Assessment of RELAP5/MOD3/V5M5 against the UPTF Test No. 11 (countercurrent flow in PWR hot leg)
- Siemens AG-KWU Group, Erlangen (DE)
Analysis of the UPTF Test No. 11 using the {open_quotes}best-estimate{close_quotes} computer code RELAP5/MOD3/Version 5M5 is presented. Test No. 11 was a quasi-steady state, separate effect test designed to investigate the conditions for countercurrent flow of steam and saturated water in the hot leg of a PWR. Without using the code`s new countercurrent flow limitation (CCFL) model, RELAP5/MOD3/V5M5 overestimated the mass flow rate of back down flowing water up to 35% (1.5 MPa runs) and 43% (0.3 MPa runs). This is the most obvious difference to RELAP5/MOD2, which did not allow enough countercurrent flow. From the point of view of performing plant calculations this is certainty an improvement, because the new junction-based CCFL option could be used to restrict the flows to a flooding curve defined by a user-supplied correlation. Very good agreement with the experimental data for 1.5 MPa -- which are relevant for SBLOCA reflux condensation conditions -- could be obtained using the code`s new CCFL option in the middle of the inclined part (riser) of the hot leg. Using the same CCFL correlation for the simulation of 0.3 MPa test series -- typical for reflood conditions -- the code underestimated by 44% the steam mass flow rate at which complete liquid carry over occurs. An unphysical result was received using a CCFL correlation of the Wallis type with the intercept C = 0.644 and the slope m = 0.8. The unphysical prediction is an indication of possible programming errors in the CCFL model of the RELAP5/MOD3/V5M5 computer code.
- Research Organization:
- Nuclear Regulatory Commission, Washington, DC (United States). Office of Nuclear Regulatory Research; Siemens AG Unternehmensbereich KWU, Erlangen (Germany)
- Sponsoring Organization:
- Nuclear Regulatory Commission, Washington, DC (United States)
- OSTI ID:
- 10163345
- Report Number(s):
- NUREG/IA--0116; KWU--E412/91/E1002; ON: TI93014893
- Country of Publication:
- United States
- Language:
- English
Similar Records
RELAP5 simulation of the ROSA-IV/LSTF SB-CL-18 test using countercurrent flow limitation modeling
Analysis of the UPTF separate effects Test 11 (steam-water countercurrent flow in the broken loop hot leg) using RELAP5/MOD2
Related Subjects
210200
99 GENERAL AND MISCELLANEOUS
990200
COMPUTERIZED SIMULATION
EXPERIMENTAL DATA
FLOW RATE
LOSS OF COOLANT
MATHEMATICS AND COMPUTERS
POWER REACTORS
NONBREEDING
LIGHT-WATER MODERATED
NONBOILING WATER COOLED
PREDICTION EQUATIONS
PRIMARY COOLANT CIRCUITS
PROGRAMMING
PWR TYPE REACTORS
R CODES
REACTOR ACCIDENTS
REACTOR VESSELS
SPECIFICATIONS
STEAM
WATER