An analysis of In-Vessel Melt Retention strategy for VVER-1000 considering the effect of torospherical lower head vessel

2021 ◽  
Vol 371 ◽  
pp. 110972
Author(s):  
Manh Long Doan ◽  
Van Thai Nguyen ◽  
Chi Thanh Tran
Keyword(s):  
Retention Strategy ◽  
Lower Head

Factors driving changes to remuneration policies in South Africa

2019 ◽  
Vol 39 (2) ◽  
pp. 43-63 ◽  
Author(s):  
Mark Bussin
Keyword(s):  
South Africa ◽  
South African ◽  
Merit Pay ◽  
Drivers Of Change ◽  
Retention Strategies ◽  
Retention Strategy ◽  
Remuneration Policy ◽  
Chi Squared ◽  
Firm Data ◽  
E Mail

This study was conducted in 2012 and replicates Bussin and Huysamen’s (2004) work, conducted in 2003, on remuneration policies. It investigates the factors driving remuneration policy in South Africa and determines whether these factors have changed since 2003. Anonymous e-mail questionnaires were received from 131 senior company representatives. All participating companies were members of the South African Reward Association (SARA) or clients of a large remuneration consulting firm. Data were analysed using a chi-squared test and factor analysis. Results support Bussin and Huysamen’s study, which found that the two main drivers of change in policy were the retention of talented staff and the financial results of the organisation. However, three components of remuneration are receiving greater prominence than they did in 2003: governance in the organisation, merit pay and retention strategies. These findings suggest a greater shareholder expectation that pay should be linked to performance, and that pay acts as a retention strategy for critical staff.

Comparative analysis of simulations of LIVE-L10 and -L11 experiments using different lower head modules of AC2

Kerntechnik ◽  
2019 ◽  
Vol 84 (5) ◽  
pp. 406-413
Author(s):  
F. Krist ◽  
C. Bratfisch ◽  
F. Gremme ◽  
J. M. Peschel ◽  
M. K. Koch
Keyword(s):  
Comparative Analysis ◽  
Lower Head

Diatom- and Chironomid-Inferred Eutrophication of Bouchie Lake, British Columbia

2005 ◽  
Vol 40 (4) ◽  
pp. 418-430 ◽  
Author(s):  
Markus L. Heinrichs ◽  
Brian F. Cumming ◽  
Kathleen R. Laird ◽  
J. Sanford Hart
Keyword(s):  
British Columbia ◽  
Land Use Changes ◽  
Head Capsule ◽  
Relative Increase ◽  
Nutrient Concentrations ◽  
The Past ◽  
Nutrient Levels ◽  
Lower Head ◽  
Lower Oxygen ◽  
Historical Land Use

Abstract Diatom and chironomid analysis of sediments encompassing the past 400 years from Bouchie Lake, British Columbia, suggests two distinct periods of limnological conditions. Prior to 1950 AD, Fragilaria construens and F. pinnata are the most common diatom species, and Chironomus, Procladius and Tanytarsini dominate the chironomid record. Moderately low nutrient concentrations consistent with oligo-mesotrophic lakes are inferred. From 1950, the diatom assemblage is dominated by Stephanodiscus parvus, a eutrophic indicator, whereas the chironomid communities show a relative increase in littoral taxa coincident with lower head capsule abundance. Higher nutrient levels, specifically total phosphorus, which increased from 8 µg L-1 prior to 1950 to 20 µg L-1 currently, are coincident with midge communities indicative of lower oxygen concentrations. Observed biotic changes and nutrient levels inferred from the sediment core correspond to historical land-use changes.

Coupling of a Reactor Analysis Code and a Lower Head Thermal Analysis Solver

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Hiroshi Madokoro ◽  
Alexei Miassoedov ◽  
Thomas Schulenberg
Keyword(s):  
Structural Analysis ◽  
Message Passing ◽  
Message Passing Interface ◽  
Severe Accident ◽  
Coupled Analysis ◽  
Accident Analysis ◽  
Analysis Tool ◽  
Lower Head ◽  
Calculation Results ◽  
Reactor Pressure

Due to the recent high interest on in-vessel melt retention (IVR), development of detailed thermal and structural analysis tool, which can be used in a core-melt severe accident, is inevitable. Although RELAP/SCDAPSIM is a reactor analysis code, originally developed for U.S. NRC, which is still widely used for severe accident analysis, the modeling of the lower head is rather simple, considering only a homogeneous pool. PECM/S, a thermal structural analysis solver for the reactor pressure vessel (RPV) lower head, has a capability of predicting molten pool heat transfer as well as detailed mechanical behavior including creep, plasticity, and material damage. The boundary condition, however, needs to be given manually and thus the application of the stand-alone PECM/S to reactor analyses is limited. By coupling these codes, the strength of both codes can be fully utilized. Coupled analysis is realized through a message passing interface, OpenMPI. The validation simulations have been performed using LIVE test series and the calculation results are compared not only with the measured values but also with the results of stand-alone RELAP/SCDAPSIM simulations.

Micro-Porous Coatings and Enhanced CHF for Downward Facing Boiling During Passive Emergency Reactor Cooling

2016 ◽  
Author(s):  
Albert E. Segall ◽  
Faruk A. Sohag ◽  
Faith R. Beck ◽  
Lokanath Mohanta ◽  
Fan-Bill Cheung ◽  
...  
Keyword(s):  
Cold Spray ◽  
Heat Removal ◽  
Porous Coating ◽  
Porous Coatings ◽  
Spray Coatings ◽  
Spray Process ◽  
External Cooling ◽  
Loss Of Coolant Accident ◽  
Lower Head ◽  
Viable Approach

During a Reaction Initiated Accident (RIA) or Loss of Coolant Accident (LOCA), passive external-cooling of the reactor lower head is a viable approach for the in-vessel retention of Corium; while this concept can certainly be applied to new constructions, it may also be viable for operational systems with existing cavities below the reactor. However, a boiling crisis will inevitably develop on the reactor lower head owing to the occurrence of Critical Heat Flux or CHF that could reduce the decay heat removal capability as the vapor phase impedes continuous boiling. Fortunately, this effect can be minimized for both new and existing reactors through the use of a Cold-Spray delivered, micro-porous coating that facilitates the formation of vapor micro-jets from the reactor surface. The micro-porous coatings were created by first spraying a binary mixture with the sacrificial material then removed via etching. Subsequent quenching experiments on uncoated and coated hemispherical surfaces showed that local CHF values for the coated vessel were consistently higher relative to the bare surface. Moreover, it was observed for both coated and uncoated surfaces that the local rate of boiling and local CHF limit varied appreciably along the outer surface. Nevertheless, the results of this intriguing study clearly show that the use of Cold Spray coatings could enhance the local CHF limit for downward facing boiling by more than 88%. Moreover, the Cold-Spray process is amenable to coating the lower heads of operating reactors.

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