SK08ST009 - inis.iaea.org

SK08ST009Fuel cycles of WER-440

Yu.M. Semchenkov,V.V. Saprykin, I.I. Yasnopolskaya, A.N. Novikov

Russian Research Center "Kurchatov Institute"

ABSTRACT

The paper has as an objective to make conclusions for works performed onmodernization of VVER-440 fuel cycles. Possibilities and perspectives on further improvementof neutronics and operation characteristics of WER-440 are discussed basing on additionaloptimizations of fuel assembly design and of fuel load patterns. Discussion is applied to reactoroperation with power levels of 100 and 112% comprising equilibrium refueling regimes.

While obtaining operation experience on VVER-440 reactors {Ref.}, numerousadvancements of fuel assembly (FA) design characteristics have been realized having as anobjective to improve reactor safety and economics of fuel cycle. Below the effect of theseadvancements is demonstrated concerning neutronics and operation core characteristics. Inparallel the development of neutronics codes was in progress that has ensured an optimization ofcore load arrangement for improving of fuel cycle economics. In particular a reloading type "in-in-out" has been assessed ensuring lower neutron leakage from the core and reduced neutronfluence on reactor vessel. Below possibilities of further fuel cycle modification are discussedconcerning an optimization of fuel assembly design characteristics and features of fuel loads.

Advancement of base design of fuel assemblies (see Table 1 and Figs. 21-23, 25)allowed to increase sufficiently an effectiveness of fuel use due to:

using of zirconium spacer grids and reducing of FA shroud tube thickness thusincreasing FA multiplication factor;grading of fuel enrichment in plane of assembly fuel clusters thus reducing apeaking factor of linear fuel pin powers and ensuring by this a lightenedrealization of core loads with reduced neutron leakage;increasing of initial enrichment of fuel feed and reducing of fuel fraction replacedduring fuel reloading;using of burnable poison on the base of Gd2Os integrated with fuel ensuringdesirable fuel load arrangement and leading to improvement of load safety.

Effects of performed modifications of VVER-440 fuel cycle are presented in Table 2and Figs. 1-13.

Fuel cycles of Variant 5 at the use of working FAs and FAs with regulating absorberpart (ARK) with average fuel enrichment of 3.82% are applied to reactors VVER-440 of Novo-Voronez NPP (Russia), Kola NPP (Russia), Dukovany NPP (Czech), Bogunice NPP (Slovakia),

105

Mohovce NPP (Slovakia), Paksh NPP (Hungary) - with realization of power increase up to108%.

Fuel cycles 5 at the use of FAs with average fuel enrichment of 4.21% are applied tothe Unit 4 of Kola NPP and to the Units 1 and 2 of Rivno NPP (Ukraine).

Fuel cycle 6 is realized at the use of FAs with average fuel enrichment of 4.4% andwith uranium-gadolinium fuel pins at the Unit 4 of Kola NPP and at the use of FAs with averagefuel enrichment of 4.38% and with uranium-gadolinium fuel pins it is being realized atDukovany NPP (Czech). The same fuel cycle at the use of FAs of Second generation (see table1) with average fuel enrichment of 4.25% and with uranium-gadolinium fuel pins is beingrealized at Slovakian NPPs.

The assessment is in progress for using of graded FAs of Second generation withaverage fuel enrichment of 4.38% and with uranium-gadolinium fuel pins at the reactor powerincreasing up to 105-107% at NPPs in Czech and Slovakia.

Characteristics of fuel cycles which could be realized due to additional possiblemodifications of FA design and optimization of fuel reloading scheme are presented in Table 3and Figs. 14-20.

Possible changing of fuel cycle characteristics at the use of FAs of the Secondgeneration (see Table 1 and Fig. 25) with the same enrichment 4.38% in working FAs and ARKsis illustrated in Table 3 (variants 8-10) and Figs. 14-16. The feature of these variants is anincreased duration of ARK operation (6-7 years).

Possibility of power load factor increasing at the use of FAs of the Second generation(see Table 1 and Fig. 25) with enrichment 4.38% in working FAs and in ARKs is illustrated inTable 3 and Figs. 17-18. Here in Variant 11 the fuel load operation between reloadings isincreased up to 18 months due to increased number of reloaded FAs (126). In Variant 12 areactor power is increased up to 1540 Mw at the increased coolant flow rate of 43000 m3/h andat the reduced peaking factor of core power distribution due to reloading scheme optimization.

