Transmutation of spent nuclear fuel

Jaroslav Šoltés1

Jiří Skalička2

1 – Czech Technical University, Prague2 – Brno University of Technology3 – Joint Institute of Nuclear Research, Dubna

Supervisor:Lukáš Závorka3

Main goals of transmutation

• Burnup of minor actinides in spent nuclear fuel to reduce its radioactivity (Am, Cm)

• Converting fertile isotopes to fissile isotopes (232Th, 238U)

Accelarator driven systems

• High energy and intensive neutron source is needed

• They cannot be obtained via standard thermal or fast fission in a reactor

• Spallation reactions are required which can be achieved only by using an accelerator driven system (ADS)

Accelerator driven systems

Neutron reactions in the ADS core

• Fission of heavy nuclei (Am, Cm, U, Th, Pu)

• Neutron capture on Th, U and fissile isotopes creation

• (n,xn) on Th creating additional neutrons

QUINTA experiment

HPGe γ - spectrometer Ortec

Measurements carried out

• Time of irradiation: 16 h

• Number of measurements: 8

• Measured 2 h, 3 h, 11 h, 28 h, 36 h, 50 h, 45 d and 105 d after irradiation

Samples evaluation

• Identification of dominant gamma peaks in spectra

• Energy calibration• Non-linearity correction• Background correction• Single escape and double escape peak

correction• Effectivity calibration correction• Isotopes identification

Identified isotopes• Fission products:

85mKr, 85mSr, 85mY, 87Kr, 88Kr, 88Rb, 90mY, 91Sr, 92Sr, 92Y, 93Y, 95Nb, 95mTc, 96Nb, 97Zr, 99Mo, 103Ru, 105Ru, 105Rh, 123I, 127Cs, 127Sb, 128Sb, 131Ba, 131I, 132Cs, 132I, 132Te, 133I, 134I, 135I, 135Xe, 138Cs, 139Ba, 139Ce, 140Ba, 140La, 141Ce, 142La, 143Ce

• Decay products of (n,xn) reactions isotopes:210Po, 210mBi, 213Bi, 214Pb, 219Rn, 223Ra, 224Ac, 226Ac, 226Ra, 227Ac, 230Th

• Activation product of 232Th: 233Pa

Detected nuclei count

Nuclei count:

232Th-11: 3,52*1020

232Th-12: 3,64*1020

233Pa-11: 7,72*108

233Pa-12: 4,46*108

Conclusion

• Detected fission products indicate fast neutron fission of the target 232Th

• Detected isotopes of 233Pa which beta-decays into 233U show effective fissile fuel breeding possibilities ADS

• (n,xn) reactions are important additional source to neutron balance

• 232Th is therefore ideal candidate for the ADS breeding zone

Thank you for your attention

soltes.jaro@gmail.comjiri.skalicka@gmail.com