1. Name of Experiment:
 ------------------
 JANUS Phase 1 (1986)

2. Purpose and Phenomena Tested:
 ----------------------------
 Neutron transport in regions of mild steel and stainless steel. The
 purpose was to test the prediction of neutron penetration through
 stainless steel when the incident spectrum was typical of that
 emerging from a fast reactor.

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 fission plate is followed by steel plates which give
 thicknesses of 17.85 cm mild steel, 40.39 cm stainless steel, and
 56.72 cm mild steel. The initial region of mild steel modifies the
 spectrum of neutrons incident upon the stainless steel to make it
 closer to that leaving a fast reactor. The array has a 61 cm thick
 biological shield of concrete behind this.

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

 Typical Counting Systematic
 Detector Diameter Thickness Mass System Absolute
 (mm) (mm) (g) Calibration
 (uncertainty)
 ----------------------------------------------------------------------
 Mn55(n,g)/Cd 12.7 0.15 0.12 NaI 1.5%

 Au197(n,g)/Cd 12.7 0.05 0.12-0.13 NaI 0.9%

 Rh103(n,n') 12.7 0.015 0.20 NaI 3.0%

 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
 ----------------------------------------------------------------------

 The Mn and Au foils were contained in cadmium boxes of thickness
 0.05 inches.

 In addition neutron spectrum measurements were made at three locations
 with three hydrogen proportional counters and an NE213 scintillator.


5. Description of Results and Analysis:
 -----------------------------------

 Measurements of the reaction rates for S32(n,p)P32, Rh103(n,n')Rh103m,
 Mn55(n,g)Mn56 Under Cd, and Au197(n,g)Au198 Under Cd were made at
 intervals of approximately 4.5cm through the stainless steel, and 5.1cm
 in the regions of mild steel. Lateral scans were made with sulphur,
 rhodium, and gold at selected positions.

 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 fast neutron spectra (E>52.5keV) were measured at three locations
 within the region of stainless steel. The reaction rates for S(n,p)
 and Rh(n,n') as derived from the spectra are compared with those
 measured directly.

 The results were corrected for the background responses due to the NESTOR
 core. For the low energy detectors measurements were made with the plate
 fuelled and unfuelled. For the threshold detectors the hydrogen
 filled proportional counters of the TNS system were used in conjunction
 with the boral shutter for Cave C at NESTOR. For the low energies the
 background varied from 19% close to the fission plate to 2% at deep
 penetrations. For the threshold detectors the corrections were small
 being typically 1% to 3%.

 Calculations were carried out with the Monte Carlo code McBEND Version 9B
 [4], [5].

6. Special Features:
 ----------------

 None

7. Author/Organizer
 ----------------
 Experiment and analysis:
 I.J. Curl, A K McCracken, P C Miller
 AEA Technology
 WINFRITH, Dorchester
 Dorset DT2 8DH
 UK

 Compiler of data for Sinbad:
 A. Avery,
 Performance and Safety Services Department,
 AEA Technology
 WINFRITH, Dorchester
 Dorset DT2 8DH
 UK

 Reviewer of compiled data:
 I. Kodeli
 OECD/NEA, 12 bd des Iles, 92130 Issy les Moulineaux, France


8. Availability:
 ------------

 Unrestricted

9. References:
 ----------

 [1] 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).
 [2] I. J. Curl,
 "CRISP - A Computer Code to Define Fission Plate Source Profiles",
 RPD/IJC/934.
 [3] J. Butler et al.
 "The PCA Replica Experiment, Part 1. Winfrith Measurements and
 Calculations", AEEW-R1763
 [4] Wright G. A., Curl I. J., Hoare C. J., McCracken A. K., Miller P. C,
 and Ziver A. K., "Monte Carlo Sensitivity Analysis of Winfrith
 Benchmark Experiment using JEF-1 Cross-Sections", Proceedings of the
 7th International Conference on Radiation Shielding, Bournemouth, p725,
 Sept. 1988.
 [5] Curl I. J., Calamand D., and Muller K. I., "The Role of the JANUS
 Experimental Shielding Programme in the Assessment of the Shielding
 Methods Employed for EFR", New Horizons in Radiation Protection and
 Shielding - ANS Topical Meeting, Pasco, p345, April 1992.
 [6] A. Avery, JANUS Phase 1 Benchmark Experiment Data for Inclusion in
 the SINBAD Database, Jan. 1998

