INE 4 - 1 Introduction to Nuclear Engineering &...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 Introduction to Nuclear Engineering & Engineering Physics Fission,Fusion and NEEP Facilities Don Steiner Fission Energy Release 2 Fission Cross Sections Low E n fission of 235 U is clearly the more favorable route for practical fission power - so let us consider this fission reaction further ~1 b ~2 b (~1MeV) High E n ~10-6 b ~580 b (~1eV) Low E n 238 U 235 U ( 29 * 235 1 236 93 141 92 143 1 37 56 55 86 U U Rb Cs 2 n n + + + Typical Fission Reaction in U235 When 235 U + n fission occurs we observe : (1)a distribution of fission fragment masses; (2)the emission of ~ 2.5 n / fission event (these observations reflect statisically based observations - a single event has unique fission fragments & an integer # of n s) 3 Neutron balances & the fission chain reaction- consider idealized reactor neutron leakage (through all faces) scattered neutrons escape system prior to absorption moderator (E.G. ) 12 6 C fuel ( 235 U + 238 U) Possible Fates of Fission Neutrons x leakage x absorption/capture in moderator 1 2 3 (absorption in 238 U or 235 U of low E n ) 4 Consider Neutron Fate Between Generations of Low E Fission (Gen) i 100 Low E n neutrons absorbed in 235 U ( 29 ( 29 c c c / ~ fission probability 580 100 ~ 85 fissions 680 ~ / ~ capture probability 100 100 ~ 15 captures 680 f f f + + Neutron Fate Between Generations of Low E Fission 85 fissions x 2.5 n / fission ~ 210 fission ns As they slow down ~20% leakout ~40 ~10% captured in 238 ~20 ~60 lost 150 survive to low E n ~20% captured in 238 & graphite @ low E n therefore ~30 lost and 120 remain The remaining 120 at low E n can be absorbed in 235 U in next time sequence / generation. (Gen) i+1 5 k neutron multiplication factor k n i+1 / n i 1.2(for our case) using n rather than n...
View Full Document

This note was uploaded on 04/07/2008 for the course ENGR 1961 taught by Professor Carracappa during the Spring '08 term at Rensselaer Polytechnic Institute.

Page1 / 19

INE 4 - 1 Introduction to Nuclear Engineering &...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online