ML19340A167

Reactor Vessel Internals Insp Following Hot Functional Testing.

ML19340A167
Person / Time
Site:	Oconee
Issue date:	09/20/1974
From:	DUKE POWER CO.
To:
Shared Package
ML19340A165	List: ML19340A164 ML19340A167
References
NUDOCS 8001100638
Download: ML19340A167 (7)

Text

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O DUKE P0WER C0MPANY OCONEE NUCLEAR ~ STATION UNIT 3 Docket No. 50-287 1

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REACTOR VESSEL INTERNALS INSPECTION FOLLOWING HOT FUNCTIONAL TESTING September 20, 1974 i

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'i.0 INTRODUCTION This report presents information requested by the Atomic Energy Commission Safety Guide 20, with regard to the Oconee Nuclear Station, Unit 3, reactor vessel internals. The prototype design for the Dconee 3 reactor vessel internals was the Oconee 1 internals. A comprehensive report on vibration measurement results for these prototype internals was submitted to the AEC in April, 1973, as Topical Report BAW-10039, " Prototype Vibration Measure-ment Results for B&W's 177-Fuel-Assembly, Two-Loop Plant." This Topical Report was incorporated into the Dconee Final Safety Analysis Report by

, reference by Revision 28, May 1, 1973 1,0-1

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SUMMARY

Hot Functional Testing of Oconee Nuclear Station, Unit 3, was conducted from May 2S, 1974 through June 27, 1974. During this period, greater than 300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> were accumulated at flow conditions, i.e., two or more reactor coolant pumps operating. Consequently, the thermal shleid, which had tha lowest l measured structural frequency (12 !!z), was subjected to more than 107 cycles under these conditions.

Following the conclusion of Oconee 3 Hot Functional Testing, the reactor l

internals were removed from the vessel and a post-test inspection program was

! Implemented. The purpose of this program was to visually inspect major internals, surfaces, and/or parts for any indications of distress, loose parts, cracking, fretting or distortion as a result of Hot Functional Testing.

l It was determined that the reactor internals sustained no structural damage due to Hot Functional Testing and that no deterioration had occurred that l might affect the structural integrity of the internals.

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30 DESCRIFTION OF PROGRAM The reactor internals support the core, maintain fuel assembly alignment, limit fuel assembly movement and maintain control rod assembly guide tube alignment between fuel assemblies and control rod drives. They also direct the flow of reactor coolant, provide gamma and neutron shielding, provide guides for incore instrumentation between the reactor vessel lower head and the fuel assemblies, support the surveillance specimen assemblies in the annulus between the thermal shield and the reactor vessel wall and support the internals vent valves. The general arrangement of the Internals is shown in Figure 1.

The internals components include the plenum assembly and the core support assembly. The plenum assembly consists of the plenum cover, upper grid, control rod assembly guide tube assemblies and a flanged plenum cylinder with openings for reactor coolant outlet flow. The core support assembly includes the core support shield, vent valves, core barrel, lower grid, flow distributor, Incore instrument guide tubes, thermal shield and survelliance specimen holder tubes.

i Following Hot Functional Testing, the reactor vessel internals were visually

inspected for any indications of distress, loose parts, cracking, fretting or distortion, items checked to assure the structural Integrity of the internals included the following

(a) The plenum cover for weld integrity.

(b) The control rod guide tube assembly to plenam cover welds for integrity.

l (c) The bolted joints between the control rod guide tube assemblies and the upper grid for loose or broken bolts and for lock weld integrity.

(d) The bolted joint between the upper grid and the plenum cylinder for loose or broken bolts and for lock weld !ntegrity.

(e) The control rod guide tube assemblies for weld integrity.

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'f) The internals vent valves for free operation.

(g) The surveillance specimen holder tubes for f ree rotation.

f (h) The bolted joint between the core support shield and the core barrel for loose or broken bolts and for lock weld integrity.

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(i) The core support shield for weld integrity.

(j) The core support assembly guide blocks for weld integrity.

(k) The incore instrument nozzles for distortion.

(1) The incore instrument guide tubes to flow distributor welds for integrity.

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(m) The lower grid and flow distributor for weld integrity.

Typical items checked for signs of fretting or surface damage included:

(a) The internals vent valves seats.

(b) The face reals of the 36" reactor vessel outlets.

(c) The control rod guide tube assemblies.

(d) The plenum assembly key ways.

(e) The core support assembly key ways.

(f) The core support assembly guide blocks.

(g) The reactor vessel guide lugs.

In addition to the above inspections, examinations were also made to determine if there were any loose or foreign objects within the reactor vessel. In particular, these included a check of the interior of the reactor vessel lower head and a check of the Interior of the plenum assembly.

The various inspections performed were similar. in type and extent to those performed on the Unit I and Unit 2 Internals following Hot Functional Testing of each unit.

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4.0 DESCRIPTION

OF RESULTS The post-Hot Functional Testing inspection of the Oconee 3 reactor vessel intctnais revealed no indicat;ons of structural integrity degradation. No

-loose or broken bolts or cracked or broken welds were observed. No significant indications of fretting or surface damage were noted.

The following foreign material was found in the bottom of the reactor vessel and removed: tape, plastic, wood, and metal band. None of these were identified as part of the Reactor Coolant System or Internals.

In general, the reactor internals sustained no structural damage due to Hot Functional Testing and no deterioration occurred that might affect the structural integrity of the internals.

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REACTOR VESSEL AND INTERNALS ARRANGEMENT O

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