6.1 UKAEA−IGH の見解に対する返書 6.2 仕様書の補足提案 新規提案事項のうちで各部相対変位について検討する条項(5′)が付加され、これに関して具体的に変位を静的または動的に検討する案も出された。これは実際上きわめて重要な意味があり必要であるが、いまただちにこの具体的な検討条件を出すことは困難であるとの理由のため、後日別途委員会において十分討議されるべきものとして今回は(5′)項のみを付加したものである。 別紙 1 Draft Preliminary Proposal for Earthquake Resistant Design of British type Nuclear Power Station
別紙 2 英国型原子力発電所の耐震設計に関する予備的提案(案)
別紙 3 Introductive Remarks to the Japanese Seismic Building Code
別紙 4 United Kingdom Atomic Energy Authority Industrial Group Headquarters EARTHQUAKE HAZARD TO CALDER HALL TYPE REACTORS A comparison has been made between the draft preliminary report received from the Japanese Special Committee for an Earthquake Resistant Reactor presented by Mr. Sasaki of the Atomic Energy Bureau of the Science and Technics Agency in Tokyo and the Report on Preliminary Investigations made by the Earthquake Working Party of the U.K. Atomic Energy Authority, Industrial Group. Although both Committees used the Japanese Building Code, the results are presented somewhat differently. This difference is however more apparent than real since the higher seismic coefficients used by the Japanese coupled with their higher allowable (parmanent, and more particularly temporary) stresses are no greater than the lower seismic force used in the British calculations taken with the lower working stresses normally used in the U.K. Table 1 Similarly the ground pressures allowed (6 tons/sq.ft, temporary loading pressure) by the Japanese Building Code are larger than those to which the U.K. Atomic Energy Authority works (3. 0 tons/sq.ft)for a similar soil under the foundations. Table II Values of the seismic coefficients used by the two Committees The figures in Colum (2) were used for the purpose of calculating what redesign of the Calder Hall nuclear power station might be required if it were installed in an earthquake-liable area. Allowing for the difference shown in Table I, the results were all within the limits specified by the figures in Column (4) as modified by Column (5) of Table II. It remains only to be clarified what figures for the seismic coefficient is recommended by the Japanese for the foundation mat (which is specially excepted by the Japanese from the main provisions in their draft), and what figures to use for stability calculations. The reasoning leading to the recommendations and the design implications, are not discussed in this paper but the final conclusions of the U. K. Atomic Energy Authority Working Party were:− "While it is obviously prudent to site nuclear power stations in regions were earthquakes are not likely or where they are small in amplitude, there appears to be no reason why, with suitable redesign, the Calder type reactor cannot be made adequately resistant to the effect of earthquakes. Indeed the structure as at present designed, apart from the foundations, is remarkable earthquake resistant without modification. It is considered that there is no reason why, with proper design and construction, nuclear power stations could not be safely operated in Japan." 2nd September, 1957 別紙 5 UKAEA−IGHの見解 コールダーホール型原子炉の耐震について(仮訳)貴国の科学技術庁原子力局佐々木局長より送付いたされました地震対策小委員会の Draft Preliminary ReportはUKAEA−IGH の地震委員会において検討されました。 表1 同様に日本の建築規準によれば、地耐力(6t/ft2短期)は英国の同じ soil に対する地耐力(3.0t/ft2)よりも大きくなっております。よって(2)欄の数値を用いてコールダーホール原子炉を再設計しても地震地帯に設置できるものと考えます。
表2 両者に使われた震度 別紙 6 The conclusions of the discussions will shortly be delivered to you through our mission to your country. For the time being the Committee wishes to send the following informations precedent to the arrival of the mission. 1.We presume that various ideas have already been discussed in connection with the aseismic reinforcement of the British type reactors in your country. Our committee has also discussed the same problem based on many published data and has reached the conclusion that all of the published Calder Hall type reactors are to be reinforced or modified to a certain extent before they are imported to our country. 2.We also discussed about the previously delivered "Preliminary Proposal". We are considering that it is better to add some additional requirements together with a few modifications. The details will be sent through our mission shortly. 