パルス超音波を用いた軽水炉用ハイブリッド型給水流量計の開発

Development of hybrid feed water flow rate measurement system for light water reactors of nuclear power plants using pulse Ultrasound

研究課題番号:15360501

代表者

  • 2003年度~2005年度

    • 木倉 宏成
    • KIKURA, Hiroshige
    • 研究者番号:00302985
    • 東京工業大学・原子炉工学研究所・助手


研究分担者

    • 森 治嗣
    • 東京電力(株)・技術開発研究所・熱流動/流体構造技術グループ・グループマネージャー(研究職)
    • 小池 義和
    • KOIKE, Yoshikazu
    • 研究者番号:30251672
    • 芝浦工業大学・工学部二部電気工学科・助教授
    • 有冨 正憲
    • ARITOMI, Masanori
    • 研究者番号:60101002
    • 東京工業大学・原子炉工学研究所・教授

研究課題基本情報(最新年度)

  • 研究期間

    2003年度~2005年度

  • 研究分野

    原子力学

  • 審査区分

    一般

  • 研究種目

    基盤研究(B)→基盤研究(B)→基盤研究(B)

  • 研究機関

    東京工業大学

  • 配分額

    • 総額:15400千円
    • 2003年度:7800千円 (直接経費:7800千円)
    • 2004年度:4600千円 (直接経費:4600千円)
    • 2005年度:3000千円 (直接経費:3000千円)

研究概要(最新報告)

本研究ではハイブリッド型超音波流速法を,軽水炉の給水流量計として開発することを目的として,信号処理の改良と実機適用性を検討しながらシステムを構築することを目的とし,以下の知見を得た.

1.現有の超音波流速分布流速計(UVP model X3PSi 2,4,8MHz)のマルチプレクサー・モードと複数超音波センサを用いた流速分布からの流量計測システム・ソフトウェアを開発した.

2.超音波の金属壁透過では最適周波数は壁の材質,厚さおよびセンサの設置角度などに依存するため,超音波透過の基礎実験装置を構築して超音波透過特性を調べた.これに伴い液体および固体壁内の音速測定,超音波透過率測定,混入粒子の選定,測定線屈折の測定および最適入射角の選定を行った.

3.本実験必要な試験流路および測定部を製作した.試験流路は直径50mmのアクリル製・直円管を用いた上昇流および下降流の垂直円管流路である.

4.現行の超音波流速分布流速計と現有の超音波パルサ・レシーバを用いて,伝播時間差型超音波流量計のプロファイルファクタを決定するシステムを構築した.

5.ハイブリッド用の超音波センサの仕様を検討し,音響インピーダンスや入射角を考慮して有限要素法による音場解析を行った上で,高温高圧実機対応型超音波センサを検討・開発し,高温条件下での実機適応性を検討した.

6.パルス超音波信号処理装置と高速デジタル信号処理装置を用いてハイブリッド型超音波流速計のシステム設計を行った.

7.実験および解析結果を総合的に検討し,パルス超音波を用いた軽水炉用ハイブリッド型給水流量計を確立した.

A new feed water flow rate measurement system for light water reactors of nuclear power plants using pulse Ultrasound has been developed for a new type of flow metering system. This new system is a hybrid of the time-of-flight (TOF) type ultrasonic flowmeter and the ultrasonic velocity profile type flowmeter with the advantages of these two types. Our final purpose is to apply the hybrid ultrasonic flow metering system to an accurate flow rate measurement of feed- water in nuclear power plants. The ultrasonic velocity profile type flowmeter called the UDM flowmeter is based on the pulse ultrasonic Doppler method (UDM) which has the capability to obtain instantaneous velocity profiles along an ultrasonic beam. The principle of the UDM flow metering system is based on the integration of an instantaneous velocity profile over a pipe diameter. The multi-beam system is expected to eliminate installation problems such as entry length, and also to follow transient flow rate precisely by increasing the number of ultrasonic transducers. However, it needs reflectors for receiving ultrasonic Doppler signals. On the other hand, the TOF ultrasonic flow metering system does not need any reflector, but it needs profile factors (PFs) which depend on velocity profiles. PF is one of the important experimental coefficients for the accurate flow rate measurement. Therefore PFs must be corrected according to the changes in flow conditions. In the present study, we investigated to what degree the hybrid ultrasonic flow metering system can correct the profile factors of TOF ultrasonic flow meters by using the UDM.

As results, the laboratory experiments appeared that for fully developed flow condition an accurate measurement of flow rate was achievable using only a single measuring line, and additionally, for non developed flow which is located just below the bend pipe the multi-lines method was successfully applied and the errors were less than 1%. The reflector of ultrasound was obtained very efficiently using ultrasonic cavitation bubbles. Even for the metallic wall pipe, it was appeared that cavitation bubbles were available to measure the instantaneous velocity profile and the flow rate accurately compared with using nylon powder. As mentioned above, it is indicated that the present multi-lines flow metering system by using ultrasonic Doppler method has very high accuracy under non-ideal flow conditions such as non-developed flow or non-axis-symmetric flow. And we constructed the basic system of a flow rate measurement in power plants using metallic pipes and cavitation bubbles as ultrasound reflectors. And according to the results of this experiment, deviation of PFs could be around 2-6% at maximum, which directly affects the estimation of flow rates. However by calibration with UDM measurement PFs could be better within ±1%.

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http://kaken.nii.ac.jp/d/p/15360501.ja.html