New calculational model for self-powered neutron detector based on Monte Carlo simulation

Figures & data

Figure 1. Configuration of SPND.

Figure 2. Calculation flow of detector sensitivity.

Table 1. Comparison of calculation models.

	This work	Warren	Goldstein	Lee
Neutron energy	Continuous	Mono	Mono	Mono
Self-shielding factor	Monte Carlo	Analytic	Monte Carlo	Monte Carlo
Beta-decay/absorption	BETA-S	Steady state	Steady state	Steady state
Beta-decay spectrum	BETA-S	Analytic	Analytic	Analytic
Electron escape efficiency	Monte Carlo	Analytic	Monte Carlo	Monte Carlo
Space-charge effect	Tabulated data	Tabulated data	Tabulated data	Tabulated data
Photon reactions	Monte Carlo	Analytic	Monte Carlo	N/A

Figure 3. Rhodium decay chain.

Figure 4. Cobalt decay chain.

Figure 5. Configuration of SPND calculation model.

Figure 6. Configuration of emitter tally region and initial source distribution for the tally cell 3.

Figure 7. Normalized intensity distributions.

Figure 8. Rhodium composition change during 10.5 years.

Table 2. SPND specifications.

		Density
Part	Material	(g/cm^3)	Length (cm)	Radius (cm)
	Rh	12.4	40	0.0254
Emitter	V	6.1	40	0.0254
	Co	8.9	40	0.0254
Insulator	Al2O3	1.9	40	0.0508
Collector	Inconel-600	8.44	40	0.1295

Table 3. Mono-energy sensitivity calculation results.

		Sensitivity (A/nv-cm)
Emitter	Escape probability	Photon	Beta-decay	Total
Rh	0.4297	0.098	1.358	1.456
V	0.7025	0.001	0.083	0.084
Co	0.0055	0.019	0.000	0.019

Table 4. Mono-energy sensitivity comparison result.

	Calculated				Measured (A/nv-cm)
Emitter	This work	Warren	Goldstein	Lee	NRX	YGN 3
Rh	1.456	1.310	1.510	0.970	1.200	0.965
V	0.084	0.073	0.087	–	0.077	–
Co	0.019	–	0.011	–	0.016	–

Table 5. Sensitivity comparisons of continuous-energy model and mono energy model.

	CE			ME	Measured (A/nv-cm)
Emitter	Photon	Beta-decay	Total	Delayed	NRX	YGN 3
Rh	0.017	1.027	1.045	1.456	1.2	0.965
V	0.001	0.045	0.046	0.084	0.077	–
Co	0.011	–	0.011	0.019	0.016	–

Table 6. Depletion specification.

Fuel assembly type	CE 16 × 16
Enrichment (wt%)	4.0
Power density (W/g)	36.86
Power/FA (MW/basis)	15.9
Average flux (#/cm^2 sec)	4.1 × 10^13

Figure 9. Vanadium composition change during 10.5 years.

Figure 10. Cobalt composition change during 10.5 years.

Figure 11. SPND beta intensity fraction.

Figure 12. SPND depletion calculation results during 10.5 years.

Figure 13. Sensitivity of cobalt SPND during 10.5 years.

Figure 14. Rhodium SPND sensitivity depletion comparisons.