JP2522703B2 - Nuclear power generation system and construction method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear power generation system using an underground dam constructed underground.

There are impermeable layers and permeable layers in the stratum, and most of these impermeable layers and permeable layers form faults, and there are several geological structures (groundwater basins) that store groundwater.

Therefore, 40% of the rain on the ground dives underground, but this water seeps into the permeable layer and collects on the impermeable layer.
It flows down to the sea.

However, underground water does not flow freely, but because there are multiple faults formed in the stratum as described above, it is blocked by the faults and flows along the fault lines.

The porosity of the permeable layer is usually 20-45%, and the permeable layer has the potential to store a lot of water (10-20% of the volume of the formation).

Recently, an underground dam was built in Okinawa in 1979 to store 700,000 tons of water by installing a 500 m long and 16.5 m high water stop wall near the exit of a groundwater basin, which has a large amount of spring water flowing out. After that, underground dams are being built one after another as shown in the table below.

These underground dam is intended primarily for the purpose of drinking water or irrigation water, if the amount that can be water intake is of the dam Kabashima a day, it is a 250m ³ about which corresponds to 1 of the 40 minutes of the total water volume.

Conventional technology Conventionally, nuclear power generation systems in Japan have used BWR (boiling water type) or PWR (pressurized water type) reactors, and uranium oxide concentrated to about 3% by uranium enrichment industry is used in the reactor. A system in which high temperature steam is produced by reaction and a turbine of a generator is rotated by the steam is installed and used on the ground.

In order to obtain an output of 500,000 Kw in nuclear power generation,
It consumes 150,000 Kw of energy, 500,000 Kw is converted to electrical energy, and the rest is thermal energy.

Primary cooling water is used as a moderator of neutrons generated from the nuclear reactor, and at the same time, the cooling water is circulated in the core to carry out the heat generated in the core to the outside.

The heated primary cooling water is designed to be cooled and returned to the core by exchanging heat with the seawater of the secondary cooling water via a condenser.

The seawater used for this secondary cooling water is a power generation type with a output of 500,000 Kw, and requires 180,000 m ³ / h, which is equivalent to 4.32 million m ³ / day per day.

The water used as the secondary cooling water is usually heated to about 7 ° C and discharged to the sea. Therefore, the energy Q ₁ lost by seawater is as follows.

Q ₁ = 432 × 10 ¹⁰ × 7 cal / day = 1.46 million Kw / sec Problems to be solved by the invention However, in the case of such a conventional nuclear power generation system, seawater is used as the secondary cooling water, but it is released. Since the flow rate is very large and the discharged seawater is not designed to send water to a considerable distance offshore, the sea is warming, causing problems such as red tide and abnormal jellyfish.

Since seawater used as secondary cooling water contains a large amount of salt, there is also a problem that the water intake, condenser, pipe, etc. are easily corroded.

Nuclear power plants are installed at locations where earthquakes are unlikely to occur, but they also have the drawback that when an earthquake occurs, it is likely that the reactor will be distorted under the influence of the earthquake. ing.

As for the location condition of a power plant, the closer it is to the center of the city where power demand is high, the better, but in the case of a nuclear power plant, it is generally located far from the place of demand for power, so the power transmission efficiency is inconvenient. There is also.

Furthermore, seawater is used as secondary cooling water, but 20
The energy E ₁ consumed when pumping 0 m ³ of water to a reactor at a height of 10 m above sea level is E ₁ = 200 × 9.8 × 10 =
It becomes 18,000 Kw, and there is also the inconvenience of poor nuclear power generation efficiency.

There is also a problem that it is difficult to install in places where seawater has high tide.

Therefore, in view of the drawbacks of the prior art, it is an object of the present invention to provide an underground nuclear power generation system that is not easily affected by an earthquake, does not need to use seawater, and can be installed in a place relatively close to the city center. To do.

Means for Solving the Problems An underground dam formed by providing a water stop wall in the groundwater basin, a reactor installed below the underground dam in a concrete shield wall on rock, and inside A primary cooling water conduit for the reactor is provided, and an evaporative cooling tower is connected to a pipe for drawing in water for cooling the water stored in the underground dam. The objective is achieved by a nuclear power generation system in which the air inlets communicate with the ground via chimneys.

The above nuclear power generation system is constructed by the following method.

The groundwater basin with the desired storage volume will be searched by geological survey.

By injecting a soil hardening agent such as concrete or water glass (sodium silicate) near the exit of the groundwater basin, which has a large amount of springwater outflow, a water blocking wall of a predetermined height and length is attached to the fault. It will be installed almost vertically and an intake well will be installed there.

While installing the reactor on the rock below the underground dam,
The reactor is covered with a concrete shield wall.

An evaporative cooling tower is installed next to the nuclear reactor, and the evaporation port of the cooling tower communicates with the ground via a chimney, and the air inlet of the cooling tower and the ground communicate with each other via the chimney.

