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Plenary session: High intensity cyclic and linear accelerators

G.L.Khorasanov, A.P.Ivanov, A.I.Blokhin (Institute for Physics and Power Engineering, Obninsk, Russia)

Neutronic and physical characteristics of an accelerator driven system with a target and core coolant from the lead-208 isotope

Presently, several research centers of the European Community are planning to construct in 2025-2030 an Accelerator Driven System (ADS), named as EFIT, with the aim to transmutate minor actinides (MA), wastes of nuclear power plants. It is supposed that thermal capacity of the EFIT subcritical core will be equal to several hundreds of MW and it will be driven by a proton

beam of energy Ep=1000

eV and current about Ip=20 mA. In supporting this project, in 2001-

2004 in Europe (MYRRHA) with

the facilities PDS-XADS with 80 MW thermal capacity and XT-ADS 50 MW thermal capacity were considered within a design phase. In these fa-

cilities a conventional proposed as a coolant

eutectic material

of natural lead (Pb-nat) and bismuth, Pb-nat(45%)-Bi(55%), was for the target and core. With the aim of hardening the ADS target

neutron spectrum, from (80-90)% of

earlier an opportunity of using the modified lead-bismuth eutectic consisted the slow neutron moderating lead isotope, Pb-208, and (20-10)% of Bi-209

has been proposed by tional conferences on

authors, that was presented at the ICONE 13 nuclear science and engineering. In this paper

and GLOBAL 2005 Interna- a possibility of using molten

pure type were core

Pb-208 as the coolant for the subcritical core of 80 MW thermal capacity of the PDS-XADS facility is considered. Calculations of neutronic and physical characteristics of the ADS performed using Monte Carlo code. The following initial data were chosen: the annular with the target in its center; the core coolant Pb-208(100%); a fuel, a mix of mono nitrides

of depleted uranium and power plutonium with a small share of neptunium and americium; target coolant, the modified eutectic, Pb-208(80%)-Bi(20%); proton beam energy 600 MeV;

the ef-

fective multiplication factor From calculations follows

of the that in

core Keff = 0.97; using Pb-208 as

thermal capacity the core coolant

of the core N the intensity


80 MW.



source of neutrons to deliver 80 MW thermal capacity sponds to proton beam current Ip = 2.8 mA and beam lead instead of Pb-208, effective multiplication factor

is equal to S = 2.29·1017 n/s, that corre-


p = 1.68

W. In using natural








falls down to the value equal to Keff trons in the core and thermal capacity

=0.95. In these conditions multiplication of external neu- of the core are below nominal by 1.55 times. For achieve-

ment the rated

core power

volume of the

core, or by


W it

1.55 times to

is required on ~20-30 % to increase the increase intensity of external source of

fuel loading and neutrons. In the

last case, the required parameters of proton beam and its target are following: intensity nal source neutrons S = 3.55·1017 n/s., beam current Ip = 4.32 mA, beam capacity

of exter- p = 2.59

W. Thus, replacement of the coolant from natural lead by the coolant from lead-208 results in economy of capacity of the proton beam on the value of Pp=0.91 MW, and using the uranium - plutonium nitride fuel allows to establish the worth of capacity of the proton beam on burning out the fuel in limits of less than 10 %, due to the core breeding ratio equal to ~1. It allows in the ADS core with thermal capacity equal to 80 MW to lower capacity of the required proton beam to the value about 2 MW instead of capacity of the proton beam equal to 3.6 MW considered the PDS-XADS project. Hence, the proposed variant of the ADS allows to save capacity of the pro- ton beam about Pp=1.6 MW. To exploit the accelerator with this lower proton beam current it will be required about ~ 56 tons of Pb-208, as a minimum, for the core coolant. Charges for it obtaining can be recovered at the expense of the economy of the proton accelerator construction cost. In this case, the accepted price of the lead isotope Pb-208 must be less than $2,860/kg.

Dr. Georgy Levanovich Khorasanov: KHORASAN@IPPE.RU


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