ML18052B414
| ML18052B414 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 12/17/1987 |
| From: | Kuemin J CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| TAC-56365, NUDOCS 8712210208 | |
| Download: ML18052B414 (3) | |
Text
y consumers Power POW ERi Nii NllCHlliAN"S PROliRESS General Offices: 1945 West Parnall Road, Jackson, Ml 49201 * (517) 788-0550 December 17, 1987 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -
STEAM GENERATOR AUGMENTED INSPECTION PROGRAM (TAC NO. 56365)
By letters dated September 28, 1984, June 5, 1987, and September 15, 1987, Consumers Power Company submitted proposed changes to the Palisades Steam Generator Inspection Program.
The supplemental letters of June 5, 1987, and September 15, 1987, were the result of discussions between NRC and Consumers Power Company staff personnel.
Apparently, all. issues, from those discussions, related to the proposed steam generator inspection program have been resolved, with one exception.
This exception is our proposed _
surveillance frequency for sleeved steam generator tubes.
The present Technical Specification requires inspection of all sleeves during each steam generator tube inspection.
Our proposed surveillance interval would be to inspect each sleeve once every three inspection periods.
This could allow no inspection of any sleeved tubes for one or two surveillance intervals.
The Palisades steam generators have a total of 33 sleeves in 26 different tubes.
Thirteen sleeves, in 11 tubes, in the "A" steam generator and 20 sleeves, in 15 tubes, in the "B" steam generator.
The sleeves were installed in 1976 and 1978 and through the last inspection (December 1985) there was no significant change in parent tube wall degradation and no additional sleeve defects or degradation.
After the last steam generator inspection a total of 6,516 unplugged tubes were in the "A" generator and 6,482 unplugged tubes in the "B" generator.
The sleeved tubes ther*efore represent a very small number of the total tubes in the steam generators.
During the 1985 inspection, which required 16 days to conduct the physical examination, approximately 65 man-rem of radiation exposure resulted.
Of this 16 days, three days were required to ~onduct the sleeve inspection alone, at a OC1287-0251-NL04
e Nuclear Regulatory Commission
-Palisades Plant S/G Augmented Inspection Program December 17, 1987 2
cost of approximately 12 man-rems.
The sleeved.tubes inspection represented about 1.5% of the total tube inspection yet accounted for approximately 18% of.
the radiation exposure.
The large dose is due to the present equipment used at Palisades to perform the sleeve inspection.
This equipment is independent of the ha_rdware used for the majority of the inspection.
We are presently procuring new probe assemblies that are adaptable to the hardware used for the normal tube
_examination.
However, the probe assemblies first have -to be manufactured and qualified for use.
Only on~ prototype motor has been built thus far and no eddy current probes have been built.
The manufacture of the new probe
- assemblies could be expedited, but due to the unknown risks associated with qualification testing and initial use, we do not think the inspection of the 33 sleeved tubes warrants any additional resources.* at this time.
Had the present outage which resulted from detecting a primary to secondary leak in steam generator "B", on December 4, 1987, began on schedule in April 1988, the new probe assemblies may have been ready for use.
However, the current equipment delivery schedules will be too late to use during this outage.
We do not belie~e the inspection of the 33 sleeves warrants the additional 12 man-rem radiation exposure that would result from conducting the inspection with the present inspection equipment.* When the new probe assembly (that can utilize the present probe manipulating hardware) is complete, the radiation exposure resulting from sleeve inspection will be considerably reduced.
However, based o~ past inspection data, we do not believe it necessary to
_conduct a total inspection of all 33 sleeves every inspection period.
As noted above, no significant degradation of the sleeves or parent material has been detected since their installation.* Furthermore, our discussions with an industry expert lead us to conclude that the lack of sleeve degradation at Palisades is like the experience of other plants utilizing volatile chemistry.
Based on the foregoing, we still believe our previously p~oposed Technical Specifications change request is appropriate. *However, in lieu of that approval, we_ propose an alternate inspection to allow a one time exemption from the present sleeve inspection requirements.
Subsequent inspections would then be conducted on approximately 1/3 of the sleeved tubes each inspection so all sleeved tubes are inspected on.ce per three steam generator tube inspection intervals.
This 1/3 sample far exceeds the random sampling-requirements for typical* steam. generator tubes. *The suggested rewording _for Specification 4.14.2.4 is:
"4.14.2.4 A baseline inspection of all newly installed sleeves shall be performed prior to plant operation.
Inspection of each installed sleeve shall be performed once per three steam generator tube inspection intervals, with approximately oiw-third of the sleeves inspected during each inspection interval.
- In the event of 0Cl287-0251-NL04 _
e Nuclear Regulatory Commission Palisades Plant S/G Augmented Inspection Program December 17, 1987 sleeve degradation the sleeve inspection interval shall be evaluated.
- Inspection of the installed sleeves during the inspection beginning in December 1987 is not required."
James,L Kuemin
. Staff Licensing Engineer CC Administrator, Region III, NRC NRC Resident Inspector - Palisades OC1287-0251-NL04 3