Radiation Physics and Chemistry 71 (2004) 517–519

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Non-destructive diagnostics of irradiated materials usingneutron scattering from pulsed neutron sources

Sergey Koreneva,*, Vadim Sikolenkob,c

aSTERIS Corporation, STERIS Isomedix Services, 2500 Commerce Drive, Libertyville, IL 60048, USAbHahn-Meitner-Institut, Glienickerstr 100, 14109 Berlin, Germany

cJoint Institute for Nuclear Research, Joliot Curie str, 6, 141980 Dubna, Russia

Abstract

The advantage of neutron-scattering studies as compared to the standard X-ray technique is the high penetration of

neutrons that allow us to study volume effects. The high resolution of instrumentation on the basis neutron scattering

allows measurement of the parameters of lattice structure with high precision. We suggest the use of neutron scattering

from pulsed neutron sources for analysis of materials irradiated with pulsed high current electron and ion beams. The

results of preliminary tests using this method for Ni foils that have been studied by neutron diffraction at the IBR-2

(Pulsed Fast Reactor at Joint Institute for Nuclear Research) are presented.

r 2004 Elsevier Ltd. All rights reserved.

Keywords: Non-destructive diagnostic; Neutron scattering; Irradiation

Irradiation of materials by pulsed high current

electron and ion beams leads to change of physical

properties, such as the crystal structure. Apart from

changes of crystal lattice parameters, a shifting of

individual atoms, disordering (ordering) or amorphisa-

tion could take place. Due to shock wave expansion

induced by irradiation, structural changes could happen

at distances substantively deeper than the charge particle

penetration depth.

The most commonly used methods of materials

structure studies are:

* standard X-ray diffraction technique,* synchrotron radiation (SR) diffraction,* thermal neutron scattering.

The first method is the most frequently used and the

cheapest, but it has some major drawbacks. The

penetration depth of X-ray in this range of energy is

very low, and the typical spatial resolution is too small

ing author. Tel.: +1-847-573-3223; fax: +1-

ess: sergey korenev@steris.com (S. Korenev).

ee front matter r 2004 Elsevier Ltd. All rights reserv

dphyschem.2004.04.065

to detect small structure changes. The SR technique

allows us to obtain a very high spatial resolution, but the

penetration depth is low. A common drawback of the

X-ray and SR techniques is low-sensitivity to light

elements, because X-ray cross-section is proportionate

to the element’s atomic number.

For structural changes of irradiated materials we

suggest the method of thermal neutron scattering from a

pulsed neutron source. Though neutron beam intensity

is low, the penetration depth is higher than SR. This

allows us to study volume effects. The neutron cross-

section does not depend on element atomic number and

therefore neutron scattering is the most useful method

for studies of structural changes of the crystal lattice

particularly in the presence of heavy elements. Using

pulsed neutron sources allows us to apply time-of-flight

(TOF) or reverse time-of-flight (RTOF) methods, where

neutron scattering takes place at fixed geometry making

it possible to observe a large number of reflexes

simultaneously.

TOF high-resolution diffractometers at pulsed neu-

tron sources, allowing to perform diagnostic of mod-

ification of irradiated materials are available for

ed.

ARTICLE IN PRESS

Fig. 1. The scheme of the high-resolution Fourier diffractometer.

6600 6800 7000 7200

0

10000

20000

30000

40000

Inte

nsity

(a.

u.)

time channel

Fig. 2. Neutron diffraction pattern of irradiated and non-

irradiated Ni foils.

Table 1

Changes of lattice parameters of Ni foils under electro

irradiation

Radiation type a, A D/d at d=1A, a.u.

Non-irradiated 3.53229(2) 1

Irradiated 3.52712(2) 1.2

S. Korenev, V. Sikolenko / Radiation Physics and Chemistry 71 (2004) 517–519518

example, at HRPD (ISIS spallation source (Rutherford

Appleton Laboratory, UK), GPPD at IPNS spallation

source (Argonne National Laboratory, USA), planning

GEN at SNS spallation source (Oak Ridge National

Laboratory, USA), HRFD at IBR-2 neutron pulsed

reactor (Joint Institute for Nuclear Research, RUSSIA).

A test of this method was made using high resolution

Fourier diffractometer (HRFD) at the IBR-2 pulsed

reactor (Aksenov et al., 1997) on Ni foil, PLZT ceramics

foils and PLZT ferroelectrics ceramic after high-current

pulsed electron beam irradiation.

Fig. 1 presents a scheme of the HRFD spectrometer.

The IBR-2 reactor generates neutron pulses (300 mswidth) with the frequency 5Hz. A Fourier chopper

modulates the incoming neutron beam. Two back-

scattering Li-glass detectors detect scattered neutrons.

The instrument resolution depends on the frequency of

the Fourier chopper rotation. In our experiments, we

used a chopper frequency of 6000 rpm and resolution

Dd/d B 10�3.

Ni foils were irradiated by high-current pulsed

electron beam with E ¼ 250 keV, t ¼ 300 ns, IeB1000A in an explosive electron–ion emission vacuum

diode (Korenev, 1993).

Fig. 2 shows the diffraction pattern of irradiated and

non-irradiated Ni foils. The weak changes in the lattice

parameters as well as changes in the peak width were

observed (Sikolenko et al., 1998). The results are

summarized in Table 1. These data could not be

obtained by other methods.

Thus, we can conclude, that high-resolution neutron

scattering from pulsed neutron sources is a powerful

and effective scientific instrument for non-destructive

diagnostics of irradiated materials. It has some impor-

tant advantages compared with other commonly used

methods. In spite of low intensity of neutron sources

and methodical difficulties, neutron scattering re-

mains practically the only method for precise volume

effects investigations. With the construction of high-flux

neutron sources of new generation in USA, the

further development of this method may be very

important.

We are very grateful to Dr. A.V. Kalmykov, Prof. S.I.

Tyutyunnikov, and V.V. Efimov for their help in

irradiation, Prof. A.M. Balagurov, Dr. G.D. Bokuchava,

and V.G. Simkin for their assistance in irradiation and

neutron diffraction experiments and for useful discussions.

ARTICLE IN PRESSS. Korenev, V. Sikolenko / Radiation Physics and Chemistry 71 (2004) 517–519 519

References

Aksenov, V.L., Balagurov, A.M., Trounov, V.A., Kudryashev,

V.A., Hiismyaki, P., Tiita, A., 1997. High resolution fourier

diffractometer at the IBR-2 pulsed reactor. J. Neutron Res.

5, 181.

Korenev, S.A., 1993. Pulsed ion sources for surface modifica-

tion of materials. Nucl. Instrum. Methods B 80/81, 242.

Sikolenko, V.V., Korenev, S.A., Bokuchava, G.D., 1998.

Neutron diffraction investigations of effects induced in

materials by high-current pulsed electron beam irradiation.

Material Science Forums, Vol. 278, 858p.