Validation of Advanced Computer Codes for VVER Technology: LB-LOCA Transient in PSB-VVER Facility

Table 1

OECD/NEA PSB-VVER project: test matrix.

Number	ID	Test	Main phenomena under investigation	Justification	Note
(1)	UP-11-08	11% upper plenum break”	Break flow; Two-phase natural circulation; Phase separation without mixture level formation; Entrainment in the core; ECCS mixing and condensation; Heat transfer in steam generator; Flow stratification in horizontal pipes; Heat transfer in the covered core; Heat transfer in uncovered core (dryout); Rewet; Thermal-hydraulics in pressurizer	Identification of similarities and differences in processes/phenomena behaviour at ISB-VVER and PSB-VVER (i.e., manifestation of “scaling effect”) and their quantitative characterization	Similar test of the ISB-VVER test
(2)	NC-1	Natural circulation	Single-phase natural circulation; Two-phase natural circulation; Mixture level and entrainment in the core; Heat transfer in steam generator; Heat transfer in covered core; Heat transfer in partly uncovered core; Loop seal clearance	Basic phenomena in transients, need of data in “clean” boundary conditions (outcome of VVER validation matrix).; Recommended by Gosatomnadzor	—
(3)	CL-4.1-03	4.1% cold leg break test	Break flow; Two-phase natural circulation; Asymmetrical loop behaviour; Mixture level and entrainment in the core; ECCS mixing and condensation; Pool formation in the upper plenum; Heat transfer in the covered core; Heat transfer in uncovered core (dryout); Rewet and quenching; Thermal-hydraulics in pressurizer; Loop seal clearance	Relevant bounding case phenomenon. Data lacking, as from recommendation of OECD support group on the VVER validation matrix. Relevant for VVER safety assessment.; Recommended by Gosatomnadzor	Counter-part of LOBI, BETHSY, SPES, and LSTF
(4)	PSh-1.4-04	Primary to secondary leak	Break flow; Two-phase natural circulation; Mixture level and entrainment into SG; Mixture level and entrainment into the core; ECCS mixing and condensation; Pool formation in the upper plenum; Heat transfer in the covered core; Heat transfer in uncovered core (dryout); Heat transfer in steam generator; Thermal-hydraulics in pressurizer; Loop seal clearance	Absence of test data for “primary to secondary leak” (VVER validation matrix). Recommended by Gosatomnadzor. Highly relevant for VVER safety assessment from point of view of radiological consequence	Analytical exercise among project participants (blind test)
(5)	CL-2x100-01	Large cold leg break	Break flow; Asymmetrical loop behaviour; Mixture level and entrainment in the core; ECCS mixing and condensation; CCFL; Pool formation in the upper plenum; Heat transfer in the covered core; Heat transfer in uncovered core (dryout); Quenching; Thermal-hydraulics in pressurizer; Loop seal clearance	Important for safety assessment evaluations, strongly supported by Gosatomnadzor	Benchmark among project participants