ML18227D348
| ML18227D348 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/17/1976 |
| From: | Bixel D Consumers Power Co |
| To: | James Keppler NRC/IE, NRC/RGN-III |
| References | |
| Download: ML18227D348 (3) | |
Text
General offices: 212 wast Mlchlgan Avenue, Jackson. Mlchfgan 49201
~ Area code 517 788-0850 June 17, 1976 Mr James G. Keppler Office of Inspection Enforcement Region III US Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-255, LICENSE DPR-20 PALISADES PLANT, REACTOR INTERNALS NOISE MONITORING TEST REPORT This letter report is submitted. in accordance with the requirements of Techni-cal Specifications Section 4.13.C.4 which requires a report, on a semiannual basis, of the results of Reactor Internals Noise Monitoring tests.
During the period, covered. by this report, the plant was shut down for the first refueling ut ge and only a minor amount of data was collected.
This data (considered d.
preliminary) indicates that the RMS noise levels are similar to those observe in May 1975 although the phase and. coherence appear to be different.
This data will be included with that compiled for our next semiannual report.
During the last refueling outage (December 1975 to May 1976), measurements were made on the core support barrel hold-down device.
The measurements taken were compared to as-installed. post repair data accumulated in March 1974.
The axial measurements indicated a change in dimensions of the measured plungers relative to the RV head. mating surface.
The average dimension of the measured.
plungers is computed. to be 14 mils below the as-installed position.
Inspection of the tops of the plungers of the hold.-down device disclosed radial scratch marks with respect to the reactor vessel too small in depth to measure.
The interface of the plungers with the reactor head did show indications of radial marks of vary-ing depth approximating 'from 0 to 2 mils.
Evidence of the plunger interface with the reactor vessel head. could be detected. at all 308 plunger locations.
The alignment keys that protrude from the core support barrel and. provide align-ment among the reactor vessel, reactor vessel head.,
core support barrel
- and, upper guide structure showed indications of what could be interpreted to be shiny metal.
Subsequent dimensional inspections of the upper guide ructure flange upper surface relative to the reactor vessel mating surface n icated an inconsistency as these dimensions show the upper guide struct e
wn further than the plunger assemblies.
The following are conclusions reached.
as a result of the inspection:
1
The visual inspection of the'isible portions of the hold-down device and interfaces with the'eactor vessel and reactor vessel head did not show evi-dence of excessive wear of the reactor internals assembly.
The marking ob-served on the interface surface of the hold-down plungers with the reactor vessel head is the result of a bearing load produced by the hold-down plunger assembly and the radial differential thermal movement of the austenitic stain-less steel reactor internals assembly relative to the reactor vessel head.
Since the reactor vessel head scratch/indentation marks were the result of heatup and cooldown and this is a low frequency occurrence, it is not expected that substantial changes will take place during future operation.
The reactor vessel head cladding will work harder due to the interaction with the hold-down plunger head and become more resistant to further galling of the cgadding material.
The changes from the post repair measurements taken in March 1974 are attri-buted to a combination of a relocation of the'ore support barrel to a lower position on the reactor vessel support ledge to more close+ approximate the measurements taken in November'3.973 and a compressing of the upper guide struc-ture flange and spacer'him to conform to the'ave in the upper surface of the core support barrel flange.
The'hanges in axial position of the top surface of the upper guide structure flange are not attributed to wear of the reactor vessel support ledge due to vibration of the reactor internals assembly..
The changes in the hold-down plunger dimensions are attributed to a rotation of the'old.-down'evice relative to,the'pper guide structure flange, a reposi-tioning of the'elleville washers within the hold-down device and the lower axial position, of the'pper guide structure relative to the reactor vessel mating surface.'he hold-down load has been evaluated'onsidering the recent measured data and still maintains substantial margins against rocking, sliding, and vertical motion of the'eactor internals assembly.
Based on the investigation conducted, it is concluded that the'resent clamping force, considering the changes in dimension of the reactor internals with respect to the mating surface, provides substantial margin over, the hold.-down force required to prevent rigid body mo-tion of the reactor internals assembly.
The changes in axial height measure-ments of the'pper guide structure flange upper surface with respect to the reactor vessel mating surface are not the'esult of excessive vibration of the reactor vessel'nternals causing additional wear of the reactor vessel support ledge.
These changes in dimension are the'esult of compressing the'pper guide structure-spacer shim assembly and. a repositioning of the'ore support barrel, approximating the'xial height'elationship to the'eactor vessel determined prerepair in November 1973.'ur present plans call for the conduct of an additional inspection, similar to, the last inspection, at the next refueling outage.'avid, A. Bixel Assistant Nuclear Licensing Administrator
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