The comparative advantages and drawbacks of some reactor-produced arsenic radioisotopes having favourable characteristics for their use as tracers are discussed. The study comprises their preparation based on: (a) capture reactions on germanium; (b) threshold reactions on germanium, selenium and bromine; (c) secondary reactions on germanium, induced by recoil protons and tritons produced by the action of neutrons on lithium. The recommended options for the production of relatively short half-life radionuclides are 77 As by capture on germanium or 76 As via (n,α) reaction on bromine, while two different ways are applicable for the production of 74 As, longer-lived radioisotope.

The studies performed in the frame of a project destined for the search of new (t,n) and (p,n) reactions of interest in nuclear reactors are described. Experimental evidences of the observations of the reactions: 46 Ti(t,n) 48 V, 48 Ti(p,n) 48 V, 52 Cr(t,n) 54 Mn, 56 Fe(p,n) 56 Co, 72 Ge(t,n) 74 As and 74 Ge(p,n) 74 As, are presented. Additional data on some secondary reactions, already characterised for the production of 7 Be, 56 Co, 58 Co, 65 Zn and 88 Y, were also obtained. The significance of these data is discussed.

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The production of 48 V in a nuclear reactor, induced on titanium by tritons generated from the 6 Li(n, t) 4 He reaction, and eventually 7 Li(n, n t) 4 He, is described. Samples of lithium titanate were irradiated for an irradiation cycle (120 h) in the RA-3 reactor, belonging to Ezeiza Atomic Centre. After a radiochemical separation, the characteristic radiations from 48 V were identified in the gamma ray spectra of the vanadium fractions.

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