SINBAD ABSTRACT NEA-1517/55
SBE 15.001
US NRC Benchmark
1. Name of Experiment: Pool Critical Assembly-Pressure Vessel Facility Benchmark (1980) 2. Purpose and Phenomena Tested: The PCA Benchmark purpose was to validate the capabilities of the calculational methodology to predict the reaction rates in the region outside a reactor core when the neutron source, material compositions, and geometry are well defined. The PCA facility mocked-up the core-to-cavity region in an LWR. 3. Description of the Source and Experimental Configurations: The PCA Source was composed of 25 material test reactor (MTR) new fuel elements, with a 93% U235 enrichment. The light-water moderated reactor core contained fuel plates of 62.548-cm-length and arranged in approximately 40-cm-square. The core contained 4 control assemblies for reactivity control. The power distribution of the fuel elements were obtained from fission chamber measurements and calculations. The core power is symmetric, therefore only 1/2 the core needs to be specified. Individual fuel element powers are provided by a two- dimensional distribution function. The PCA mockup consists of stacked slabs of the following: 1)aluminum window simulator 2)Thermal Shield 3)Pressure Vessel Simulator 4)Pressure Vessel Cavity Simulator (Void). Water filled the gaps between the slabs of materials. 4. Measurement Systems and Uncertainties: The measurements were made with Np237 and U238 fission chambers and Rh103, In115, Ni58, and Al27 activation dosimeters at the core midplane. The positions included key reactor capsule locations of 1/4 T, 1/2T, and 3/4T of the RPV. The experimental access tubes allowed centralized placement of dosimeters and were filled with a similar material that surrounded each tube to minimize flux perturbations. All fuel element specifications are within +/- 0.1 cm (2 sigma), and the experimental configuration is within +/-0.2 cm (2 sigma) of the specified dimensions. The as-built and plan design specifications for the 12/13 experiment show differences of up to 0.4 cm for material placement. The uncertainties for the measured equivalent fission fluxes are between 6 and 10%. 5. Description of Results and Analysis: The measurements are reported at distances from the aluminum window simulator of 12, 23.8, 29.7, 39.5, 44.7, 50.1, and 59.1 cm. All reaction rate measurements are converted to Equivalent Fission Fluxes and normalized to the core neutron source strength of 1 n/s. The reaction cross sections, averaged over U235 fission spectrum are provided. Only the 12/13 results are provided here (12 cm water between aluminum window and thermal shield, 13 cm water between thermal shield and pressure vessel) 6. Special Features: None 7. Author/Organizer: Experiment and analysis: W. N. McElroy, et al. Compiler of data for SINBAD: Hamilton Hunter, Radiation Shielding Information Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6362, fax 423-574-6182, e-mail h3o@ornl.gov. Reviewer of compiled data: I. Remec, Nuclear Analysis and Shielding Section, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6363. 8. Availability: Unrestricted 9. References: [1] I. Remec and F. B. K. Kam "Pool Critical Assembly Pressure Vessel Facility Benchmark," NUREG/CR-6454 ORNL/TM-13205 1997. [2] W. N. McELroy, ed., "LWR Pressure Vessel Surveillance Dosimetry Improvement Program:PCA Experiments and Blind Test," NUREG/CR-1861 (HEDL-TME 80-87 R5), July 1981. [3] Personal Communication with I. Remec, June, 1998. 10. Data and Format: Tables: (1) PCA Fuel Element Position, (2) PCA Core Dimensions, (3) Dimensions of PCA ex-core components, (4) Material compositions for PCA ex-core components Figures: Fig. 1 PCA Facility, Fig. 2 PCA plan view, Fig. 3 PCA elevation, Fig. 4 Fuel element position, Fig. 5 Fuel cell boundary/aluminum window Fig. 6 Fuel element Fig. 7 Fuel side plates Fig. 8 Fuel plates Fig. 9 Control rod Fig.10 PCA measurement coordinate system Fig.11 1/2 core integral power density Fig.12 1/4 core normalized measured power densities Fig.13 PCA Detector results Document is HTML v.3.02 Format with ASCII Tables and Figures in GIF format. Abstract Generation Date: 06/98 Abstract Last Update: 08/98