By

Tasneem Fatima

Karachi Nuclear Power Plant (KANUPP)

Pakistan Atomic Energy Commission (PAEC)

1

CANDU Reactor

First Fuel Loading in 1971

Full power operation started in 1972

6180 FPDs / ~17 FPYs of operation since commissioning

Completed 30 years design life in the year 2002

By refurbishment & safety upgrades, KANUPP operational lifehas been extended up to 2021

Under water storage of spent fuel bundles in spent fuelstorage bay

2

Reactor Power: 433 MWth at 100% RP; 137 MWe

Licensing Power: 98 MWe (77% RP)

Allowable Bundle Power: 453 kW

Outer Fuel Element Power Rating: 52 kW/m

No. of Fuel Channels 208; 206 in Operation & 2 are Defueled

No. of Fuel Bundles / Fuel Channel 11

Fueling Regime Single Bundle Push in 52 Channels; Double Bundle Push in 156 Channels

Current Moderator Operating Band: 173 – 176 inch

Design Average Discharge Burnup: 7400 MWD/TeU (177.6 MWh/KgU)3

11 spent fuel bundles stored in one storage tray

Storage Layout (Original Design): 120stacks of trays each consisting of 18 tiers of trays

Design Storage capacity: 23,760 spent fuel bundles

Total Water Depth : 5.94 m

Water Shield thickness: 3.96 m

8.7E-3 mSv/hr is maintained at 30.5 cm(1 foot) above the water surface

4

KANUPP spent fuel dry storage (KSFDS) was planned toserve

❖ As an ultimate solution of storage problem toenable the plant to operate safely up to 2021

❖ To store the spent fuel safely in a dry storagefacility for approx. 50 years till the availability ofthe National Repository

KSFDS has started its full swing operation in August2019

Four casks each consisting of 108 spent fuel bundleshave been transferred to dry fuel storage facility

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6

Description Quantity (Nos.)

Design bundle capacity of spent fuel storage bay 23760

Enhanced bundle capacity by implementation of HDTR System

31680

Total number of HDTRs to be placed in storage bay (Planned)

60

Number of HDTRs loaded in bay 57

No. of Casks filled and transferred to KSFDS facility 04

Total spent fuel bundles in 4 casks 432

Total No. of Spent Fuel Bundles Currently Stored in SFSB

30871

Spent fuel bundles had to be shifted from wet storage todry fuel storage (KSFDS) to create space in the SFB as wellas for interim storage during KANUPP Decommissioning

The spent fuel characterization was performed as a primerequirement for the design of spent fuel basket andstorage cask.

Shielding requirement and dose rate estimation

Development of model to be used in evaluating theability of spent fuel to meet specific waste acceptancecriteria

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9

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Ave

rage

Dis

char

ge B

urn

up

(MW

D/T

eU)

Years

≥ 10 Years

< 10 Years

10

11

Histogram of Reactor Power

Bundle Power at 100% RP

Evaluated Bundle Power

Irradiation days

Simulation of a fuel bundle model using ORIGEN2

Characteristics of a KANUPP Spent Fuel

Composition of a Fuel Bundle

ORIGEN code processed irradiation histories usingdecay, cross-section and photon libraries of CANDUreactor model to generate information for FP,Actinides & AP

❖ Isotopic composition (grams)

❖ Activity (Curies)

❖ Decay Heat (Watts)

❖ Gamma Spectrum

❖ Neutron Production data

12

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47

Ther

mal

Po

wer

(W

atts

)

Act

ivit

y (C

uri

es)

Post Irradiation Time (Years)

Activity (Curies) (9000 MWd/TeU)

Activity (Curies) (6500 MWd/TeU)

Thermal Power (Watts) (9000 MWd/TeU)

Thermal Power (Watts) (6500 MWd/TeU)

13

1.E+12

1.E+13

1.E+14

1.E+15

1.E+16

1.E+17

0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47

Ph

oto

ns

Rel

ease

Rat

e (p

ho

ton

s/se

c)

Cooling Time (years)

Photons/sec (9000 MWd/TeU)

Photons/sec (6500 MWd/TeU

14

Actinides Mass (grams)

U235 2.3E+01

U236 1.1E+01

U238 1.32E+04

Np237 4.7E-01

Pu238 6.8e-02

Pu239 3.9E+01

Pu240 1.7E+01

Pu241 2.3E+00

Pu242 1.2E+00

Am241 1.5E+00

Fission Products Mass (grams)