In Variants 13 and 14 the possibility of further design optimization for FAs of theSecond generation is presented (see Table 1 and Figs. 19, 20, 27) due to:

increasing of average fuel enrichment up to 4.87%;increasing of fuel pin weight due to increasing of fuel pellet diameter up to 7.8mm and liquidation of pellet central hole(fuel pins of the Third generation).

Analyzing the results presented in Table 2 it could be concluded that the mentionedmodifications in the FA design of the Second generation allow to increase additionally aneffectiveness of fuel use in WER-440.

Almost all neutronics calculations (at coolant flow rate of 39000 m3/h and reactor inlettemperature of 270 C) have been performed with modern code complex of VVER physicsDepartment in the Institute of Nuclear Reactors of Russian Research Center "KurchatovInstitute": TVS-M and KASKAD (BIPR-7A and PERMAK-A). Calculations for the variant with112% power have been performed at the coolant flow rate of 43000 m3/h at reactor inlet.

Calculational results allow to believe that all considered perspective variants of fuelcycles will meet design requirements. Introduction of fuel cycles with increased power of 112%and reactor operation duration of 18 months will increase significantly a power load factor.Application of increased fuel enrichment and increased fuel pin weight improves aneffectiveness of fuel use.

106

REFERENCE

Gorokhov A.K., Dragunov Yu.G., Lunin G.L., e. a., Assessment of neutronics andradiation parts of VVER designs. M., Akademkniga, 2004 (in Russian).

107

Characteristics of fuel assemblies

Table 1

Types of fuel assemblies

Characteristics of fuelassemblies

1Length of IF A active part incold state, cmWeight of uranium in IFA, kgLength of CA active part in coldstate, cmWeight of uranium in CA, kgSize "for key" of FA shroudtube (IFA/CA), cmFuel enrichment profiling acrossFA cross section

Burnable absorbers

Weight content of U-235/Gd2O3

in fuel of"tvegs", %Fuel enrichments in fuelrods, %Average fuel enrichment inFA, %Thickness of shroud tube of FAIFA/CA, mmMaterial of FA shroud tube

Material of spacer grids

Number of fuel rods in FAPitch of fuel rodslocation, cmOuter diameter of fuelrod, mmThicknes of fuel rodcladding, mmMaterial of fuel rod cladding

Diameter of fuel pellet, mm

FA of basictype

2

242120.2

232115.2

14.4/14.4no

absent

1.6, 2.4,3.6,4.4-

2/2.1zirconium

alloyStsteel

126

1.22

9.1

0.65zirconium

alloy7.56

Shtatny FA

3

242120.2

232115.2

14.5/14.4Yes

(see fig.21-23,25)

Gd2O3 - in 6fuel rods4.0/3.35

3.3,4.0,4.4,4.6

3.82,4.21,4.38,4.4

1.5/2.1zirconium

alloyzirconium

alloy126

1.23

9.1

0.65zirconium

alloy7.56

FA of 2d

generation

4

248126.2

236120.2

14.5/14.5Yes

(see fig24-27)


3.3,4.0,4.4,4.6

3.84, 4.25,4.87,4.38

1.5/1.5zirconium

alloyzirconium

alloy126

1.23

9.1

0.65zirconium

alloy7.6

FA of 2d gen.With rods of3d gen

5

248136.5

236129.9

14.5/14.5Yes

(see fig 27)


4.95, 4.6,4.4

4.87

1.5/1.5zirconium

alloyzirconium

alloy126

1.23

9.1

0.6zirconium

alloy7.8

108

Table 1 (continued)

1Diameter of central hole infuel pellet, mmDuration on FA operationin reactor, yearContent of Hf in materialsof fuel rod cladding and FAshroud tubes, %Correspondence betweenFA marking and averagefuel enrichment in FA

21.4

< 4

0.05

IFA E-2.4%IFAF-3/6%CAN-24%

31.4

< 5

0.05

IFA 1-2,4%,IFA G-3.6%CAS-2.4%CAH-3.6%IFAK-4.4%IFAU-4.4%

proff.IFAO-3.82%IFAP-4.21%IFAV-4.38%

41.2

7

0.01

CAC OG-3.84%

IFA VW-4.25%CACY-4.87%CAFY-4.87%

IFAFUV-4.38%

CA CVU-4.38%

50

7

0.01

IFA FZ-4.87%CACZ-4.87%

109

o «

aj

B'51

8'O

_o"3

. 3J UIll!

t equ

ilibr

i

CS

ics

ii

2cs

ii

u"3ato

w

ecifi

&

o

s'3aj

CO

fuel

Ave

rage

1

© >

nme

irat

iO8° ~zG 5

ump

latu

i

8©

a -o

burn

updi

scha

n

*̂sJ3 S!

orks

'a23

FA,

,̂n

4> **"

H T3.

