Authors & Affiliations
Ekhlakov I.A., Alekseev P.A.
A.I. Leypunsky Institute for Physics and Power, Obninsk, Russia
This paper considers two factors of space radiation that can impact a space reactor safety at its start-up stage. The detailed studies like these are only possible with the use of state-of-the-art calculation software that allows simulation of neutronic processes and specifically reactor physics with a 3-D heterogeneous model of a nuclear power system (NPS). So, the NPS interaction with space radiation was calculated with the use of the GEANT4 software package. First, interaction of ultrarelativistic protons, with the energy up to 100 TeV, with structural materials of the space nuclear power system was studied. The quantitative, spatial and time characteristics of neutron cascades formed and fission rate distributions in the reactor core in probability became available. Based on the data obtained the conclusion was made about an absolute safety of these events for the reactor start-up. Then consideration was given to the effect of solar flare power on the reactor operation. Estimation of the number of fission events in the reactor at the maximum solar flare demonstrated a potential hazard of this factor of space radiation. The analysis of reactor kinetics in the start-up period showed that the level of impact on the nuclear power system operation would be also determined by the proton flux peaking time. The obtained results show that in the course of developing programs for launching spacecraft with a nuclear power system on board and when choosing the time of reactor start-up on the orbit, it is necessary to take into account the effect of powerful solar flares.
Reactor physics, nuclear power system (NPS), thermionic reactor-converter (TRC), ultrarelativistic heavy charged particle (HCP), neutron flux, accelerated particle flux, neutron cascade
1. The Role of Nuclear Power and Nuclear Propulsion in Peaceful Exploration of Space, Vienna, September, STI/PUB/1197. URL: http://www.pub.iaea.org/MTCD/publications/PDF/Pub1197_web.pdf
2. Ionkin V.I., Yarygin V.I. Rol' yadernoj energetiki v kosmicheskikh issledovaniyakh. Opyt i dostizheniya SSSR/Rossii. Sovremennoe sostoyanie i perspektivy razvitiya [The Role of Nuclear Power in Space Exploration. The Experience and Achievements of the USSR/Russia. The Current Status and Prospects of Development]. Obninsk, 2004.
3. Available at: http://geant4.web.cern.ch/geant4/
4. Available at: http://www.slac.stanford.edu/comp/physics/geant4/slac_physics_lists/G4_Physics_Lists.html
5. Available at: http://www.litmir.net/br/?b=106098&p=645
6. Panasjuk M.I. Stranniki Vselennoj ili eho Bol'shogo vzryva [Voyagers of the Universe or an Echo of the Big Bang]. Frjazino, Nauka dlya vsekh Publ., 2005, 272 p.
7. Pupko V.Ya., Makarenkov Yu.D., Marin S.N., et al. Issledovanie nekotorykh vozmozhnykh avarij pri puskovykh rezhimakh kosmicheskoj YaYeU [Studies of Possible Accidents under Conditions of Space NPS Start-up]. Voprosy atomnoy nauki i tekhniki. Ser. Fizika yadernykh reaktorov - Problems of atomic science and technology. Series: Physics of Nuclear Reactors. 1995, no.4, pp. 77–81.
8. Shannon M. Bragg-Sitton and James Paul Holloway, Reactor Start-up and Control Methodologies: Consideration of the Space Radiation Environment. Proc. of Space Technology and Application International Forum-STAIF. 2004.
9. Available at: http://www.spenvis.oma.be/spenvis/
10. Vernova S.N. Model' kosmicheskogo prostranstva. T.1 Fizicheskie usloviya v kosmicheskom prostranstve. [Outer Space Model. V.1 Physical Conditions in Space]. Moscow, House of Moscow University Publ., 1983, 599 p.
11. Kazanskij Yu.A. Kinetika yadernykh reaktorov. Uchebnoe posobie po kursu «Fizicheskaja teoriya yadernykh reaktorov» [Nuclear Reactor Kinetics. Training Manual for the Course Titled “Physical Theory of Nuclear Reactors”]. Obninsk, IATE Publ., 2003, 96 p.