3.Some ambiguous statement in the preliminary proposal are given more precisely as follows. (1) The design seismic coefficient for the foundation mat. 1.5 C0 as assumed in your letter in Table 2. Column 4. (2) Stability criteria We do not worry much about the stability (overturning) of tbe reactor structures other than the graphite pile. However, if required, the stability criteria may be read as follows. (a) All structures and structural parts (except the graphite structures) should be safe against overturning under the action of the seismic forces as specified under the corresponding articles. (b) The stability criterion for the graphite structures is to be specified later appropriately according to the nature of the construction. 4.A few misunderstandings seem to be probable on the following items. In Table 1, the allowable unit stresses for concrete are specified in 3 folds; compression due to bending, direct compression and shear. In Japan, both in compression due to bending and in direct compression, the single value of 2,000 psi is specified as the maximum allowable unit stress. Table 2. Column 4. Finally we wish to add a short remark that we convince the sound earthquake resistant design of a unique structure like the present example can only be achieved by a close cooperation of the professional knowledges of the reactor engineers and the other professional knowledges and experiences of the earthquake engineers based on sound overall engineering judgement. 別紙 7 コールダーホール型原子炉の耐震に関するUKAEA−lGH の見解に対する返書(仮訳) コールダーホール型原子炉の耐震に関する1957年9月2日付貴信は、原子炉地震対策小委員会において検討されました。 1.コールダーホール型原子炉の耐震補強については、貴方においても種々検討されていることと考えますが、すでに発表されたコールダーホール型の各種の原子炉の構造について本委員会で検討の結果はこれを耐震化するためには相当の補強あるいは改造を要するものと考えられます。 2.さきのpreliminary proposalについてはその後種々補足、修正すべき事項等を検討いたしましたが、その細目についても調査団から直接連絡する予定であります。 3.貴信の中で、さきの proposal 中不明とされている点について御返事いたしますと、 (1)Foundation mat の計算用震度 (2)Stability の計算について (a)構造物、構造部分(グラファイト構造物を除く)は、さきに規定した地震力の運動の overturning に対し安定であること。 (b)グラファイト構造物の Stability については、構造の性質にしたがって後で定めることといたします。 4.貴信に示された数値のうち下記のごとき誤解点があると考えます。 表2の(4)欄において
表1においてコンクリートの許容応力をそれぞれ曲げによる圧縮、単純圧縮、せん断の3種あげておられますが、日本においてはこのようにせず、曲げによる圧縮も単純圧縮も一つにして最大許容量2,000psi としています。 別紙 8 Supplementary Requirements for Earthquake Resistant Design of Britishtype Nuclear Power Station The present requirements are prepared to cover some of the items which are not specified in the previous "Preliminary Proposal". Since the time when the Committee (Special Committee for Earthquake Resistant Reactor) prepared the Preliminary Proposal, we have studied more about the British-type reactors and naturally we have become possible to specify more in details. However, as stated in the Introductive Remarkes of the Proposal, we convince that the most reasonable design seismic coefficients should be given according to the nature of the structures. Therefore, we have not reached the state of being able to draw any definite lines concerning the final requirements. Consequently it is strongly desired all designs and analyses of structural parts are to be reviewed by us before they are finally decided. 1. (Unaltered) 2. (Altered) "Reactor building and attached steam raising structures, except・・・・・・" is to be read "Reactor building and foundation mat, except 3. (Altered) "Biological shielding structure and its principal sub-structure (except foundation mat) ・・・・・・" is to be read. "Biological shielding structure, steam raising units and their principal sub-structures (except foundation mat) ・・・・・・". 4. (Unaltered) 5. (Unaltered) 5'. (Added) Biological shielding structure, graphite pile, pressure vessel, cooling system and steam raising units should be designed safe against all possible damages due to their relative displacements or deformations. 