O oa j ^—'a emS .53 -3

—

3 -S3 "3

* 1

S

c

cs'

1

cs"O• } :

Si,*m

m±±

CS•a*

i

reac

tor

g fFA

)an

d7)

FA f

orfe

edin

:Fr

e:

^â •to

mbe

r oe

tab.

1fig

.21-

2

a °

Fuel

cyc

le ty

4̂ a3 .2a" cs

5

s-a•238

-in

i

"SO

.139

o

f^

d

31.2

"̂

BJorT

a.

s

E-2

.4%

3.6%

(

to

T3

CS

rT1-H

e>•<»

ri

<u

init

ial

tnrc

tye

ar f

uel c

yt

.135

s

<s

d

29.7

tosf i

1/3^ î—l

.a . ^•— ^ "O

O W f °

sirts \o r i

. 5 «

Thr

ee-y

eai

fuel

cyc

le w

izi

rcon

ium

spac

er g

rid

_B

"j;

In-(

o o< ^

6

[

.123

©

0 0

d

37.9

V3O N

©ON

si

(se

\H-3

.(1

2)

u

3

* ou

r-ye

ar in

cycl

e

m

.123

©

</io

d

47.8

©

a . ^"J" M h•g « -a

a ^ ^

(66/

60)

(6/1

2)

^ ^

"7 ^* S3

£6u

Five

-yea

r F<

•g

•8

In-i

(78/

72)

S?«s00

20

IFA

.122

©

1-H

1—1

d

41.6

1/5©

T f0 0

si

a>

(se

*s

\ T-

3.8

0

U

Four

-yea

r F

V5

oT• 08CS

00

(6/1

2)

3

a

In-

(66/

60)

-4.3

8%

>

IFA

.123

©

1 / )

©

d

49.0

©

t~-

ttitSa

»S

k T-

3.8

U

U

Four

-yea

r F

ID

T5acs

©

(6/1

2)

.117

©

l - H

d

50.1

00<s

vo

•t-1 ^~v3 . tnO &X) *Hi *" "C

•S <u a• a c«

M a ^ ^ «s•H 1-H

(60/

54)

. (6/

12)

•4.3

8%-3

.84°

/

< <

Five

/six

-yea

rFC

ire

giin

g

•ao

iiel

re

S3

' 3a

'«w

sti

*—•8"3eses

41

eye]

3fa

esh

FA

fo

r re

acto

i .

fa

1 1 | |£ ° «M

O — es

1 | 1 ! 3 |0. S a 2 «

£ &< £ - && £5 ^j fj^ ^3

> * H3 *̂<! §

H T3

0 (2

"a a fa3 =3

5r es—

ex a"33 .2 u

fa 1 i

feed

ing

(num

ber

of F

A)

(see

tab

. 1

an

dfi

g.25

,27)

cL?"3

"333fa

_ aj a «4J " - ! eS pO

fa ^ 1 i> a

F H

©

©ON

©

V)

^ .00

©vo

-out

fig.

a A) ^

a w

I f*&00 m

iifa V& u

u

S3>-,

^ fam>fa

OO

©'

ON

©

V5

VO©ff)

voVO

0 ei1 !B ^

•2 « FH

A F

UV

-4.3

8%(6

0;A

CV

U-4

.38%

(6)

fa

ON

F H

©

©

ONON

©

3 *1 £M ^"â u v©

"" 4) H

a w

rr "*>- pp >fa u

Ufa

s3Ofa

V©

FH

©

.22

s

rnT f

VO©

126

0 ei1 W <—

"1 v ' H

a w

FH < ^

p >:fa 0

00 "33

r «s«i a yH g

^,F H

a"Tk-

G

VO

00

>Pfa<

0

0000FH©

1/5

O N•<t

rsONfS

r-

oio

oj 2aj '"'

^ ^

s

: C

VU

- 4.

