ML18054A578
| ML18054A578 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 02/24/1989 |
| From: | Bordine T CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8903090035 | |
| Download: ML18054A578 (6) | |
Text
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consumers Power POWE RI Nii MICHlliAN'S PROliRESS General Offices: 1945 West Parnall Road, Jackson,'MI 49201 * (517) 788-0550 February 24, 1989 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -
STEAM GENERATOR ISSUES, STATUS AND PLANS On February 10, 1989, representatives of Consumers Power Company met with NRC staff members at NRC Headquarters in White Flint to discuss the results of a Steam Generator Tube Inspection at our Palisades Plant.
The plant shut down on January 30, 1989 following identification of primary to secondary leakage in Steam Generator B.
During the meeting, Consumers Power Company committed to respond within 15 days to concerns expressed by the NRC staff members.
This letter provides our response.
NRC requested that we review the status of our tube flaw size/vibration analysis during postulated accidents and accelerate its completion if possi-ble.
Our letter of January 31, 1989 committed to complete and submit the analysis by August 30, 1989.
We have reviewed the status and conclude this analysis can be completed more expeditiously.
A second meeting was held at MPR Associates offices in Washington, DC, with the NRC technical reviewer on February 16, 1989 to better define and bound the analysis.
At that session, general agreement was reached as to how the evaluation should be conducted and what the critical issues were.
The NRC was provided an analysis scope which will be changed to reflect the comments made at the meeting.
Our technical representatives indicated that the analysis could be completed in a May-June time frame.
Consumers Power Company, therefore, will revise our commitment due date and submit this analysis to NRC by May 31, 1989.
NRC requested that we complete qualification of the MIZ-18 inspection process and b~ prepared to inspect tubes using MIZ-18 during a. May-June, 1989 time frame.
We have reviewed our qualification schedule and conclude that it is not possible to meet the accelerated schedule.
This is due primarily to the extensive amount of metallography work required to support the qualification and the fact that we had already accelerated completion of the qualification process from an original planned completion of December, 1989.
8903090035 890224 PDR ADOCK 05000255 Q
PDC OC0289-0057A-NL04 A CMs ENERGY COMPANY
Nu~lear Regulatory Commission Palisades Plant S/G Issues, Status & Plans February 24, 1989 At this time calibration standards consistent with the chemical and physical material specifications and flaw characterization of the Palisades steam generator tubes have been fabricated.
Eddy current data is currently being collected from the standards.
The qualification activities remaining to be completed are as follows:
- 1.
IGA present in each sample through 2
Determine actual depth of metallographic evaluation sample to be evaluated).
(there are 84 samples with two defect areas Expected* completion dat,e is May 31, 1989.
per.
- 2.
Determine the statistical accuracies of each t~chnique. The techniques being evaluated include bobbin coil (540, 560 and 580 diameters), 4C4F, 8Xl, MRPC and rotating axial wound differential.
Expected completion date is June 16, 1989.
- 3.
Determine the optimum techniques based on the results of the statistics and write the qualification report.
Expected completion date is June 30, 1989.
- 4.
Perform a second party independent review of the qualification.
Expected completion date is July 22, 1989.
- 5.
Write MIZ-18 method procedures and interpretation guideline.
Expected completion date is July 31, 1989.
We, therefore, can commit completion of our MIZ-18 qualification process no earlier than the end of July 1989.
However, we expect the MIZ-18 examinations to confirm our existing examination methods.
We have established MIZ-12 as a reliable method to detect defects and will continue to use the method in the event that another outage is required before the end of July 1989.
NRC requested that we complete a rim/lug cut of the upper support plates during a May - June, 1989 time frame.
In the event that primary to secondary tube leakage persists fo!lowing our February 1989 start-up, the suggested time frame may be appropriate.
However, there are three factors pertinent to the decision to complete the rim/lug cut of the upper support plates.
These are availability of Consumers Power Company personnel to perform the subsequent eddy current inspection and repair activities, completion of the MIZ-18 qualification, and the completion of a support plate stress evaluation.
We are currently reviewing a proposal from Combustion Engineering to perform the rim/lug cut.
