the first european cold neutron source with a focussing modorator

the first european cold neutron source with a focussing modorator

THE FIRST EUROPEAN COLD NEUTRON SOURCE
WITH A FOCUSSING MODORATOR CHAMBER
- OPERATIONAL EXPERIENCE AND NEUTRONICS
RESULTS -
W. Knop, P. Schreiner
GKSS--Forschungszentrum Geesthacht GmbH
GKSS
Max Planck
Planck--Straße, 21502 Geesthacht – Germany
12.06.2009
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The GKSS research centre Geesthacht GmbH
operates the MTR
MTR--type swimming pool reactor
FRG--1 (5 MW) for more than 50 years.
FRG
years. The
FRG--1 has been upgraded and refurbished many
FRG
times to follow the changing demands of safe
operation and today’s needs of high neutron
flux for scientific research.
research.
High neutron fluxes with highest availability is
the permanent demand of the science on the
operation of a neutron source.
source.
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WHY COLD NEUTRONS

Long wavelength (cold) neutrons with
high intensity are indispensable probe for
the study of the microstructure and
dynamics of condensed matter
matter.. These are
necessary
for
its
macroscopic
characterization in applied as well in basic
for example in materialmaterial-, biologicalbiological- and
polymer research.
research. With the existent CNS
the number of long wavelength neutrons
with wavelength > 0.4 nm were increased
by a factor of more than 20 compare to the
thermal flux.
flux.
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Examples
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Schematic View of the
GKSS – CNS
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FRG--1 3X4 COMPACT CORE
FRG
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Increasement
of the cold neutrons flux

For a further increase of the important cold
neutron flux, which feed more than half of the
neutron
scattering
instrumentations,
the
moderator chamber of an existing spare unit
should be replaced by a new one
one.. Model of the
new layout were the focusing moderator
chambers of the American research reactors
MURR and ORNL.
ORNL. These new moderator
chambers resulted in gain factors between 50 to
150%
150
%.
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Existing Moderator Chamber
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INPILE LINER
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New moderator chamber





 Simple design (hemispherical shape) and
fabrication
 The same material specification for the new
moderator chamber as for the existing one
 The same technical inspection as for the
existing one
 The same incident conditions (pressure,
melting etc.) as for the existing one
 Comparable nuclear heating for the new and
exiting chamber
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Old an new moderator chamber
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Gain factors at the entrance to the neutron guide
1,93E+00-2,00E+00
Gewinnfaktor
1,85E+00-1,93E+00
2,000
1,78E+00-1,85E+00
1,925
1,850
1,775
1,700
1,625
1,550
1 475
1,475
1,400
1,325
1,250
1,175
1,100
1,025
0,950
0,875
0,800
0,725
0,650
0,575
0,500
1,70E+00-1,78E+00
1,63E+00-1,70E+00
1,55E+00-1,63E+00
1,48E+00-1,55E+00
1,40E+00-1,48E+00
1 33E 00 1 40E 00
1,33E+00-1,40E+00
1,25E+00-1,33E+00
1,18E+00-1,25E+00
1,10E+00-1,18E+00
1,03E+00-1,10E+00
9,50E-01-1,03E+00
8,75E-01-9,50E-01
8,00E-01-8,75E-01
7,25E-01-8,00E-01
28,8
14,4
0
-45,3
-27,18
5,75E-01-6,50E-01
5,00E-01-5,75E-01
Horizontale Position
-14,4
-9,06
Vertikale Position
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6,50E-01-7,25E-01
9,06
27,18
-28,8
45,3
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Parameters of the
discus chamber moderator
and the
hemisphere chamber
Discus Shape Chamber
Hemisphere Chamber
Volume
Mass
Power
Volume
Mass
Power
[cm3]
[g]
[W]
[cm3]
[g]
[W]
Moderator H2
796.0
55.0
353.8
1329.5
100
457.1
AlMg3
298.6
788.4
998.4
416.5
1090
1054.5
∑
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1352.2
1511.6
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Milestones of the new
moderator chamber



License procedure from May to September
2006
fabrication and installation of new
moderator chamber (January to Mai
2007),
Mounting of the new Inpile Liner with new
moderator chamber and set in operation
programm May / June (3 weeks)
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Inpile part with the
new moderator chamber
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Dismounting of the
old Inpile Liner
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Mounting
of the new Liner
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Connection of the
new Liner
with the beam tube
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Gain measurements
at the experiment Nero
180
Referenzdesign Aufpun
Variante 5 Aufpunkt 1
160
140
120
100
80
60
40
20
0
0
2
4
6
8
10
12
wavelength (Angström)
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GeNF
10 m
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Summary

GKSS has already realized a continuous increase
of the neutron flux by 2 core compactions and
by the installation of the first elliptical CNS. The
installation of the focussing moderator chamber
is a new step for a further increase of the
important cold neutron flux. With the additional
gain of cold neutrons by approx. 60%, the FRG
FRG-1 results in an interesting middle flux neutron
source available to the national and international
user community.
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