JPS59195190A - Bwr type reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a boiling water nuclear reactor (hereinafter referred to as BWR), and particularly relates to an improvement of a lid for closing an upper opening of a reactor pressure vessel.

[Technical background of the invention]

Generally, in a BWR, there is a water supply pipe that supplies coolant into the reactor pressure vessel, a main steam pipe that takes out the steam generated in the reactor pressure vessel and introduces it to the turbine system, and a forced circulation reactor that circulates the coolant forcibly. In the reactor pressure vessel, recirculation piping with a recirculation pump inserted is connected to the reactor pressure vessel.

Piping rupture accidents may occur in these water supply piping, main steam piping, recirculation piping, etc. In the unlikely event that a pipe rupture accident occurs, the reactor would have to be brought to an emergency shutdown, and there is a risk that coolant containing radioactive materials could leak out and cause a secondary disaster. In Kamimachi, it is being considered to reduce the probability of pipe rupture accidents by eliminating the water supply piping and main steam piping. Further, the entire steam generation system including the heat exchanger has been made more compact, and for example, a heat exchanger-internal reactor is being considered in which the heat exchanger is placed inside the reactor pressure vessel.

Hereinafter, the above-mentioned nuclear reactor with internal heat exchanger will be explained with reference to FIGS. 1 to 3. Reference numeral 1 in FIG. 1 indicates a reactor pressure vessel. The reactor pressure vessel 1 has a lower diameter smaller in diameter than the upper part from the viewpoint of improving space utilization. This reactor pressure vessel 1 is connected to the reactor building 3 via a ring garter 2.
is supported by

A coolant 4 is housed in the reactor pressure vessel 1, and a lid 5 is provided to close the upper opening IA. Reference numeral 6 in the figure indicates a bolt that fixes the lid 5 to the reactor pressure vessel 1. In the lower part of the reactor pressure vessel 1,
A reactor core 8 made up of a plurality of fuel assemblies (not shown), control rods 7, etc. is supported by a core support mechanism 9 and arranged. A core upper mechanism 10 is provided above the core 8 so as to penetrate through the lid 5.

The upper core mechanism 10 includes a control rod guide tube 11, a control rod drive mechanism (hereinafter referred to as CHD) 12 that moves the control rods 7 up and down along the control rod guide tube 11, and a fuel exchanger (not shown). It is composed of A lower shroud 13k is fixed to the reactor pressure vessel 1 between the reactor core 8 and the reactor pressure vessel 1, and a middle shroud 13k is provided between the reactor core upper mechanism 10 and the reactor pressure vessel 1. A single shroud 13B is provided above the lower shroud 13A, and an upper shroud 13C is further provided above the intermediate shroud 13B. A plurality of openings 14k are formed in this upper shroud 13C. Further, between the upper shroud 13C and the reactor pressure vessel 1, a primary heat exchanger 15 is supported by a support member 16 and penetrates through the self-lid 5 before the force is applied. As shown in FIG. 2, eight heat exchanger flange 15A are provided, and the upper end thereof is fixed to a heat exchanger 7 flange 15A that closes the opening 5A of the lid body 5. A guide pipe 17 is provided on the lower outer periphery of the primary heat exchanger 15 and is supported by the reactor pressure vessel 1 . In the figure, reference numeral 15B indicates a heat transfer tube, and reference numeral 18 indicates a bolt that is fixed to the upper S exchanger seven flange 75At' cover body 5.

In the above configuration, the coolant 4 rises from the bottom to the top of the reactor core 8 as shown by the arrow in the figure, and is boiled at this time. Then, it flows out above the reactor core 8 and flows out into the vicinity of the primary heat exchanger 15 through the opening 14kf of the upper shroud 13C.

There, it is cooled by exchanging heat with the secondary side coolant, flows into the lower part of the reactor core 8 again, and repeats this cycle thereafter. All of this is done through natural circulation.

Next, another example will be explained with reference to FIG. That is, the first
In the example shown in the figure, the primary heat exchanger 15 is provided through the lid 5 and supported by the lid 5, whereas the third
In the example shown in the figure, the primary heat exchanger 15 is completely housed within the reactor pressure vessel 1, and the support member 1 is attached to the circumferential wall of the reactor pressure vessel 1.
It is fixed via 9. The rest of the configuration is the same as the example shown in FIG. 1, so a description thereof will be omitted.

