Development of A Simple Continuous Monitoring System for Possible Fuel Failure in A Pool-type Reactor

一个简单和敏感连续的monitoring system for the possible fuel failure of A pool-typenuclear reactor was successfully developed. Fuel failure detection （FFD）可以制造fission products (EP's) leaking from fuel element containers. In our system，fission rare gases (i - 188 D1Kr, i - 189 D1Kr, i - 188 D1KrD1138 D1Xe) in the cooling water are collected with bubbled nitrogen gas那么他们连续led into a vertical empty column （a decay and extraction chamber）φ 100mm × 2000mm), where they decay to yield daughter nuclides (i D188 D1Rb, i D189 D1Rb，D1138 D1Cs which are extracted to aqueous phase. The radioactivity of daughter nuclides inthe aqueous phase is continuously measured using a flow-through Ge-detector with excellentsignal - to - noise ratios,因为集体fission rare gases are completely isolated from non-volatile backgroundradioactive unclides in the reactor coolant. An only volatile component coming from the coolantar -41,使用bubbled nitrogen gas into the solution containing rubidium and cesiumprior to detection. The new developed continuous FFD system responded with so high sensitivitythat a possible anomalous (twice) change in the concentration of FP rare gases in the coolant wouldbe detected within about 30 minutes using the short-lived D189 D1Kr- D189 D1Rb pair. Inaddition to the above system, we tried to test, as the decay and extraction chambersa packed column, a rotating drum, and a gass -washing bottle, which are less effective in the FFD。

A simple and sensitive continuous monitoring system for the possible fuel failure of a pool-type nuclear reactor was successfully developed. Fuel failure detection (FFD) can be made by the detection of fission products (EP's) leaking from fuel element containers. In our system, fission rare gases (ィイD188ィエD1Kr, ィイD189ィエD1Kr, and ィイD1138ィエD1Xe) in the cooling water are collected with bubbled nitrogen gas, and then they are continuously led into a a vertical empty column (a decay and extraction chamber, φ100 mm × 2000 mm) , where they decay to yield daughter nuclides (ィイD188ィエD1Rb, ィイD189ィエD1Rb, and ィイD1138ィエD1Cs) which are extracted to aqueous phase. The radioactivity of daughter nuclides in the aqueous phase is continuously measured using a flow-through Ge-detector with excellent signal-to-noise ratios, because the collected fission rare gases are completely isolated from non-volatile background radioactive unclides in the reactor coolant. An only volatile component coming from the coolant is Ar-41, which is easily removed with bubbled nitrogen gas into the solution containing rubidium and cesium prior to detection. The newly developed continuous FFD system responded with so high sensitivity that a possible anomalous (twice) change in the concentration of FP rare gases in the coolant would be detected within about 30 minutes using the short-lived ィイD189ィエD1Kr-ィイD189ィエD1Rb pair. In addition to the above system, we tried to test, as the decay and extraction chambers, a packed column, a rotating drum, and a gas-washing bottle, which are less effective in the FFD.