ML20199H425
| ML20199H425 | |
| Person / Time | |
|---|---|
| Issue date: | 01/23/1998 |
| From: | Mace M NRC OFFICE OF ADMINISTRATION (ADM) |
| To: | Pellegrino L, Troyer D PURDUE RESEARCH FOUNDATION |
| References | |
| CON-FIN-W-6749, CON-NRC-04-97-046, CON-NRC-4-97-46 NUDOCS 9802050043 | |
| Download: ML20199H425 (7) | |
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j NUCLEAR REGULATORY COMMISSION I E WASHINGTON, D.C. 20t4H001 k ~ ~ / '
ww Purdue Research Foundation-
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ATTN: Diane E. Troyer 1021 Hovde Hall. Purdue University West Lafayette, IN 47907-1021
Dear Ms. Troyer:
SUBJECT:
TASK ORDER NO. 5 ENTITLED 'SUBC00 LED BOILING AT LOW PRESSURE" UNDER CONTRACT NO. NRC-04-97-046 In accordance with Section G.4. Task Order Procedures, of the subject contract, this letter definitizes Task Order No. 5.
This effort shall be performed in accordance with the enclosed Statement of Work.
The period of performance for Task Order No. 5 is January 14, 1998 through December 31, 1998. The total estimated cost for full performance of this task order is $151,960.00, Funds in the amount of $125,000 are hereby obligated for performance of this task order. The Contractor shall not incur costs for this task order which exceed this obligated amount.
Accounting data for Task Order No. 5 is as follows:
B&R No.: 860-15 21-100-5 Job Code: W 6749 BOC Code: 252A RES 10: RES-C98 010 Appropriation No.: 31X0200 Obligated Nnount: $125.000.00 The following individuals are considered by the Government to be essential to the successful performance of the work hereunder:
V1 jay K. Dhir The contractor agrees that such personnel shall'not be removed from the effort L
under this task-orden without compliance with Contract Clause.H.2-Key Personnel
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9802050043 900123 l
>v PDR CONTR NRC-04-97-046 PDR
Purdue Contract No. NRC-04-97-096 Task Order No. 5 Page 2 of 2 The issuance of-this task order does not amend any terms or conditions of the subject contract.
Your contac ; during the course of this task order are:
Technical Matters:
Jennifer Uhle, Project. 0fficer (301) 415-6023 Contractudi Matters:
Stephen Pool, Contra' (301) 415-8 D8 Please indicate your acceptance of this a k order by having an official, authorized to bind your organization, execute three copies of this document in the space provided and return two copies to the Contract Specialist.
You should retain the third copy fe your records.
Sincerely, l
Mary H.
< ace, Contract 1 g Officer Contract Management Branch No. 1 Division of Contracts and Property Management Office of Administration
Enclosure:
As stated ACCEPTED: TASK ORDER NO. 5
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O NAME DATE s
Louis Pellegrino, Diactor Office of Research Admir'stration TIll E
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i STATEMENT OF WORK
-TASK ORDER #5,'SUBCOOLED BOILING AT LOW PRESSURE'
Background
Since passive reactor designs rely on gravity driven cooling systems, the primary pressure must
"' ' not greatly exceed atmospheric pressure, or an' excessively large head of waterwould have to "
be maintained before long term cooling could be established. For example, the AP600 operates at approximately 0.2 MPa during the low pressure phase. At this low pressure, the density ratio of Nuid to vapor is more than 1300. Often correlations that are a function of density difference and are applicable to operating pressures of 15 MPa (with a density ratio of six) must be reformulated to account for the factor of 200 change in density ratio Subcooled boiling is an exampie of such a model.
- In the two fluid formulation used in current reactor system analye Mes, generally the net vapor g9neration rate is determined by the heat transfer from tn call to the fluid (assuming liquid wets the wall) and the subsequent transfer from the liquid and the vspor to the interface,-
assumed at saturation temperature, in subcooled boiling cot ditions, the vapor is not superheated so that the heet transfer from the vapor to the is torface is negligible. Since by L
de'mition, the bulk liquid volume is wbcooled, the heat transfer from the liquid to the interface L
yields a negative contribution to the not veoor generation inte. Since no numerical modeling of the near wall ragion so done, there is essentially no mechanism for bubble nucleation.
