各種リサイクル概念の経済性比較

The economics of various fuel cycle systems

小藤 博英  ; 小野 清 

Kofuji, Hirohide; not registered

高速増殖炉の経済性目標の妥当性を検討するため、現在の国内の状況を反映した各種燃料サイクル概念の発電コストを推定試算し、経済性の比較・検討を行った。燃料サイクル概念としては、軽水炉ワンススルー、軽水炉-再処理、プルサーマル、高速増殖炉の4つのシナリオを設定した。燃料サイクル各ステージの単価は、極力現状の国内の実質的な値を使用することに努めた。これらの単価の設定が本報告書のポイントである。発電コスト試算の結果、国内におけるリファレンスケースと考えた軽水炉-再処理シナリオは8.2円/kWh、ワンススルーシナリオは7.5円/kWh、プルサーマルシナリオは8.2円/kWhとなった。これら3者は同一の原子炉を想定したことから、発電コストの差は燃料サイクル費の差である。ワンススルーと再処理シナリオのフロントエンド費用は同等であり、また使用済燃料や高/低レベル廃棄物の埋設費は燃料サイクル費の中で占める割合が小さいことから、両者の発電コストの相違はほぼ再処理費相当分となる。プルサーマルシナリオではウラン関連費用が節約されるが、MOX燃料加工費がウラン燃料加工費に比べて高いことから、燃料サイクル費全体としてはほぼ相殺され、再処理シナリオと同等となった。FBRシナリオは現状技術では軽水炉-再処理シナリオの約1.6倍の13.3円/kWhと試算されるが、今後の研究開発により約6.7円/kWhへの削減が見込まれる。これらの試算によりFBRの経済性目標の妥当性は確認されたが、今後の軽水炉サイクルの動向やFBRサイクルの研究開発の進展に伴い、随時評価を見直していくことが必要である。

The economics of various fuel cycle based on the current domestic situation were evaluated to confirm the adequacy of the economical target of the FBR fuel cycle. Four types of fuel cycle concepts, LWR-once through, LWR-reprocessing, LWR-Pu and FBR, were selected. The unit costs of the fuel cycle components were based on the domestic business base price or estimated values from published construction costs. These setting of the unit costs were the key point of this report. As the results, generating electricity cost of the LWR-reprocessing scenario which was thought to be the domestic reference scenario was estimated to be 8.2 yen/kWh, that of once through scenario was 7.5 yen/kWh, and LWR-Pu scenario was 8.2 yen/kWh. These differences of the generating electricity costs due to the deference of the fuel cycle costs because those three scenario were based on the same reactor concept. The generating electricity cost of the once through scenario is smaller than that of the reprocessing scenario equivalent for the reprocessing cost because that front end costs of the both scenario were equal and spent fuel or waste disposal cost occupied merely small parts of the fuel cycle costs. In the PWR-Pu scenario, natural uranium and enrichment cost were cut down but the fuel cycle cost was the same as the reprocessing scenario due to the relatively high cost of MOX fabrication. On the other hand, though the gcnerating electricity cost of the FBR scenario based on the current technology is 13.3 yen/kWh which is about 1.6 times of that of the LWR reprocessing scenario, its future cost was estimated to be 6.7 yen/kWh which is lower than every LWR scenario results of the future R&D. These economical evaluation showed the adequacy of the economical target of the FBR cycle, it is necessary to improve the evaluation accompanying with the trend of the LWR cycle and the progress of the R&D of the FBR cycle.