SINBAD ABSTRACT NEA-1517/69
VENUS-3
1. Name of Experiment:
------------------
VENUS-3 LWR-PVS Benchmark Experiment (1988)
2. Purpose and Phenomena Tested:
----------------------------
Mock-up of the pressure vessel internals representative of a 3 Loop Westinghouse
LWR.
Methods to reduce Lead Factor and to improve its prediction were investigated,
taking into account axial source distribution. As proposed for some early built
reactors, at the most critical corners of the core periphery part of the fuel
length was replaced by the Partial Length Shielded Assemblies thus reducing the
Lead Factor at the level of the pressure vessel horizontal welding.
Pin-to-pin pitch was typical for 17x17 PWR fuel assemblies.
The LWR-PVS-BENCHMARK experiment in VENUS was aimed at validating the analytical
methods needed to predict the azimuthal variation of the fluence in the pressure
vessel.
3. Description of the Source and Experimental Configuration:
--------------------------------------------------------
The VENUS Critical Facility is a zero power reactor located at CEN/SCK, Mol
(Belgium).
The Partial Length Shielded Assemblies were loaded at the corners of the
core periphery. The shielded part was obtained by replacing part of the
fuel length by a stainless steel rod. For benchmarking this improvement,
the VENUS-3 core has been built with 3/0-SS rods at the periphery (the
3/0-SS rods were made of half a length of stainless steel and half a length
of 3.3 % U-235 enriched UO2 fuel).
The core is made of 16 "15x15" subassemblies, instead of "17x17" ones
(the pin-to-pin pitch remains typical of the "17x17" subassembly).
The second water gap and the pressure vessel are not simulated; a validation
of the calculation up to the thermal shield was considered as acceptable;
the complete simulation in the radial direction was indeed investigated in
a slab geometry with the PCA mock-up.
Except for the baffle- and the reflector minimum-thickness, the thicknesses
have been somewhat reduced to fit the VENUS geometry.
The angular shape of the core barrel is such that both quadrant and
octagonal symmetries are achieved with acceptable reflecting conditions
(in stainless steel) at 0°, 45° and 90° respectively.
The angular shape of the thermal shield, so-called Neutron Pad was limited
by the available space (it is moreover removable); the quadrant and octagonal
symmetries are also achieved with reflecting conditions in water at 0° and 90°
and with reflecting conditions in stainless at 45°. This geometry was moreover
considered as representative of some BABCOCK & WILCOX designs.
The exact dimensions and the material compositions are given in ven3-exp.htm.
The data were taken from [6].
The power distributions are measured precisely through gamma activity
measurements at the measurement positions shown on ven3-f7.gif.
The relative uncertainty of the neutron fission source with regard to absolute
power is below 4% and the uncertainty of source space distribution is between
1.5% and 4%. The missing points were determined through interpolation procedure
RECOG-ORNL performed at the NEA. The interpolation procedure is described in [7].
The input and output data for the RECOG code are also provided here, see e.g.
recog1.inp and recog1.out. The complete 3-D map of the neutron source power
distribution is given in venus3.src. The corresponding uncertainty estimations,
defined as a difference between the measured values and those calculated by
the RECOG code, are included in venus3.err.
The reference measured fission rate is 8.845E9 (+-4%) fissions/sec/pin/quadrant
and should be used as a multiplication factor for converting the provided
normalised 3D neutron source to the source at 100% power( the total fission
rate value per quadrant was obtained from absolute measurements at several
locations using U-235 miniature fission chambers; this measurement yielded a
value of 5.652E12 fissions per second per core quadrant which then was divided
by 639 pins per quadrant yielding 8.845E9 fissions/sec/pin/quadrant).
4. Measurement System and Uncertainties:
------------------------------------
Measurement locations: the 21° and 45° angles, which correspond to the
maximum - and minimum fast fluxes respectively, were provided with
experimental holes. In particular, access holes were accommodated at 21° and
at the centre with a view to performing neutron- and gamma-spectrometry.
