Technical note Determination of alpha activity in organic solvents using CR-39 Pranav M. Joshirao a , Chirag K. Vyas a , Taesung Kim b , Puran C. Kalsi c , Vijay K. Manchanda a,n a Department of Energy Science, Sungkyunkwan University, Suwon 440746, South Korea b Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440746, South Korea c Radiochemistry Division, BARC, Mumbai 400085, India HIGHLIGHTS  First ever attempt to evaluate the response of a SSNTD toward alpha in organic media.  The organic solvents are more efficient in track registration vis-à-vis aqueous medium.  The aliphatic diluents have smaller stopping power for alpha.  Hexane was found to be the most promising medium. article info Article history: Received 4 July 2012 Received in revised form 9 March 2013 Accepted 5 April 2013 Available online 18 April 2013 Keywords: Alpha radiations Solid state track detector CR-39 Hexane High level waste abstract Solid State Nuclear Track Detector (SSNTD) like CR-39 offers a unique opportunity to measure alpha radiations in a complex matrix like high level nuclear waste due to its sensitivity to only alpha radiations in the presence of intense beta–gamma radiation field. There is however a concern about the lower sensitivity of SSNTD when the radiation source is present in solution vis-à-vis solid medium. The sensitivity of CR-39 toward detection of alpha particles homogenously distributed in n-hexane, n-dodecane and n-octanol has been investigated and was found to be better than that obtained in 3 M HNO 3 . & 2013 Elsevier Ltd. All rights reserved. 1. Introduction Over the last five decades, about 350 thousand tons of spent nuclear fuel has been discharged from power reactors world- wide. Major fraction of this (about two thirds) is awaiting geological disposal. One third of this material has been repro- cessed to recover valuable U and Pu generating high level liquid waste employing the well known PUREX process. At present the most accepted approach for the management of high level liquid waste (HLLW) is to vitrify it in a silicate glass/ceramic matrix followed by its disposal in deep geological repositories. It is reported that alpha recoil damage considerably shortens the life time of glasses to ∼2000 years and of zircon (a ceramic matrix candidate) to ∼1400 years whereas the desired immobilization time scales are of the order of 10 6 years (Dran et al., 1980; Farnan et al., 2007). Future of nuclear energy depends a great deal on devising innovative schemes to protect our eco-system from the radiotoxicity associated either with spent nuclear fuel or with HLLW. Radiochemists are actively pursuing a program on partitioning of minor actinides (MAs, viz. 237 Np, 241/243 Am, and 245 Cm) which envisages their complete removal from HLLW employing designer extractants (Ansari et al., 2011) and their subsequent incineration in the high flux, high energy reactors/accelerators driven subcri- tical systems (transmutation). MAs though constitute only ∼1% of the total dissolved salts, yet are the major cause of radiotoxicity of the HLLW due to the fact that they are long lived alpha emitters and some of their oxidation states are mobile under the influence of aquatic environment. ICRP classifies a waste as alpha free if its activity is o4000 Bq/g. The challenge for radio-analytical che- mists is to develop a methodology which can estimate such low level alpha activity in the presence of large quantities of beta/ gamma activity (Ci/l), inactive/short lived nuclides (5–30 g/l) and nitric acid (3–4 M). Precise composition of HLLW depends on (a) the nature and burn up of nuclear fuel, (b) the nature and concentration of process chemicals used during dissolution and reprocessing and (c) the efficiency of U, and Pu recovery in the PUREX process. 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.2013.04.013 n Corresponding author. Tel.: +82 31 299 6272; fax: +82 31 299 4279. E-mail addresses: vkm49@skku.edu, vkm25749@gmail.com (V.K. Manchanda). Applied Radiation and Isotopes 78 (2013) 68–71