[Problems with background technology]

In the case of the configuration shown in FIG. 1, for example, when removing the lid 5 to perform fuel exchange, the primary heat exchanger 15 must also be removed at the same time, and at least the heat transfer tube 15B of the primary heat exchanger 15 must be removed. Therefore, residual heat cannot be removed after the reactor is shut down, and a long-term fuel exchange operation cannot be started until the temperature of the coolant 4 has decreased. Moreover, when the primary heat exchanger 15 is taken out together with the lid body 5, dog-shaped equipment such as a crane is required, and the work is difficult. In the configuration shown in FIG. 1, for example, when performing maintenance and inspection of the primary heat exchanger 15, the lid body
-5 must be removed at the same time as the CHD 12f:l, and it is not easy to remove the primary heat exchanger 150 and perform maintenance and inspection work.

By providing a top cover for removal and a top cover for fuel exchange independently, it is possible to easily remove the heat exchanger when performing maintenance and inspection of the heat exchanger. Another object of the present invention is to provide a boiling water nuclear reactor that can prevent loss of cooling capacity and remove residual heat while leaving a heat exchanger as is.

[Summary of the invention]

The boiling water reactor according to the present invention includes a reactor pressure vessel that accommodates a coolant, a smooth lid body that closes an upper opening of the reactor pressure vessel, and a a reactor core housed in a reactor core, a core upper mechanism provided above the reactor core by penetrating the lid body, the core upper mechanism, a reactor pressure vessel removal top cover, and a fuel exchange top cover, each of which are independent of each other. This is the configuration provided.

Therefore, when performing maintenance and inspection of the heat exchanger, you can remove only the top cover for removing any heat exchanger, and since the top cover for fuel exchange is not integrated as in the past, the heat exchanger can be removed. The top cover is small and lightweight and can be easily removed. On the other hand, for the 18th station where fuel exchange work is to be performed, it is only necessary to remove the fuel exchange top cover, and the work is easy. Further, since work can be performed with the heat exchanger as it is, residual heat can be removed without loss of cooling capacity.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIGS. 4 and 5. Reference numeral 101 in FIG. 4 indicates a reactor pressure vessel. The reactor pressure vessel 101 has a lower diameter smaller than the upper part from the viewpoint of improving space utilization. This reactor pressure vessel 1
01 is supported by the reactor building 103 via a ring gutter 102. There is a coolant 1 in the reactor pressure vessel 101.
04 is accommodated. Also, in the lower part of the reactor pressure vessel 101, there are a plurality of fuel assemblies (not shown) and control rods 10.
A core 1θ8 made up of 7 etc. is supported by a core support mechanism 109 and arranged. A core upper mechanism 110 is provided above the reactor core 10B, penetrating through a refueling top cover 120 provided so as to close the upper opening 101A) of the reactor pressure vessel 101. The upper core mechanism 110 is composed of a control rod guide tube 111 and a control rod drive mechanism (hereinafter referred to as CHD) that moves the control rods 107 up and down along the control rod guide tube 111. A lower shroud 11 is located between the reactor core 10g and the reactor pressure vessel 10).
3N is fixedly provided to the reactor pressure vessel 101, and an intermediate shroud 113B is provided above the lower shroud 113A between the upper core mechanism 110 and the reactor pressure vessel 101, and furthermore, an intermediate shroud 113B is provided above the lower shroud 113A. An upper shroud 113C is provided above 113B. A natural circulation flow path is formed by the lower shroud 113A, the intermediate shroud 113B, and the upper shroud 113C. In addition, the intermediate shroud 1
13B also has the function of supporting the control rod guide tube 111f, and is configured to be detachable from the lower shroud 113 when replacing fuel. A plurality of openings 114A are formed in the upper shroud 113C. Between the upper shroud 113C and the reactor pressure vessel 101, there is a
The secondary heat exchanger 115 is supported by a support member 116 fixed to the inner circumferential wall of the reactor pressure vessel 101, and is fixed to seven independently provided heat exchanger flanges 121,
Multiple at equal intervals in the circumferential direction (e.g. 8 as shown in Figure 5)
It is provided. The seven heat exchanger flange 121 is provided independently of the fuel exchange upper cover 120 and is fixed to the reactor pressure vessel 101 with bolts 118. A guide pipe 1 is provided on the outer periphery of the lower part of the primary heat exchanger 115.
17 is supported by the reactor pressure vessel 101. That is, the primary heat exchanger 115 is configured to be restrained from being displaced in the horizontal direction during an earthquake or the like by the guide tube 117 and the support member 116. Code 115B in the figure
indicates a heat transfer tube through which secondary coolant flows.

