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Research Papers: Nuclear Power

# Experimental Comparisons of 3D Reconstructed Pin-Power Distributions in Full-Scale BWR Fuel Assemblies

[+] Author and Article Information
Flavio D. Giust

Paul Scherrer Institute (PSI), Villigen CH-5232, Switzerland; École Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland; Axpo Kernenergie AG, Parkstrasse 23, Baden CH-5401, Switzerland

Peter Grimm

Paul Scherrer Institute (PSI), Villigen CH-5232, Switzerland

Rakesh Chawla

Paul Scherrer Institute (PSI), Villigen CH-5232, Switzerland; École Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland

J. Eng. Gas Turbines Power 133(5), 052909 (Dec 13, 2010) (13 pages) doi:10.1115/1.4002823 History: Received July 09, 2010; Revised July 13, 2010; Published December 13, 2010; Online December 13, 2010

## Abstract

In this paper, reconstructed local fission rates obtained with the two-group nodal diffusion program PRESTO-2 , used at the Leibstadt Nuclear Power Plant (KKL) in Switzerland, are compared with experimental results and MCNPX calculations. The experimental facility consists of a test zone, where the measurements are made, surrounded by a buffer zone and two driver zones that render the system critical and also contain the control rods. The test zone consists of a tank that contains a $3×3$ array of BWR fuel assemblies of type $SVEA-96+$. Four cases are considered, all corresponding to a 1.23 m high active zone moderated with light water at room temperature: (1) axially uniform enrichment and gadolinium content, (2) like case 1 but with an L-shaped control blade completely inserted, (3) enrichment and gadolinium content change at the core midplane, and (4) like case 2 but with the control blade partially inserted. The comparisons give insight into the accuracy of the pin-power reconstruction methodology. The axially uniform case without control blade shows a good radial agreement and a well predicted axial curvature of the flux. On the other hand, systematic deviations are observed in the radial direction for the controlled cases, with the axial heterogeneities causing deviations around the discontinuity and also in the axial curvature of the flux.

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## Figures

Figure 1

Schematic view showing the main components of the LWR-PROTEUS reactor, in particular, the test zone with the 3×3 array of SVEA-96+ fuel assemblies and the L-shaped control blade used in the controlled configurations

Figure 2

Configuration I-1A: radial distribution of (C/E−1)×100, corresponding to MCNPX and PRESTO-2 . The maximum, minimum, and standard deviation are shown in the area representing the central water canal.

Figure 3

Configuration I-1A: axial comparison of calculated total fission rates with measured fission chamber signals at pin position E02. All distributions are normalized to 1.0 over the 22 measured points.

Figure 4

Configuration I-2A: radial distribution of (C/E−1)×100, corresponding to MCNPX and PRESTO-2 . The maximum, minimum, and standard deviation are shown in the area representing the central water canal. The gray bars symbolize the presence of the control blade.

Figure 5

Configuration I-2A: axial comparison of calculated total fission rates with gamma-scan measurements on pin J01 (left hand side) and with signals of a TIP probe facing pin position A01. All distributions are normalized to 1.0 over the corresponding set of measured points (11 and 12, respectively).

Figure 6

Configuration I-1C: 3D comparison of calculated and measured total fission rates at pin positions C10 (axially uniform) and G05 (gadolinium in the upper part only). All distributions are normalized to 1.0 over the complete 3D set of 153 measured points.

Figure 7

Configuration I-1C: 3D comparison of calculated and measured total fission rates at pin positions B09 (axial enrichment change but with axially uniform neighbors) and E08 (axially uniform but with axially nonuniform neighbors). All distributions are normalized to 1.0 over the complete 3D set of 153 measured points.

Figure 8

Configuration I-6A: 3D comparison of calculated and measured total fission rates at pin positions J10 (corner facing the control blade vertex) and A01 (opposite corner). All distributions are normalized to 1.0 over the complete 3D set of 221 measured points.

Figure 9

Configuration I-6A: 3D comparison of calculated and measured total fission rates at pin positions J05 (adjacent to control blade) and J01 (near edge of control blade wing span). All distributions are normalized to 1.0 over the complete 3D set of 221 measured points.

Figure 10

Configuration I-6A: 3D comparison of calculated and measured total fission rates at pin positions E08 and D03, located at the third and seventh row counted from the nearest control blade wing, respectively. All distributions are normalized to 1.0 over the complete 3D set of 221 measured points.

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