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Why Faster is Better: On Minor Actinide Transmutation in Hard Neutron
KTH, School of Engineering Sciences (SCI), Physics.
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

In this thesis, options for efficient transmutation of transuranium elements are discussed. The focus is on plutonium, americium and curium mainly because of their long-term contribution to the radiotoxicity of spent nuclear fuel. Two innovative helium-cooled core designs are proposed, dedicated to the transmutation of actinides. The performance of the more promising of the two is studied in realistic transient fuel cycle scenarios. During the 1150 day irradiation cycle, a minor actinide consumption of 355 kg/GWth·year is achieved. An analysis of the efficiency of spallation neutron sources in helium-cooled cores is also performed. It is shown that the proton source efficiency, ψ∗, is improved by about 10% when helium is used as coolant, rather than lead-bismuth eutectic. Further, a proposal is made to transmute actinides in the upper part of a BWR core. A net consumption of transuranics is shown possible in the BWR park already when 50% of the BWR fuel is of the proposed evolutionary type.

The thesis concludes that efficient transmutation of transuranic elements in dedicated helium-cooled subcritical cores is possible. But, in many instances fuel cycles without dedicated cores may lead to comparable final states. Especially, the evolutionary BWRfuel proposed seems interesting.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , x, 86 p.
Series
Trita-FYS, ISSN 0280-316X ; 2007:05
Keyword [en]
nuclear physics, nuclear engineering
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-4280ISBN: 978-91-7178-567-1 (print)OAI: oai:DiVA.org:kth-4280DiVA: diva2:11605
Public defence
2007-02-23, F3, KTH, Lindstedtsvägen 26, Stockholm, 14:15
Opponent
Supervisors
Note
QC 20100820Available from: 2007-02-19 Created: 2007-02-19 Last updated: 2011-10-03Bibliographically approved
List of papers
1. Neutronic and Safety Aspects of a Gas-Cooled Subcritical Core for Minor Actinide Transmutation
Open this publication in new window or tab >>Neutronic and Safety Aspects of a Gas-Cooled Subcritical Core for Minor Actinide Transmutation
2005 (English)In: Nuclear Technology, ISSN 0029-5450, Vol. 154, no 1, 41-51 p.Article in journal (Refereed) Published
Abstract [en]

We have designed a gas-cooled accelerator-driven system dedicated to transmutation of minor actinides. Thanks to the excellent neutron economy of the uranium-free fuel employed, the pin pitch to diameter ratio (P/D) could be increased to 1.8. The increased coolant fraction allows for decay heat removal at ambient pressure. The large coolant fraction further results in a low, pressure loss-26 kPa over the core, 35 kPa in. total. Thanks to the large P/D, the elevation of the heat exchanger necessary to remove decay heat by natural circulation is just more than I m. The absence of uranium in conjunction. with the presence of 35% (heavy atom) americium in the fuel results in a low effective delayed neutron fraction and a vanishing Doppler feedback, making subcritical operation mandatory.

Keyword
Accelerator-driven systems; Helium cooling; Minor actinide fuel; Actinides; Cooling; Heat exchangers; Monte Carlo methods; Nuclear reactors; Plutonium; Uranium; Actinide transmutation; Doppler feedback; Gas-cooled accelerator-driven system; Nuclear fuels
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-6790 (URN)000236616200003 ()2-s2.0-33645918000 (Scopus ID)
Note

QC 20141127

Available from: 2007-02-19 Created: 2007-02-19 Last updated: 2014-11-27Bibliographically approved
2. On TiN-particle fuel based helium-cooled transmutation systems
Open this publication in new window or tab >>On TiN-particle fuel based helium-cooled transmutation systems
2006 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 33, no 16, 1322-1328 p.Article in journal (Refereed) Published
Abstract [en]

We have designed a sub-critical helium-cooled core with TiN-coated particle fuel, dedicated to the transmutation of minor actinides. The excellent neutronic properties of helium allows for a low plutonium fraction in the fuel, which yields a low reactivity swing, Delta k = 2600 pcm, for a burnup of 31.2%. Further the neutron spectrum is hard, limiting the buildup of Cm and Cf. The high burnup combined with a minor actinide burning rate of 355 kg/GWth year makes the present design an attractive transmutation system.

