1. New radiochemical technologies of spent nuclear fuel reprocessing
V.I. Volk, А.V. Vatulin , P.P. Poluektov,
А.Yu. Vakhrushin, L.P.Sukhanov
A.A. BOCHVAR ALL-RUSSIA RESEARCH INSTITUTE OF INORGANIC MATERIALS 1

2. New technology of spent nuclear fuel (SNF) reprocessing should be decide following major problems:
-separation of fissile materials for recycling in nuclear fuel cycle;
separation of actinides and fission products in form of two factions, one of which should contain heat generated cesium and strontium, and second - long-lived minor actinides: neptunium, americium and curium;
immobilization of the two factions in matrix materials meet the requirements to reliable and safe supervised storage (Cs, Sr) and transmutation or disposal (Np, Am, Cm). 3

3. SNF rerocessing technology developing for RT-2 plant
In the long term there is supposition of new complex creation for domestic and foreign SNF reprocessing.
For this complex is designing the drastically new technology based on operations of embrittlement and chopping of clad material, gaseous conversion of fuel oxides in nitrate salts, crystallization separation of bulk of uranium and mother liquor extraction reprocessing.

4. New items in SNF reprocessing technology.
“REPA - process”
Reprocessing tasks
Fission materials separation for recycling into nuclear fuel cycle;
Transplutonium elements and fission products separation as two faction, as minimum. First faction must contain heat-regenerating Cs and Sr, and second one - super-longlived minor-actinides: Np, Am, Cm;
immobilization of obtaining factions into matrix materials, corresponding to the request of reliable and safe storage (Cs, Sr) and transmutation or storage (Np, Am, Cm)
Potential advantages
Ecological acceptability
Technological support of non-proliferation
Compactness
Possibility of coat creation over the reprocessing plant
Thermo-mechanical destruction of clade
Gaseous conversion of U-oxide to nitrate
U separation and affinage by HNU fission cake crystallization
Extraction with simultaneously partitioning
SNF
CO2-N2O4
Mother liquor
Hexahydrate of uranyl nitrate (HNU)
Isolation of radioactove noble gases and tritium
Gas-mixture adjustment
Leaching of HNU fission cake
Jacket materials
U + Pu
REE/TPE & FP faction
Cs/Sr & FP faction
Compactization
Conversion into UF6 and adjustment of isotope composition
Fuel for thermal reactors
MOX-fuel for Fast Reactors
Immobilization into mineral-like matrix
Immobilization into the glass
Cs & Sr isolation for commercial use
TPE separation for transmutation

5. The principle scheme of head operation and unit of gas conversion from oxides to nitrates
Clade materials washing
FA dismantling. Brittle failure of
Zr – jackets and FA destruction
Oxidizing re-crystallization. NSF separation from clade material
Conversion to nitrates
N2+ О2 оС
Т from clade,
~ 1% J, 1% Kr, 1% Xe оС
~ 98% C
~ 98%J, 98% Kr, 98% Xe
NO2 O2
 5 % Zr + ~1%U3O8
95% Zr
HNO3
UO2(NO3)2*6H2O
UO2(NO3)2*6H2O, Pu,Minor actinides, FP
 800 g/l
H2O
U3O8 (UO3) + 5% Zr
 = 3,3 г/см3
N2O4 O2
<2% J, <2% C
<2% Kr, <2% Xe, <2% T
CO2
Periodically ourput
Heat-exchanger
Aerosol purypying
iodine-129 recovery
Tritium oxidizing to НТО, СО to СО2
НТО recovery
СО2 recovery
Xe recovery
Kr recovery
Iodine reprocessing to the product forms for storage
Gas vent to atmosphere
GAS-purifying system
WWER-1000
fuel assembly (FA)
Fultration

6. Equipment with СО2–N2O4 natural circulation for conversion from actinide oxides to nitrate salts (“Radium Inst.”)
Equipment with СО2–N2O4 natural circulation for conversion from actinide oxides to nitrate salts (GHK)

7. Hot cell experimental model of crystallizer

8. Components distribution on main technological flows during the process of HNU continuous crystallization

9. Technology compactization
Extraction process uranium flow
100 g/l
Crystallization process uranium flow
1000 – 1100 g/l

10. Extragent regeneration TPE / REE re-extraction
Flow sheet of improving extraction cycle
Extractant washing
U+Pu re-extraction
U+Pu extraction
SNF solution
8 М HNO3
0,5 М HNO3
U+Pu re-extract
0,1 М HNO3
U+Pu extractant
Extragent regeneration
Na2CO3 solution
Soda regenerate
Evaporation
Adjustment
TPE / REE extraction
TPE / REE re-extraction
Recycling extragent
Still
Cs+Sr faction
To vitrification
(boron-silicate glass )
TPE/REE faction
To partitioning and immobilization into mineral-like matrix
raffinate

11. - U-Pu faction obtaining; - Cs-Sr faction obtaining;
Extraction cycle
~ 15 % feed flow
Purposes:
- U-Pu faction obtaining;
- Cs-Sr faction obtaining;
- МА-REE faction obtaining

12. The parameters of partitioning and separation of MA, REE, Cs, Sr
The flow sheet of RAW partitioning process in improving extraction cycle F
Re1 S E1 E2 E3 E4 E5 E6 E7 E8 1 2 3 4 5 6 7 8 R4 R3 R2 R1
Re3
Re2 R5
Re4
F – initial solution; S – extragent; En – extractant after “n” stage; Rn – raffinate after “n” stage; Ren – re-extragent after “n” stage.
The parameters of partitioning and separation of MA, REE, Cs, Sr
MA-REE output, %
98,5
Cs–Sr output, %
≥ 99
МА content in Cs–Sr fraction, %
1,5
Cs–Sr content in МА fraction, %
≤ 1