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Table 6. Atom percent concentration of the various nuclides in MA targets irradiated<br />

in BR2 and MYRRHA during 200, 400 and 800 EFPD, followed by 5 years cooling<br />

Target<br />

0 EFPD<br />

BR2<br />

MYRRHA<br />

200 EFPD 400 EFPD 800 EFPD 200 EFPD 400 EFPD 800 EFPD<br />

237 Np<br />

Am<br />

234 U<br />

237 Np<br />

238 Pu<br />

239 Pu<br />

240 Pu<br />

241 Pu<br />

242 Pu<br />

241 Am<br />

243 Am<br />

244 Cm<br />

Fissium<br />

Sum<br />

234 U<br />

237 Np<br />

238 Pu<br />

239 Pu<br />

240 Pu<br />

241 Pu<br />

242 Pu<br />

241 Am<br />

242m Am<br />

243 Am<br />

243 Cm<br />

244 Cm<br />

245 Cm<br />

246 Cm<br />

Fissium<br />

Sum<br />

0<br />

100.0<br />

0<br />

0<br />

0<br />

0<br />

0<br />

0<br />

0<br />

0<br />

0<br />

100.0<br />

0<br />

0<br />

0<br />

0<br />

0<br />

0<br />

0<br />

78.08<br />

0<br />

21.92<br />

0<br />

0<br />

0<br />

0<br />

0<br />

100.0<br />

1.0<br />

50.2<br />

25.4<br />

6.4<br />

1.6<br />

1.1<br />

0.4<br />

0.6<br />

0.1<br />

~ 0<br />

13.2<br />

100.0<br />

1.5<br />

0.2<br />

40.9<br />

2.3<br />

1.6<br />

0.2<br />

~ 0<br />

22.9<br />

0.2<br />

14.0<br />

0.9<br />

6.2<br />

0.5<br />

0.1<br />

8.3<br />

99.8<br />

0.8<br />

25.2<br />

20.3<br />

6.1<br />

1.9<br />

1.8<br />

1.6<br />

0.6<br />

0.7<br />

0.3<br />

40.5<br />

99.8<br />

1.6<br />

0.1<br />

39.3<br />

5.7<br />

2.7<br />

0.9<br />

0.3<br />

7.0<br />

0.1<br />

8.8<br />

1.0<br />

8.7<br />

0.8<br />

0.3<br />

22.4<br />

99.7<br />

0.3<br />

6.4<br />

6.9<br />

2.2<br />

1.1<br />

0.8<br />

1.6<br />

0.2<br />

1.4<br />

1.6<br />

75.9<br />

98.4<br />

0.9<br />

~ 0<br />

17.2<br />

4.8<br />

2.6<br />

1.4<br />

1.3<br />

1.0<br />

~ 0<br />

3.3<br />

0.3<br />

8.4<br />

0.8<br />

0.9<br />

55.4<br />

98.3<br />

0.1<br />

93.5<br />

4.0<br />

~ 0<br />

~ 0<br />

~ 0<br />

~ 0<br />

0.1<br />

~ 0<br />

~ 0<br />

2.3<br />

100.0<br />

0.1<br />

0.7<br />

3.1<br />

~ 0<br />

0.2<br />

~ 0<br />

~ 0<br />

72.4<br />

0.3<br />

20.7<br />

~ 0<br />

0.7<br />

~ 0<br />

~ 0<br />

1.8<br />

100.0<br />

0.3<br />

87.4<br />

7.4<br />

~ 0<br />

~ 0<br />

~ 0<br />

~ 0<br />

0.1<br />

~ 0<br />

~ 0<br />

4.8<br />

100.0<br />

0.2<br />

0.7<br />

5.8<br />

0.1<br />

0.3<br />

~ 0<br />

~ 0<br />

67.6<br />

0.6<br />

19.6<br />

~ 0<br />

1.3<br />

~ 0<br />

~ 0<br />

3.7<br />

99.9<br />

0.5<br />

76.5<br />

12.8<br />

~ 0<br />

~ 0<br />

~ 0<br />

~ 0<br />

0.1<br />

~ 0<br />

~ 0<br />

10.0<br />

99.9<br />

0.4<br />

0.7<br />

10.2<br />

0.3<br />

0.6<br />

~ 0<br />

~ 0<br />

59.0<br />

1.0<br />

17.5<br />

0.1<br />

2.3<br />

0.2<br />

~ 0<br />

7.7<br />

100.0<br />

When comparing the performances of MYRRHA and BR2, one should also take into account the<br />

operation regime. Currently, BR2 only operates about 105 days per year while MYRRHA is to<br />

operate about 9 months per year: the MYRRHA utilisation factor would hence be 2.6 times that of<br />

BR2.<br />

5.4 Comparison of the performances of Accelerator Driven Systems and Fast Reactors<br />

In Reference [15], the performances of FRs and ADS systems were compared: the conclusion<br />

was that the neutron-flux-averaged cross-sections governing the transmutation of MAs and LLFPs do<br />

not lead to very important differences in the performances of ADS devices compared to FRs. The<br />

absolute neutron flux levels, on the other hand, which are proper to each individual device, do<br />

strongly influence the transmutation capacity. In the case of fast reactors the neutron flux levels can<br />

only vary within certain limits, while in the case of ADS the neutron flux levels are directly<br />

proportional to the proton beam current delivered by the accelerator and to the multiplication factor of<br />

the subcritical system, and also depend on the energy of the proton beam (the higher the energy, the<br />

higher the neutron/proton ratio in the spallation reaction). From the core reactivity control point of<br />

view, the ADS devices present undeniable advantages in the case of variable core loadings with large<br />

804

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