ML18051A891
| ML18051A891 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 05/11/1984 |
| From: | Johnson B CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8405170208 | |
| Download: ML18051A891 (5) | |
Text
consumers Power company General Offices: 1945 West Parnall Road, Jackson, Ml 49201 * (517) 788-0550 May 11, 1984 Dennis M Crutchfield, Chief Operating Reactor Branch No 5 Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -
XNB CORRELATION FOR PALISADES APPLICATION -
ADDITIONAL INFORMATION NRC Letter, dated May 3, 1984, requested that additional information be provided by Consumers Power Company in regards to XNB correlation for the Palisades Plant (Exxon report XN-NF-709, Revision O).
The following informa-tion is in response to the above request.
Question
Response
Section 2.0 "Analysis of Data", of the topical report states, "The differences in fluid conditions for the limiting subchannel between the rod indicating CHF and the XCOBRA prediction of the rod indicating CHF were observed to be small."
A)
How are the fluid conditions for the limiting subchannel obtained other than the XCOBRA prediction?
B)
Provide comparisons of the limiting subchannel fluid conditions between those of the rod indicating CHF and those predicted by XCOBRA.
Fluid conditions for each subchannel are obtained by XCOBRA-IIIC analysis.
Comparisons of fluid conditions are presented in Table 1 (attached).
The XCOBRA predicted hot rod was rod 15.
The experimentally observed hot rod was
- 23.
The worst fluid conditions for rod 15 are in channel 35.
The worst fluid conditions for rod 23 are in channel 34.
The differences between the fluid enthalpies between these subchannels is of the order of 6 BTU/LB while the flow difference is of the order of 1 to 2 percent.
In the test, the adverse flow conditions from the channels surrounding rod 23 (namely 33, 34, 35, and
- 36) contributed to rod 23 being the rod observed in CHF.
The fluid conditions OC0584-0007A-NL02
,--- ----------511 ___ -----1
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of channel 35 in combination with the higher flux of rod 15 result in the XCOBRA prediction of rod 15 being the limiting rod.
Physically, subcooled mixing tests were performed.
These subcooled mixing tests demonstrated large temperature gradients between the wide-wide gap and the interior of the array.
In terms of enthalpy, the gradients were of the order of 100 BTU/LB.
In CHF tests, high rates of mixing helped keep hot rods cool and allowed the slightly cooler rods to indicate DNB first.
Question
Response
The ENC-204 test data, which are used for justification of the application of the XNB correlation to Palisades consist of uniform axial power shape data only.
It is the position of the staff that all possible power distributions expected for power operation be used in the development of any CHF correlation.
Therefore, rather than using the ENC-204 data solely to derive the DNBR limit, it is necessary that the ENC-204 data belong the to same population as other data presented in XN-NF-621, Revision 1.
Provide your statistical analysis to show that the ENC-204 data is in the same population.
The staff review of the XNB correlation resulted in the subdivision of the XNB data base into three (3) populations.
Further, the conclusion was stated by the staff that the 95/95 limit is based on three populations recommended by the staff consultant; therefore, the 95/95 limit of one population will be conservative when compared to the limit of a population containing all the test data.
The XNB correlation itself was derived using test sections with a variety of axial profiles. Therefore, since the ENC-204 test section has a limit which is within the limit for the correlation as a whole, it is expected that the correlation limit of 1.17 is applicable for applications for this case.
As a verification of how ENC-204 fits in with one of the three populations suggested by the staff, a comparative one way analysis of variance test was performed.
This comparative test was chosen to provide consistent calculational methodology. Two groupings were considered.
One group was provided as reference consisting of the population recommended by the staff as ENC-3, ENC-4, ROSAL-4, and WH-164.
The other group was provided to show the effect of including ENC-204 and consisted of ENC-3, ENC-4, ROSAL-4, WH-164, and ENC-204.
The reference group showed a calculated F of 3.02.
The probability of being in the same population for this group is between 2.5% and 5%.
The expanded group showed a calculated F of 2.50 and also showed a probability of being in the same population between 2.5% and 5%.
The conclusion is reached that since the reference group was acceptable as a OC0584-0007A-NL02
population, the expanded group consisting of ENC-3, ENC-4, ROSAL-4, WH-164, and ENC-204 is also acceptable as a population.
