ML19241B551
| ML19241B551 | |
| Person / Time | |
|---|---|
| Issue date: | 06/08/1979 |
| From: | Baer R Office of Nuclear Reactor Regulation |
| To: | Scherer A ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY |
| References | |
| NUDOCS 7907180912 | |
| Download: ML19241B551 (3) | |
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'JUN 0 81979 Mr. A. E. Scherer Licensing Manager Combustion Engineering, Inc.
1000 Prospect Hill Road Windsor, Connecticut 06095
Dear Mr. Scherer:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION In order to complete our review of topical report CENPD-177-P, "CEDNBR - A Com-puter Code for Transient Themal Margin Analysis of a Reactor Core," we find we need additional information.
The additional informat:an required is identified in the Enclosure. Within seven days after receipt of this letter, please inform us of your schedule for submitting the complete response.
Since rely, J >2A $ /540 h
Robert L. Baer, Chief Light Water Reactors Branch No. 2 Divisicn of Project Management
Enclosure:
Request for Additional In formation 7907180 7/1 496 001
A'N 0 81979 ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION i
1.
The following Errata have been identified in the subject topical report.
Please correct '. clarify.
(a) (Page A-4, third line).
Equation 2-5 should be Equation 2-6.
~ (b) (Page A-4).
EqJation A-10 should include RH0A+ (i,j) term.
(c) (Page A-5, Statement 4).
HTPAL(j) should be HTAPL(j).
(d) (Page A-6).
The channel 3 and 4 power density equations are not numbered.
FTABL(j) should be HTAPL(j).
(e) (Page B-7, Line 4). There is no B-4 in the References f6r Appendix B.
What is the correct reference?
2.
Discuss the applicability of mixing factors derived from a core-wide steady state code calculation to transient calculations using a'.two channel code.
Show the sensitivity of CEDNBR to the mixing factor inputs.
3.
Discuss the code design provisions to insure that all conditions during the course of a calculated transient remain within the ranges of the empirical correlations.
4.
Equation 6-1 expresses d P as the difference between measured emi and predicted pressure drop in the test section.
- However, Figure 6-1 appears to show predicted pressure drops higher than those measured, which would result in a negative mean pressure loss error as tabulated in Table 6-1.
Clarify thi: interpretation of the discussed statistical analysis.
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JUN 0 8 ngg 5.
Discuss your calculations and justify the selection of time incre-
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s ments to obtain the time-dependent input values for the peaking factors.
6.
(Page 2-9).
Describe a typical application where a second hot subchannel (Channel 4) would be used in your CEDNBR model.
7.
In the rubroutine MIX (Pages C-21, C-22 and C-23), the derivation of the expression for the mixing factor FMIX for the case when YMIX0 = -1.0 is not evident.
Describe the development of this ex-pression and the relation to the similar expression for YMIX0 = +1.0.
8.
(Pe.ge4-1). The procedure for selecting input daia includes the aseumption that the fuel assembly containing the hot channel experiences the same total axial pressure loss as the core average.
Discuss any sensitivity studies performed to justify this assumption.
9.
What is the maximum error inherent in the assumptions on pages 4-1 anc 4-2:
"(4) the time dependent normalized axial heat flux profile in the fuel assembly containing the hot subchannel is the same as that for the hot subchannel itself, and (5) the time depen-dence of the normalized heat flux, inlet temperature and system pressure are the same in the hot subchannel as in the fuel assembly containing the hot subchannel."?
10.T.(Page 4-4).
Discuss the basis for not considering the hypothetical hot subchannel to be adjacent to an instrument thimble (guide tube).
11.
(Page B-3).
The installation of a stainless steel washer in place of the ceramic washer creates the possibility of producing a deformation in the heater. tube in the form of a hump at the CHF location.
Discuss the effect of this possibility on the thermo-couple measurement.
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