Authors:G. Kim, W. Hong, H. Woo, J. Kim, C. Eum, J. Chang, and K. Park
A nanosecond proton bunching system has been constructed at Korea Institute of Geoscience and Mineral Resources (KIGAM). This
pulsed ion beam will be converted into corresponding duration of neutron pulse, which can reduce the scattered neutron background
during neutron spectroscopy. The pulsed beam is obtained by deflection and double bunching by RF field. RF fields are applied
to deflection and bunching electrodes as 2 kV p-p, 4 MHz and 2 kV p-p, 8 MHz, respectively. A push-pull RF amplifier has been
designed and constructed with a maximum output power of 300 W continuous wave (CW) between 2 and 30 MHz. The main parameters
of bunching beam were as follows: 8 MHz repetition rate, 2 ns FWHM, approximately 20% of duty factor and the maximum energy
spread of 2 keV within a pulse.
Authors:G. Kim, H. Woo, H. Choi, N. Kim, T. Yang, J. Chang, and K. Park
Neutron capture cross sections on 63Cu and 186W were measured by fast neutron activation method at neutron energies from 1 to 2 MeV. Monoenergetic fast neutrons were produced
by 3H(p,n)3He reaction. Neutron energy spread by target thickness, which was assumed to be the main factor of neutron energy spread,
was estimated to be 1.5% at neutron energy of 2.077 MeV. Neutron capture cross sections on 63Cu and 186W were calculated by reference comparison method on those of 197Au(n,γ). Not only statistical errors of gamma-counts from samples but also systematic errors in the counting efficiency for
HP Ge detector and the uncertainty of areal density of samples were considered in calculating neutron capture cross section.
Estimated neutron capture cross sections on 63Cu and 186W were also compared with ENDF-6 data.
Authors:R.-L. Yun, Y.-M. Chang, C.-H. Lin, K.-H. Hu, and C.-M. Shu
In industrial processes, information
on the safety property of chemicals is essentially crucial for safe handling
during unit operations. Ensuring the safe use of combustible or flammable
substances in processes is unlikely without detailed investigations of their
flammability characteristics and related hazards. We studied 3-methyl pyridine
(3-picoline), e.g., flammability limits (LFL/UFL), maximum explosion pressure
explosion pressure rise (dP/dt)max, minimum oxygen concentration
(MOC), vapor deflagration index (Kg),
and characterized the influence of inert steam (H2O)
on critical parameters for 3-picoline/water mixtures at 270C, 1 atm,
various oxygen concentrations, and vapor mixing ratios (100/0, 30/70, 10/90
and 5/95 vol.%) with a 20-L-Apparatus in simulated conditions, respectively.
The results showed that the flammability characteristics
of 3-picoline(aq) all increased with the oxygen concentration.
However, as the composition of inert steam increased, the flammability parameters
and the degree of fire and explosion hazards were significantly reduced, instead.
This study elucidated the flammability properties of 3-picoline mixed with
inert steam. The conclusions could be applied to proactively prevent the relevant
processes from incurring fire and explosion accidents.
Authors:Chang-Kyu Kim, A. Takaku, M. Yamamoto, H. Kawamura, K. Shiraishi, Y. Igarashi, S. Igarashi, H. Takayama, and N. Ikeda
A new analytical technique using ICP-MS was applied to the determination of237Np in some environmental samples. The accuracy and precision of the new method were assessed by comparison with those of conventional NAA and -spectrometric method as well as by analysis of the intercomparison sample of Ravenglass NRPB silt. The results obtained by ICP-MS were in good agreement with those by NAA or -spectrometry at a relative deviation of 2–9%. The detection limit is 0.02 mBq/ml (26 mBq=1 ng).