Experimental studies on the upward fuel discharge for elimination of severe recriticality during core-disruptive accidents in sodium-cooled fast reactors

Figures & data

Figure 1. Schematics of event sequences for CDA.

Figure 2. Concept of FAIDUS designs.

Figure 3. Schematic of experimental devices for out-of-pile series tests.

Table 1. Initial conditions for out-of-pile tests.

		Pressure difference between
	Mass of alumina in the	the core-simulating vessel	Sodium temperature in the inner
Test No.	core-simulating vessel (kg)	and the upper vessel (MPa)	duct/the upper vessel (K)
2	5.6	0.48	660/650
3	5.8	0.31	680/600
4	5.9	0.04	640/640

Note: Test 1 was the first trial and some modifications for the test device were made based on results of test 1.

Figure 4. Schematic of the experimental device for the in-pile test.

Figure 5. Realized energy insertion history.

Figure 6. Sensors arrangement and measured data in test 3.

Figure 7. Measured data below the core-simulating vessel in test 3.

Figure 8. Solidified alumina distributions after test 3.

Table 2. Summary of the experimental results.

		Masses of solidified alumina (kg)^a
Test No.	Discharge duration (s)	Core-simulating vessel	Crust on the discharge duct	Upper vessel
2	0.7	3.6	0.2	1.6
3	1.4	2.6	1.4	1.1
4	3.6	4.4	0.6	0.6

^aThe core-simulating vessel has an exhaust line to release an over-pressure event and a sodium drain line. Masses of solidified alumina found in these lines were not included in this table, and, therefore, there are differences between “Mass of alumina in the core-simulating vessel” in Table 1 and summations of “Masses of solidified alumina” in this table.

Figure 9. An interpreted sequence of the upward melt discharge.

Figure 10. Measured data in the in-pile test.

Figure 11. Power transient used to evaluate the required flow rate of molten fuel.

Figure 12. Model to evaluate the required flow rate of molten fuel.

Figure 13. Required flow rates for molten fuel through the inner duct and the time difference between failures of the wrapper tube and the inner duct.

Figure 14. Average flow rates predicted from the out-of-pile and in-pile tests.

Figure 15. Prediction of average flow rates to supposed CDA conditions.