Title:	Burnable absorber layer in HTR coated particles for OTTO fuel cycle
Authors:	Lovecký, Martin Závorka, Jiří Jiřičková, Jana Škoda, Radek
Citation:	LOVECKÝ, M., ZÁVORKA, , JIŘIČKOVÁ, J., ŠKODA, R. Burnable absorber layer in HTR coated particles for OTTO fuel cycle. In: Proceedings : 27th International Conference Nuclear Energy for New Europe (NENE 2018). Ljubljana: Nuclear Society of Slovenia, 2018. s. 214.1-214.8. ISBN 978-961-6207-45-4.
Issue Date:	2018
Publisher:	Nuclear Society of Slovenia
Document type:	konferenční příspěvek conferenceObject
URI:	http://hdl.handle.net/11025/33728
ISBN:	978-961-6207-45-4
Keywords in different language:	nuclear fuel;burnable absorber;OTTO fuel cycle
Abstract in different language:	High temperature reactor is loaded by fuel pebbles that slowly flow through the reactor core. Reactor operation is described by a continuous on-power refueling with two possible fuel cycles. Multi-pass scheme allows lower peak power density. Moreover, multiple passing through the core shifts power peak into central parts of the core. On the other hand, multi-pass scheme requires complicated refueling machine. Single-passing scheme known as OTTO cycle (Once-Through-Then-Out) avoids refueling machine with the disadvantage of high peak power density located at the top of the core. There are few paths for diminishing and shifting of the power peak - non-cylindrical core shapes, absorbing reflectors, thorium fuel, radial fuel zoning and burnable absorbers. From construction point of view, burnable absorbers are the first choice. In contrast to LWR reactors, HTR reactor is randomly filled by hundred thousand fuel assemblies (pebbles), each fuel pebble contains thousands of coated particles stochastically embedded in the graphite matrix. Because of this double heterogeneity, fuel design studies should be based on both fuel assembly level as well as core level calculations. Standard LWR burnable absorber materials gadolinium, boron and erbium were analyzed for HTR, however, other materials are proposed for specific HTR conditions, mainly very high fuel discharge burnup. Coated layer created by burnable absorber is small, therefore, thermal and chemical compatibility with UO2 matrix is not needed and the choice of optimum material can be more focused on neutronics analysis. Monte Carlo approach with Serpent 2 code is used because of a specific random walk implementation that is distinctively faster than the standard ray tracing methods.
Rights:	Plný text je přístupný v rámci univerzity přihlášeným uživatelům. © Nuclear Society of Slovenia
Appears in Collections:	Konferenční příspěvky / Conference papers (KEV) Konferenční příspěvky / Conference papers (RICE) OBD

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