Therefore, a special sabcooled boiling model is added to the two-fluid model to account for the
- fact that the near wall region is ag+td end nucleation can occur. Net vapor generation is calculated by summing the interfacial component which tends to condense the bubbles and the near weil subcooled boiling contnbution.
As a result, three separate mechanisms must be accounted for when calculating the net vapor generation rate during su'.> cooled t'oilmg: the fraction of wall heat flux that results in vapor generation; and the interface components.- In RELAP5, a modified form of the Lahey subcooled boiling model (1978) is used to determine the fraction of the wall heat flux that results in varor generation. This model utilizes a liquid to vapor density ratio to account for buoyancy induced
" pumping' that mixes the near wall region and suppresses nucleation. Therefore, due to this pumping term, at low pressures with a large density ratio, the net vapor generation rate is dramatically under-predicted.
The computed vapor generation rate tends to be not only inaccurate but oscillatory as well. At low heat fluxes (1W/m ) the subcooled boiling mooel predicts negligible amounts of nucleation 2
until the bulk liquid temperature is very close to saturation, following the trend that the fraction of the voll heat flux that induces nucleation varies from zero at a subcooling of 0.5 K to a value of one at N.turation. With the high density ratio at low pressure, the volumetric expansion induced by even a small amount of vaporization can induce a numerica' geysering effect as a computational volume (on the order of 0.5 meters in height) rapidly trareitions from single-phase liquid to a void fraction in the slug flow regime.
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It is apparent that at low pressures, the method used to determine the net vapor generation rate requires modification. The near waii region (or subcooled bciling) model must be modified but l
done so in a consistent manner with the interfacial heat transfer, so that the net vapor generation rate is well predicted. Minimizing the oscillations can be done when the model is
2 implemented into the systems code but modeling techniques that are vulnerable to these types of oscillations should be recognized and avoided. Additionally, the physics and numerics of the model shall merge with those that control vapor generation rate (interfacial heat transfer, wall heat transfer and interfacial drag) at high pressure in the NRC consolidated code, so that code
'Indubsd 'oscillctions in' void fraction and vapor generation rate are avoided. -
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The aim of this research is to organize the existing database for subcooled boiling at low pressures and to perform experimentation to supplement the data, which NRC will then use to identify or develop models for both the interfacial and near wall region heat transfer components, so that the net vapor generation rate is adequately predicted at low pressure, low to moderate (1000 kg/m'-s) mass fluxes and heat fluxes from 1 W/cm' up to the critical heat flux for the system conditions. The experimental plan must ensure that parameters measured are consistent with the tow-fluid formulation of NRC thermal-hydraulic codes.
Since void fraction is the code state variable that must be adequately predicted and is a function of both the vapor generation rate and interfacial drag, the future approach used to develop a subcooled boiling model will have to Lither separate the latter effect or both the experimental and modeling approach will have to account for it. The test plan devised and implemented under this contract must taks Ws comp'ication into consideration.
Objectives L
The objectives of this work are to:
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Organize and document the existing database relevant to the work defined;
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Review cu: rent literature for subcooled boiling mode;a consistent with the two-fluid model formulation; 4
Perform and document experiments to supplement the database.
Work Requirements:
Task 1: Literature Review A literature review shall ba performed to identify both experime W1 'ata and modeling appioaches of subcooled boiling at the specified range of conditiens (soe Background). The identified work shall be compiled into a list organized by the categories of c.nalytical studies, experimenta' work, and a combination of both analytical and experimental work. This list shall be submitted to NRC in the form of a letter report in both text and electronic format. All reports shall be written in Frame Maker.
Estimated completion daw i month after initiation.of the task order Deliverable:
Letter report in text and electronic format 1
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3 Task 2: Database Task 2.1: Compilation of Database
' ' ' " Ups completioh of Tatk'1; all' data taken in the identified experiments shall be compiled into a v
-4 database for use in further modeling efforts and developmental code assessment. All measured parameters in the experiment (pressure, flow rate, etc.) ahall be listed as a function of massurement location and labeled accordingly. The data shall be put in a form consistent -
with the NRC Databank format, as attached.
