to dispersion-hardened martensitic and ferrite-martensitic steel: foreign-made steel with different chromium content and domestically produced dispersion-hardened steel based on Kh13 (See Table 1) as a promising material for fast-reactor fuel-element cladding and, possibly, for the first wall of thermonuclear reactors [2].

The effect of dislocation on defects in 316L stainless steel irradiated by helium

“…For Peak4 in deformed specimens, it is noticed that Peak3 and Peak4 in samples 2 (CR-10 %) and 3 (CR-10 %@723 K) are next to each other, but Peak4 in sample 4 (CR-20 %@723 K) is far away from Peak3 and it has a low helium desorption rate. It is likely that the presence of small helium bubbles causes a desorption peak [24,25]. Peak6 in Fig.…”