ML20147B315
| ML20147B315 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 11/30/1987 |
| From: | Jensen R INTERMOUNTAIN TECHNOLOGIES, INC. |
| To: | |
| Shared Package | |
| ML20147B307 | List: |
| References | |
| NUDOCS 8801150200 | |
| Download: ML20147B315 (18) | |
Text
[. . _ _ _ . _ _ _ . -
REVISION TO THE YAEC -
REFLOOD HEAT TRANSFER CORRELATION November 1987 Prepared for YANKEE ATOMIC ELECTRIC COMPANY 1671 Worcester Road Framingham, MA 01701 Prepared by R. T. Jensen INTERMOUNTAIN TECHNOLOGIES, INC.
3100 Rollandet Ave., P. O. Box 1604 Idaho Falls, ID 83403 1604 P
NOTIS This report was prepared by the organization (s) named below as an account of work sponsored ty the Yankee Atcusio Electric Company (YAEC). Neither YAEC, members of YAEC, the organization (s) named below, nor ag person act.ing on behalf of ag of them: (a) makes ag warranty, express or implied, with respect to the use of ag information, apparatus, method, or process disclosed in this report or that such use may not infringe grivately owned rights; or (b) assumes ag liabilities with respect to the use of, or for damages resulting free the use of, ag izformation, ap;*ratus, method or proossa disclosed in this report.
Prepared tg INTTR10UNTAIN TECHNCL(IlIES, INC.
1.0 INTRODUCTION
10CFR, Part 50, Appendix K states that:
"For reflood rates of one inch per second or higher, reflood heat transfer coefficients shall be based on applicable experimental data for unblocked cores including FLECHT results ("PWR FLECHT (Full Length Emergency Cooling Heat Transfer) Final Report," Westinghouse Report WCAP 7665, April 1971). The use of a correlation derived from FLECHT data shall be demonstrated to be conservative for the transient to which it is applied: presently available FLECHT heat transfer correlations (*PWR Full Length Emergency Cooling Heet Transfer (FLECHT) Group i Test Report," Westinghouse Report WCAP 7544, September 1970: PWR FLECHT Final Report Supplement," Westinghouse Report WCAP 7931, October 1972) are not acceptable. New correlations or modifications to the FLECHT heat transfer correlations are acceptable only after they are demonstrated to be conservative, by comparison with FLECHT data, for a range of parameters consistent with the transient to which they are applied."
The currently approved ECCS evaluation model for Yankee F 'we meets these requirements by using the WCAP 7931(I) FLECHT correlation with a set of multipliers (2) which were developed to make the correlation a best estimate at the reflood rates and pressures of interest. The multipliers were defined such that the time integrals of heat transfer coefficients for the experimental and predicted values are equal for each of nine FLECHT correlation time periods. The FLECHT correlation is normally divided into three time periods. For the purpose of defining the multipliers, the three time periods were further divided to give 9 time periods. The multipliers were also defined for a total of 5 elevations give a total of 45 multipliers.
The currently approved set of multipliers are referred to as the ENC 2 FLECHT multipliers, in addition, since no experimental data were available for reflood heat transfer for fuel rod diameters typical of the Yankee Rowe fuel, the heat transfer coefficients are further reduced by multiplying by 0.8.
The resulting correlation, called the ENC 2 correlation, can be expiessed as h,J=
l 0.8
- M I ,J
- h I
where I = elevation (i = 2,4,6,8,10 feet)
J = time period subdivision (J = 1 thru 9) I Unear interpolation is used for other elevations.
Th3 proposed new correlation will use data from the FLECHT SEASET(3) test series, which simulates the Yankee Rowe fuel rod diameters, to eliminate the 0.8 factor and I
to define a new set of multipliers, M ,J such that the correlation provides a best estimate correlation for reflood heat transfer in the range of plant parameters representative of the Yankee Rowe reactor.
2.0 DESCRIPTION
OF PROPOSED CORRELATION The FLECHT correlation is a function of the following reflood parameters.
Tinit, maximum cladding temperature at the start of reflood, F Omax, maximum linear heat generation rate at the start of reflood, kW/ft P, system pressure during reflood, psia ATsub, inlet subcooling during reflood, F V , the core inlet velocity,in/sec in For Yankee Rowe, the range of values expected for these parameters is T 1600 - 1700 F nit O max 0.36 0.43 kW/ft P 30 - 40 psia ATsub 136 F V
in 0.6 1.5 in/sec The test runs from FLECHT/SEASET were reviewed and it was determined that the runs summarized in Table 2.1 were most representative of the Yankee Rowe plant parameters. The first five runs listed in Table 2.1 were used in developing the multipliers. The last three were used only to demonstrate the adequacy of the new model for variable and very low flooding rates.
Heat transfer coefficient data from the FLECHT/SEASET tests in Table 2.1 was previously obtained from Westinghouse by Intermountain Technologies, Inc. (ITI).
