ML19269D127
| ML19269D127 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 02/21/1979 |
| From: | Utley E CAROLINA POWER & LIGHT CO. |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| GD-79-408, NUDOCS 7902270360 | |
| Download: ML19269D127 (4) | |
Text
7 (1
Carolina Power & Light Company February 21, 1979 FILE:
NG-3514(B)
SERIAL: GD-79-408 Office of Nuclear Reactor Regulation ATTENTION:
Mr. T. A. Ippolito, Chief Operating Reactors Branch No. 3 United States Nuclear Regulatory Commission Washington, D. C.
20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 1 DOCKET No. 50-325 LICENSE NO. DPR-71 REACTOR RECIRCULATION SYSTEM SAFE END INSPECTION PROGRAM
Dear Mr. Ippolito:
The purpose of this letter is to document the results of the recent reinspection of the Brunswick Unit 1 recirculation inlet nozzle safe ends. The reinspections were performed from January 17 through January 21, 1979, during the unit's scheduled refueling outage.
On December 22, 1978, Carolina Power & Light Company,'ubmitted to your office the proposed inspection plans. Subsequently, on January 12, 1979, at a meeting held at the plant, members of your staff reviewed and approved the inspection plans as presented. Additional tests were requested by your con-sultants. At that meeting, the results of a test block study performed by our consultant, Lambert, McGill, Thomas, Inc., were presented. The study confirmed the ldB difference in sound attenuation due to water and the ability to cover the entire area of concern with the ultrasonic beam.
Subsequent to the actual examinations, complete copies of the field datn were transmitted to your con-sultants for review. briefly describes the inspection parameters and the requested additional tests performed during the January, 1979 inspections. summarizes the results of the previous inspections and compares the results of the January, 1979 reinspections.
Based on CP&L's review of the test results, we have concluded that no detectable change exists in the data for safe ends N2A, N2B, N2D, N2E, N2G, N2H, N2J, and N2K.
Safe end N2C exhibited generally similar response patterne to the previous results with a slight increase in the DAC responses for indications in the lower quadrant.
Safe end N2F had an overall slight increase in DAC responses with a maximum 20 percent level at approximately 2 o' clock. The differences noted are very slight and are possibly the result of technique or personnel differences from the previous inspections. The changes fall within the industry accepted range of + 2dB or approximately 25 percent DAC for inspection repeatability.
790227o360
- G ; J L m. r ; m C ; s i y c 2ls;2
(
m___ ___
,Q
'Mr. T. A. Ippolito February 21, 1979 Carolina Power & Light Company will continue to monitor the safe ends by ultrasonic examinations at each refueling outage, in accordance with our previously stated commitment. We will be available to discuss the test results or future inspection plans, if you so require.
Yours very truly,
/
/
E. E. Utley Senior Vice Presid nt Power Supply LRH/ JAM /mf Attachments
a Brunswick Steam Electric Plant, Unit 1 Recirculation System Safe Er. Inspection Test Parameters A 45 shear angle was uned wi th a 1.5 MHz focused pitch / catch transducer. The calibrations were perfe med on a 12" diameter Inconel 600 block with 10% notches. The inspections were performed at 86dB which is approximately 6 times the code required sensitivity.
Strip chart recordings were made of the amplitude and range of all indications exceeding the ambient noise level.
The data was also recorded on magnetic tape for subsequent analysis on digital storage scopes. Additionally, a master / slave instrument was set up which afforded the persons observing the strip chart recordings during the examination an opportunity to view the actual indications as seen by the operator. Head sets and microphones were used to provide constant communication between the UT operation and the observers outside the drywell.
The actual inspections were performed at the code requirement 6"/sec. speed and an oscillating motion of the transducer. The safe ends were divided into 5-zone designations. A complete inspection was performed for each zone, including scanning axially upstream and downstream, and radially clockwise and counterclockwise.
This zone scanning was an improvement over the techniques used in the September, 1978 examinations.
In the previous inspections the entire safe end was scanned from end to end and the operator called out the transducer position of significant indications observed.
Supplemental Tests At the request of the NRC consultants on site, a complete rescan of safe end N2D was performed. Different technicians were used.
The purpose of the rescan was to confirm repeatability of the data.
This was confirmed. Additional time was taken to closely examine certain areas to better characterize the indications.
A rescan of the area of interest was performed using a nominal 36 shear wave transducer. The overall response was roughly similar to the 45 search unit, but at a lower amplitude because the steeper incident angle caused more sound energy to be deflected.
It was concluded that the 45 search unit provided equal or better signal definition.
f SUMMAR7 OF UT RESULTS BSEP REACTOR RECIRCULATION SAFE ENDS Nozzle Unit No. 1 Inspection Unit No. 1 Reinspection Unit No. 1 Reinspection 9/27/78 11/18/78 1/17/79 A
Intermittent linear No detectable change indications -
maximum 10% DAC B
Low level inter-No detectable change mittent linear indi-cations - maximum 9%
DAC - random 360 C
Spots at 360 -
General response 20% DAC maximum similar - slight increase to 40% DAC response for indica-tions in the lower quandrant D
Indication from 9:00-Indication 9:00-12:00 No detectable change 12:00 maximum 78% DAC
<78%
E Intermittent 300 Intermittent 360 No detectable change maximum 31% DAC maximum 33% DAC F
One indication -
Overall slight 8% DAC increase in DAC response with maximum 20% level at 2:00 G
Two spot indications No detectable change 8% DAC II One spot indication No detectable change 71/2%
J Intermittment 360 Intermittent 360 No detectable change maximum 30% DAC maximum 40% DAC K
Intermittment 360 Intermittment 360 No detectable change maximum 43%
maximum 48% DAC