Keyword
accelerator-driven systems, minor-actinide, neutronics, reactor, design
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-16212 (URN)10.1016/j.anucene.2006.08.012 (DOI)000242927300007 ()2-s2.0-33751081851 (Scopus ID)
Note

QC 20100820

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
3. Source efficiency as function of fuel and coolant in accelerator-driven systems
Open this publication in new window or tab >>Source efficiency as function of fuel and coolant in accelerator-driven systems
2006 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 33, no 9, 829-832 p.Article in journal (Refereed) Published
Abstract [en]

We have studied the efficiency of spallation neutron sources for different combinations of coolant and fuel in 80 MWth, sub-critical, cores. It has been found that the proton source efficiency, psi*, is reduced by 10% when switching coolant from helium to lead-bismuth eutectic. Substituting MOX fuel with an americium based fuel, results in another 10% reduction of psi*. The relatively high source efficiencies found for prototype accelerator-driven systems, using standard MOX fuel and helium coolant, may thus be difficult to achieve in future systems dedicated to the transmutation of higher actinides. Our results are in agreement with previous investigations of the dependence of the source efficiency on the selection of coolant.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-6750 (URN)10.1016/j.anucene.2006.03.007 (DOI)000239532900010 ()2-s2.0-33745584785 (Scopus ID)
Note
Tidigare titel: Source efficiency studies in gas- and leadbismuth- cooled sub-critical accelerator-driven cores. Uppdaterad från submitted till published: 20101005. QC 20101005Available from: 2005-09-22 Created: 2005-09-22 Last updated: 2011-10-03Bibliographically approved
4. Impact of ADS on nuclear fuel cycles
Open this publication in new window or tab >>Impact of ADS on nuclear fuel cycles
(English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100Article in journal (Other academic) Submitted
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-6793 (URN)
Note
QS 20120328Available from: 2007-02-19 Created: 2007-02-19 Last updated: 2012-03-28Bibliographically approved
5. Hafnium clad fuels for fast spectrum BWRs
Open this publication in new window or tab >>Hafnium clad fuels for fast spectrum BWRs
2008 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 35, no 1, 60-67 p.Article in journal (Refereed) Published
Abstract [en]

We show that by use of hafnium cladding, a fast neutron spectrum is achievable in the top of uprated BWRs. Monte Carlo calculations have been made for Hf clad inert matrix nitride and low fertile MOX fuels, with fuel segments located in the upper part of an uprated BWR, where the coolant void fraction exceeds 70%. The nitride fuel results in the hardest neutron spectrum, but the low fertile MOX fuel still yields fission probabilities for even neutron number nuclides similar to those of sodium cooled reactors. The inert matrix nitride fuel configuration yields high burning rates, permitting to stabilise TRU inventories with less than 50% BWR cores of the here suggested type in the power park. The core with low fertile MOX fuel is less efficient, but still a zero net producer of TRU. Fuel and coolant temperature feedbacks are affected by introduction of absorbing elements in the fuel, but remain within acceptable ranges for the low fertile MOX fuel. Although control rod worths are reduced, shutdown margins are sufficient to ensure sub-criticality in cold conditions. From a materials point of view, the behaviour of hafnium clad MOX fuel would be similar to zircalloy clad MOX fuel already used extensively in nuclear industry. Thus, if dynamic stability of the core can be ensured, the here proposed fuel may be considered as a low cost solution for transmutation of minor actinides on industrial scale.

Keyword
Cladding (coating); Coolants; Hafnium; Monte Carlo methods; Void fraction; Clad fuels; Fission probabilities; Low fertile MOX fuels; Sodium cooled reactors; Boiling water reactors
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-6794 (URN)10.1016/j.anucene.2007.05.006 (DOI)000252911000006 ()2-s2.0-36148992195 (Scopus ID)
Note

QC 20100823. Uppdaterad från Submitted till Published 20100823.

Available from: 2007-02-19 Created: 2007-02-19 Last updated: 2016-04-19Bibliographically approved

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