In the above configuration, the coolant 104 rises from the bottom to the top of the reactor core 108 as shown by the arrow in the figure, and is heated and boiled at this time. Then, it flows out above the reactor core 10.8 and flows out into the vicinity of the primary heat exchanger through the opening 114kf of the upper shield 113C. There, it is cooled by exchanging heat with the secondary side coolant, flows into the lower part of the core 10B again, and repeats this cycle thereafter. All of this is done through natural circulation.

Next, a case where fuel replacement and maintenance/inspection of the primary heat exchanger 115 are performed will be described. First, when performing fuel replacement, only the fuel replacement top cover 120 is removed and replacement work is performed using a fuel exchanger or the like. At that time, heat exchanger 1 is used as in the conventional method.
Since it is not integrated with the flange 12 for deep organs, removal work is easy. Also, the primary heat exchanger 1
15 can be maintained in the same state, so residual heat can be removed after the reactor is shut down. Therefore, unlike conventional methods, it is not necessary to wait for a long time until the temperature of the coolant 104 falls before starting fuel replacement work. Since fuel replacement work can be started immediately without any problems, the work time can be greatly shortened, and safety during work can be improved.

Next, the case in which maintenance and inspection work of the exchanger 115 is performed will be explained. In this case, any one of the
Only the seven flange 121 of the secondary heat exchanger 115 needs to be removed, thereby allowing the primary heat exchanger 115 to be taken out. Therefore, as in the past, the upper lid 1 for fuel replacement is
20, and only the seven flange 121 corresponding to each primary heat exchanger 115 need be removed, making the work extremely easy.

Otsu Next, another embodiment will be described with reference to FIG.

While the above embodiment is a natural circulation reactor, the reactor shown in FIG. 1 is a forced circulation reactor. That is, ←
÷A plurality of jet pumps 122 are arranged between the lower shroud 113 and the reactor pressure vessel 101, and a recirculation pipe 125 is connected to a recirculation pump (not shown) installed outside the reactor pressure vessel 101. It is connected via an inlet nozzle 123 and an outlet nozzle 124. This recirculation pump supplies driving water to the jet pump 122 to forcefully circulate the coolant 104 into the reactor core 108.

Even if the present invention is applied to such a forced circulation nuclear reactor, the same effects as in the above embodiment can be achieved.

It should be noted that the same parts as in the previous embodiment are denoted by the same reference numerals, and the explanation of the same constituent parts is omitted.

〔Effect of the invention〕

A boiling water reactor according to the present invention includes a reactor pressure vessel containing a coolant, a lid body provided to close an upper opening of the reactor pressure vessel, and a reactor pressure vessel housed in the reactor pressure vessel. A configuration consisting of a reactor core, a core upper mechanism provided above the core by penetrating the lid, this core upper mechanism, a reactor pressure exchanger removal top cover, and a fuel exchange top cover, each of which is provided independently. It is.

Since the fuel exchange top cover is not integrated as in the past, the heat exchanger removal top cover is lightweight and small, and removal work is easy.