Detectors used: Ni-58(n,p), In-115(n,n') and Al-27(n,alpha) reaction rates were
measured at several points in the reactor. The measurement positions and the
corresponding results are given in venus3.res and r_rates.xls, expressed in
terms of the measured reaction rates. This was preferred to equivalent fission
fluxes since involving only (or to higher degree) the measured values.
If preferred the equivalent fission fluxes can be found in [9] and [11]. Note
however that the equivalent fission fluxes were derived by dividing the reaction
rates by the fission averaged detector cross-sections measured at MOL (see
report of Maerker/ORNL [12]):
Ni-58(n,p): 0.1085 b
In-115(n,n'): 0.1903 b
Al-27(n,alpha): 0.706E-3 b
The above values were used for all the measurement positions in the VENUS-3
reactor.
The literature cites the relative uncertainty of the neutron fission source with
regard to absolute power below 4% and the source space distribution between 1.5%
and 4%. The relative uncertainty of the individual measured reaction rates is
given as 3% and the estimated composite of all measurement uncertainties of the
fission equivalent fluxes is below 5%. However the information related to the
dosimeter activity measurements is not sufficient.
5. Description of Results and Analysis:
-----------------------------------
Calculations were performed by the ANISN, DORT, TORT and MCNP-4 codes. The
analyses performed in the scope of the NEA Nuclear Science Committee organised
blind benchmark intercomparison are described in details in [9] and [10]. The
following computational models using TORT and MCNP4B inputs are included here:
- mcnp4b.inp: MCNP4B input for VENUS-3, provided by J. Marian, Instituto de
Fusion Nuclear (DENIM), Madrid, Spain.
- gipv3.inp, tortv3.inp: input data for the GIP cross-section preparation
(using BUGLE-96 ENDF/B-VI data, not provided here) and TORT 3D transport
calculation, prepared at NEA.
- gip-enea.inp, tort_rtz.inp, tort_xyz.inp: input data for GIP (using BUGLE-96
ENDF/B-VI cross-sections, not provided here), TORT r-theta-z and TORT xyz
calculations, provided by M. Pescarini et al., ENEA Bologna, Italy.
The cross-section sensitivity and uncertainty analysis using the SUSD3D code to
evaluate the neutron flux uncertainties is described in [7] and [8].
6. Special Features:
----------------
None
7. Author/Organizer
----------------
Experiment and analysis:
L. Leenders, A. Fabry, et al.
SCK-CEN, Belgium
Compiler of data for Sinbad:
I. Kodeli
OECD/NEA, 12 bd. des Iles,
92130 Issy les Moulineaux, France
e-mail: ivo.kodeli@oecd.org
Reviewer of compiled data:
8. Availability:
------------
Unrestricted
9. References:
----------
[1] LWR Pressure Vessel Surveillance Dosimetry Improvement Program Review
Meeting, NBS, Maryland, Oct.26-30, 1981: Exploratory calculations
carried out at WESTINGHOUSE, S. ANDERSON in cooperation with
G. GUTHRIE (HEDL).
[2] A. FABRY, VENUS-3 PLSA Conceptual Design Considerations, CEN/SCK Note
AF/sa 380/87-02, Feb.2, 1987
[3] Design Studies of VENUS-3, a Benchmark Experiments of PLSA calculational
procedures to be performed in the VENUS critical Facility at Mol.
[4] LWR Pressure Vessel Surveillance Dosimetry Program "Activities, Status
and Scheduling", March 29-April 2, 1982.
[5] M. L. Williams et al., "Calculation of the Neutron Source Distribution
in the VENUS PWR Mockup Experiment," Proceedings of ehe Fifth
ASTM-EURATOM Symposium on Reactor Dosimetry, Volume 2, 711-718,
Geesthacht, F.R.G., September 24-28, 1984.
