10 Years of CANDU-6 in Romania

IFIN-HH: D. Galeriu, A. Melintescu, D. Slavnicu

CNE-PROD: I. Popescu, E. Bobric

INTRODUCTION

• In 1999, IFIN-HH researchers have been asked to introduce CANDU6 reactors in the context of an Int. Symposium “ Radiological impact assessment in South-Eastern Mediterranean Area” [1]. After refreshing the knowledge on CANDU6 radionuclide production and release into the environment, we used a published paper from S.Korea on the reactor physics of tritium production and release into the environment, based on Wolsong 1 experience [2] and a full paper was also published [3]. We have used specific data from Wolsong 1 :

• Total heavy water inventory (M, kg) : 9.57 104 in coolant and 2.62 105 in moderator

• Heavy water under neutron flux (m, kg): 6.03 103 in coolant and 1.92 105 in moderator

• Neutron absorbtion cross section (, cm²) 3.4 10-28 in coolant and 4.19 10-28 in moderator

• Thermal neutron flux (, cm¯²s¯¹) 1.235 10 14 in coolant and 2.3 10 14 in moderator

• Average plant capacity factor 0.85• Average escaped heavy water 18 t/y• Average escaped fraction from coolant 0.93• Average recovery fraction 0.78

Plant capacity factor

87.27 86.1984.51

88.3 88.2589.37

79.52

89.71 90.0891.37

74767880828486889092

Ca

pa

cit

y F

ac

tor

(%)

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

Year

Year 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

cap fact 0.87 0.86 0.84 0.883 0.883 0.894 0.795 0.897 0.901 0.913

escaped T/y 81.3 24.9 45.9 31.9 21.2 28.1 31.7 30.58 27.65 32.1

recovered T/y 76.4 22.9 43.4 27.5 17.4 23.5 27.6 27.2 23.6 26.9

year standard with yearly

1 5.23E+01 5.37E+01

2 1.02E+02 1.04E+02

3 1.48E+02 1.50E+02

4 1.92E+02 1.96E+02

5 2.34E+02 2.39E+02

6 2.73E+02 2.81E+02

7 3.10E+02 3.14E+02

8 3.45E+02 3.52E+02

9 3.78E+02 3.88E+02

10 4.10E+02 4.22E+02

T RELEASE TBq/y

Source of release

• Releases into the environments depend strongly on the source of escaped heavy water. Most of losses are from coolant with a low tritium specific activity. In the standard case we considered that 93 % of losses are from coolant with a recovery fraction of 0.78. In practice this figures have a range as it depend of many factors (vapor to liquid escape fraction, tubing and vanes fragility, human errors etc.) Based on past experience we asses the coolant contribution can vary between 0.91 and 0.97 in normal plant operation conditions

• We compare the measured release to the environment ( atmospheric + liquid) with model calculation under the above range of coolant contribution- see figure

Release CANDU6-U1

0.0E+00

1.0E+02

2.0E+02

3.0E+02

4.0E+02

5.0E+02

6.0E+02

7.0E+02

8.0E+02

9.0E+02

1.0E+03

0 2 4 6 8 10 12

year of full operation

TB

q/y

measured

standard

Y-91

T-93

Y-95

Y-97

On average, liquid releases are 61% from total but varies significantly

total

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1990 2000 2010 2020 2030 2040 2050

The unit 2 will be fully operated in 2008, unit 3 in 2013 and unit 4 in 2014. NO DETRITIATION

Isotope Half life (years)

Rokkashoaerial

Rokkasho (liquid)

La Hague (aerial)

La Hague (aerial

Cernavoda (aerial)

Cernavoda (aerial)

3H 12.3 1900 18000 67 12000 2000 2000

14C 5730 52 - 17 8.7 100 10

RELEASE COMPARISON

ROKKASHO AND LA HAGUE TARGETS ARE <30 microSv/y for public