Critique of in-place annealing of SM-1A nuclear reactor vessel

Potapovs, U.; Knighton, G.W.; Denton, Arthur S.

doi:10.1016/0029-5493(68)90015-0

Cited by 14 publications

(1 citation statement)

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“…This is also true for the restoration of the properties of reactor vessels. It is well known that abroad the vessel of a small-size military reactor SM-1A was annealed by nuclear heat ("wet" annealing) to extend service life [5]. The experiments performed at the Prometey Central Research Institute of Structural Materials also showed a substantial decrease of embrittlement with the irradiation temperature increased briefly from 270 to 340°C [6].…”

Section: Model Materialsmentioning

confidence: 99%

Reactor annealing of pre-irradiated model materials

Bachuchin¹,

Krasikov²,

Nikolaenko³

2011

At Energy

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Experiments on annealing together with reactor irradiation of diamond and silicon carbide which have been pre-irradiated at low temperature are described. The results are compared with the data on annealing of the same pre-irradiated samples without irradiation -annealing in a furnace. It is shown that in a certain range of experimental conditions annealing with irradiation is more effective than thermal annealing alone. The lattice parameters of diamond and silicon carbide are restored more rapidly with such irradiation stimulated annealing than with simple annealing in a furnace at the same temperature and for the same time. The effect obtained depends on the intensity of the irradiation -the higher the intensity, the more quickly and completely the properties of the pre-irradiated samples are restored. Thus a paradoxical situation arises on some time segment of annealing with simultaneous irradiation where the concentration of defects actually decreases with increasing irradiation dose.The present article examines annealing in a furnace under laboratory conditions and in a reactor of samples of model materials -diamond and silicon carbide -which have been pre-irradiated at low temperature. First it shall be shown that the results of prolonged repeated irradiation are independent of the preceding state.It is evident in Fig. 1 that the difference in the expansion of the diamond lattice after repeated irradiation decreases and gradually vanishes. This shows that the expansion of the diamond lattice under irradiation is independent of the preceding state.Another experiment consisted of repeated irradiation of diamond pre-irradiated at 80°C followed by annealing in a furnace for 3 h at 298, 425, and 660°C. The expansion of the diamond lattice after the first irradiation was 4.89%, which on annealing it decreased to 4.14, 3.33, and 1.77%, respectively. The results presented in Fig. 2 show that with repeated irradiation the difference in the expansion of the differently annealed samples gradually decrease and the lattice expansion in all samples saturates as the neutron fluence increases.Thus, the experiment shows that the final state of diamond (expansion of the lattice) is determined by the conditions of re-irradiation and not by the initial state -whether the diamond was pre-irradiated at a different temperature or annealed after the first irradiation.Let us now examine the annealing of diamond pre-irradiated in an MR reactor at 80°C. The conditions and results of this irradiation are as follows: flux density 2.3·10 13 sec -1 ·cm -2 , neutron fluence 1.2·10 20 cm -2 , lattice expansion 3.75%. Some samples were annealed at 275°C in a furnace and others were annealed in MR at the same temperature for 3.3·10 4 and 5.9·10 4 min at neutron flux density about 4·10 13 sec -2 ·cm -2 , i.e., with additional irradiation. After this, the expansion of the diamond lattice decreased from 2.16 and 2.26%, respectively. It is evident in Fig. 3 that the dependence of the lattice expansion of diamond on the time logarithm with annea...

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Section: Model Materialsmentioning

confidence: 99%