[6] L. Leenders, LWR-PVS Benchmark Experiment VENUS-3, Core description
and Qualification, FCP/VEN/01, SCK/CEN, September 1, 1988.
[7] I.Kodeli, E. Sartori, Analysis of VENUS-3 Benchmark Experiment,
Proc. Reg. Meeting on Nuclear Energy in Central Europe, Catez, Slovenia
(Sept. 7-10, 1998)
[8] I. Kodeli, Multidimensional Deterministic Nuclear Data Sensitivity
and Uncertainty Code System, Method and Application,
Nucl. Sci. Eng., 138, 45-66 (2001)
[9] Prediction of Neutron Embrittlement in the Reactor Pressure Vessel,
OECD/NEA report 2000
[10] M. Pescarini, R. Orsi, M.G. Borgia, T. Martinelli, ENEA Nuclear Data
Centre Neutron Transport Analysis of the VENUS-3 Shielding Benchmark
Experiment, Report KT-SCG 00013 (2001)
[11] Bok-Ja Moon, VENUS-3 PWR UO2 Core 3-Dimensional Benchmark Experiment,
IRPhE Project Compilation
[12] R. E. Maerker, Analysis of the VENUS-3 Experiments, NUREG/CR-5338
ORNL/TM-11106, Oak Ridge National Laboratory, August 1989.
10. Data and Format:
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FILE FILENAME bytes Description
---- ------------ ------- ------------------------------------------------
1 ven3-abs.htm 14,579 This information file
2 ven3-exp.htm 42,620 Description of Experiment & material compositions
3 venus3.src 106,782 VENUS3 Neutron Source Distribution
4 venus3.err 106,799 Neutron Source Uncertainty Information
5 venus3.res 19,048 Measured Reaction Rates
6 r_rates.xls 43,008 Measured Reaction Rates
7 mcnp4b.inp 204,478 MCNP4B input (provided by J. Marian, DENIM)
8 gipv3.inp 11,442 GIP Input for XS Preparation (prepared at NEA)
9 tortv3.inp 96,500 TORT Input for 3D Calculation (prepared at NEA)
10 gip-enea.inp 38.560 Input for GIP (provided by M.Pescarini et al., ENEA)
11 tort_xyz.inp 577,080 Input for TORT xyz Calculation (provided by ENEA)
12 tort_rtz.inp 1,535,873 Input for TORT r-theta-z Calc. (provided by ENEA)
13 recog1.inp 30,403 RECOG Input for Source Interpolation (Ax.level 1)
14 recog1.out 141,053 RECOG Output - Source Interpolation (Ax.level 1)
15 recog2.inp 30,403 RECOG Input for Source Interpolation (Ax.level 2)
16 recog2.out 141,053 RECOG Output - Source Interpolation (Ax.level 2)
17 recog3.inp 30,403 RECOG Input for Source Interpolation (Ax.level 3)
18 recog3.out 141,032 RECOG Output - Source Interpolation (Ax.level 3)
19 ven3-f1.gif 53,749 Fig. 1: Vertical cross section of VENUS3 facility
20 ven3-f2.gif 87,408 Fig. 2: Core description (horizontal cross section)
21 ven3-f3.gif 62,764 Fig. 3: Top view of VENUS core
22 ven3-f4.gif 53,398 Fig. 4: Vertical cross sectional view of VENUS3 core
23 ven3-f5.gif 55,325 Fig. 5: VENUS3 model (horizontal cross section)
24 ven3-f6.gif 75,050 Fig. 6: VENUS3 model (vertical cross section)
25 ven3-f7.gif 14,520 Fig. 7: xy coordinates of measured power distribution
26 venus3-6.pdf 934,625 Reference 6
27 catez98.pdf 356,653 Reference 7
28 nea2128.pdf 2,949,681 Reference 9
29 enea.pdf 2,768,257 Reference 10
Figures are included in GIF digitized page image form.
SINBAD Benchmark Generation Date: 02/2004
SINBAD Benchmark Last Update: 02/2004
