22.1 Introduction
22.2 Experimental Study on Criticality Control for Fuel Debris
22.2.1 Modification of STACY
Item | Present STACY | Modified STACY | |
---|---|---|---|
Core tank | Closed tank | Open tank | |
Replaceable (cylinder, slab, heterogeneous, interaction) | Cylinder (1.8 m in diameter, 1.9 m in height) | ||
Core size | Same as each core tank | Maximum 60 cm × 90 cm | |
Critical height 40–140 cm | Critical height 40–140 cm | ||
Maximum thermal power | 200 W | 200 W | |
Maximum integrated power | 100 W · h/operation, 300 W · h/week, 3 kW · h/year | 100 W · h/operation, 300 W · h/week, 3 kW · h/year | |
Fuel | Fuel solution | 6-, 10 wt.%-enriched uranyl nitrate solution | Not used |
Maximum concentration | 500 gU/l | ||
Fuel rods | 5 wt.%-enriched UO2 pellets | 5 wt.%-enriched UO2 pellets (<10 wt.% available) | |
Cladding | Zircaloy cladding (9.5 mm in diameter, 150 cm in length) | Zircaloy cladding (9.5 mm in diameter, 150 cm in length) | |
Maximum loading | 400 rods | 900 rods | |
Volume ratio of moderator to fuel (lattice pitch of fuel rods) | 1.9–15 (13.0–29.0 mm) | 0.9–11 (10.9–25.5 mm) | |
Moderator | Solution fuel | Light water | |
Temperature | Room temperature ~40 °C | Room temperature ~70 °C | |
Reactivity control | Solution level | Water level | |
Maximum excess reactivity | 0.2 dollar in normal operation | 0.3 dollar in normal operation | |
0.8 dollar in abnormal transient | 0.8 dollar in abnormal transient | ||
Maximum reactivity addition rate | 3 cent/s | 3 cent/s | |
Emergency shutdown | Insertion of safety plates | Insertion of safety plates | |
Drain of fuel solution | Drain of light water moderator | ||
Shutdown margin | <0.985 in k
eff
| <0.985 in k
eff
| |
One-rod stuck margin | <0.995 in k
eff
| <0.995 in k
eff
|