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17th Symposium of AER

on VVER Reactor Physics and Reactor Safety

September 24-29, 2007, Yalta, Crimea, Ukraine  

ADVANCED FUEL CYCLES

FOR VVER-1000 REACTORS  

Semchenkov Y.M., Pavlovichev A.M., Pavlov V.I., Spirkin E.I.,

Styrin Y.A. and Kosourov E.K.

RRC “Kurchatov Institute”

Moscow, Russia

2

Introduction

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In the present report following themes are discussed:

Stages of development of the Russian uranium fuel from the

point of view of increase of safety and profitability of fuel

loadings operation

Neutron-physical and economic characteristics of present-day

and perspective uranium fuel cycles

Potential of uranium-plutonium regenerate use in VVER-1000

reactors

Potential of weapon-grade plutonium disposition in VVER-

1000 reactors

3

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Evolution of VVER-1000 fuel cyclesEvolution of VVER-1000 fuel cyclesFFaaccttoorr ssccoorree FFaaccttoorr YYeesstteerrddaayy TTooddaayy FFuuttuurree

RReessuullttss

zziirrccoonniiuumm FFAA ssttrruuccttuurraall mmaatteerriiaall sstteeeell HHff

DDeelleetteerriioouuss nneeuuttrroonn aabbssoorrppttiioonn

BBuurrnnaabbllee aabbssoorrbbeerr BBoorriicc rrooddss UU--GGdd ffuueell RRaaddiioo--aaccttiivvee wwaassttee

MMaaxx KKrr,, QQll

SSttaabbiilliittyy ooff FFAA ggeeoommeettrryy LLooww HHiigghh FFAA bbuurrnnuupp lliimmiitt

MMaaxx KKrr,, QQll

FFuueell eennrriicchhmmeenntt,, %% nnoo mmoorree tthhaann 44..44 44..9955 PPeelllleett oouuttssiiddee ddiiaammeetteerr,, mmmm CCeennttrraall hhoollee ddiiaammeetteerr,, mmmm

77..5577 11..55//11..44

77..66 11..22

77..88 00..00

FFuueell hheeiigghhtt,, mmmm 33553300 33553300 ((33668800))

FFAA bbuurrnnuupp lliimmiitt,, MMWWdd//kkggUU

4499 5555 6600--6688

FFAA eenneerrggyy ppootteennttiiaall

NNuummbbeerr ooff ffrreesshh FFAA oonn ccoorree ppeerriipphheerryy ,, %%

110000 ~~ 6600 00 -- 3300 NNeeuuttrroonn lleeaakkaaggee

NNeeuuttrroonn fflluuxx oonn rreeaaccttoorr vveesssseell

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Average burnup versus number of loaded FAs,

FA enrichment and cycle length

30

35

40

45

50

55

60

200 250 300 350 400 450 500 550

Cycle length, EFPD

Ave

rag

e b

urn

up

, MW

*d/k

qH

M

48 54

5.0%

36 42

60 66

72 78 3.6%%%5

3.8%

4.0% 4.2%

4.4%

4.6% 4.8%

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Natural uranium consumption versus number of loaded FAs,

FA enrichment and cycle length

190

200

210

220

230

240

250

260

270

200 250 300 350 400 450 500 550

Cycle length, EFPD

Na

tura

l u

ran

ium

co

ns

um

pti

on

, g

/MW

d1

2

3

36

42

48

54

60

66

72

78 3.6% 3.8% 4.0% 4.2% 4.4% 4.6% 4.8% 5.0%

1

2

3

– 81 FA, steel

– 54 FA, steel

– 48 FA

– 42 FA

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Cost of electricity generation versus number of loaded FAs,

FA enrichment and cycle length (cost of fuel-20%, reloading – 65 days)

0.94

0.96

0.98

1

1.02

1.04

1.06

1.08

200 250 300 350 400 450 500 550

Cycle length, EFPD

Co

st

of

ele

ctr

icit

y g

en

era

tio

n,

rel

5.0%

36

42 48

54 60 66 72 78

3.6%%%5

3.8%

4.0% 4.2%

4.4% 4.6%

4.8%

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Cost of electricity generation versus number of loaded FAs,

FA enrichment and cycle length (cost of fuel-30%, reloading – 65 days)

