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Protvino concrete labyrinth benchmark (ALARM-CF-AIR-LAB-001)

A californium-252 neutron source of intensity $5.66 \cdot 10^8$ n/s is located on entrance to a 3-section concrete labyrinth [1]. The goal is computation of spatial distribution of a neutron flux linear functional which relates to the Bonner sphere detector count rates. Those are considered Case 5A (2 polyethylene plates in 2nd section) and Case 6B (covered source and dead-end).

Computed flux functional - pulse rate by the detector response function is taken from the benchmark data for the case of 5 in. Bonner polyethylene sphere diameter.


Figure 1: Horizontal cross-section of Case 5A model


Figure 2: Horizontal cross-section of Case 6B model

Thicknesses of volumetric detectors are equal to 10 cm. Results of the two 11.2 hours computations, ran concurrently, are performed in Figures 3-5.


Figure 3: Global plot of count rates spatial distribution for Case 5A, pulse/sec


Figure 4: Local plot of count rates spatial distribution for Case 5A, pulse/sec


Figure 4: Plot of count rates spatial distribution rates for Case 6B, pulse/sec

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References

Mark Nikolaev, Natalia Prokhorova, Tatiana Ivanova, “Neutron Fields in Three-Section Concrete Labyrinth from Cf-252 Source,” ALARM-CF-AIR-LAB-001, “International Handbook of Evaluated Criticality Safety Benchmark Experiments,” OECD Nuclear Energy Agency, NEA-1486/19, 2021 (DVD).