On the other hand, when performing fuel exchange work, it is necessary to similarly remove only the fuel exchange top cover, and the work is easy. Further, since the heat exchanger can be operated as it is, the cooling capacity is not lost and residual heat can be removed, which is a great advantage.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams showing conventional examples. Figure 1 is a longitudinal sectional view showing the configuration of a boiling water reactor, Figure 2 is a plan view, and Figure 3 is a longitudinal sectional view showing the configuration of a boiling water reactor.
The figure is a longitudinal sectional view. 4 and 5 are diagrams showing an embodiment of the present invention. FIG. 4 is a longitudinal sectional view showing the configuration of a boiling water reactor, and FIG. 5 is a plan view. FIG. 6 is a longitudinal sectional view of a boiling water reactor showing another embodiment. □01... Reactor pressure vessel, 101k... Upper opening of reactor pressure vessel, 104... Coolant, 108...
Reactor core, 110... Core upper mechanism, 115... Primary heat exchanger, 120... Upper cover for fuel replacement, 121... Flange for heat exchanger (upper cover for heat exchanger removal). Applicant's representative Patent attorney Takehiko Suzue Figure 2, 1-6-1 Otemachi, Chiyoda-ku, Tokyo Japan Atomic Power Company ■0 Inventor Hirohisa Ueda 1-1 Uchisaiwai-cho, Chiyoda-ku, Tokyo ■No.6 No.: Tokyo Shibaura Electric Co., Ltd., Tokyo Office 0 Applicant: Tokyo Electric Power Co., Inc. Applicant: Hokkaido Electric Power Co., Ltd. 1-2 Odori Higashi, Chuo-ku, Sapporo ■Applicant: Tohoku Electric Power Co., Ltd. Sendai Fu Ichibancho 3-7-1-0 Applicant Chubu Electric Power Co., Ltd. 1 Higashishinmachi, Higashi-ku, Nagoya Applicant Hokuriku Electric Power Co., Ltd. 3-1 Sakurabashi-dori, Toyama City Applicant Kansai Electric Power Co., Ltd. 3-3 Nakanoshima, Kita-ku, Osaka No. 22 Applicant: Chugoku Power Line Company, 4-33 Komachi, Naka-ku, Hiroshima Applicant: Shikoku Electric Power Co., Ltd., 2-5 Marunouchi, Takamatsu City Applicant: Kyushu Electric Power Co., Ltd., 2-1-82 Watanabe-dori, Chuo-ku, Fukuoka City Person: Japan Atomic Power Co., Ltd. 1-6-1-1, Otemachi, Chiyoda-ku, Tokyo, Inc., Indication of the case, Patent Application No. 5'8-'70425 No. 2, Name of the invention, Boiling Water Reactor 3, Person making the amendment Relationship with Patent applicant (307) Tokyo Shibaura Electric Co., Ltd. 4 Agent 6 Name of the invention subject to amendment, content of specification 3 The scope of the patent claims is corrected as shown in the attached sheet. j31 Specification page 1, line 18, page 7, line 1 to 2, page 4, line 11, page 11, line 1, page 13, line 1
Correct "boiling water reactor" in line 1, line 18 of the same page, line 11 of page 13, and line 19 of the same page to "boiling water reactor." (4) "Paper nuclear reactor with built-in heat exchanger" in line 19 of page 2 and lines 1 to 2 of page 3 of the specification is corrected to "reactor with built-in heat exchanger." The statement on page 12, line 13 of the specification has been corrected to ``Natural circulation diagnosis ``Natural circulation type''. "In the specification, page 12, line 14 and page 13, line 4,"
"Forced circulation type" is corrected to "Forced circulation type." 2. Claims: A reactor pressure vessel that accommodates a coolant, a lid provided to close an upper opening of the reactor pressure vessel, and a reactor core housed within the reactor pressure vessel; A boiling water reactor comprising a core upper mechanism provided above the reactor core passing through the lid, and a heat exchanger provided between the reactor pressure upper mechanism and the reactor pressure vessel. In , the above-mentioned lid body is the upper lid for removing the heat exchanger and the agent for the fuel replacement applicant, Discriminator Hiko Suzu Ebu.

Claims (1)

[Claims] A reactor pressure vessel containing coolant, a lid provided to close an upper opening of the reactor pressure vessel, a reactor core housed in the reactor pressure vessel, and a lid above the core. In a boiling water reactor equipped with a core upper mechanism installed through the reactor body and a heat exchanger installed between the core upper mechanism and the reactor pressure vessel, the lid body is A boiling water nuclear reactor characterized by having an upper cover for removing an exchanger and an upper cover for replacing fuel, each of which is provided independently.