Kr 85 4.5E-02

Sr 90 1.5E+00

Y 90 3.6E-04

Ru106 1.0E-03

Rh106 4.8E+00

Sb125 4.7E-03

Cs134 9.4E-03

Cs137 3.6E+00

Pm147 6.3E-02

Eu154 4.2E-02

Eu155 8.6E-0315

Actinides Activity (Curies)

U235 4.9E-05

U236 7.0E-04

U238 4.4E-03

Np237 3.3E-04

Pu238 1.2E-01

Pu239 2.4E+00

Pu240 3.9E+00

Pu241 2.4E+02

Pu242 4.5E-03

Am241 5.1E+00

Fission Products Activity (Curies)

Kr 85 1.8E+01

Sr 90 2.0E+02

Y 90 2.0E+02

Ru106 3.3E+00

Rh106 3.3E+00

Sb125 4.8E+00

Cs134 1.2E+01

Cs137 3.1E+02

Pm147 5.8E+01

Eu154 1.1E+01

Eu155 4.0E+0016

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+07

1.0E+08

1.0E+09

1.0E+10

1.0E+11

1.0E+12

1.0E+13

1.0E+14

Ph

oto

ns

Rel

eas

e R

ate

(ph

oto

ns/

sec)

Mean Energy (MeV)

Photons/sec (9000 MWd/TeU)

Photons/sec (6500 MWd/TeU)

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1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+07

1.0E+08

1.0E+09

1.0E+10

1.0E+11

1.0E+12

1.0E+13

1.0E+14

Y 90 RH106 SB125 CS134 BA137M PR144

Ph

oto

n R

elea

se R

ate

(ph

oto

ns/

sec)

Radionuclides 18

Before submitting the decommissioning plan to ourNational Regulator, preliminary radiologicalcharacterisation of whole inventory of KANUPP fueland in-core reactor components have beenperformed to provide bundle of information:

❖ Radionuclide Inventory

❖ Radionuclide activities and distribution

❖ Decay Heat

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Basis for:

❖ KANUPP Decommissioning Plan and Strategy

❖ Cost Estimation of Decommissioning Project

❖ Environmental and Personnel Safety Assessment

❖ Provide dose assessments for the workers duringthe implementation of decommissioning

❖ Planning of National Repository

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Total No. of Spent Total Mass Total Activity Thermal Power

Fuel Bundles (Kg) (Curies) (Watts)

31303 5.2E+05 3.9E+07 1.3E+05

No. of In-Core Total Activity No. of Booster Total Activity

Fuel Bundles (Curies) Assemblies (Curies)

2266 9.5E+07 8 1.8E+03

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0

200

400

600

800

1000

1200

1400

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+07

20

19

20

17

20

15

20

13

20

11

20

09

20

07

20

05

20

03

20

01

19

99

19

97

19

95

19

93

19

91

19

89

19

87

19

85

19

83

19

81

19

79

19

77

19

75

19

73

No

. of

Sp

ent

fuel

Bu

nd

les

Act

ivit

ies

(Cu

ries

)

Years

No.BundlesKR 85

SR 90

Y 90

Y 91

ZR 95

NB 95

RU103

RU106

RH106

AG110M

SN119M

SB125

PR144

CS134

CS137

22

0

200

400

600

800

1000

1200

1400

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

20

19

20

17

20

15

20

13

20

11

20

09

20

07

20

05

20

03

20

01

19

99

19

97

19

95

19

93

19

91

19

89

19

87

19

85

19

83

19

81

19

79

19

77

19

75

19

73

No

. of

Sp

ent

fuel

Bu

nd

les

Act

ivit

y (C

uri

es)

Years

No.BundlesU235

U236

U237

U238

PU238

PU239

PU240

PU241

PU242

AM241

AM243

23

0

200

400

600

800

1000

1200

1400

0

1

5

50

500

5000

20

19

20

17

20

15

20

13

20

11

20

09

20

07

20

05

20

03

20

01

19

99

199

7

19

95

19

93

19

91

19

89

19

87

19

85

19

83

19

81

19

79

19

77

19

75

19

73

No

. of

Spen

t fu

el B

un

dle

s

Act

ivit

y (C

uri

es)

Years

No. Bundles

FE 55

NI 63

ZR 95

NB 95

SN119M

SB125

TE125M

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The characterization study has defined the SourceTerm required for shielding design of a spent fuelstorage cask.

4 KANUPP storage casks have been shifted to spentfuel dry storage facility.

Dose rate measured at the cask surface is inagreement with the dose rate calculated usingORIGEN generated source term

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