ML20039E159
| ML20039E159 | |
| Person / Time | |
|---|---|
| Site: | 05000561 |
| Issue date: | 02/23/1977 |
| From: | Cox T Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML111090060 | List:
|
| References | |
| FOIA-80-515, FOIA-80-555 NUDOCS 8201060595 | |
| Download: ML20039E159 (5) | |
Text
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UNITED STATES O'-
t NUCLEAR REGULATORY COMMisslON WASHINGTON, D. C. 20556 a
/
FEB 2 31977 i
l Docket No. STN 50-561 VENDOR: Babcock and Wilcox Company (B&W)
SUBJECT:
SUMMARY
OF MEETING TO DISCUSS BSAR-205 ANALYSES OF SMALL STEAM LINE BREAKS On February 17, 1977 representatives of B&W and the NRC staff met to discuss B&W plans to submit additional infonnation concerning the vendor's analysis of small steam line breaks using the TRAP 2 program.
The additional information is to be submitted in response to staff requests for information, numbers 222.19, 20 and 21, which were first addressed in BSAR-205 Amendment 9 submitted on February 4, 1977.
The staff judged the Amendment 9 responses to be inadequate, which led to this meeting.
Enclo ure 1 is the meeting attendance list.
The staff and B&W agreed that the issues to be resolved were separable l
into two general areas:
1) validation of an appropriate TRAP 2 model for small break analyses, and l
2) the identification, in BSAR-205, of requirements which will be I
imposed on an applicant to establish the conservatism of the mass and energy releases to the specific containment and i
engineered safety features d tsigns which the applicant proposes.
l Staff concerns regarding the TRAP 2 model for small break analysis were expressed in staff request numbers 222.19, 20 and 21 issued December 27, i
1976. These requests are included as Enclosure 2 of this summary.
j J. Cudlin of B&W stated that he saw no technical difficulty in incorporating a condensing heat transfer correlation as requested in 222.19, and suggested the Carpenter-Colburn correlation for heat transfer between steam and vertically oriented tubes.
He felt that the correlation should be used in the calculation where fluid volumes were calculated to be at 100% quality or superheated steam. The staff agreed to this approach.
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FEB 2 31977
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The minimum value of the heat transfer coefficient used by B&W to compute reverse heat transfer in the liquid region of the intact steam generator was discussed.
J. Cudlin pointed out that B&W had a minimum value assigned to the forced convection coefficient used, so that even at very low flow rates,a finite value of the reverse heat transfer coefficient is utilized.
B&W will submit a justification for the minimum coefficient.
The staff has suggested, in request number 222.21, that the homogeneous flow model used in TRAP 2 for secondary side fluid may not be conservative for small break analyses. B&W feels that a demonstration calculation is warranted to verify whether or not a finite bubble rise velocity l
should be incorporated into the model.
B&W will calculate mass / energy j
releases from a given break size for two bubble rise velocity assumptions, one zero, the other some finite value selected by B&W.
If the results indicate that both the total mass and energy released and an appropriate average fluid temperature of the release are greater for the zero bubble rise velocity assumption, then the staff will accept that assumption. For any other result, additional justification for a zero bubble rise velocity will still be required.
W. Jensen of the staff also requested that B&W recheck the assumptions used in TRAP 2 affecting heat transfer from the reactor fuel to the reactor coolant during secondary system rupture transients.
B&W was asked to produce some quantitative evidence that essentially all of the heat energy produced in the reactor during the transient is transported to the containment.
I Some discussion concerned the number and size of "small" breaks that should be analyzed with TRAP 2 after the staff concerns with model assumptions are resolved. The group consensus on this question was that at least two break sizes should be examined, one of which could be the 0.22 square foot break previously described by B&W.
f Staff and B&W agreed that TRAP 2 model assumptions and input data i
specific to the small break calculations must be explicit in BSAR-205.
I T. Cox of the staff reiterated that if the secondary system mass / energy release data included in BSAR-205 are not clearly sufficient to
)g conservatively design any and all containments that might be proposed s by applicants referencing BSAR-205, then appropriate statements must i be included as interface data, recognizing and calling attention to the
- possible limitations in the included mass / energy release data and
. associated analytical assumptions.
FEB 2 31977
-3_
J. Hamilton of B&W stated that B&W would consider the possibility of including all necessary data tables in the BSAR-205 and that a decision i on this matter would be made in the near future.
b Thomas Cox, Project Manager i
Light Water Reactors Branch No. 3 j
Division of Project Management
Enclosures:
1.
Attendance List 2.
Requests for Additional Information, Numbers 222.19, 3
~
20 and 21 cc: w/ enclosures:
Babcock & Wilcox Company Mr. W. E. Kessler j
ATTN: Mr. Kenneth E. Suhrke Commonwealth Associates, Inc.
l Manager, Licensing 209 East Washington Nuclear Power Generation Jackson, Michigan 49201 P. O. Box 1260 Lynchburg, Virginia 24505 Robert J. Kafin, Esq.
I 115 Maple Street Washington Public Power Supply System Glen Falls, New York 12801 AlTN: Mr. J. J. Stein Managing Director Mr. B. M. Miller P. O. Box 968 Ohio Edison Company 3000 George Washington Way 76 South Main Street Richland, Washington 99352 Akron, Ohio 44308 Mr. Robert Borsum Bethesda Representative i
Babcock & Wilcox Nuclear Power Generation Division Suite 5515, 7735 Old Georgetown Road Bethesda, Maryland 20014 B. G. Shultz Project Engineer Stone & Webster Engineering Corp.
P. O. Box 2325 Boston, Massachusetts 02107 l
j
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ENCLOSURE 1 MEETING 0F B&W & NRC STAFF - 02/17/77 NRC T. Cox l
F. Odar T. Greene W. Jensen B&W l
G. Brazill j
J. Happell R. Brockman J. Hamilton i
R. Schomaker R.oVosburgh J. Cudlin i
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ENCLOSURE 2 REQUESTS FOR ADDITIONAL INFORMATION u
BSAR-205 DOCKET NO: STN 50-561 222.19 The Dittus-Boelter forced convection correlation is incorrectly applied to the condensing heat transfer which is described in the intact steam generator. Provide analyses using an appropriate condensing heat transfer correlation for which you have provided justification.
222.20 Provide the detailed steam generator performance study which you reference in answer to question 222.11 (1).
Since this coefficient is multiplied by the flow before it is used in the TRAP code, the calculation will not be conservative for low flow rates. Provide analyses for which you have included I
a justified minimum value of reverse heat transfer from the t
liquid in the intact steam generator to the tubes.
222.21 The homogeneous flow model using a zero bubble rise velocity which you use in the TRAP code may not be conservative for l
f analysis of small breaks requested by staff question 022.7.
l For these break sizes a portion of the steam generator tubes may remain uncovered during the transient causing additional superheating of the steam leaving the break. Isentropic compression of this superheated steam within the containment may produce higher containment temperatures than would be obtained using the saturated steam assumed in the homogeneous model.
Provide justification that the homogeneous flow model t{
used in the TRAP code is conservative for small break sizes.