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Osifo, Otasowie
Publications (5 of 5) Show all publications
Willman, C., Håkansson, A., Osifo, O., Bäcklin, A. & Jacobsson Svärd, S. (2006). A nondestructive method for discriminating MOX fuel from LEU fuel for safeguards purposes. Annals of Nuclear Energy, 33(9), 766-773
Open this publication in new window or tab >>A nondestructive method for discriminating MOX fuel from LEU fuel for safeguards purposes
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2006 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 33, no 9, p. 766-773Article in journal (Refereed) Published
Abstract [en]

Plutonium-rich mixed oxide fuel (MOX) is increasingly used in thermal reactors. However, spent MOX fuel could be a potential source of nuclear weapons material and a safeguards issue is therefore to determine whether a spent nuclear fuel assembly is of MOX type or of LEU (Low Enriched Uranium) type.

In this paper, we present theoretical and experimental results of a study that aims to investigate the possibilities of using gamma-ray spectroscopy to determine whether a nuclear fuel assembly is of MOX or of LEU type.

Simulations with the computer code ORIGEN-ARP have been performed where LEU and MOX fuel types with varying enrichment and burnup as well as different irradiation histories have been modelled. The simulations indicate that the fuel type determination may be achieved by using the intensity ratio Cs-134/Eu-154.

An experimental study of MOX fuel of 14 x 14 PWR type and LEU fuel of both 15 x 15 and 17 x 17 type is also reported in this paper. The outcome of the experimental study support the conclusion that MOX fuel may be discriminated from LEU fuel by measuring the suggested isotopic ratio.

National Category
Physical Sciences
Research subject
Applied Nuclear Physics; Physics with specialization in Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-94789 (URN)10.1016/j.anucene.2006.04.006 (DOI)000239532900003 ()
Available from: 2006-09-08 Created: 2006-09-08 Last updated: 2017-12-14
Willman, C., Håkansson, A., Osifo, O., Bäcklin, A. & Jacobsson Svärd, S. (2006). Nondestructive assay of spent nuclear fuel with gamma-ray spectroscopy. Annals of Nuclear Energy, 33(5), 427-438
Open this publication in new window or tab >>Nondestructive assay of spent nuclear fuel with gamma-ray spectroscopy
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2006 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, Vol. 33, no 5, p. 427-438Article in journal (Refereed) Published
Abstract [en]

An important issue in nuclear safeguards is to verify operator-declared data of spent nuclear fuel. Various techniques have therefore been assigned for this purpose. A nondestructive approach is to measure the gamma radiation from spent nuclear fuel assemblies. Using this technique, parameters such as burnup and cooling time can be calculated or verified.

In this paper, we propose the utilization of gamma rays from 137Cs, 134Cs and 154Eu to determine the consistency of operator-declared information. Specifically, we have investigated to what extent irradiation histories can be verified.

Computer simulations were used in order to determine limits for detecting small deviations from declared data. In addition, the technique has been experimentally demonstrated on 12 PWR fuel assemblies.

A technique for determining burnup and cooling time for fuel assemblies where no operator-declared information is available is also presented. In such a case, the burnup could be determined with 1.6% relative standard deviation and the cooling time with 1.5%.

National Category
Subatomic Physics
Research subject
Applied Nuclear Physics; Physics with specialization in Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-77666 (URN)
Available from: 2007-02-13 Created: 2007-02-13 Last updated: 2012-03-09
Willman, C., Osifo, O., Håkansson, A. & Jacobsson Svärd, S. (2005). A Semi-Empirical Technique for Verification of Spent Nuclear Fuel Assemblies. In: 27th Annual Symposium on Safeguards and Nuclear Materials Management (ESARDA).
Open this publication in new window or tab >>A Semi-Empirical Technique for Verification of Spent Nuclear Fuel Assemblies
2005 (English)In: 27th Annual Symposium on Safeguards and Nuclear Materials Management (ESARDA), 2005Conference paper, Published paper (Other scientific)
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-77503 (URN)
Available from: 2006-03-15 Created: 2006-03-15
Jacobsson Svärd, S., Håkansson, A., Bäcklin, A., Osifo, O., Willman, C. & Jansson, P. (2005). Nondestructive Experimental Determination of the Pin-Power Distribution in Nuclear Fuel Assemblies. Nuclear Technology, 151(1), 70-76
Open this publication in new window or tab >>Nondestructive Experimental Determination of the Pin-Power Distribution in Nuclear Fuel Assemblies
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2005 (English)In: Nuclear Technology, ISSN 0029-5450, Vol. 151, no 1, p. 70-76Article in journal (Refereed) Published
Abstract [en]

A need for validation of modern production codes with respect to the calculated pin-power distribution has been recognized. A nondestructive experimental method for such validation has been developed based on a tomographic technique. The gamma-ray flux distribution is recorded in each axial node of the fuel assembly separately, whereby the relative rod-by-rod content of the fission product 140Ba is determined. Measurements indicate that 1 to 2% accuracy (1 sigma) is achievable.

A device has been constructed for in-pool measurements at reactor sites. The applicability has been demonstrated in measurements at the Swedish boiling water reactor (BWR) Forsmark 2 on irradiated fuel with a cooling time of 4 to 5 weeks. Data from the production code POLCA-7 have been compared to measured rod-by-rod contents of 140Ba. An agreement of 3.1% (1 sigma) has been demonstrated.

It is estimated that measurements can be performed on a complete BWR assembly in 25 axial nodes within an 8-h work shift. As compared to the conventional method, involving gamma scanning of individual fuel rods, this method does not require the fuel to be disassembled nor does the fuel channel have to be removed. The cost per measured fuel rod is estimated to be an order of magnitude lower than the conventional method.

Keywords
tomography
National Category
Subatomic Physics
Research subject
Applied Nuclear Physics; Physics with specialization in Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-77332 (URN)
Available from: 2006-03-15 Created: 2006-03-15 Last updated: 2017-01-21
Jacobsson Svärd, S., Håkansson, A., Bäcklin, A., Osifo, O., Willman, C. & Jansson, P. (2003). Non-destructive experimental determination of the pin-power distribution in nuclear fuel. In: : . Paper presented at Advances in Nuclear Fuel Management III.
Open this publication in new window or tab >>Non-destructive experimental determination of the pin-power distribution in nuclear fuel
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2003 (English)Conference paper, Published paper (Other academic)
Abstract [en]

A need for validation of modern core-analysis codes with respect to the calculated pin-power distribution has been recognized. A non-destructive experimental method for such validation has been developed, based on a tomographic technique. Each axial node of the fuel assembly is measured separately and the relative pin-by-pin content of the direct fission product Ba-140 is determined. Investigations performed so far indicate that 1-2% (1 σ) accuracy can be obtained.

A measuring device has been constructed which, when fully equipped, is designed to measure a complete BWR assembly in 25 axial nodes within an eight-hour work shift. The applicability of the constructed device has been demonstrated in measurements at the Swedish BWR Forsmark 2 on irradiated fuel with a cooling time of 4-5 weeks. Data from the core-analysis code POLCA-7 have been compared to measured pin-by-pin contents of Ba-140. An agreement of 3.1% (1 σ) has been demonstrated.

As compared to the conventional method, involving gamma scanning of individual fuel pins, this method does not require the fuel to be disassembled. Neither does the fuel channel have to be removed. The cost per measured fuel pin is in the order of 20 times lower than the conventional method.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-77504 (URN)0-89448--670-5 (ISBN)
Conference
Advances in Nuclear Fuel Management III
Available from: 2006-03-15 Created: 2006-03-15 Last updated: 2015-01-27
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