Analysis of an Advanced Test Reactor Small-Break Loss-of-Coolant Accident with an Engineered Safety Feature to Automatically Trip the Primary Coolant Pumps

2000 ◽  
Vol 132 (1) ◽  
pp. 167-178 ◽  
Author(s):  
Steven T. Polkinghorne ◽  
Cliff B. Davis ◽  
Richard T. McCracken
Keyword(s):  
Primary Coolant ◽  
Safety Feature ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant ◽  
Test Reactor

Lower Plenum Voiding

1982 ◽  
Vol 104 (3) ◽  
pp. 479-486 ◽  
Author(s):  
D. Bharathan ◽  
G. B. Wallis ◽  
H. J. Richter
Keyword(s):  
Reactor Core ◽  
Reactor Vessel ◽  
Pressurized Water Reactor ◽  
Coolant Circuit ◽  
Two Phase ◽  
Primary Coolant ◽  
Pressurized Water ◽  
The Core ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant

One of the phenomena involved in a loss-of-coolant accident in a pressurized water reactor may be lower plenum voiding. This might occur during the blowdown phase after a cold-leg break in the primary coolant circuit. Steam generated in the reactor core may flow out of the bottom of the reactor core, turn in the lower plenum of the vessel, in a direction countercurrent to the emergency core coolant flow, and escape via the break. If its velocity is high enough, this steam may sweep water from the bottom (lower plenum) of the reactor vessel. Emergency coolant added to the vessel may also be carried out by the escaping steam and thus the reflooding of the core would be delayed. This paper describes a study of two-phase hydrodynamics associated with lower plenum voiding. Several geometrical configurations were tested at three different scales, using air to simulate the steam. Comparisons were made with data obtained by other researchers.

ATHLET Analysis of OECD/NEA ROSA-2 Test 7 Experiments on Intermediate-Break LOCA at Cold Leg

2013 ◽  
Author(s):  
Zheng Du ◽  
Xiaoliang Fu ◽  
Nan Yu ◽  
Lifang Liu ◽  
Zhen Cao ◽  
...  
Keyword(s):  
Large Scale ◽  
Flow Model ◽  
Test Facility ◽  
One Dimension ◽  
Primary Coolant ◽  
The Core ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant ◽  
Post Test ◽  
Scale Test

Test 7 intermediate-break loss-of-coolant accident (IBLOCA) with 13% break at cold leg was conducted in OECD/NEA ROSA-2 Project using Large Scale Test Facility (LSFT). In this test, auxiliary feedwater was assumed to fail and all safety injection was injected only into the intact loop. Core started to dryout when break valve opened. Liquid level in the core dropped rapidly before loop seal clearing (LSC). ATHLET Mod 2.1 Cycle A was used in the post-test analyses of this LSTF experiment. A basis model with two primary coolant loops, one group steam generator U-tube, and three channels in core was built to simulate this test. One dimension finite critical flow model was employed to simulate a nozzle type break with an over predicted result. The major calculated parameters were compared with the test data, and the overall trend of the test was well calculated by the code, it reveals that ATHLET model could predict such IBLOCA with reasonable results.

scholarly journals A Study of Prediction Model Improvement for Air-Oxidation Breakaway in a Postulated Spent Nuclear Fuel Pool Complete Loss of Coolant Accident

2021 ◽  
Vol 13 (3) ◽  
pp. 1442
Author(s):  
Sanggil Park ◽  
Jaeyoung Lee ◽  
Min Bum Park
Keyword(s):  
Kinetic Model ◽  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Complete Loss ◽  
Air Oxidation ◽  
Loss Of Coolant Accident ◽  
Spent Nuclear Fuel Pool ◽  
Loss Of Coolant ◽  
Model Derivation ◽  
Model Improvement

The temperature of zirconium alloy cladding on the postulated spent nuclear fuel pool complete loss of coolant accident is abruptly increased at a certain time and the cladding is almost fully oxidized to weak ZrO2 in the air. This abrupt temperature escalation phenomenon induced by the air-oxidation breakaway is called a zirconium fire. Although an air-oxidation breakaway kinetic model correlated between time and temperature has been implemented in the MELCOR code, it is likely to bring about unexpected large errors because of many limitations of model derivation. This study suggests an improved time–temperature correlated kinetic model using the Johnson–Mehl equation. It is based on that the air-oxidation breakaway is initiated by the phase transformation from the tetragonal to monoclinic ZrO2 at the oxide–metal interface in the cladding. This new model equation is also evaluated with the Zry-4 air-oxidation literature data. This equation resulted in the almost similar air-oxidation breakaway timing to the actual experimental data at 800 °C. However, at 1000 °C, it showed an error of about 8 min. This could be inferred from the influence of the ZrN phase change due to the nitrogen existing in air.

Analysis of loss of coolant accident without ECCS and DHRS in an integral pressurized water reactor using RELAP/SCDAPSIM

2021 ◽  
Vol 134 ◽  
pp. 103648
Author(s):  
Katarzyna Skolik ◽  
Chris Allison ◽  
Judith Hohorst ◽  
Mateusz Malicki ◽  
Marina Perez-Ferragut ◽  
...  
Keyword(s):  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant

Analysis of the small break loss of coolant accident in the VVER-1000/V446 reactor

Kerntechnik ◽  
2015 ◽  
Vol 80 (6) ◽  
pp. 545-556
Author(s):  
S. M. Altaha ◽  
M. Mansouri ◽  
G. Jahanfarnia
Keyword(s):  
Loss Of Coolant Accident ◽  
Loss Of Coolant
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