Cold Critical Pre-Experiment Simulations of KRUSTy

Transcription

1 Cold Critical Pre-Experiment Simulations of KRUSTy Kristin Smith * Rene Sanchez, Ph.D. * University of Florida, Nuclear Engineering Program Los Alamos National Lab, Advanced Nuclear Technology LA-UR

2 Acknowledgement This work was supported by the DOE Nuclear Criticality Safety Program, funded and managed by the National Nuclear Security Administration for the Department of Energy. Slide 2

3 Introduction Overview Three main sections: fuel, reflector, shield Cold critical configuration Simulations and calculations Preliminary results for worth of BeO ring reflectors Estimates of heights needed for various configurations Slide 3

4 What is KRUSTy? Kilowatt Reactor Using Stirling Technology Designed to power space applications Mounted on Comet, a vertical assembly machine Slide 4

5 Fuel 93% HEU 8 wt.% molybdenum Eight slots for heat pipes or support rods Slide 5

6 Reflector Beryllium Oxide (BeO) Three main zones Top reflector Bottom reflector Ring reflector Height of ring reflector is variable Slide 6

7 Shielding Stainless steel outer shield Multi-layered top shield with B 4 C Multi-layered bottom shield with B 4 C Slide 7

8 Differences Slide 8

9 Simulations Created KENO-VI and MCNP6 models Varied the heights of the ring reflectors Used various cross section libraries Slide 9

10 Reactivity Worth ($) Sub-critical Critical Delayed Critical Prompt Critical k < 1 k = 1 k > 1 k = 1 + β $0.00 $1.00 $ ρρ ββ eeeeee = kk eeeeee 1 kk eeeeee ββ eeeeee β eff of an HEU system is taken as Slide 10

11 Average Reflector Height h = VV AA = ππ h iiiiiiiiii 2 rr mmmmmmmmmmmm 2 rr iiiiiiiiii 2 + h oooooooooo rr oooooooooo 2 ππ rr2 oooooooooo rr iiiiiiiiii 2 rr mmmmmmmmmmmm r inner = cm r middle = 12.7 cm r outer = cm h inner and h outer vary based upon configuration Slide 11

12 Code Comparison KENO-VI k eff MCNP6 k eff Percent Difference ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Slide 12

13 Cross Section Library Comparison ENDF/B VII 252 multi-group k eff ENDF/B VII.1 continuous energy k eff ENDF/B VII continuous energy k eff ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Slide 13

14 Reactivity vs. Average Reflector Height Slide 14

15 Subcritical Configuration k eff = ± Inner reflector height = cm Outer reflector height = cm Slide 15

16 Delayed Critical Configuration k eff = ± Inner reflector height = cm Outer reflector height = cm Slide 16

17 Prompt Critical Configuration k eff = ± Inner reflector height = cm Outer reflector height = cm Slide 17

18 $3-Excess-Reactivity Configuration k eff = ± Inner reflector height = cm Outer reflector height = cm Slide 18

19 Fully Inserted Configuration k eff = ± Inner reflector height = cm Outer reflector height = cm Slide 19

20 Results Average reflector ring worth of $5.22/inch Delayed critical configuration: cm average reflector height k eff range Prompt critical configuration: cm average reflector height k eff range $3-Excess-Reactivity configuration: cm average reflector height k eff range Slide 20

21 Thanks for listening! Any questions? Kristin Smith Rene Sanchez Slide 21

22 Reactivity vs. Average Reflector Height Slide 22