10. Data and Format:
 ---------------

 DETAILED FILE DESCRIPTIONS
 --------------------------
 Filename Size[bytes] Content
 ---------------- ----------- -------------
 1 jan1-abs.htm 11.065 This information file
 2 jan1-exp.htm 34.633 Description of Experiment
 3 MCBEND.inp 301.814 Input Data for McBEND M/C Code
 4 FIG1.TIF 135.496 Figure 1: The ASPIS Mobile Shield Tank in the NESTOR 
   Cave C (high quality)
 5 FIG2.TIF 178.240 Figure 2: Schematic Side Elevation of the Experimental 
   Shield of the JANUS Phase 1 in the ASPIS Trolley (high quality)
 6 FIG3.TIF 156.226 Figure 3: The Enriched U/Al Alloy Fission Plate (high quality)
 7 FIG4.TIF 203.604 Figure 4: Details of the Fuel Loading Pattern When Viewed
   Looking Towards the NESTOR Cave (high quality)
 8 FIG5.TIF 153.738 Figure 5: The Individual U/Al Alloy Fuel Element 
   (high quality)
 9 FIG6.TIF 176.778 Figure 6: The Fuel Element Configuration and Manganese 
   Foil Positions (high quality)
10 FIG7.TIF 117.838 Figure 7: Mesh Boundaries for the Fission Plate Source 
   (high quality)
11 FIG8.TIF 130.445 Figure 8: Location of Fission Discs in the Demountable 
   Fuel Element (high quality)
12 FIG9.TIF 287.269 Figure 9: Measurement Locations for JANUS Phase 1 
   (high quality)
13 FIG10.TIF 121.929 Figure 10: A Schematic for the Arrangement of the 
   Spectrometer at the Measurement Locations (high quality)
14 FIG1.gif 19.324 Figure 1: The ASPIS Mobile Shield Tank in the NESTOR 
   Cave C (preview)
15 FIG2.gif 24.192 Figure 2: Schematic Side Elevation of the Experimental 
   Shield of the JANUS Phase 1 in the ASPIS Trolley (preview)
16 FIG3.gif 17.999 Figure 3: The Enriched U/Al Alloy Fission Plate (preview)
17 FIG4.gif 20.477 Figure 4: Details of the Fuel Loading Pattern When Viewed 
   Looking Towards the NESTOR Cave (preview)
18 Fig5.gif 16.245 Figure 5: The Individual U/Al Alloy Fuel Element (preview)
19 Fig6.gif 23.546 Figure 6: The Fuel Element Configuration and Manganese 
   Foil Positions (preview)
20 Fig7.gif 12.619 Figure 7: Mesh Boundaries for the Fission Plate Source 
   (preview)
21 Fig8.gif 13.990 Figure 8: Location of Fission Discs in the Demountable 
   Fuel Element (preview)
22 Fig9.gif 28.184 Figure 9: Measurement Locations for JANUS Phase 1 (preview)
23 Fig10.gif 19.648 Figure 10: A Schematic for the Arrangement of the Spectrometer
   at the Measurement Locations (preview)
24 janus1.pdf 2.172.714 Reference

 File JAN1-EXP.HTM contains the following tables:
 One table (1) of axial dimensions and (2) of material specifications, two
 tables (3 & 4) describing the source distribution, one table (5) of the
 measured reaction rates, four tables (6-9) showing the lateral scans,
 and three tables (10-12) giving the measured spectra.

 Figures describing the geometry of the experiment are included in
 TIFF5 compressed and GIF (preview) format .