ML18051A882
| ML18051A882 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 05/09/1984 |
| From: | Johnson B CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-CR-0718, RTR-NUREG-CR-718 NUDOCS 8405140215 | |
| Download: ML18051A882 (2) | |
Text
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consumers Power company General Offices: 1945 West Parnall Raad, Jackson, Ml 49201 *.{5171 7!;1$-0550 May 9, 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 - RESPONSE TO NRC STEAM GENERATOR CONCERNS -
SUPPLEMENTAL' INFORMATION In a letter dated April 25, 1984, Consumers Power Company submitted informa-
. tion to the NRC relating to concerns indentif ied during the Palisades Steam Generator Tube Plugging Meeting of April 10, 1984.
The following information is intended to supplement the previous submittal.
Data presented to the NRC on February 21, 1984 included the attached Figures 1, 2 and 3.
The graphs presented in Figure 1 were taken from NUREG CR-0718.
These' data were selected based on tubing (0.750 x 0.050) representative of Palisades Steam Generator Tubing.
A composite plot of burst pressures for EDM axial slots, elliptical wastage and uniform thinning was generated as a function of through wall degradation (see Figure 2).
The following observation were made from Figure 2:
The greater the depth of the defect the more scatter was observed.
If one plots the burst pressures, for the various defects, as a function of defect length (see Figure 3) the following observations can be made:
In general, for shallow defects (25-30% through wall) tube burst pressures are independent of defect length.
.fi.s the depth of the defect increases (55-60% through wall) a significant increase in burst pressures is observed for small defect lengths relative t~ the infinite and uniform defect burst pressure.
The limiting case becomes the near through wall defect (85-90%
through wall) which demonstrates the highest dependence on defect length.
OC0584-0004A-NL02
DMCrutchf ield, Chief Palisades Plant NRC S/G CONCERNS May 9, 1984 2
Using a straight line fit for defects with lengths of 0.24 to 1.53 inches and 85-90% through wall (see Table F.3, NUREG CR-0718) one finds that:
Burst Pressure = -2134 (L) + 6320 (1)
Where the burst pressure is in psi and "L" is the axial length of the defect.
Solving equation 1 for a localized defect of 0.38 inches in length results in a burst pressure of 5,509 psi.
This value is well above Palisades most limiting condition as specified by code allowables (three times normal operating primary to secondary differential pressure).
Solving equation 1 for the maximum permissi,ble defect length, given the Palisades normal operating differential pressure, results in a permissible defect length of 1.02 inches.
In summary, for the region of interest (defect lengths of 0 - 0.50 inches) the CR-0718 burst data is tightly bound and indicates a considerable margin of conservatism in the selection of the repair basis defect.
Brian D Johnson Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades OC0584-0004A-NL02