Induced nuclear reactions: processes – systems – and elements – Reactor structures – Circulating fluid within reactor
Reexamination Certificate
2002-06-18
2004-01-06
Carone, Michael J. (Department: 3641)
Induced nuclear reactions: processes, systems, and elements
Reactor structures
Circulating fluid within reactor
C376S383000, C376S361000, C376S402000, C376S211000, C376S904000, C060S644100, C060S647000
Reexamination Certificate
active
06674830
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a nuclear reactor plant.
2. Prior Art
A gas such as helium can be considered as a coolant in a direct cycle nuclear reactor wherein a turbine is directly driven by the coolant heated in the nuclear reactor. However, the nuclear reactor can hardly be operated by helium because helium is inferior in cooling capability. Therefor, power density of the nuclear reactor can not help reducing. Accordingly, a core volume is required to be expanded to gain a large amount of power generative output. Consequently, a problem had been arisen such that the production cost is increased in response to an increase of the amount of materials for the nuclear reactor plant.
Carbon dioxide can be considered as a gaseous coolant in the direct cycle nuclear reactor instead of helium. Because carbon dioxide of super critical state has a couple of times as much cooling capability (heat transmission ratio and heat transportation power) as gaseous helium, etc., have. Thus, this allows the nuclear reactor to be operated in higher temperature compared with the case when helium is used as the coolant even though carbon dioxide is not condensed. Consequently, the nuclear reactor can be miniaturized.
Moreover, both temperature and pressure of a critical point of carbon dioxide (approximately 304K and 7.4 MPa) are higher than that of helium (approximately 5.2K and 0.2 MPa).
However, the coolant (carbon dioxide) is discharged from the turbine after said turbine is driven, and the coolant is compressed to around the critical point (the area out of ideal gas characteristic) in the direct cycle nuclear reactor wherein carbon dioxide is used as the coolant. Thus a compressive work can be drastically reduced compared with the case when helium is used as the coolant.
Accordingly, when a direct cycle nuclear reactor is constituted by using gaseous carbon dioxide as the coolant, output density of the nuclear reactor can be improved compared with the case when helium is used as the coolant. Consequently, this causes the nuclear reactor plant to be miniaturized for reducing construction cost.
However, even though carbon dioxide is used as the coolant in the direct cycle nuclear reactor (hereinafter is referred to as “non-condensation cycle reactor”) such that the coolant is circulated under the gaseous state, the temperature of coolant at inlet of the turbine must be high temperature (approximately 700 C°) to gain high cycle efficiency since working volume is so large to compress the gaseous coolant. Consequently, both system and equipment are greatly heated for causing a problem such as being restricted to the selection of materials for the nuclear reactor.
In order to solve the above problem, the inventors suggested a direct cycle fast reactor using Rankine cycle utilized condensation ability of carbon dioxide (Patent Application No.2000-148151).
The direct cycle fast reactor disclosed in the Patent Application No.2000-148151 will be now described with reference to the accompanying drawing of FIG.
5
.
The direct cycle fast reactor shown in
FIG. 5
has a nuclear reactor
111
, a turbine
112
, and a power generator
113
. Furthermore, a regenerative heat exchanger
114
, a condenser
115
, and a pump
116
are provided between outlet of the turbine
112
and inlet of the nuclear reactor
111
.
Besides, arrows in the figure indicate current directions of the coolant in the direct cycle fast reactor.
The coolant (carbon dioxide) in a super critical state is heated in the core of the nuclear reactor
111
for being directly introduced to the turbine
112
. And then the turbine
112
is driven for driving the power generator
113
, which is connected with the turbine
112
. The coolant discharged from the turbine
112
becomes gaseous state to be introduced into the condenser
115
via the regenerative heat exchanger
114
.
The condenser
115
has cooling water, etc., introduced from outside for allowing the coolant to be chilled. Consequently, full amount of the coolant is liquefied.
The liquefied coolant is transferred to the regenerative heat exchanger
114
by the pump
116
for being pressurized to be more than a critical pressure through heat exchanging with said coolant discharged from the turbine
112
to be increased to the temperature at inlet of the nuclear reactor
111
. The coolant being increased to the supper critical state in this manner is transferred to the core of the nuclear reactor
111
to be reheated.
An electric power is generated by continuous driving of the power generator through repeating above process.
Carbon dioxide as the coolant of the condenser
115
is fully condensed in the direct cycle fast reactor of the Patent Application 2000-148151.
Certainly the coolant is liquefied in the direct cycle fast reactor. Compression for gaseous coolant performed in a non-condensation cycle reactor can be replaced with compression for a liquid coolant having a small specific volume. Therefore, a compressive work of the coolant can be reduced.
Besides, a direct cycle nuclear reactor described in the Patent Publication No.2000-148151 such as liquefying full amount of the coolant is sometimes called “a full condensation cycle reactor”. However, when the full condensation cycle reactor can not sufficiently chill the coolant to be less than a critical temperature [approximately 304K (31° C.)] in the condenser
115
, a pressure evacuation from the turbine
112
is increased since a saturated vapor pressure is increased. Accordingly, since the coolant can not be sufficiently expanded in the turbine
112
and a work volume to drive the turbine
112
is reduced, a heat evacuation discharged from the condenser
115
is relatively increased. Consequently, new problem will be arisen such that a cycle efficiency is not improved so much.
The present invention has been made with the forgoing background in mind. The present invention is to provide the direct cycle nuclear reactor wherein carbon dioxide is used as the coolant, and the coolant directly rotates the turbine for generating the electric power. Also the nuclear reactor of the present invention is characterized in that the heat evacuation caused by liquefying the coolant can be reduced while the compressive work can be reduced by using condensation ability of carbon dioxide. Accordingly, the subject of the present invention is to provide the nuclear reactor plant enhancing the cycle efficiency than ever by taking above mentioned characteristic.
SUMMARY OF THE INVENTION
The present invention is comprised as follows to solve the aforementioned subject.
The present invention according to the following claim
1
is a nuclear reactor plant having a nuclear reactor and a turbine, and is characterized in that a coolant in a super critical state is heated by the heat of the nuclear reactor, said heated coolant directly drives the turbine, and a gaseous coolant discharged from said turbine is chilled and compressed for being in a critical state after said turbine is driven, and then the coolant is circulated again into said nuclear reactor, and is also characterized in that carbon dioxide is used as said coolant, and a predetermined ratio of the gaseous coolant discharged from said turbine is liquefied for being compressed in a liquid state, while a rest of gaseous coolant is compressed in a gaseous state.
As described in prior art, a full condensation cycle reactor can reduce a compressive work of the coolant since carbon dioxide using as the coolant is fully condensed for liquefying. However, if the coolant can not be sufficiently low temperature, a heat evacuation (hereinafter is referred to as “heat evacuation from acondenser”) wastefully discharged from a condenser is increased for degrading a cycle efficiency of a nuclear reactor plant.
Therefore, the present invention relates to the nuclear reactor such that a compressive work of the coolant can be reduced to solve disadvantage of a non-condensation cycle reactor while a heat evacuation form a condenser can be reduce
Kato Yasuyoshi
Nitawaki Takeshi
Carone Michael J.
President of Tokyo Institute of Technology
Richardson John
Sughrue & Mion, PLLC
LandOfFree
Nuclear reactor plant does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Nuclear reactor plant, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nuclear reactor plant will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3251451