6. (Altered) A seismic switch is required which immediately starts the scramming mechanism of the reactor as soon as the horizontal acceleration at the foundation mat reaches or exceeds a certain specified value. (Adjustable for the range 50-150 gals.) The reactor should be equipped with the emergency shut down system separately from the one required above. This emergency shut down system should be capable of shutting off the reactor completely even during the action of the seismic force which is one and one half times as large as specified under Article 4 of the present proposal. It is further required that thesystem should work automatically and immediately as soon as the horizontal acceleration at the foundation mat reaches or exceeds 200 gals, or when ever the scramming mechanism fails to operate. The reactor should be re-operable after once the emergency shut down system worked. 6'. (Added) Instrumentation system and control system indispensable for emergency operations should be earthquake resistant and hold their treatments during and after the action of the seismic force of the intensity as specified under Article 4. 7. (Discarded) 8. (Unaltered) 9. (Unaltered) 10. (Unaltered) 10'. (Added) Fuel handling machine should have a locking mechanism lest it should be dislocated by earthquake during the operation. 11. (Added) The soundness of the graphite structure may be required to be proved experimentally. 12. (Added) If necessary, a specific design criterion may be specified for each specific design of the structural part or parts. 別紙 9 英国型原子力発電所の耐震設計に関する補足提案(仮訳) これはさきの「予備的提案」に盛られなかった事項を補足するためのものである。原子炉地産対策小委員会は「予備的提案」作成以後も英国型原子炉についてなお一層の研究をすゝめ、より細部にわたって提案できるようになった。しかしながらさきの提案の序言で述べたように、最も妥当な設計震度は構造物の特性に応じて定められるべきものと考える。したがってわれわれは最終的な要求を提示するほどまでにはたちいたっていない。以上のことから構造各部のすべての設計と数値計算については最終決定の前にあらかじめ当方と協議されるよう強く要望するものである。 1.(変更なし) 2.(一部改訂) 3.(一部改訂) 4.(変更なし) 5.(変更なし) 5'.(追加) 6.(全文改訂) 6'.(追加) 7.(削除) 8.(変更なし) 9.(変更なし) 10.(変更なし) 10'.(追加) 11.(追加) 12.(追加) 別紙10 Draft Proposal for Earthquake Resistant (I) Introduction to the Supplementary Requirements (November, 1957) The present requirements are prepared to cover some of the items which are not specified in the previous "Preliminary Proposal". Since the time when the Committee (Special Committee for Earthquake Resistant Reactor) prepared the Preliminary Proposal, we have studied more about the British-type reactors and naturally we have become possible to specify more in details. However, as stated in the Introductive Remarkes of the Proposal, we convince that the most reasonable design seismic coefficients should be given according to the nature of the structures. Therefore, we have not reached the state of being able to draw any definite lines concerning the final requirements. Consequently it is strongly desired all designs and analyses of structural parts are to be reviewed by us before they are finally decided. (II) Introduction to the Preliminary Proposal (June, 1957) The Present proposal is prepared by the Special Committee for Earthquake Resistant Reactor, and it presents a general guide for the aseismic design of a Britishtype Nuclear Power Station to be built in Japan. The underlying principles of the present proposal are : (1) To guarantee the public and employees security against the radiation. (2) To guarantee the publicient strength and serviciability for such parts where the post-operation repair work is not feasible, or the failure of such parts will be fatal to the power generation. The proposed items are listed below. However, some of the numerical values may be modified later along with the progress of design, consulting with the nature of structure employed therein. (III) Complete Items 1.All building and other structures should be designed in accordance with the Japanese Building Code requirements except those specified elsewhere. Note: It is pre-assumed that the procedures to be followed in the course of structural design and analysis are similar to those specified in the Code. (Building Standard Law Enforcement Order, Chapter 3, Sections 1-8.) 2.Reactor building and foundation mat, except those specified under Article 3-5, should be so designed as to safely resist the seismic force which is one and one half times the specified values in the Code. 3.Biological shielding structure, steam raising units and their principal sub-structure (except foundation mat) should be designed to the 3 times as large seismic force as specified in the Code. Note: 3 times as large seismic force as specified in the Code (Article 88 in the Law Enforcement Order) is assumed to act upon the biological shielding structure and, if any, all structural units which are structurally connected to it. 4.All structures and structural parts inside the biological shielding structure should be designed to the equally as large horizontal force as specified under Article 3 of the present proposal in all directions, together with a vertical force which is one half of the previously mentioned horizontal force. These horizontal and vertical forces are considered to act simultaneously. 