Implantable self-powered detector for on-line determination of neutron flux in patients during NCT treatment

The value of the reactor thermal power (RTP) is used in the VVER-1000 control systems in most algorithms for generation of control, blocking and protection signals. Besides, the technical and economic indicators of the power unit are determined by this parameter. Plans to increase VVER‑1000 RTP to 101.5%, and later to 104-107% of the nominal require additional justification of the accuracy of the RTP determination. Therefore, the task of increasing the accuracy of RTP determination is important. The paper describes the ways to improve the accuracy of weighted mean thermal power (WMTP) determination by selecting the optimal weight coefficient (that subsequently is used for WMTP determination) of each of the methods of RTP determination, namely: by thermotechnical parameters of the primary and secondary sides by neutron flux in the in-core monitoring system (ICMS) and in the neutron flux control equipment (NFCE). Another possibility of increasing the accuracy of WMTP determination, namely by increasing the number of methods of RTP determination, is also considered in the paper. The analysis of changes in the background signals of self-powered neutron detectors (SPNDs) during the VVER-1000 fuel campaigns shows the fundamental possibility of using the total background signal as a separate and independent method for RTP determination. The paper presents the results of the calculation of RTP determination error taking into account the coefficients of the components of the total RTP determination error: systematic, dynamic and random errors, which must be determined during the commissioning phase. The results of reduction of the error of WMTP determination in case of application of the additional method of RTP determination based on background signals of the SPNDs are presented. Theoretically, possible minimum values of the WMTP determination error are given depending on the values of the error of the RTP determination by separate methods.

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Fast calibration of CBED patterns for quantitative analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100149209 ◽

1993 ◽

Vol 51 ◽

pp. 674-675

Author(s):

M.A. Gribelyuk ◽

M. Rühle

Keyword(s):

Reciprocal Lattice ◽

Accurate Determination ◽

Incident Beam ◽

Crystal Thickness ◽

Structure Model ◽

Beam Direction ◽

Transmitted Beam ◽

Reciprocal Vector ◽

On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

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