The individual data channels were carefully reviewed to assure that all factors which might bias the correlation in a nonconservative direction were eliminated. None of the thermocouples on unpowered heater rods were used in the correlation. In addition, all thermocouples on rods adjacent to an unpowered rod were discarded.
The effects of the test assembly housing walls were accounted for by discarding all thermocouples in the outer two rows. To further assure conservatism, any of the remaining data channels which exhibited obviously non typical behavior such as early quench were also discarded. As the result of this elimination process to assure conservative correlations, approximately 40% of the total temperature data channels were not used in the correlation.
Even though approximately 40% of the total temperature channels were discarded, the number of remaining channels was large and difficult to manage during the heat transfer coefficient correlation procedure. An average transient heat transfer coefficient at each test elevation was therefore defined by taking the arithmetic mean of the test data from various channels for each time scan.
The multipliers were determined by comparison of the experimental heat transfer coefficients, hp , to the predicted heat transfer coefficients, h,, obtained using the TOODEE254) subroutine WCORR. The FLECHT correlation is divided into three time periods as discussed in Reference 1. The first two FLECHT time periods were further divided into four periods each, thus giving a total of nine periods. The third FLECHT time period occurs just prior to quench and since temperature turnover has long since occurred, it is not necessary to subdivide that time period. Software was written to integrate both the calculated and experimental heat transfer coefficients and to compute the multipliers as given by:
MI '0 =
hfdt hf dt t j_1 t),3
The lategrals were evaluated for elevations of 2,4,6,8, and 10 feet in each of the first five FLECHT/SEASET runs shown in Table 2.1. The values for the nine multip!!ers for each of the five runs were averaged at each of the five elevations to give the final set of 45 multipliers. Linear interpolation is used within the elevation range of the multipliers. Outside the elevation range, end values are used.
The new YAEC multipliers are given in Table 2.2.
Table 2.1 RUN PARAMETERS FOR FLECHT SEASET RUNS USED IN YAEC MODEL FL RATE PRESS TINIT- DELT SUB POWER HYD DIA RUN 1.52 40. 1615. 141. 0.4 0.465 31021 0.97 40. 1585. 144. 0.7 0.465 31504 0.81 40. 1600. 143. 0.7 0.465 31805 1.07 20. 1621. 133. 0.4 0.465 31922 0.82 20. 1637. 138. 0.42 0.465 34610 0.59 39. 1620. 142. 0.4 0.465 34006*
6.36(SSEC) 40. 1630. 140. 0.7 0.465 32333
- 0.82(ONWARD) 6.53(5SEC) 20. 1630. 140. 0.7 0.465 32235
- 0.98(200SEC) 0.62(ONWARD)
- Verification only
- a. YANKEE ROWE HYD. DIA. = 0.412 in FLECHT SEASET HEATER ROD DIA = 0.374 in l YANKEE R0WE FUEL ROD DIA = 0.365 in l
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Table 2.2 YAEC FLECHT MULTIPLIERS 2 FT 10.7 3.8 2.3 2.7 3.8 3.6 4.3 5.6 3.1 4 ft 1.18 0.74 0.85 1.08 1.30 1.C . 1.73 1.91 1.14 6 ft 0.64 0.93 0.82 0.77 0.88 1.00 1.16 1.09 0.92
, 8 ft 0.10 0.35 0.46 0.54 0.61 0.71 0.76 0.90 0.90 10 ft 0.06 0.04 0.14 0.29 0.43 0.84 0.92 1.05 1.01 l
b 4
3.0 JUSTIFICATION OF THE NEW CORRELATION The new YAEC corralation, which results from using the multipliers defined in Section 2 w3h the FLECHT correlation, is justified by comparing the peak cladding temperatures calculated uaing the new correlation in the TOODEE2 computer code to the experimental values reported in Reference 3. The results of these comparisons are shown in Figures 3.1 through 3.8. The TOODEE2 results can be seen to be clea.iy conservative with respect to most of the test data. The only notable exception is that for elevations greater than 0 feet, the TOODEE2 results for run 34006 become non-conservative with respect to the experimental data. TPis is acceptable for Yankee Rowe because the very low flooding rates of (1st 34006 (0.6 in/sec) are not reached until late in the transient and the Yankee Rowo core length is only 91 inches (7.6 ft).
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! FIGURE 3-7. TOODEE FLECHT SEASET SIMULATION, FLECHT/SEASETTEST32235 i
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4.0 REFERENCES
Suoolement 1: Further Definitions and Justifications to Reflood Heat Transfer Models, XN-75-41 (Supplement 1), August 14,1975.
- 3. M. J. Loftus, et al, PWR FLECHT SEASET Unblocked Bundle. Forced and Gravity Reflood Task Data Report. Volume 2: Aooendix C. NRC/EPRl/ Westinghouse Report No. 7, September 1981.
- 4. G. N. Lauben, TOODEE2: a Two-Dimensional Time Dependent Fuel Element Thermal Analysis Procram, NUREG 75/057, May 1975.
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