This particular expanded population retains the approved characteristic of a 95/95 limit which is conservative with respect to the data grouping of all test sections within the data base.
The group 95/95 limit was calculated as 1.14 which is less than 1.17.
Test Series Group ENC-3, ENC-4, ROSAL-4, WH-164 ENC-3, ENC-4, ROSAL-4, WH-164 ENC-204 F-Ratio 3.02 2.50 Probability of Being In The Same Population 2.5 -
5%
2.5 -
5%
Question In the letter dated January 3, 1983 (from J C Chandler to L E Phillips, JCC-001:83), ENC requested that the ENC-1 and ENC-2 test sections be removed from the data base for the XNB correlation because these two test sections are either non-representative of any grid or atypical of the power distribution in the reactors.
Response
As stated in XN-NF-709, both ENC-1 and ENC-2 represent the rod size and pitch of Palisades.
What is the impact of the removal of this data on the applicability of XNB for Palisades?
As the grids were non-prototypic of production grids, or the power distribu-tion was non-prototypic, the removal of the data has no impact on the applica-bility of XNB to Palisades.
The reports XN-NF-709 and XN-NF-621, Rev 1 make no use of these data sets in support of the XNB correlation.
Brian D Johnson Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades Attachment OC0584-0007A-NL02
ATTACHMENT Consumers Power Company Palisades Plant - Docket 50-255 TABLE 1 XNB Correlation - Additional Information 1 Page OC0584-0007B-NL02
TABLE 1 COMPARISON OF SUBCHANNEL CONDJTIONS FDR CHANNELS NEAR OBSERVED HOT ROD AND PREDICTED HOT ROD Data CHF Rod Channels CHF Rod Channel Channel Channel 34 Channel 35 Channel 36 7
8 9
13 14 15 16 17 18 22 23 24 25 26 29 30 31 40 46 47 48
!..:9 54 Observed Predicted 33 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 15 15 11 11 23 11 11 33-36 33-36 33-36 33-36 33-36 33-36 33-36 33-36 33-36 33-36 33-36 33-36 33-36 33-36 33-36 33-36 33-36 35 35 33 33 33-36 33 33 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 G
H G
H G
H G
H 35 1.30 766.9 1.28 770.6 1.30 767.5 1.34 763.5 35 1.60 762.4 1.56 765.8 1.60 762.9 1.65 759.3 35 1.00 776.4 0.99 780.7 1.00 777.3 1.03 772.9 35 0.98 765.7 0.96 770.9 0.98 766.4 1.00 761.2 35 1.26 759.9 1.24 763.8 1.26 760.5 1.30 756.0 35 1.54 747.0 1.51 751.0 1.54 747.4 1.59 742.7 35 1.54 734.7 1.52 739.3 1.54 735.3 1.59 729.9 35 1.21 743.5 1.19 749.8 1.21 744.1 1.25 737.4 35 0.94 757.4 0.93 764.4 0.94 758.8 0.97 751.7 35 1.18 737.4 1.16 743.6 1.18 738.2 1.22 730.1 35 1.50 726.1 1.47 731.4 1.50 726.9 1.53 719.9 35 1.44 724.1 1.42 729.4 1.44 724.1 1.49 716.8 35 0.93, 745,.5 0.92 752.9 0.93 746.6 0.96 737.4 35 1.15 731.7 1.13 738.0 1.14 732.8 1.16 725.5 35 0.92 731.2 0.91 738.8 0.92 733.2 0.94 725.0 35 1.41 702.0 1.38 707.9 1.40 703.1 1.45 695.9 35 1.16 740.8 1.14 747.2 1.15 741.9 1.19 734.7 35 1.40 683.6 1.37 687.8 1.40 683.9 1.45 678.8 35 1.07 698.4 1.04 704.6 1.06 699.0 1.10 691.2 35 1.31 682.9 1.28 688.1 1.31 683.5 1.35 676.7 35 1.29 676.8 1.26 681.8 1.28 677.4 1.33 670.2 35 1.07 687.2 1.05 692.6 1.07 688.0 1.11 680.6 35 1.03 688.1 1.01 694.6 1.03 689.2 1.06 680.0 35 1.30 667.3 1.28 672.3 1.30 668.1 1.34 661.1