0.94

0.96

0.98

1

1.02

1.04

1.06

1.08

200 250 300 350 400 450 500 550

Cycle length, EFPD

Co

st

of

ele

ctr

icit

y g

en

era

tio

n,

rel

5.0%

36 42 48 54 60 66

72 78

3.6%%%5

3.8%

4.0%

4.2%

4.4% 4.6%

4.8%

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Cost of electricity generation versus number of loaded FAs,

FA enrichment and cycle length (cost of fuel-20%, reloading – 40 days)

0.94

0.96

0.98

1

1.02

1.04

1.06

200 250 300 350 400 450 500 550

Cycle length, EFPD

Co

st

of

ele

ctr

icit

y g

en

era

tio

n,

rel

5.0% 36

42 48 54 60 66 72 78

3.6%%%5 3.8%

4.0% 4.2%

4.4% 4.6%

4.8%

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Average burnup versus number of loaded FAs,

FA enrichment and cycle length

35

40

45

50

55

60

65

70

250 300 350 400 450 500 550 600 650

Cycle length, EFPD

Ave

rag

e b

urn

up

, MW

*d/k

g H

M

36 42

54

66

78

36

42

54

66

78

В1 В2 В3

B1 – Fuel rod characteristics -7.57/ 1.4/ 353 cm, reduced leakage B2 – Fuel rod characteristics - 7.57/ 1.4/ 353 cm, low leakage B3 – Fuel rod characteristics -7.60/ 1.2/ 368 cm, low leakage B4 – Fuel rod characteristics -7.8/ 0/ 368 cm, low leakage

В4

В2 В3 В4

4.4%

5.0%

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Loading patterns of Loading patterns of advanced equilibrium cyclesHeight of core – 3680 mm, fuel pellet diameter -7,6 mm, central hole - 1,2 mm

12-month cycle (36 FAs)Average enrichment – 4,83%Cycle length – 324 EFPDFA operational time – 4 or 5 cycles

18-month cycle (60 FAs)Average enrichment – 4,88%Cycle length – 478 EFPDFA operational time – 2 or 3 cycles

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Main neutronic characteristics of advanced equilibrium cycles

11

Advanced cycles Today's 12-month 12-month 18-month

Core height, cm 353 368 368 Amount of loaded uranium FAs, pcs 42 36 60 Amount of UGBA rods in loaded uranium FAs, pcs 252 216 900 Average enrichment, % 4,33 4,83 4,88 Reactivity compensated by liquid boron, % k/k (BOC) 8,1 8,4 9,5 Cycle length, EFPD 297 324 478

Average Burnup of unloaded uranium FAs, MWd/kg HM Maximum over FAs

49,2 53

58,5 62

52,0 61

Boric acid critical concentration at BOC, HFP, (g/kgH2O) 6,3 7,2 8,7 Maximal relative power of fuel rods in the core, Krmax 1,46 1,59 1,56 Maximal value of fuel rods linear heat rate, W/cm 285 323 318 Moderator temperature reactivity coefficient at BOC, HZP ( pcm/C) -4,7 -4,4 -0,6

Boric acid concentration at BOC, CZP, no Xe, =-2% (g/kg H2O) 10,7 12,4 13,8 Repeated criticality temperature at EOC, Xe и Sm, no boron ( oС) 182 195 182 Effective fraction of delayed neutrons, % BOC

EOC 0,63 0,56

0,63 0,56

0,66 0,55

Natural uranium consumption, g/MWd 200 188 214

12

Uranium-plutonium regenerate in VVER-1000

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It was proposed to use uranium-plutonium regenerate in thermal reactors by using spent fuel of these reactors cleaned from other actinides and fission products, and by following mixing of cleaned fuel with enriched uranium

Weight fraction of uranium-plutonium regenerate and highly enriched uranium at their mixing is 0,8 and 0,2 correspondingly

Enrichment of highly enriched uranium has been defined from a set of calculations under condition that the equilibrium cycle of VVER-1000 with feed by 42 fresh FAs has the same cycle length as the design uranium cycle. The enrichment of highly enriched uranium for uranium-plutonium fuel was 17,1%

13

Isotopic content of regenerated fuel (kg/tHM)

