4 research outputs found
Investigation of solution techniques for large sparse band width matrix equations of linear systems
Includes bibliographical references (leaves 107-108
WOSUB : a subchannel code for steady-state and transient thermal-hydraulic analysis of BWR fuel pin bundles.
The WOSUB-codes are spin-offs and extensions of the
MATTEO-code [1]. The series of three reports describe WOSUB-I
and WOSUB-II in their respective status as of July 31, 1977.
This report is the first in a series of three, the
second of which contains the user's manual [2] and the third
[3] summarizes the assessment and comparison with experimental
data and various other subchannel codes.
The present report introduces the drift-flux and vapor
diffusion models employed by the code, discusses the solution
method and reviews the constitutive equations presently built
into the code. Wherever applicable, possible exteriors of the
models are indicated especially with due regard of the findings
presented in [3].
Overall, the review of the model and the package of
constitutive equations demonstrate that WOSUB-I and II
constitute true alternatives for BWR bundle and PWR test bundle
calculations as compared to the commonly applied COBRA-IIIC,
and COBRA-IIIC/MIT codes which were primarily designed for PWR
subchannel and core calculations, respectively. In fact, the
incorporation of the drift flux and the vapor diffusion pro-
cesses into a subchannel code has to be cdnsidered.a major step
towards a more basic understanding and a well balanced engineer-
ing approach without the extra burden of a true two-fluid two-
phase model.
Recommendations for improvements in the various areas
are indicated and should serve as guidelines for future develop-
ment of this code which in light of the encouraging results pre-
sented in [3] seems to be highly warranted.
The WOSUB-code is still in the stage of evolutionary
development. In this context, the review reflects the achieve-
ments as of July 1977.Topical report for Task 3 of the Nuclear Power Reactor Safety Research Program sponsored by New England Electric System, Northeast Utilities Service Co. under the M.I.T. Energy Laboratory Electric Power Program
WOSUB : a subchannel code for steady-state and transient thermal-hydraulic analysis of BWR fuel pin bundles. Volume III. Assessment and Comparison
The WOSUB-codes are spin-offs and extensions of the
MATTEO-code [1]. The series of three reports describe WOSUB-I
and WOSUB-II in their respective status as of July 31, 1977.
This report is the third in a series of three, the
first of which [2] contains all the information about the
models, solution methods and constitutive equations and the
second [3] being the user's manual of the code.
This report summarizes the assessment of the WOSUB-
code against experiments and compares its results with the
results of other subchannel codes. The following experiments
are used for the purpose of the assessment of the code under
steady-state conditions:
1) 9-rod GE-tests with radially uniform and non-
uniform peaking factor patterns.
2) 16-rod Columbia tests with slight power tilts.
3) Planned 9-rod Swedish tests with very strong
power tilts.
4) Actually performed 9-rod Swedish tests with
power tilt.
5) 9-rod GE-CHF experiments.
The comparison with these data shows that WOSUB is capable of
predicting the lower-than-average behavior of the corner sub-
channel and the higher-than-average behavior of the center
subchannel for both quality and mass flux. None of the other
well-known subchannel codes is indeed capable of specifically
predicting the correct corner subchannel behavior. These codes
seem to inherently suffer from major deficiencies associated
with their incorporated mixing models. Therefore, it is con-
cluded that only improved models for the description of two-
phase flow phenomena are capable of handling these situations
and that the vapor drift flux model together with the vapor
diffusion model as incorporated into WOSUB is doing a good job.
The fact that WOSUB does not perfectly match the experimental
results over the whole spectrum of experimental evidence can
be attributed to the vapor diffusion model which was originally
fitted to air-water test results in a geometry consisting of
two subchannels only. Obviously, this geometry leads to over-
emphasizing the importance of the vapor diffusion as compared
to what actually happens in a multi-rod geometry.
WOSUB gives the user the option of calculating the
critical power as a function of the boiling length - a concept
which is especially useful to easily account for axially nonuniform power profiles and which closely resembles the
procedure now used by GE. Furthermore, the code determines
four heat transfer coefficients around the circumference of the
fuel pin, thus giving the user the possibility of selecting
the minimal one for the purpose of hot spot calculations.
Overall, the assessment and comparison presented in
this volume show that the WOSUB-code has to be considered a
valuable tool for BWR bundle and PWR test bundle analysis with
a potential for further improvements.
The commonly used concept of power-to-flow ratio
fails to explain most of the test data used for comparison in
this report.
The WOSUB-code is still in the stage of evolutionary
development. In this context, the results presented in this
present report have to be considered preliminary. They
reflect the development as of July 1977
WOSUB : a subchannel code for steady-state and transient thermal-hydraulic analysis of BWR fuel pin bundles. Volume II. User's Manual
WOSUB (Computer program).The WOSUB-codes are spin-offs and extensions of the MATTEO-
code [ 2 ]. The series of reports describe WOSUB-I
and WOSUB-II in their respective status as of July 31, 1977.
This report is the second of a series of three reports
describing the WOSUB code. It gives a detailed description of
the input data, flow charts, and output, and contains the list-
ings of WOSUB-I and WOSUB-II. For the purpose of future ex-
tensions parameters, common blocks and variables used in the
code are listed in full detail.
WOSUB-I and WOSUB-II are subchannel computer codes for the
steady-state and transient analysis of the thermal-hydraulic
characteristics of Boiling Water Reactor (BWR) fuel rod bundles.
Both codes are also applicable'to analyze PR bundles, especially
when these are ducted--a situation which most often arises in
experimental set-ups.
The main difference between WOSUB-I and WOSUB-II is that
the former is designed to analyze small bundles, whereas the
latter is capable to handle symmetric sections of today's large-
sized BWR bundles. In addition, WOSUB-II does not contain all
of the additions made in WOSUB-I yet, because it is deemed
appropriate to introduce these into the smaller code first,
before they are implemented into the bigger one.
Both codes are still in the stage of evolutionary develop-
ment. Thus, changes are to be expected in the near future. There-
fore, it should be noticed that this report reflects the develop-
ment as of July 1977 only.opical report for Task 3 of the Nuclear Power Reactor Safety Research Program sponsored by New England Electric System, Northeast Utilities Service Co. under the M.I.T. Energy Laboratory Electric Power Program