38%

(6)

R-1

.6%

(1)

0

siS °i FH

a 110 **•fa ^

F H

©

0 00 0

©

O N«T)

O N0 0

TfV)

0 fti)1 C â w ON• "a w

FA F

Y-4

.87%

(48)

:A C

Y-

4.87

%(6

)

e*

5u> fa

"§a

c

8I-H

00

00

faPL

ON

©

©

.19

©

06IT)

F H

6JD!S

CA C

Z-4

.87%

:s

©ue

l ro

ds o

f 3 g

en

^ fa

0 50 100 150 200 250 300

50 100 150 200 250 300

0 50 100 150 200 250 300W= 1375 MW

I In. I i |imnni|,ni

0 50 100 150 200 250 300

1.60 ^

1.52J-

1.441-

L36J-

0 50 100 150 200 250 300T, EFPD

Fig. 1. Main neutronic characteristics in the equilibrium fuel reloading regimes(variant 1, odd year of operation)

112

0 50 100 150 200 250 300 0 50 100~ 150 200 250 300T, EFPD

Fig. 2. Main neutronic characteristics in the equilibrium fuel reloading regimes(variant 1, even year of operation)

113

50 100 150 200 250 300

310

300

290

280

270

0 50 100 150 200 250 300W = 1375 MW

120CH-

0 50 100 150 200 250 300 0 50 100 150 200 250 300

0 50 100 150 200 250 300 0 50 100 150 200 250 300T, EFPD


114

50 100 150 200 250 300

310 1-

". 30°-i-li 290 j-^ 280 |-I 270 4;.

0 50

12001

800-!

400 \

0 1

100 150 200 250W= 13'

3005MW

0 50 100 150 200 250 300

1.26 |-

1 24l\

3 1.22 -I-

1.20 -1-

0 50 100 150 200 250 300

1.18-40 50 100 150 200 250 300 0 50 100 150 200. 250 300

T, EFPD


115

0 50 100 150 200 250 300

310 i -

300-j-

290-j-

280 f

270 1

0 50 100 150 200 250 300W = 1375 MW

1200- j -

S 800€ -

0 50 100 150 200 250 300 0 50 100 150 200 250 300

0 50 100 150 200 250 300 0 50 100 150 200 250 300T, EFPD

Fig. 5. Main neutronic characteristics in the equilibrium fuel reloading regimes (variant 3)

116

0 50 100 150 200 250 300

310

300

290

2 a o

270

0 50 100 150 200 250 300

1.26 4

1200-1-

800-j-

400^-

0+r

50 100 150 200 250 300W = 1375 Mff

•I I | M I

0 50 100 150 200 250 300

0 50 100 150 200 250 300 50 100 150 200 250 300T, EFPD


117

0 50 iOO 150 200 250 3000 1 u i inr t i j;TrTTTTrrrnTnTTrrfrrrrrrnT|

0 50 100 150 200 250 300VI = 1375 Mff

0 50 100 150 200 250 300

1200^-

400 i-

00 50 100 150 200 250 300

TTTJTTTTTrfrTTTTrTTTfnTTTTnTfn^

0 50 100 150 200 250 300 0 50 100 150 S00 250 300T, EFPD

Fig. 7. Main neutionic characteristics in the equilibrium fuel reloading regimes(variant 4, even year of operation)

118

TE0BC= 285.3 EFPDTmv= 304.8 EFPDTEOc= 304.6 EFPD g

J

0 50 100 150 200 250 300

310 -I"300 4-290-j-280 J-270 4 .

0 50

1200 |

400 \

0 1 .

100 150

lm|

200

m,|ii.n

2bW =

) 3001375 MVf

0 50 100 150 200 250 300

1.36-r

0 50 100 150 200 250 300

0 50 100 150 200 250 300 0 50 100 150 200 250 300T, EFPD


119

0 50 100 150 200 250 300 0 50 100 150 200 250 300W= 1375 MW

310|-300-j-290-]-2801-270 I-

1200 4-

| 8001-

* 400-j-

.1 In0 50 100 150 200 250 300

1.35 |-

1.34jr

1.33-j-

1.32-j-

1.31 j

0 50 100 150 200 250 300

50 100 150 200 250 300

0 50 100 150 200 250 300T, EFPD


120

0 50 100 150 200 250 300

o 3 1 0 f5% 3001-SJ 290f% 2ao -j-J - 270-1-

c

1200 i

800]

400 \

0j

50 100 lbU

TTTTtTTTT,

200 250W = 13

TTTTKTTT-

30075 MW

0 50 100 150 200 250 300

0 50 100 150 200 250 300 0 50 100 150 200 250 300T, EFPD


121

0 50 100 150 200 250 300

o 3 1 01"p 300\-~A 290o°h 280-j-| 270I-

TEOC= 303.1 EFPD

0 50 100 150 200 250 300

0 50 100 150 200 250 300

E

1200-

| 800-

* 400-

0-

1.68-

> 1.60-

1.52-

D

D

\

50

50

, '

i . i n l i i i u .

