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NESDIP-2 Benchmark Experiment (ASPIS)

1. Name of Experiment:
 NESDIP-2 Benchmark Experiment (ASPIS)

2. Purpose and Phenomena Tested:
 Neutron transport in a shield simulating the radial shield of a PWR,
 including the cavity region and the backing shield.

3. Description of the Source and Experimental Configuration:
 The source is a fission plate constructed of 93% enriched uranium aluminium
 alloy driven by a thermal flux from the extended graphite reflector of the
 NESTOR reactor. The effective radius of the fission plate is 56 cm and the
 thickness 2 mm. The energy spectrum of the source is that of neutrons
 emitted from the fission of U-235. The absolute source strength is
 determined by fission product counting and the spatial distribution via
 detailed low energy flux mapping with activation detectors.
 The shield simulates the radial shield of a PWR and consists of 12.1 cm of
 water, a 6.3 cm stainless steel plate simulating the thermal shield,
 13.2 cm of water, five mild steel plates giving a thickness of 22.8 cm to
 simulate the pressure vessel, a 29.4 cm cavity region and a backing shield
 of aluminium, water and mild steel.

4. Measurement System and Uncertainties:
 The detectors used were:

 Typical Counting Systematic
 Detector Diameter Thickness Mass System Absolute
 (mm) (mm) (g) Calibration
 Rh103(n,n') 12.7 0.015 0.20 NaI 3.0%

 In115(n,n') 38 1.63 12.79 GeLi 1.9%

 S32(n,p) 38.1 2.41 5 Plastic 5.0%
 Pressed Pellet Scintillator

 S32(n,p) 51 5.6 22 Plastic 5.0%
 Cast Pellet Scintillator

5. Description of Results and Analysis:

 Measurements of the reaction rates S32(n,p)P32, In115(n,n')In115m and
 Rh103(n,n')Rh103m were made in activation foils between the mild steel
 plates (reactor pressure vessel region) and in the cavity whilst
 Rh103(n,n')Rh103m measurements were also made in the water regions.

 In addition, during all irradiations of activation detectors within the
 shields, three sulphur pellets were placed in locations at the centre of
 the front face of the fission plate to monitor its run-to-run power via
 the S32(n,p)P32 reaction.

 The results were corrected for the background responses due to the NESTOR
 core. Using the hydrogen filled proportional counters of the TNS system
 the correction was found to be around 2(+/-1)% in the RPV and cavity and
 1(+/-1)% in the water cell.

 Calculations were carried out with the Monte Carlo codes McBEND Version 7B
 [1], [5].

6. Special Features:


7. Author/Organizer
 Experiment and analysis:
 A. Avery, S. Bell, I.J. Curl, G.A. Wright
 AEA Technology
 WINFRITH, Dorchester
 Dorset DT2 8DH

 Compiler of data for Sinbad:
 I. Kodeli
 OECD/NEA, 12 bd des Iles, 92130 Issy les Moulineaux, France

 Reviewer of compiled data:
 A. Avery,
 Reactor Physics, Shielding and Criticality Department, AEA Technology
 WINFRITH, Dorchester
 Dorset DT2 8DH

8. Availability:


9. References:

 [1] A. Avery, AEA-RS-5629, private communication
 [2] M. J. Armishaw, J. Butler, M. D. Carter, I. J. Curl, A. K. McCracken,
 A Transportable Neutron Spectrometer (TNS) for Radiological
 Applications, AEEW-M2365 (1986).
 [3] I. J. Curl,
 CRISP - A Computer Code to Define Fission Plate Source Profiles,
 [4] P. C. Miller,
 A Review of LWR Pressure Vessel Dosimetry and Associated Shielding
 Studies, Proceedings, 7th International Conference on Radiation
 Shielding, Sept. 12-16, 1988, Bournemouth, UK, Vol.1, p.37.
 [5] G. A. Wright, A. Avery, M. J. Grimstone, H. F. Locke, S. Newbon,
 Benchmarking of the JEFF2.2 Data Library for Shielding Applications,
 Proceedings, 8th International Conference on Radiation Shielding,
 April 24-28, 1994, Arlington, Texas, U.S.A., vol.2, p.816.

10. Data and Format:

 Filename Size[bytes] Content
 ---------------- ----------- -------------
 1 nes2-abs.htm 8.007 This information file
 2 nes2-exp.htm 23.538 Description of the experiment
 3 NESD2-1V.TIF 78.510 Figure 1: Cross-section of the shield (high quality)
 4 NESD2-2V.TIF 21.372 Figure 2: Measurement locations (high quality)
 5 NESD2-3V.TIF 116.100 Figure 3: Schematic diagram of fission plate 
   (high quality)
 6 NESD2-4V.TIF 13.786 Figure 4: Fuel element (high quality)
 7 NESD2-5V.TIF 80.340 Figure 5: Disposition of fuel in fission plate 
   (high quality)
 8 NESD2-6S.TIF 648.635 Figure 6: Positioning of the fission plate (high quality)
 9 NESD2-1V.gif 26.444 Figure 1: Cross-section of the shield (preview)
10 NESD2-2V.gif 14.414 Figure 2: Measurement locations (preview)
11 NESD2-3V.gif 23.306 Figure 3: Schematic diagram of fission plate (preview)
12 NESD2-4V.gif 6.995 Figure 4: Fuel element (preview)
13 NESD2-5V.gif 23.589 Figure 5: Disposition of fuel in fission plate (preview)
14 NESD2-6S.gif 21.107 Figure 6: Positioning of the fission plate (preview)
15 NESDIP2.pdf 886.561 Reference
16 aspis_0.pdf 608.178 Reference
17 jef-476.pdf 578.980 Reference on of Experiment

 One table (1) of axial dimensions and (2) of material specifications, one
 table (3) describing the source distribution, and 3 tables (4-6) of the
 measured reaction rates.

 Figures describing the geometry of the experiment are included in
 TIFF4 image format and GIF (preview).