Die Rauschthermometrie als Temperaturmeßmethode in Kernreaktoren
Die Rauschthermometrie als Temperaturmeßmethode in Kernreaktoren
Noise thermometry has been developed and tested as a measuring method for precise and reliable temperature measurements in nuclear reactors. In contrast to the thermometers which have been used up to now (thermocauples, resistance thermometers, etc .), the noise thermometer is independent of all env...
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Personal Name(s): | Brixy, H. (Corresponding author) |
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Contributing Institute: |
Publikationen vor 2000; PRE-2000; Retrocat |
Imprint: |
Jülich
Kernforschungsanlage Jülich, Verlag
1972
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Physical Description: |
124 p. |
Document Type: |
Report Book |
Research Program: |
ohne Topic |
Series Title: |
Berichte der Kernforschungsanlage Jülich
885 |
Link: |
OpenAccess |
Publikationsportal JuSER |
Noise thermometry has been developed and tested as a measuring method for precise and reliable temperature measurements in nuclear reactors. In contrast to the thermometers which have been used up to now (thermocauples, resistance thermometers, etc .), the noise thermometer is independent of all envirenmental influences, such as reactor radiation er atmosphere . It is independent of its previousthermal and mechanical treatment and of the material used . Consequently, the noise thermometer retains its initial precision even after anly length of application time . Thisproperty is important for the applieation in nuclear reactors requiring Jong periods of exposure. Noise thermometry is based an the Nyquist theorem of thermal noise. Avcording to this theorem, a statistically fluctuating voltage, the mein square of which is proportional to the absolute temperature, is generated aeross the terminals of a passive unloaded network . The amplitude of the noise voltage lies in the range of 10$^{-7}$ and 10$^{-6}$ V. In order to avoid the difficulties of an absolute measurement of these 1ow voltages, a comparison method is being used, which, at the same time, has been developed as Zero method. The noise voltages of two resistors, one being at the unknown temperature and the other at a reference temperature, are being compared, Tf the noise voltages of both resistors are equal, the quotient of the resistance determines the quotient of the absolute temperatures. []wring the firnt noise temperature measurements in the laboratory, the electronic measuring equipment was tested. Nereby, an accuracy of 0 .1 % could be reached in the range of 300 K and 1200 K . Noise temperature measurement were carried out in fuel element positions in the FRJ-2, and it was experimentally proved that even an intense reactor radiation does not influence the function of the noise thermometer . Pur these measurements, a fuliy transistorized measuring equipment had been used, in which the noise of the amplifier was eliminated by Gross correlation . The measuring sensor was heated up by the gamma radiation of the reactor, and the temperature could be varied within certain Limits by the gas supply of the measuring rig. The thermal neutron flux at theux sensor position amounted to 6 x 10$^{13}$ nv and the gamma fl amounted to 2,5 . 10$^{8}$ R/h. A series of measurements was carried out in the range of 300 K and 500 K where all the noise temperatures were within the range of a calibration accuracy of 0 .5 % of the referencethermocouples. At the end of the experiment (duration : 3 reactor periods), the noise thermometer had been expnsed to an integral thermal, neutron flox of 3 x 10$^{20}$ nvt,and the noise resistance had changed by 6 %. The operating capacity of the noise thermometer had, of course, not been impaired in any way by this process. The experiment has also shown that the noise thermometer is applicable even at long distances between thermometer and amplifier (in our Gase 15 m} and in an environment with intense electro-magnetic interference fields. Noise thermometry can therefore be used as a measuring method under rough conditions in nuclear reactors . |