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Nuclide

Uranium fuel,

kg/tHM

Regenerated uranium fuel,

kg/tHM

Regenerated uranium-

plutonium fuel, kg/tHM

234U

235U 236U 238U U

238Pu 239Pu 240Pu 241Pu 242Pu Pu

235U+239Pu+241Pu

0 43,3

0

956,7 1000

0

0

0 0 0 0

43,3

1,5E-3 44,98 4,77

950,25 1000

0 0 0 0 0 0

44,98

1,5E-3 41,40 4,71

943,90 990 0,25 5,37 2,55 1,14 0,69 10

47,91

14

Main neutronic characteristics of equilibrium cycles with regenerated uranium-plutonium fuel

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Uranium fuel

Regenerated uranium

fuel

Regenerated uranium-plutonium

fuel Amount of loaded FAs, pcs 42 Content of 235U, % 4,33 4,48 4,14 Content of 235U+239Pu +241Pu, % 4,33 4,48 4,79 Cycle length, EFPD 297 Reactivity compensated by liquid boron, BOC, % k/k 8,1 8,0 6,4 Boric acid critical concentration at BOC, HFP, g/kg H2O 6,3 6,3 6,0 Maximal relative power of fuel rods in the core (Krmax) 1,46 1,47 1,46 Maximal value of fuel rods linear heat rate, W/cm 285 293 288 Moderator temperature reactivity coefficient at BOC, HZP, pcm/C -4,7 -6,0 -11,6

Boric acid concentration at BOC, CZP,=-2%, g/kg H2O 10,7 11,2 12,3 Repeated criticality temperature at EOC, Xe и Sm, no boron, oС 182 183 185 Effective fraction of delayed neutrons, % BOC

EOC 0,63 0,56

0,63 0,56

0,58 0,55

Effective lifetime of fission prompt neutrons, 10-5 s BOC EOC

2,0 2,3

1,9 2,2

1,6 1,9

Natural uranium consumption, g/MWd 200 185 168

15

Weapon Plutonium MOX FA in VVER-1000 core

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Fuel rod with high plutonium content

Fuel rod with medium plutonium content

Fuel rod with low plutonium content

UGBA rod

Guide tube

Instrumental tube

Preliminary researches with participation of US, French and German experts have shown possibility of use of W-МОХ fuel in existing VVER-1000.

The pattern of the typical MOX FA

16

Loading patterns of equilibrium cycles with MOX FAs

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MOX FAs- 30, UOX FAs-24 MOX FAs- 36, UOX FAs- 36 307 EFPD 465 EFPD 684 UGBA 1188 UGBA

17

Main characteristics of equilibrium cycles with MOX fuel

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* CR CPS boron is enriched by the isotope boron-10 up to 80%

12-month

18-month

Amount of loaded uranium FAs, pcs 24 36 Amount of loaded MOX FAs, pcs 30 36 MOX fuel rods part in core, % 38.2 40.3 Cycle length, EFPD 307 465 Annual plutonium consumption, kg 445 450 Average burnup of unloaded uranium FAs, MWd/kg HM 50.4 46.3 Average burnup of unloaded MOX FAs, MWd/kg HM 31.1 43.5 Maximal relative power of fuel rods in the core (Krmax) 1.41 1.47 Maximal value of fuel rods linear heat rate, W/cm 278 306 Boric acid critical concentration at BOC, HFP, (g/kg H2O) 7.7 10.7

Moderator temperature coefficient ( pcm/C) -6 -1

Boric acid concentration at BOC,CZP,=-2%,(g/kg H2O) 13.2 16.2 Repeated criticality temperature, oС 180* 177*

Natural uranium consumption, g/MWd 200 185

18

Conclusion

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Advanced uranium fuel cycles for VVER-1000 ensure under meeting safety requirements:

effective use of natural uranium; 

possibility of cycle length variation in a wide interval and consequently possibility of NPP power production adaptation to demands of power net and to eventual changes in relations between components of electricity generation cost; 

reducing of neutron fluence on reactor vessel in view of its service life prolongation.

Expanding of fuel raw material nomenclature is possible for VVER-1000 by using regenerated uranium and uranium-plutonium fuel.

VVER-1000 reactors could ensure a high rate of weapon-grade plutonium disposition at effective using of plutonium power potential.