Hiroshima and Nagasaki Initial Radiations: Delayed Neutron Contributions and Comparison of Calculated and Measured Cobalt Activations

Loewe, W.E.

doi:10.13182/nt85-a33577

Cited by 7 publications

(3 citation statements)

References 3 publications

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“…This difference has been termed the "Hiroshima -~ 10.0 thermal neutron discrepancy". As indicated above, the o ~ radionuclides 152Eu and 6~ were assessed independently by Japanese teams, by means of gamma spectroscopy, and _-3 1.0 O9 the results were in apparent agreement with those obtained for 36C1, for large distances from the epicenter in Hiroshima [6,8,9,10,11,19,21,23,24,25,26,27] ( Fig. 1).…”

Section: Introductionsupporting

confidence: 72%

36Cl measurements in hiroshima granite samples as part of an international intercomparison study

Huber

Rühm²,

Hoshi

et al. 2003

Radiat Environ Biophys

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Within the effort to resolve the so-called Hiroshima neutron discrepancy, an international intercomparison study has been carried out on granite samples from Hiroshima, with participating institutions from Japan, the US, and Germany. (36)Cl and (152)Eu produced in these samples by thermal neutrons from the A-bomb explosion were assessed independently by means of different techniques. At the Maier-Leibnitz-Laboratory near Munich, Germany, (36)Cl concentrations were measured by accelerator mass spectrometry. Measured (36)Cl/Cl ratios ranged from 1,670 x 10(-13) (at a distance of 146 m from the hypocenter) to 2.2 x 10(-13) (at a distance of 1,163 m from the hypocenter). One granite sample not exposed to A-bomb neutrons was measured as a control, and a (36)Cl/Cl ratio of 2.6 x 10(-13) was obtained. On average, our experimental results are 20-30% lower than those provided by model calculations based on the dosimetry system DS86. The results presented here do not support previous assessments of (36)Cl, (60)Co, and (152)Eu which had suggested much larger thermal neutron fluences than those calculated on the basis of DS86 for distances from the hypocenter of more than 1,000 m.

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Section: Introductionsupporting

confidence: 72%

36Cl measurements in hiroshima granite samples as part of an international intercomparison study

Huber

Rühm²,

Hoshi

et al. 2003

Radiat Environ Biophys

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“…Significant discrepancies became evident, however, between the 60 Co activation data from Hashizume et al [31] and the DS86 calculations. The measured 60 Co activities were about 50% below DS86 predictions for a ground range of about 200 m in Hiroshima, but were about a factor of 3 times greater for ground ranges of 1000 m in Nagasaki and for 1200 m in Hiroshima [46]. Therefore, in the final report of DS86, it was stated that '…the conclusion of this chapter on neutron measurements must be that the neutron doses are in doubt until further work is done' [47].…”

Section: Tentative 1965 Doses (T65d)mentioning

confidence: 99%

“…It is important to realize at this point that due to limited computer power at the time, most of the transport calculations in DS86 were performed in terms of a limited number of energy groups [46]. For example, thermal neutrons were described by a single energy group ranging from 10 -5 to 0.4 eV.…”

Section: Developments After the Release Of Ds86mentioning

confidence: 99%

The dosimetry system DS86 and the neutron discrepancy in Hiroshima - historical review, present status, and future options

Rühm¹,

Kellerer²,

Korschinek

et al. 1998

Radiation and Environmental Biophysics

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The historical development of the dosimetry systems for Hiroshima and Nagasaki is outlined from the time immediately after the A-bomb explosions to the publication of the dosimetry system DS86 in 1987, and the present status of the so-called Hiroshima neutron discrepancy is summarized. Several long-lived radionuclides are discussed with regard to their production by neutrons from the A-bomb explosions. With the exception of 63Ni, these radionuclides have not, up to now, been measured in samples from Hiroshima and Nagasaki. Two of them, 63Ni in copper samples and 39Ar in granite samples, were predominantly produced by fast neutrons. 63Ni can be determined by accelerator mass spectrometry with a gas-filled analyzing magnet. It should be measurable, in the near future, in copper samples up to 1500 m from the hypocenter in Hiroshima. 39Ar can be measured in terms of low-level beta-counting. This should be feasible up to a distance of about 1000 m from the hypocenter. Three radionuclides, 10Be, 14C, and 59Ni, were produced predominantly by thermal neutrons with smaller fractions due to the epithermal and fast neutrons, which contribute increasingly more at larger distances from the hypocenter. State-of-the-art accelerator mass spectrometry is likely to permit the determination of 10Be close to the hypocenter and of 14C up to a distance of about 1000 m. 59Ni should be detectable up to a distance of about 1000 m in terms of accelerator mass spectrometry with a gas-filled magnet. The measurements of 10Be, 14C, 39Ar, 59Ni -- and potentially of 131Xe -- can be performed in the same granitic sample that was already analyzed for 36Cl, 41Ca, 6Co, 152Eu, and 154Eu. This will provide extensive information on the neutron spectrum at the specified location, and similarly complete analyses can conceivably be performed on granite samples at other locations.

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36Cl and41Ca depth profiles in a Hiroshima granite stone and the Dosimetry System 1986

Rühm

Kato

Korschinek

et al. 1992

Z. Physik A - Hadrons and Nuclei

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Hiroshima and Nagasaki Initial Radiations: Delayed Neutron Contributions and Comparison of Calculated and Measured Cobalt Activations

Cited by 7 publications

References 3 publications

36Cl measurements in hiroshima granite samples as part of an international intercomparison study

36Cl measurements in hiroshima granite samples as part of an international intercomparison study

The dosimetry system DS86 and the neutron discrepancy in Hiroshima - historical review, present status, and future options

36Cl and41Ca depth profiles in a Hiroshima granite stone and the Dosimetry System 1986

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