5.Cooling system of the reactor assembly should hold sufficient cooling capacity even when the reactor assembly is subjected to such a seismic force as mentioned in Article 3. It is further required that any probable leakage of the coolant will never endanger personnel on duty. 5'.Biological shielding structure, graphite pile, pressure vessel, cooling system and steam raising units should be designed safe against all possible damages due to their relative displacements or deformations. 6.A seismic switch is required which immediately starts the scramming mechanism of the reactor as soon as the horizontal acceleration at the foundation mat reaches or exceeds a certain specified value. (Adjustable for the range 50-150 gals.) The reactor should be equipped with the emergency shut down system separately from the one required above. This emergency shut down system should be capable of shutting off the reactor completely even during the action of the seismic force which is one and one half times as large as specified under Article 4 of the present proposal. It is further required that the system should work automatically and immediately as soon as the horizontal acceleration at the foundation mat reaches or exceeds 200 gals, or when ever the scramming mechanism fails to operate. 6'.Instrumentation system and control system indispensable for emergency treatments should be earthquake resistant and hold their functions during and after the action of the seismic force of the intensity as specified under Article 4. 7.(Discarded) 8.The fuel discharging system should be so designed that, in emergency cases, it is feasible to remove the damaged fuel elements as quickly as possible lest the radiation from the fission products should endanger the personnel. 9.Making a due consideration on an earthquake damage of the station, an emergency electric power supply should be installed. Its capacity should be sufficient to ensure the safe keep up of the entire power station. 10. All mechanical equipments and their installations of the power station should be adequately designed according to the type and location of each unit in accordance with the corresponding requirements as previously stated. 10'.Fuel handling machine should have a locking mechanism lest it should be dislocated by earthquake during the operation. 11.The soundness of the graphite structure may be required to be proved experimentally. 12.If necessary, a specific design criterion may be specified for each specific design of the structural part or parts. 別紙11 英国型原子力発電所の耐震設計に関する提案(案)(仮訳) 〔I〕 補足提案の序言(1957年11月) 〔II〕 予備的提案の序言(1957年6月) (1)放射能に対して周囲の人々ならびに従業員の安全を確保すること。 (2)修理が困難な部分および致命的重要部に対しては十分の強度と安全性を保有させること。 を目標としている。 〔III〕 全文 1.発電所の全建物および構造物は以下に特に指示した場合を除き、一般に日本の建築法規に基いて設計する。
2.Reactor Building および基礎版は、3ないし5項に示す部分を除き、日本の建築法規に示した数値の1.5倍の地震力に対して安全なるように設計する。 3.Biological Shielding Structure, Steam Raising Unitsおよびこれを支持する主要構造物(基礎版を除く)は、日本の建築法規に示した数値の3倍の地震力に対して安全なるように設計する。
4.Biological Shielding Structure の内部の各部は3項に示す水平震度(各方向)とその50%の垂直震度に対して安全なるように設計する。この場合上記の水平力、垂直力は同時に作用するものとする。 5.原子炉のCooling System は第3項に示した地震力を受けた場合でも原子炉の冷却のために十分な能力を有し、かつ冷却材の漏洩が作業員に危険を及ぼさないように設計する。 5'.生体遮蔽、黒鉛パイル、圧力容器、冷却系統、Steam Raising Units 等は地震による変形および相対変位によって損傷を与えてはならない。 6.基礎版上一定以上の水平加速度の地震が生じたとき自動的に原子炉の Scram を働かせる Seismic Switchを設ける。(調整範囲は50〜150galとする。) 6'.Emergency 処置用のInstruction System およびControl System は、4項に規定する地震力をうけた場合にもその機能を保持すること。 7.(削除) 8.地震により原子炉内の燃料要素が万一損傷した場合、分裂生成物逸出の危険を除去するため燃料取替装置は可及的すみやかにこれを取り去るよう設計する。 9.発電所の震害を考慮して非常電源を準備し、その容量は発電所の保全に十分なるものとする。 10.発電所の機械設備およびその取付部についてはその状況に応じ上記各項に準じて耐震設計を行う。 10'.燃料取扱装置は燃料取扱中地震動によって移動しないように固定装置を設けること。 11.黒鉛パイルについては、必要に応じて受入れに際し試験を行う。 12.このほか、各部構造の細部については、必要に応じてその設計基準を示すことがある。 |