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Fuel residence time in BWRs with nitride fuels
KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.ORCID iD: 0000-0002-6082-8913
2012 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 47, 182-191 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents a neutronics study of a BWR core with uranium nitride fuels. Replacing the standard UO2 fuel with UN or UN-ZrO2 allows for a higher uranium content, which leads to an increase of the in-core fuel residence time. With the nitride fuels, the total void worth increases and the efficiency of the control rods and burnable poison deteriorates. Taking into account the higher amount of burnable poison needed at the beginning of life, the in-core fuel residence time increases by about 1.4 year comparing to UO2 fuel with the same enrichment. This implies 1.4% higher availability of the plant and it is therefore of economic interest to the nuclear power plant operators. A similar increase of the fuel in-core lifetime in a UO2 core could be reached by an increase of the average enrichment of the oxide fuel by roughly 1%.

Place, publisher, year, edition, pages
2012. Vol. 47, 182-191 p.
Keyword [en]
BWR, Uranium nitride, Enrichment, Fuel cycle, Neutronics
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Other Physics Topics
Identifiers
URN: urn:nbn:se:kth:diva-100775DOI: 10.1016/j.anucene.2012.03.033ISI: 000306448800026Scopus ID: 2-s2.0-84861828049OAI: oai:DiVA.org:kth-100775DiVA: diva2:545009
Note
QC 20120817Available from: 2012-08-17 Created: 2012-08-17 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Advanced fuels for thermal spectrum reactors
Open this publication in new window or tab >>Advanced fuels for thermal spectrum reactors
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The advanced fuels investigated in this thesis comprise fuels non− conventional in their design/form (TRISO), their composition (high content of plutonium and minor actinides) or their use in a reactor type, in which they have not been used before (e.g. nitride fuel in BWR). These fuels come with a promise of improved characteristics such as safe, high temperature operation, spent fuel transmutation or fuel cycle extension, for which reasons their potentialis worth assessment and investigation. Their possible use also brings about various challenges, out of which some were addressed in this thesis. TRISO particle fuels with their superior retention abilities enable safe, high−temperature operation. Their combination with molten salt in the Advanced High Temperature Reactor (AHTR) concept moreover promises high operating temperature at low pressure, but it requires a careful selection of the cooling salt and the TRISO dimensions to achieve adequate safety characteristic, incl. a negative feedback to voiding. We show that an AHTR cooled with FLiBe may safely operate with both Pu oxide and enriched U oxide fuels. Pu and Minor Actinides (MA) bearing fuels may be used in BWR for transmutation through multirecycling; however, the allowable amounts of Pu and MA are limited due to the degraded feedback to voiding or low reactivity.We showed that the main positive contribution to the void effect in the fuelswith Pu and MA content of around 11 to 15% consist of the decreased thermalcapture probability in Pu-240, Pu-239 and Am-241 and increased fast and resonance fission probability of U-238, Pu239 and Pu-240. The total void worthmoreover increases during multirecycling, limiting the allowable amount ofMA to 2.45% in uranium−based fuels. An alternative, thorium−based fuel allows for 3.45% MA without entering the positive voiding regime at any point of the multirecycling. The increased alpha−heating associated with the use of transmutation fuels, is at level 24−31 W/kgFUEL in the uranium based fuels and 32−37 W/kgFUEL in the thorium−based configurations. The maximum value of the neutron emission, reached in the last cycle, is 1.7·106 n/s/g and 2·106 n/s/g for uranium and for thorium−based fuels, respectively. Replacing the standard UO2 fuel with higher−uranium density UN orUNZrO2 fuels in BWR shows potential for an increase of the in-core fuelresidence time by about 1.4 year. This implies 1.4% higher availability of the plant. With the nitride fuels, the total void worth increases and the efficiency of the control rods and burnable poison deteriorates, but no major neutronics issue has been identified. The use of nitride fuels in the BWR environment is conditioned by their stability in hot steam. Possible methods for stabilizing nitride fuels in water and steam at 300◦ C were suggested in a recent patentapplication.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. xii, 55, p.
Series
Trita-FYS, ISSN 0280-316X ; 2012:73
Keyword
BWR, transmutation, thorium, Pu, MA, Am, Cm, AHTR, thermal, reactor, neutron
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Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-103085 (URN)
Public defence
2012-10-12, FA32, AlbaNova University Center, Roslagstullsbacke 21, Stockholm, 13:00 (English)
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Note

QC 20121004

Available from: 2012-10-04 Created: 2012-10-03 Last updated: 2012-10-04Bibliographically approved

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