IEC 61501:1998 pdf download – Nuclear reactor instrumentation – Wide range neutron fluence rate meter -Mean square voltage method

IEC 61501:1998 pdf download – Nuclear reactor instrumentation – Wide range neutron fluence rate meter -Mean square voltage method.
IEC 61501 applies to instrument and measurement channels which generate a calculation of the mean square voltage (MSV) of a signal arising from a neutron detector, in order to extract from it information relating to the neutron I luence rate of a nuclear reactor. After calibration, this information can be used to derive the relative power and the time constant, for example expressed In terms of period, doubling lime, decades per minute or percent per second.
The method used to calculate the mean square voltage of the signal is also known as “fluctuation treatment” or “the Campbell method”.
Associated with other techniques of measurement, such as pulse rate counting or current measurement, the calculation of the mean square voltage allows the assembly of a series of wide range neutron I luence rate measurements for the simplification of nuclear Instrumentation systems in the control of nuclear reactors.
This standard describes the principles, the terminology, the characteristics, the requirements and the testing methods related to Instrumentation and measurement of the neutron Iluence rate using MSV techniques for nuclear reactor control.
Typical examples of the application of the MSV techniques are given.
2 NormatIve references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions Indicated were valid. All normative documents are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 60050(101)1998, International Electrotechnical Vocabulary (1EV) — Part 101: Mathematics
IEC 60050(393):1996, International Electrotechnical Vocabulary (1EV) — Chapter 393: Nuclear instrumentation: Physical phenomena and basic concepts
IEC 60050(394):1 995, International Electrotechnical Vocabulary (1EV) — Chapter 394. Nuclear instrumentation: Instruments
IEC 60359:1987. Expression of the performance of electrical and electronic measuring equipment
IEC 60527:1975, Direct current amplifiers: characteristics and test methods
lEG 60650:1979, Analogue counting ratemeters — Characteristics and test methods
IEC 60880:1986, Software for computers In the safety systems of nuclear power stations
3 Definitions
For the purpose of this International Standard, the definitions given in IEC 60050(101), IEC 60050(393) and 60050(394). as well as the following apply.
NOTE — The prInciple of the method Is based on tne variations analysts 01 the output of a detector and amplIfier channel Thee. variations have many origins: the pulses induced by the reactions of detection and the perlurbationa internal or external to the channel To ensure clarity in the document. the terms which characterize the origin of the signal are detined. Generally the term nolse retera to the e.ignal variations linked to the pertuibations.
3.1
fluctuations
random variations of a physical quantity around its mean value
NOTE – In this standard, ‘lluctuations means the vanatmons of the measured signal induced by ionizing plmenorrmena inside the detector These variations are produced by the gamma radiation, by the alpha emission of the sensitive coaling or by the neutron reactions induced in the coating. Far the considered applications omy, the fluctuations from neutron reactions are useful
electronic noise
variation of a signal produced by the thermal agitation of the components of the electronic circuits. it is an internal perturbation of the measuring channel.
system noise
all variations of the signal with an origin external to the measuring channel
3.4
white noise
random process whereby the power density spectrum is constant and independent of the frequency
3.5
Poisson process
process defined according to the three following hypotheses:
— the number of events noted in a time interval T is independent of time and tndependent of any events which have already occurred;
— the probability of having one event, and one only. in a time interval T is proportional to T when T —. 0;
— the probability of having more than one event in a time interval T tends towards 0 faster than Twhen T —, 0.