The proposal requires ten weeks for the engineering (planning, tooling, scheduling) before the actual cutting work begins.
The availability of Consumers Power Company personnel to perform the eddy current inspection and repair activities offer a fall 1989 outage alternative as more appropriate than a spring 1989 outage.
Due to ALARA considerations resulting from our previous steam generator outages and the fact that the same individuals are also utilized and scheduled for various plant outages at our other fossil and nuclear facilities, a fall schedule will best accommodate use of our own personnel.
We prefer to keep the knowledge and experience gained OC0289-0057A-NL04
Nuclear Regulatory Commission 3
Palisades Plant S/G Issues, Status & Plans February 24, 1989 from any repair work in-house, rather than losing the experience through use of contract personnel, although we recognize that sometimes this is unavoidable.
Following the rim/lug cut an extensive eddy current inspection is anticipated to ensure the integrity of the tubing.
Completion of the MIZ-18 qualification to support this inspection is highly desirable since we expect the duration of the inspection to be reduced (resulting in lower radiation exposure) due to the ease of collecting data with the MIZ-18 system.
NRC requested that we perform an evaluation to iden~ify tubes which are most susceptible to failure due to tube/support plate interaction during a May -
June, 1988 time frame.
The study will be conducted by MPR Associates and take into consideration the periphery tubes near the support lugs and will identify highly stressed tube regions resulting from the combination of normal operation stresses induced by support plates, previous tube denting, internal tube configuration, temperature and other related parameters.
The study is currently scheduled to be completed by May 1, 1989.
In addition to the support plate stress evaluation, Consumers Power Company has commissioned MPR Associates to review the historical and present-day problems, corrective actions taken, and results achieved to provide long-term recommendations in regard to the steam generators.
NRC requested that we also consider reducing our hot leg temperature following start-up from the February 1989 outage.
Following review of all factors associated with our previous experience, we have concluded that we may improve reliability by reducing the hot leg temperature to not exceed 585°.
Consumers Power Company therefore plans to operate at a power level which should main-tain TEOT ~ 585°F until fall 1989.
However, we wish to emphasize that this reduction is only for reliability purposes and is not due to any safety concern.
Prior to our next planned shutdown, we may elect to increase power level while monitoring off-gas for a period of time to obtain any data points that may have developed during the period.
Final decisions regarding applicability of a fall outage to perform a rim/lug cut of the upper plates will be made following completion and review of the support plate stress evaluation, the qualification of MIZ-18, the long term recommendations and the results of the current operating run at a reduced power level.
We do intend to perform a 100% inspection of all tubes in both steam generators using the MIZ-18 tester no later than the next refueling outage.
During the February 10, 1989 meeting, NRC staff members also requested that a correlation of primary - secondary leakage, corresponding to the condenser off-gas alarm set points be provided. provides an example graph when PCS Xenon concentration is 25 uCi/kg.
This was approximately the concen-tration just prior to shutdown.
Although the alarm set points for condenser off-gas radiation monitor (RIA-0631) apply to radiological effluent technical specifications and not primary to secondary leakage, they may be used to provide early indication of potential leakage.
The "Alert" set point is at OC0289-0057A-NL04
Nuclear Regulatory Palisades Plant S/G Issues, Status February 24, 1989
- Commission
& Plans 5,000 cpm.
The "Hi Alarm" set point is at 10,000 cpm.
Assuming a typical off-gas flow rate of 4 cfm, and the example Xenon, the graph indicates that the Alert set point corresponds to a primary to secondary leak rate of
.005 gpm.
This is a factor of 20 below our current administrative limit for initiating shutdown and a factor of 60 below our Technical Specification limit.
This provides the operators with a prompt warning and preliminary estimate of primary to secondary leakage until required sampling and analysis is performed to provide a more accurate leak rate.
Thomas C Bordine Plant Licensing Administrator CC Administrator, Region III, NRC NRC Resident Inspector - Palisades Attachment OC0289-0057A-NL04 4
h OC0289-0057A-NL04 ATTACHMENT 1 Consumers Power Company Palisades Plant Docket 50-255 CYCLE 8 RIA-0631 OFF GAS MONITOR February 24, 1989 1 Page
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