| 摘要 |
<p>The instrument for monitoring of the cooling conditions in the reactor core of a light water reactor includes a probe (2), which is introduced into the reactor vessel and comprises a casing (12) made from a low neutronabsorbing and waterresistant material, a resistor (11) being hermetically enclosed in the casing (12). The resistor (11) is connected to power supply lines (5). The resistance of the resistor (11) is dependent on the temperature of the resistor. The instrument also includes sensing means providing an output signal, which is dependent on the resistance of the resistor (11), when current flows through the same. In a first mode of operation the monitor is used for detection of a reduction or loss of cooling capacity of the coolant surrounding the probe (2). A relatively high power is then supplied to the resistor, and the supplied power is adjusted to match the cooling capacity in such a way, that the heat, which is developed in the resistor as a result of the supplied power, is carried off by the coolant surrounding the probe (2). However, if the cooling capacity by any reason, for example in case of a loss of coolant accident, is reduced, the temperature in the resistor (11) will rise. Since the resistance of the resistor (11) is strongly dependent on the temperature, the resistance is changed and as a consequence the output signal derived from the sensing means is changed.</p> |
