title: Benchmark test of neutron transport calculations: indium, nickel, gold, europium, and cobalt activation with and without energy moderated fission neutrons by iron simulating the Hiroshima atomic bomb casing.
abstract: A benchmark test of the Monte Carlo neutron and photon transport code system (MCNP) was performed using a bare- and energy-moderated 252Cf fission neutron source which was obtained by transmission through 10-cm-thick iron. An iron plate was used to simulate the effect of the Hiroshima atomic bomb casing. This test includes the activation of indium and nickel for fast neutrons and gold, europium, and cobalt for thermal and epithermal neutrons, which were inserted in the moderators. The latter two activations are also to validate 152Eu and 60Co activity data obtained from the atomic bomb-exposed specimens collected at Hiroshima and Nagasaki, Japan. The neutron moderators used were Lucite and Nylon 6 and the total thickness of each moderator was 60 cm or 65 cm. Measured activity data (reaction yield) of the neutron-irradiated detectors in these moderators decreased to about 1/1,000th or 1/10,000th, which corresponds to about 1,500 m ground distance from the hypocenter in Hiroshima. For all of the indium, nickel, and gold activity data, the measured and calculated values agreed within 25%, and the corresponding values for europium and cobalt were within 40%. From this study, the MCNP code was found to be accurate enough for the bare- and energy-moderated 252Cf neutron activation calculations of these elements using moderators containing hydrogen, carbon, nitrogen, and oxygen.
authors.affiliation: Faculty of Engineering, Hiroshima University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Iwatani
authors.forename: M
authors.initials: M
authors.lastname: Hoshi
authors.forename: K
authors.initials: K
authors.lastname: Shizuma
authors.forename: M
authors.initials: M
authors.lastname: Hiraoka
authors.forename: N
authors.initials: N
authors.lastname: Hayakawa
authors.forename: T
authors.initials: T
authors.lastname: Oka
authors.forename: H
authors.initials: H
authors.lastname: Hasai
mesh_terms: D003035:Cobalt / Q000737:chemistry; D005063:Europium / Q000737:chemistry; D005214:Fast Neutrons; D006046:Gold / Q000737:chemistry; D007204:Indium / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D007564:Japan; D009010:Monte Carlo Method; D009532:Nickel / Q000737:chemistry; D009689:Nuclear Warfare; D011874:Radiometry
chemical_list: D007204:Indium; D003035:Cobalt; D005063:Europium; D006046:Gold; D009532:Nickel; D007501:Iron