Induced nuclear reactions: processes – systems – and elements – Nuclear transmutation – By charged particle bombardment
Reexamination Certificate
2000-02-08
2002-11-05
Jordan, Charles T. (Department: 3641)
Induced nuclear reactions: processes, systems, and elements
Nuclear transmutation
By charged particle bombardment
C376S192000, C376S193000, C376S195000, C376S196000, C376S197000, C376S199000, C376S202000, C376S376000, C376S388000, C376S398000, C376S453000, C376S454000, C376S102000, C376S103000, C376S105000, C376S106000, C376S108000, C376S109000, C250S250000, C250S305000, C250S315300, C250S39600R, C250S492230
Reexamination Certificate
active
06477217
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a target for a neutron scattering installation.
FIG. 1
shows an example of a neutron scattering installation for performing various research studies on physical properties using neutrons. In the installation, protons from a proton emitter
1
are accelerated by a linear accelerator
2
to enter into an accumulation ring
3
where the protons are circulated by curving their orbits with a deflecting electromagnet and are increased in velocity using high frequency electric current until required energy can be reached.
The protons thus having the required energy are emitted from the ring
3
to a target
4
where they are brought to collide against liquid heavy metal such as mercury held in the target
4
. Fast neutrons generated by nuclear spallation reaction are passed through a moderator such as liquid hydrogen (20 K; 1.5 MPa) held in a moderator container
5
so that they are converted into thermal or cold neutrons suitable for research purpose; these are guided via a beam line
6
to a laboratory
7
.
FIG. 2
shows a conventional target for a neutron scattering installation which comprises a container body
8
arranged to counter a proton beam P, which advances approximately horizontally, and a partition
9
having its opposite edges contiguous with a lower inner surface portion of the body
8
and extending from a base end of the body
8
to a position near a forward end of the body
8
.
The container body
8
has, at its base end, inflow and outflow ports
11
and
13
. The inflow port
11
serves to communicate outside of the body
8
with a liquid-heavy-metal incoming passage
10
, which is a space defined between the inner surface of the body
8
and a lower surface of the partition
9
. The outflow port
13
serves to communicate outside of the body
8
with a liquid-heavy-metal return passage
12
, which is a space defined between the inner surface of the body
8
and an upper surface of the partition
9
.
The inflow port
11
is connected with a discharge port of a pump
14
and the outflow port
13
is connected with a suction port of the pump
14
via a heat exchanger
15
. Thus, the pump
14
, inflow port
11
, incoming and return passages
10
and
12
, outflow port
13
and heat exchanger
15
compose a closed loop which is filled with mercury M as liquid heavy metal.
In the target shown in
FIG. 2
, fast neutrons are generated by collision of the protons against the mercury M, which flows via the incoming passage
10
to an inner forward end of the container body
8
. The mercury M having received heat from the nuclear spallation reaction is then guided via the return passage
12
to the heat exchanger
15
so as to be cooled down.
However, in the system shown in
FIG. 2
, the whole of the mercury M supplied to the inflow port
11
makes up a mercury stream which flows via the incoming passage
10
to the inner forward end of the body
8
and turns back via the return passage
12
, so that stagnation and/or re-circulation flows R tend to occur near the inner forward end of the body
8
. Constant stagnation of the mercury M may lead to occurrence of local increase in temperature (hot spots).
Since the mercury M is brought to continuously flow at higher flow rate in the container body
8
so as to remove the heat caused by nuclear spallation, extremely high burdens are applied on cooling means of, for example, the mercury circulation pump
14
and heat exchanger
15
, which makes it difficult to cope with nuclear spallation reaction having higher heat generated.
The present invention was made to solve the above problems and has its object to provide a target for a neutron scattering installation which can provide a stead and highly uniform stream of liquid heavy metal throughout in the system.
BRIEF SUMMARY OF THE INVENTION
In a target for a neutron scattering installation according to any of claims
1
to
3
of the invention, the flow of the liquid heavy metal from the liquid-heavy-metal inflow port toward the inner forward end of the container body is rectified by a plurality of incoming-passage guide vanes installed closer to one side in the container body, and the flow of the liquid heavy metal from the forward end of the container body toward the liquid-heavy-metal outflow port is rectified by a plurality of return-passage guide vanes installed closer to the other side in the container body, thereby suppressing occurrence of stagnation and/or re-circulation flows of the liquid heavy metal in the container body.
In a target for a neutron scattering installation according to claim
2
of the invention, the container body in which the liquid heavy metal flows is covered with a container outer shell, thereby preventing any leakage of the liquid heavy metal to outside as may be caused by damage of the container body.
In a target for a neutron scattering installation according to claim
3
of the invention, the container body in which the liquid heavy metal flows is dually covered by container intermediate and outer shells, thereby preventing any leakage of the liquid heavy metal to outside as may be caused by damage of the container body.
REFERENCES:
patent: 3886483 (1975-05-01), Miley
patent: 4696191 (1987-09-01), Claytor et al.
patent: 5311955 (1994-05-01), Ganijew et al.
patent: 2435603 (1975-02-01), None
patent: 11-273896 (1999-10-01), None
patent: 11-297498 (1999-10-01), None
patent: 2000-82598 (2000-03-01), None
Anbo Noriaki
Hino Ryutaro
Kaminaga Masanori
Kinoshita Hidetaka
Terada Atsuhiko
Agency of Industrial Science and Technology Japan Atomic Energy
Jordan Charles T.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Richardson John
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