Determination of 63 Ni and 59 Ni in spent ion-exchange resin and activated charcoal from the IEA-R1 nuclear research reactor M.H.T. Taddei a , J.F. Macacini a , R. Vicente b , J.T. Marumo b , S.K. Sakata b , L.A.A. Terremoto b,n a Laborato ´rio de Poc - os de Caldas (LAPOC/CNEN-MG), Rodovia Poc - os de Caldas - Andradas km 13, CEP 37701-970, Poc - os de Caldas, MG, Brazil b Instituto de Pesquisas Energe ´ticas e Nucleares (IPEN/CNEN-SP), Avenida Professor Lineu Prestes 2242, Cidade Universita ´ria, CEP 05508-000, S ~ ao Paulo, SP, Brazil HIGHLIGHTS c A radiochemical method was adapted for determination of 59 Ni and 63 Ni. c 59 Ni and 63 Ni were determined in samples of radioactive wastes from research reactor. c The activity concentration of 59 Ni was measured by X-ray spectrometry. c The activity concentration of 63 Ni was measured by liquid scintillation counting. c Average ratio of measured activity concentrations of 63 Ni and 59 Ni agrees with theory. article info Article history: Received 25 June 2012 Received in revised form 10 September 2012 Accepted 18 February 2013 Available online 27 February 2013 Keywords: Research reactors Radioactive wastes Difficult to measure radionuclides Ni radioactive isotopes Radiochemical method abstract A radiochemical method has been adapted to determine 59 Ni and 63 Ni in samples of radioactive wastes from the water cleanup system of the IEA-R1 nuclear research reactor. The process includes extraction chromatographic resin with dimethylglyoxime (DMG) as a functional group. Activity concentrations of 59 Ni and 63 Ni were measured, respectively, by X-ray spectrometry and liquid scintillation counting, whereas the chemical yield was determined by ICP-OES. The average ratio of measured activity concentrations of 63 Ni and 59 Ni agree well with theory. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction The IEA-R1 is a 5 MW pool-type nuclear research reactor moderated and cooled by light water. It is located at the Nuclear and Energy Research Institute (IPEN/CNEN-SP) and used for scien- tific research as well as to produce radioisotopes (Vasconcellos and Saiki, 2006; Vasconcellos et al., 2004). Currently, the core of the IEA-R1 nuclear research reactor employs 24 plate-type elements usually designated as Material Testing Reactor (MTR) fuel elements (Terremoto et al., 2000; Mora et al., 2011), as well as 4 fork-type control rods of silver–indium–cadmium alloy (Ag–In–Cd alloy in proportion of 80%, 15%, 5%, respectively) with a thin cladding of metallic Ni. Nuclear reactions in the reactor generate radioactive isotopes of Ni as activation products, mostly when thermal neutrons impinge on the cladding of the control rods, although neutron activation of a few stainless steel structural components also contributes to gen- erate these radionuclides. Such activation products are released by corrosion and carried along with the cooling water to the cartridge filters, activated charcoal beds and ion-exchange resin beds that constitute the water cleanup system of the reactor. When the purification capability of these materials is exhausted, they are replaced and become low- level radioactive waste. Their radioactive inventory must be deter- mined as a first and fundamental management step. For radioactive waste characterization, the relevant Ni isotopes are 59 Ni and 63 Ni, whose properties are summarized in Table 1. These Ni isotopes are included among the difficult to measure (DTM) radionuclides (IAEA, 2009) because of their long half-life and radioactive decay with no emission of gamma-rays. As a consequence, quantitative and selective separation of 59 Ni and Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/apradiso Applied Radiation and Isotopes 0969-8043/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.apradiso.2013.02.014 n Corresponding author. Tel.: þ55 11 31339464; fax: þ55 11 31339423. E-mail address: laaterre@ipen.br (L.A.A. Terremoto). Applied Radiation and Isotopes 77 (2013) 50–55