The UNICO multi-physics code to analyze transients in sodium fast reactors

УДК: 621.039.51

Issue of journal:


The Russian multi-physics code UNICO is designed to analyze in detail the temperature and velocity fields in the fast reactor core, under transient conditions. The code is meant to make 3D coupled computation of neutronic, thermal-hydraulic and thermal-mechanic characteristics accurate to each separate core fuel assembly (FA). A core thermal hydraulic model is a set of fuel assemblies installed into an inter-wrapper space. Sodium thermal hydraulics in the core inter-wrapper space is calculated in 3D approximation and the relevant equation system is solved in the triangular computational mesh. Sodium velocity and temperature distribution are taken into account inside each fuel assembly. A 3D FA model is used to calculate the temperature of fuel and steel cladding. Based on the information about the temperature of fuel, fuel element cladding and FA wrappers the core deformation behaviour is analyzed and then the respective changes in neutronic characteristics are calculated. The results of test calculations are given; they confirm the fact that insufficiently correct consideration of spatial distribution of thermal hydraulic parameters in the reactor core can cause appreciable errors (uncertainties).

1. Rachkov V.I. Atomnaya energetika kak vazhnejshij faktor ustojchivogo razvitiya Rossii v XXI veke [Nuclear energy as an important factor for sustainable development of Russia in XXI century]. Energosberezhenie i vodopodgotovka. 2006, no. 6, pp. 2–4.
2. Rachkov V.I., Poplavskij V.M., Tsibulya A.M. e.a. Koncepciya perspektivnogo energobloka s bystrym natrievym reaktorom BN1200 [Concept of prospective of power unit with fast neutron reactor BN1200]. Atomnaya energiya. 2010, vol. 108, no. 4, pp. 201–205.
3. Adamov E.O., Dzhalovyan A.V., Lopatkin A.V. e.a. Konceptual’nye polozheniya strategii razvitiya yadernoj energetiki Rossii v perspektive do 2100 g. [Conceptual Development Strategy of Russian nuclear power in the run up to 2100]. Atomnaya energiya. 2012, vol. 112, no. 6, pp. 319–330.
4. Shvecov Yu.E. SACTA3D – teplogidravlicheskij kod dlya pokassetnogo analiza temperaturnogo sostoyaniya aktivnoj zony. Sbornik dokladov mezhvedomstvennogo seminara «Teplogidravlicheskie aspekty bezopasnosti aktivnyh zon, ohlazhdaemyh vodoj i zhidkimi metallami». [SACTA3D thermohydraulic code for assemblybyassembly analysis of core temperature. Proceedings of the Interdepartmental Workshop on Thermohydraulic Aspects of Water and Liquid MetalCooled Core Safety]. Obninsk, SSC RFIPPE, 2008. (in Russian).
5. Kuznetsov I.A., Shvetsov Yu.E. Calculation of thermalhydraulic parameters of fast neutron with account of interfuelassembly space influence. Book of extended synopses, International meeting FR09, Dec. 711, 2009. IAEA, Kyoto, Japan. CN 176. 2009. 483 p.
6. Verification and validation of LMFBR static core mechanics codes. Part I. Final report of coordinated research program on intercomparison of LMFBR core mechanics codes. IAEAIWGFR/75, Vienna, Austria. 1990.
7. Zabud’ko L.M., Lihachev Yu.I., Proshkin A.A. Rabotosposobnost’ TVS bystryh reaktorov. [Performance of fast reactor fuel assemblies]. Moskow, Energoatomizdat Publ. 1988.
8. Suslov I.R., Babanakov D.M. MAG – The Code for Fine Mesh WWER Calculations. Proc. of 6 th Symposium AER. 1996.
9. Suslov I.R. A preliminary result of calculation of extrapolatedtozeromeshsize solution (EZMSS) of the second AER kinetic benchmark by finitedifference code MAG. Procedings of the tenth Symposium of AER. Moscow, 2000, pp. 449–454.
10. Suslov I.R. Sistema vychislitel’nyh benchmarkov dlya nejtronnofizicheskih raschetov WWER [Computing system benchmarks for neutronic calculations of WWER]. Izvestiya vuzov. Yadernaya energetika. 2008, no. 2, pp. 80–89.

For full access to information log in or register here.