- Tad 2.b!: Documentation of Database i
The form of the data from each experiment and the run number of the experiment shall be documented so that someone unfamiliar with this contract can utilize the database for model development and code developr9 ental assessment. Therefore, for each experiment, a brief summary shs.li be provided includmg the geometrical set-up of the experiment depicted with diagrams clearly denoting the locahons of the instrumentation. The labels of the
. instrumentation shall be consistent with the labeling method used in the database.- The conditions of the experi nent shall be summarized so that the user will not have to refer to the -
- database to determine the ranges of conditions studed. All facility description given in the -
publication shall be documented. The documentation shall includo any data relevant to model
@@ Tent if the experiment is comprised of several runs, the aforementioned documentation shall be provided for each run. The results of Subtask 2.2 shall be submitted to NRC in the form of a letter report in both text and electronic format.
Estimated completion date: 4 months after the initiation of the contract Deliverable:
Data in NRC Databank format and a letter report in text and electronic format 1
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- Task 3: Development of a Test Plan
- The models/ correlations identified in the literature search as appropriate to this work shall be reviewed as a means of defining what types of information is required in subcooled boiling model development and assesstr.ent. thing this information, a separate effects test matrix shall be prepared with the aim of exterdino and improving the existing database to aid model selection / development in Task 4.
The rationale for the test matrix (why a particular test is needed), the deficient ranges of data in t's atabase, and the test matrix shall be documented and submitted to NRC as a letter report
'e t etF text and electronic format. The letter report shall include how the proposed experiments wd., usod to develop a model suitable for incorporation into a two-fluid systems thermal-
.. hydraulic code..For. instance, the reoort shall list the instumentatior) and note what parameters,
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will be measured and inferrede Assumptions made to calculate the inferred quantities shall also be explicitly described as wall as the relevance of both the measured and calculated data to model development. Upon review of this documenta,lon. NRC will authorize the experimentation.' No experimentation is to be performed until NRC autho,-i2.ation is received.
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Estimated Completion Date: 5 months after initiation of the contract s
Deliverable:
Letter report in text and electronic format
- Task 4: Experimental Design
.s This task is comprised of 4 subtasks. All experiments shall be performed in support of rectifying
- deficiencies in the experimental database as authorized by NRC in Task 3. NRC will review the experimentr.; plan and facility design and if cost effective, will opt to sponsor the experimental and mood development effort.
Subtask 4.1: Schedule l
A schedule of the test program shall be developed. This schedule shallinclude what steps will-
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be required before each test is run. For example, if a set-up must be built in support of a test,
- then the required time must be allotted on the schedule The schedule shall be submitted to NRC as a letter report in both text and electronic format.- Once reviewed and accepted, the -
experimentation may begin.
Subtask 4.2: Design For each run that requires an experimental set-up, the design, instrumentation location and uncertainty and scaling rationale shall be submitted to NRC for review in the form of a letter -
report in both text and electronic format. Once authorized, construction of the facility may begin. The design description must include all details required for code assessment and must conform to the documentation procedures outlined in hbtask 2.2.
Subtask 4.3: Construction Once authorized upon completion of Subtask 4.2, the construction of the facility may ensue.
Subtask 4.4: Measurements The authorized experiments shall then be run and the data recorded. - The test procedure and results t hall be documented for each run and shall be submitted to NRC as a letter report in both text and electror.ic format. Any modifications made to the facility design described in the letter report of Subtask 4.2 shall be included and shal' be consistent with the documentation requirements outlined in Subtask 2.2. Additionally, the data obtained shall be submitted to NRC in a format consistent with the NRC Databank.
Estimated Duration:
.12 months after the initiation of the contract Deliverable:
Data in NRC Databank format and a letter report in text and electronic format s
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5 Meetings and Travel:-
For successful comp;ation of the work required in this contract, it is anticipated that the contractor shall travel to the NRC office in Rockville, MD. The contractor may propose
- ' 1dditional travel deemed necessary for the successful completion of this effort: All travel shall be approved in advance by the Project Officer, be specifically performed in support of this contract and be in compliance with Federal Transportation Regulatior..
Tasks 1,2,3: Upon complet'on of Tcsk 3, one 2 day trip for one person Task 4:
In support of Task 4, one 2 day trip for one person
Attachment:
NRC Databank Format Description - issued with RFP letter w