ML20203L677
| ML20203L677 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/25/1986 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| 5211-86-2147, NUDOCS 8608290050 | |
| Download: ML20203L677 (4) | |
Text
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GPU Nuclear Corporation g
gf Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
August 25, 1986 5211-86-2147 Office of Nuclear Reactor Regulation Attn:
J. F. Stolz, Director PWR Projects Directorate No. 6 U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Stolz:
Three Mile Island Nuclear Station Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Fluence Projections Per 10 CFR 50.61 Attached are responses to the three questions forwarded by your letter dated June 20, 1986.
Sincerely,
. D. H k'll Vice President and Director, TMI-l HDH:jh:3748f/0653A cc:
J. Thoma R. Conte Enclosure 8608290050 860925 PDR ADOCK 05000289
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P pop I
GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION Question 1:
On page 4-6 of BAW-1895 the fluence to reach the screening criteria is stated 1
as 7.0 x 10 6 n/cm2 This is inconsistent with (a) the last line of Table 4-4 and (b) our own estimate which is close to your estimate which shows the fluence to reach the screening criteria = 6.4 x 1018 n/cm2 Please clarify.
Response
Item #4 in the heading of Table 4-4 on page 4-6 states that the " fluence at screening criteria" is 7.0 x 1018 n/cm2 This should have read " peak fl ue nce".
Longitudinal weld SA-1526 is the first to reach the screening criteria at an accumulated f.luence of 6.4 x 1018 n/cm2 This weld is at a circumferential location (0*) where the fluence is lower than the peak accumulated fluence by a multiplication factor of 0.91.
It should be noted that more recent fluence projections have resulted in lower estimates of reactor vessel accumulated fluences at license expiration.
These data are provided in B&W Topical Report BAW-1901, " Analysis of Capsule THI-1-C..." (March 1986), (GPUN letter 5211-86-2080, dated May 5,1986).
BAW-1901 used the same assumptions for future TMI-l fuel cycle strategies as were used in BAW-1895 (i.e., Cycles 6 and 7: low leakage design and Cycles 8 and beyond: very low leakage design).
Improved D0T-4 transport code methods, described in the report, were used and specific power distributions for Cycles l
2 to 4 were included in the calculation.
the new estimated fluence value at license As shown in Table 7-5 of BAW-1901, 2 at SA-1526, the critical RV weld.
expiration (2008) is 5.33 E 18 n/cm This gives a PTS Evaluation reference temperature of 260* F, providing 10* margin to the screening criteria.
Using the new fluence projections the SA-1526 weld will reach the screening criteria in 2015.
Question 2:
In BAW-1895 it is stated that future fYux reductions have not been taken ipto account. Under this assumption we estimate a 32 EFPY fluence = 15.45 x 1016 n/cm2 18 n/cm2.; however, the corresponding value in Table 4-4 is 9.1 x 10 Please state the assumptions and the projected low-leakage loadings.
Response
Assumptions regarding future fuel cycles are listed in Table 3-1 on page 3-4.
For TMI-1, it is assumed that conversion to a low-leakage-cycle will occur with Cycle 6 and conversion to very-low-leakage cycles will occur with Cycle 8.
That is, it is assumed that Cycles 6 and 7 will be low-leakage and Cycle 8 and beyond will be very-low-leakage. The footnote to Table 2-1 on page 2-3 states, " assumes 0.80 utilization factor (EFPY/ calendar year) and no :hange in future fuel cycles". This was intended to mean no change in future fuel cycles from what has been assumed in this report and is presently anticipated.
The assumptions for the TMI-l analysis are discussed in the first full paragraph on page 3-2.
Based on previous B&W fuel cycle analysis for TMI-l and other plants it was determined that an effective azimuthal flux distribution factor of 0.91 was applicable to TMI-1 for calculating flux at the 0* major axis location of the critical weld (SA-1526), compared to the peak flux for the first seven cycles of operation (i.e., critical weld flux =
0.91 x peak flux). For Cycles 8 and beyond the Reference 5 (BAW-1884) results were used which gave a flux reduction ratio at the vessel wall of 0.665, specifically calculated at the 0* location, for very low leakage fuel cycles compared to low-leakage cycles.
Question 3:
In Table 3-1 (BAW-1895) it is indicated that Cycle 8 will be a very-low-leakage cycle. State the expected flux reduction for Cycle 8 and also for Cycles 7 and 6 and for Cycles 1-5.
State the corresponding EFPY's to the end of the operating license.
Response
The ratio of flux at the limiting weld (SA-1526) for each cycle to that for Cycle 1 -is provided in Table I along with the EFPYs at the end of each cycle and to expiration of license. Table I is based on methods used to calculate fluences reported in BAW-1895 and expanded above in response #2.
It should be noted that more recent fluence projections are provided in BAW-1901, i
~
TABLE I: TMI-1 CRITICAL WELD (5A-1526) FLUX REDUCTION AND FLUENCE VALUES e'
Flux Reduction EFPY From End Of Factor Incremental l
EFPV for Cumulative Cycle To License Referenced Fluence Fluence Cumulative Cycle Cycle Type Cycle EFPY Expiration (1)
To Cycle 1 per EFPY (1018) for Cycle (1018)
Fluence (1018) 1 Standard 1.28 1.28 19.72 1.000 0.416(6) 0.53 0.53 2
Standard 0.70 1.98 19.02 1.137(2) 0.473 0.33 0.86 3
Standard 0.79 2.77 18.23 1.203(2) 0.500 0.40 1.26 4
Standard 0.75 3.52 17.48 1.199(2) 0.499 0.37 1.63 5
Standard 0.77 4.29 16.71 1.220(2) 0.508 0.39 2.02 6
Low Leakage 1.13 5.42 15.58 1.000(3) 0.416 0.47 2.49 7
Low Leakage 1.20 6.62 14.38 0.878(4) 0.365 0.44 2.93 8
Very Low 1.20 7.82 13.18 0.584(5) 0.243 0.29 3.22 Leakage 9-19 Very Low 13.2 0.584 0.243 3.21 6.43 Leakage (1) At license expiration (May 18, 2008) EFPY = 21.0, based on anticipated start of Cycle. Seing January 1989 and 18 month cycles with 0.8 utilization (EFPY/ calendar year) through end of ifcense.
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(2) Based on calculated baffle flux ratio.
(3) 1.22 x 0.82 based on baffle flux ratios calculated for 1st Low Leak-to-Last Out In.
(4) 1.22 x 0.72 based on baffle flux ratios calculated for 2nd Low Leak-to-Last Out In.
(5) 1.22 x 0.72 x 0.665 at critical weld location (0* from major a.is), based on Fluence Reduction Study, BAW-1884, xeference 5 of BAW-1895.
(6) B8W Topical Report, BAW-1439, " Analysis of Capsule TMI-IE..." (Jarsuary 1977), Table 6-5 data with critical weld azimuthal reduction factor of 0.91 applied.
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