Further, the primary cooling water of the nuclear reactor is guided to the cooling tower and the water of the underground dam is guided to the cooling tower to exchange heat with each other.

The dam water used for cooling is constructed so that it will be completely evaporated without returning it to the underground.

The amount of water stored in the underground dam is adjusted to the output of nuclear power generation, but in the case of the evaporative cooling tower system, the output is 500,000 Kw / h and 2,016 m.
^{Since 3} / h is required and 48,384 m ³ of water is required per day, a total storage capacity of 5 million m ³ or more will be constructed at 100 times conversion.

Example The present invention will be described in detail below with reference to an example shown in the drawings.

FIG. 1 is a schematic cross-sectional view of the stratum surface, which is mainly composed of a permeable layer 1 and an impermeable layer 2. These layers 1 and 2 form a fault in the part indicated by discontinuity lines 3 and 4. There is.

Then, water collects in this permeable layer 1 and flows along the impermeable layer 2 as a groundwater basin.

Therefore, as shown in Fig. 1 and Fig. 2, the water blocking wall 5 is on the impermeable layer and is almost perpendicular to the fault discontinuity lines 3 and 4.
To provide.

This water stop wall 5 is a pipe that is vertically driven into the ground, and cement soil in which cement is dissolved in water through the pipe, a mixture of cement and cement milk, or a soil hardening agent such as water glass (sodium silicate) is used. It is made by injecting and filling the gaps in the permeable layer.

Reference numeral 6 is a concrete shield for biological shielding of the nuclear reactor, which is provided on the bedrock 7 below the water blocking wall 5, and a metallic containment vessel 10 is installed in the concrete shield 6 and further stored therein. A nuclear reactor 8 for reacting uranium oxide to generate heat is installed in a container 10.

The nuclear reactor 8 is provided with a primary cooling water circulation inlet 12 for cooling the heat generated by the nuclear reaction and an outlet 14 for discharging the primary cooling water vaporized by the heat from the nuclear reactor 8. The reactor 8 is controlled so as not to overheat.

The steam discharged from the discharge port 14 of the nuclear reactor 8 is guided to the turbine 16 for power generation through the pipe means, and the turbine 16 is generated there.
Power is generated by driving the reactor, but after being discharged from the turbine 16, it is guided to the evaporative cooling tower 20 and condensed, and is returned from gas to liquid, and then the reactor is supplied via the feed water pump 18 and the purifier 19. Returned to 8

The primary cooling water is configured to circulate in the closed circuit because it is exposed to radioactivity in the nuclear reactor 8.

As shown in FIG. 3, the evaporative cooling tower 20 has an exhaust port 2 at the upper side.
2. A pipe having a suction port 24 on the side surface and having a heat conduction pipe through which the primary cooling water passes is wound into a coil. Above the pipe, there is a pipe 26 from the water blocking wall 26, and a tank 28. A sprinkler 30 for sprinkling water guided through is installed near the intake port 24, and a large fan 32 for sucking air from the ground and expelling steam toward the ground is installed. There is.

The evaporative cooling tower 20 uses the latent heat of evaporation of water to absorb the energy of the primary cooling water, and can absorb a large amount of energy with a small amount of secondary cooling water.

34 is a chimney connected to the exhaust port of the evaporative cooling tower 20 for discharging steam to the ground, and 36 is a chimney connected to the intake port 24.

The diameter of these chimneys is determined in relation to the output of the nuclear reactor 8 and the amount of cooling water and the amount of blown air, and a relatively large diameter is preferable.

In FIG. 3, 38 is an overflow pipe provided above the water blocking wall 5 for discharging overflow water generated by the difference between the amount of water springing to the underground dam and the amount of water absorbed from the underground dam, The overflow pipe is 30
A hydroelectric turbine 40 installed at a head position of about 50 m is rotated to generate electric power with a generator 41.

The water used for power generation is discharged to the second underground dam dammed by the water blocking wall 42 installed in the groundwater basin below the underground dam.

The water of the second underground dam can be pumped to the first underground dam via the pump 43.

Pumping up may be performed using surplus power generated by nuclear power plants at midnight.

This is to supplement the amount of water stored in the first underground dam by pumping up when the amount of water storage has decreased significantly and has not reached the required amount for secondary cooling.

The inlets of the secondary cooling water intake pipe 26 and the overflow pipe 38 are provided in an intake well 44 dug near the water blocking wall 5 of the upper underground dam. In this embodiment, the second underground dam is installed underground, but the present invention is not limited to this, and the overflow water is forcibly discharged into the groundwater vein in the permeable layer. Is also good.

39 is a storage room installed more than 1,000m underground to store the spent fuel.

Incidentally, the amount of secondary cooling water required in nuclear power output 500,000 Kw in evaporative cooling tower will 33.6M ³ required one day in terms 48,384M ³ per minute.

