Short-lived fission product measurements from >0.1 MeV neutron-induced fission using boron carbide Erin Finn • Lori Metz • Larry Greenwood • Bruce Pierson • Judah Friese • Rosara Kephart • Jeremy Kephart Received: 13 January 2012 / Published online: 4 February 2012 Ó Akade ´miai Kiado ´, Budapest, Hungary 2012 Abstract A boron carbide shield was designed, custom fabricated, and used to create a fast fission energy neutron spectrum. The fissionable isotopes 233, 235, 238 U, 237 Np, and 239 Pu were separately placed inside of this shield and irra- diated under pulsed conditions at the Washington State University 1 MW TRIGA reactor. A unique set of fission product gamma spectra were collected at short times (4 min to 1 week) post-fission. Gamma spectra were collected on single-crystal high purity germanium detectors and on Pacific Northwest National Laboratory’s Direct Simulta- neous Measurement system composed of HPGe detectors connected in coincidence. This work defines the experi- mental methods used to produce and collect the gamma data, and demonstrates the validity of the measurements. It is important to fully document this information so the data can be used with high confidence for the advancement of nuclear science and non-proliferation applications. The gamma spectra collected in these and other experiments are publicly available at https://spcollab.pnnl.gov/sites/gammadata/default. aspx or via the link at http://rdnsgroup.pnnl.gov. A revised version of this publication will be posted with the data to make the experimental details available to those using the data. Keywords Boron carbide Á Short-lived fission products Á Gamma spectra Á Fast fission energy neutrons Introduction Analysis of short-lived fission product isotopes is useful in discriminating the fissionable parent actinide, with improved discrimination at higher neutron energies [1–4]. This is applicable to the process of active interrogation of interdicted samples. In active interrogation, an interdicted sample is exposed to a neutron flux and the fission products are analyzed within a short timeframe and without chemical separations. Knowledge of the expected fission products and gamma radiation signatures generated from fission of each type of fissile material is key to the success of active interrogation and its ability to differentiate the fissionable material. Experiments involving the neutron irradiation of various actinides and subsequent fission product measurements are traditionally conducted at times greater than 5 days, result- ing in the analysis of fission products with half-lives in the range of 1 day to 30 years. These measurements may be made by mass spectrometry or radiochemical means fol- lowing chemical separations [5, 6]. Shorter lived radionuc- lides with half-lives ranging from 75 s to 3 days are typically not experimentally measured due to the logistical difficulty of such measurements. Methods to interpret short-lived gamma spectra are poorly developed because of the limited availability of experimental data. When short-lived isotope gamma data is collected, most cases involve some form of chemical separation before measurement to simplify data interpretation [2, 7–10]. In some cases only selected nuclides are analyzed [10, 11]. Data in the fission energy spectrum ( [ 0.1 MeV) are especially limited due to the limited avail- ability of research reactors with pure fission neutron spectra, the majority of reactors in the United States having pre- dominantly thermal neutron spectra [12]. In this work, the Washington State University (WSU) TRIGA reactor was used to induce fission of the E. Finn (&) Á L. Metz Á L. Greenwood Á B. Pierson Á J. Friese Á R. Kephart Á J. Kephart Pacific Northwest National Laboratory, 902 Battelle Blvd, P.O. Box 999, MSIN J4-80, Richland, WA 99352, USA e-mail: erin.finn@pnnl.gov B. Pierson University of Michigan, Ann Arbor, MI 48109, USA 123 J Radioanal Nucl Chem (2012) 293:267–272 DOI 10.1007/s10967-012-1652-y