ML19317F463
| ML19317F463 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 11/29/1972 |
| From: | Maccary R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8001140696 | |
| Download: ML19317F463 (3) | |
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- '4/J R. C. DeYoung, Assistant Director for Pressurized Water Reactors Directorate of Licensing STATUS REPORT ON OCONEE 1, 2, AND 3 - FLOW INDUCED VIBRATION TO RF1sCTOR INTERNALS AND ACCEPTANCE OF TOPICAL REPORTS BAW-10050 AND BAW-10037 j
Plant Name:
Oconce 1, 2, and 3 Licensing Stage:
OL Docket Nos.:
50-269 270 287 Responsible Branch and Project c. nager:
PWR Branch No. 4, I. A. Peltier Review Status:
BAW-10050 & BAW-10037 - Complete BAW-10051 & BAW-10038 - Partial The Mechanical Engineering Branch, Directorate of Licensing, has reviewed
___ four topical reports (BAW-10037,10038,10050 and 10051) concerning the hot functional vibration failurea submitted by Babcock & Wilcox (B&W). The HEB conclurions and comments on these topicals are as follows:
1.
BAR-19050 - B&W conducted an investigation on the cause of the preoperational test failure. The metallographic examination of the failure surfaces concluded that the fatigue due to flow induced vibratory motion was the major failura mode.
Component redesign was based upon (a) further separation of structural frequencies from vortex shielding frequencies, and (b) further reduction of the stresses to a level below the material endurance limit. We concur wid B&W that such design modifications will improve the structural integrity of the reactor internals.
t 2.
BAW-10037 - Reactor vessel flow testing was conduct.ed on a onc-sixth i
scale model to investigate flow distribution, pressure loss and the pattern of flow mixing from the various inlets. The flow characteristics inside the core and vent valve testing were emphasized. Both the original and the modified designs were tested. The tests results showed that the modified design provides more uniform flow distribution with acceptable pressure loss. However, B&W indicated that since the i
flow rate was slightly higher at certain portions of the core, further minor modifications in design will be required. We concur with B&W on the approach used to verify the core flow distribution.
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BAU-10051 - B&W has attempted to justify the reactor internals design modifications in BAU-10051 by computing responses of modified conponents 1
However, the actual flow forcing functions may not be verified until the new preoperational vibration test program i
for Oconce 1 has been completed.
We concur that internals have been redesigned based upon a conservative application of the response and failure data from the Oconee 1 preoperational tests.
However, due to a lack of valid flow forcing functions and complete response determination, we cannot complete our evaluation of this topical at this time. The
' applicant has stated that further efforts, including component testing of instrument guide tubes and incore nozzle assemblics will be performed to provide a better understanding of the vibration behavior. The thermal
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shield vibration response characteristics will be further defined by further evaluation of the Oconce 1 response and failure data.
1 4.
BAW-10038 - The prototype preoperational vibration testing program including
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a subsequent inspection program for reactor internals is described in BAW-10038. The applicant cannot provide valid vibration predictions as required by Safety cuide 20 due to inconclusive dynamic analysis.
Therefore, we cannot complete our evaluation of this report at this tice.
We concur with B&W that the design modifications on the internals have been based on a conservative application of the response and failure data from Oconee 1.
However, due to a lack of concrete analytical evidence to assure structural integrity of reactor internals under the transient loadings, satisfactory completion of the new preoperational vibration testing should be considered as a' prerequisite for issuing an operating license.
BAW-10051 and BAW-10038 may be approved when the additional tests and evaluations indicated above are completed to provide the basis for vibration predictions.
When the information is received and reviewed, Oconce 1 may then be qualified as a valid prototype plant. The information contained in BAW-10050 and BAW-10037 will be. acceptable by reference in the Oconce 1, 2, and 3 applications.
We are not preparing Topical Report Evaluations on these topicals since these topicals are practically unique to the Oconce application.
'l R. R. Maccary, Assistant Director for Engineering i
Directorate of Licensing
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