Therefore, the amount of heat Q _{2 that} is lost when water at 15 ° C evaporates assuming that there is no energy loss is as follows per day.

Q ₂ = 85 ℃ × 48,384m ³ × 10 ⁶ ＋ 539 × 48,384m ³ × 10 ⁶ ＝ 3.02 × 10 ¹³ cal / day ＝ 1.46 million Kw / sec Furthermore, heat energy is absorbed by heating the blast air.

In the evaporative cooling tower, 30% of the secondary cooling water is evaporated and cooled, and 70% is used as a liquid for cooling.

Therefore, the amount of power generated by underground nuclear power generation can be calculated from the relationship between the total amount of groundwater stored, the amount of spring water, and the amount used, but it is better to set a larger total amount of stored water for safety reasons.

Table-2 shows the relationship between the amount of secondary cooling water required by the evaporative cooling tower at the output of 100,000,500,000 or 1 million Kw and the total storage amount of the groundwater dam required from the above values. It becomes a street.

When the power output of nuclear power generation is set to 500,000 Kw, the amount of water that normally spouts in an underground dam per day is 96,768 m ³ , and the theoretical hydraulic power generation amount Q when this surplus water is used for hydraulic power generation is Q = 9.8 × 0.56m ³ / s × 40m (fall) = 219Kw.

In this embodiment, the water overflowed from the groundwater dam is used for hydroelectric power generation, but the present invention is not limited to this.

Alternatively, groundwater may be pumped up and used as irrigation water for plants on the ground, and the plants may be used as a barometer for measuring conditions such as acid rain.

Effect As described above, in the nuclear power generation system according to the present invention, the groundwater that is abundantly buried underground is constructed so that the required amount of water is taken by the formation of the underground dam, and the secondary cooling is performed. It can be installed anywhere in the groundwater basin that has a water storage capacity, and because it does not require pumping of groundwater, it is energy efficient.

Since the nuclear power generation system is configured to be installed underground, the effect of seismic S-waves (transverse waves) is significantly attenuated compared to the conventional installation of equipment on the ground, and therefore, the earthquake resistance is far superior.

Furthermore, because the reactor is configured to be installed several tens of meters underground, even if radioactivity is generated from the reactor during abnormal times, the concrete and impermeable layers in the stratum will shield the organisms, thus ensuring safety. Excellent in.

Also, unlike the conventional method, the secondary cooling water is not seawater,
Since groundwater is used, equipment such as pipes is less likely to corrode and has excellent durability.

Since the water that spouts underground is used without drought and the water used for cooling is not returned to the groundwater vein, the groundwater is not contaminated.

[Brief description of drawings]

FIG. 1 is a sectional view showing the relationship between a permeable layer and a non-permeable layer in the stratum, FIG. 2 is a sectional view of an underground water dam installed in the underground, and FIG. 3 is a schematic sectional view of a system showing an embodiment according to the present invention. It is a figure. 1 ... Permeable layer, 2 ... Impermeable layer 3, 4 ... Fault, 5 ... Water blocking wall 6 ... Shield, 8 ... Reactor 10 ... Metal containment vessel, 12 ... Circulation inlet 14 ... Exit, 16 ... Turbine for power generation 18 ... Water supply pump, 19 ... Purification device 20 ... Evaporative cooling tower, 22 ... Exhaust port 24 ... Intake port, 26 ... Pipe 28 ... Tank, 30 ... Sprinkler 32 ... Large fan, 34, 36 ... Chimney 38 ... Overflow pipe, 39 … Storage 40… Hydroelectric turbine, 42… Water stop wall 43… Generator, 44… Intake well

Claims (2)

(57) [Claims] 1. An underground dam formed by providing a water stop wall in a groundwater basin, a reactor installed in a concrete shield wall on rock below the underground dam, and the reactor inside the reactor. And an evaporation type cooling tower connected to a pipe for drawing water stored in the underground dam to cool the water guiding pipe. A nuclear power generation system characterized in that the outlet and the air intake are respectively connected to the ground via a chimney. 2. A method of constructing an underground nuclear power generation system comprising the following steps. a) The process of searching for a groundwater basin having a desired storage amount by geological survey, b) Injecting a soil hardening agent made of concrete or water glass (sodium silicate) near the outlet of the groundwater basin, where the discharge of groundwater is large By doing so, a process of installing a water stop wall of a predetermined height and length approximately perpendicular to the fault to form an underground dam and installing an intake well, c) Reactor on rock below the underground dam And the step of covering the reactor with a concrete shielding wall, d) installing an evaporative cooling tower adjacent to the reactor, and communicating with the ground through a chimney at the evaporation port of the cooling tower Connecting the air inlet of the cooling tower to the ground through the chimney, e) further guiding the primary cooling water of the reactor with a water pipe and installing the water in the cooling tower, and also the water of the underground dam to the cooling tower. The process of leading,