100

100

Trrfrrm

150

150

• l l l l l . M

200

200

/

250 300W= 1375 MW

250 300

/

0 50 100 150 200 250 300T, EFPD


122

is I

0 40 80 120 160 200 240 280 0 40 80 120 160 200 240 280

W = 1375 MW

0 40 80 120 160 200 240 280 0 40 80 120 160 200 240 280

T, EFPD


123

0 40 80 120 160 200 240 280

I -3101- - -300|-290|-280|-270-t

0 40 80 120 160 200 240 280

1200^

40 80 120 160 2U0 240 280

W = 1375 MW

1 I n n0 40 80 120 160 200 240 280

0 40 80 120 160 200 240 280 0 40 80 120 160 200 240 280T, EFPD


124

310 f-

300|-

290J-280 j-

270 i-

t

1200 i

400 4

40

,ni|,,n.

80 120 160 200W =

40 280

1375 MW

Inimii.lnn120 160 200 240 280 40 80 120 160 200 240 280

120 160 200 240 280

T.EFPD


125

0 50 100 150 200 250 300

310

300

290

280

270

1.40

1

0 50

12001

| 800 \

* 400 \

j

100

1

150 200 250 300W= 1375 MW

0 50 100 150 200 250 300 0 50 100 150 200 250 300

1.68 #

> 1-60 J-I

1 1 I l l0 50 100 150 200 250 300 0 50 100 150 200 250 300

T, EFPD


126

3l2 |

al

T"

[ : :

c=310.8 EFPDc= 330.1 EFPD= 330.1 EFPD

50 100 150 200 250 300

7

3101-

300-1-

290 j-

2ao|-270 i-

0 50 100 150 200 250 300¥= 1375 MW

1200-̂ -

400

00 50 100 150 200 250 300 0 50 100 150 200 250 300

1.32 ̂0 50 100 150 200 250 300 0 50 100 150 200 250 300

T, EFPD


127

0 50 100 150 200 250 300 350 400 450 500 50 100 150 200 250 300 350 400 450 500

T, EFPD


128

310300290280270

0 50 100 150 200 250 300

0 50 100 150 200 250 300

=

1200-

400^

0-

1.68-1

g 1.60l

1.52-1

D 50

3 50

I n n

100

100

150

150

— \ ^

^rr+rrm

200

200

250 300W= 1540 MW

250 300

/ '

0 50 100 150 200 250 300 0 50 100 150 200 250 300T, EFPD


129

0 40 80 120 160 200 240 280 0 40 80 120 160 200 240 280

T, EFPD

Fig. 19. Main ncutronic characteristics in the equilibrium fuel reloading regimes (variant 13)

130

0 50 100 150 200 250 300

310

300

290

270 j-

0 50 100 150 200 250 300

0 50

1200 -i

800 i

400^

100 150 200 250 300W= 1375MW

0 50 100 150 200 250 300

0 50 100 150 200 250 300 0 50 100 150 200 250 300T, EFPD


131

CENTRAL TUBE

4.0% (84)

3.6% (24)

3.3% (18)

Fig.21. Diagram of fuel enrichment in the FA of O and T types (3.82%)

132

CENTRAL TUBE

4.6% (84)

4.0% (36)

4.0%U235 + (3.35%Gd2O3) (6)

Fig.22. Diagram of fuel enrichment in the FA of U type (4.40% c Gd2O3)

133

CENTRAL TUBE

4.4% (84)

4.0% (24)

3.6% (18)

Fig.23. Diagram of fuel enrichment in the FA of P type (4.21%)

134

CENTRAL TUBE

4.4% (84)

4.0% (30)

3.6% (6)

4.0%U235 + (3.35% Gd2O3) (6)

Fig.24. Diagram of fuel enrichment in the FA of VW type (4.25 % c Gd2O3)

135

CENTRAL TUBE

4.6% (84)

4.0% (30)

3.6% (6)

4.0%U235 + (3.35%Gd2O3) (6)

Fig.25. Diagram of fuel enrichment in the FA of V, FUV and CVU types (4.38 % c Gd2O3)

136

CENTRAL TUBE

4.0% (84)

3.6% (18)

3.3% (18)

4.0%U235 + (3.35%Gd2O3) (6)

Fig.26. Diagram of fuel enrichment in the FA of VW type OG (3.84 % c Gd2O3)

137

CENTRAL TUBE

4.95% (102)

4.4%U235 + (3.35%Gd2O3) (6)

4.6% (18)

Fig.27. Diagram of fuel enrichment in the FA of FZ, FY, CZ and CY types (4.87 % c Gd2O3)

138

SK08ST009 - inis.iaea.org

Documents