ML20210Q978
| ML20210Q978 | |
| Person / Time | |
|---|---|
| Site: | Mcguire |
| Issue date: | 05/24/1999 |
| From: | Ferlisi M DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML20210Q974 | List: |
| References | |
| NUDOCS 9908170005 | |
| Download: ML20210Q978 (8) | |
Text
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McGuire Nuclear
- Station, Unit 2
l Class MC ISI Summary Report for Refueling Outage EOC12 l
l By:
Date:
6/
9 (Mark (/Ferlisi, P.E.)
Reviewed By:
Date:
J /g_ gp
'((2pfGq Approved By:
,lb,
[v Date:
1 i
i 9908170005 990810 PDR ADOCK 05000370 G
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McGuire' Nuclear Station, Unit 2 Class MC ISI Summary Report Refueling Outage EOC12 Page 2 of 8 l
i ASME Code,Section XI, Division 1 and Regulatory Requirements for Class MC ISI Summary Reports Inservice inspections of. Class MC components are performeB in accordance with the ASME Boiler and Pressure Vessel Code,Section XI, Subsection IWE, 1992 Edition with the 1992 Addenda.
Article IWA-6000, Records And Reports, paragraph IWA-6210, requires the Owner to prepare inservice inspection summary reports for inservice inspections performed on Class 1 and 2 pressure retaining components and their supports.
IWA-6000 does no,t address inservice inspection summary reports for Class MC pressure retaining components and their supports, and the Code does not require preparation and l
submittal of summary reports for Class MC components.
As such, this Class MC ISI Summary Report does not contain L
information specified in IWA-6220 or IWA-6230.
Please note that this report is being submitted within 90 calendar days following the completion of the refueling outage at McGuire Unit 2, in accordance with IWA-6240(b).
l Duke Energy Corporation is maintaining a separate Inservice Inspection Program for Class MC pressure retaining components and their integral attachments.
Therefore, this Class MC ISI Summary Report contains only that inservice inspection information applicable to Code Class MC components.
ISI Summary Reports for other Code Class components are to be submitted separately.
This Class MC ISI Summary Report includes applicable information required by 10 CFR 50.55a (b) (2) (x) (D), which states:
(D)
The following may be used as an alternative to the requirements of INE-2430.
(1)
If the examinations reveal flaws or areas of degradation exceeding the acceptance standards of Table IWE-3410-1, an evaluation shall be performed to determine whether additional component examinations are required.
For each flaw or area of degradation identified which exceeds acceptance standards, the licensee shall j
provide the following in the ISI Summary Report j
required by IWA-6000:
1
m McGuire Nuclear Station, Unit 2 Class MC ISI Summary Report Refueling Outage EOC12 Page 3 of 8 (i)
A description of each flaw or area, including the extent of degradation, and the conditions that led to the degradation.
(ii)
The acceptability of each flaw or area, and the need for additional examinations to verify that similar degradation does not exist in similar components, and; (iii)
A description of necessary corrective actions.
(2)
The number and type of additional examinations to ensure detection of similar degradation in similar components.
l l
l Discussion of Alternative to IWE-2430 Used During Inspection l
The alternative permitted by 10CFR50.55a (b) (2' (x) (D) was used during this inspection following the detection of conditions on 2 moisture barriers (Examination Category E-D
(-
Items) which, according to our procedures, failed to meet l
the acceptance standards of Table'IWE-3410-1.
This Class MC l
ISI Summary Report provides information required by 10 CFR i
50.55a (b) (2) (x) (D) when using the alternative to IWE-2430.
These conditions were identified during the performance of ASME Code,Section XI, IWE VT-3 Visual Examinations in accordance with Table IWE-2500-1, Category E-D, Item E5.30.
Please note that other IWE examinations were performed during refueling outage EOCl2, and that no other conditions requiring evaluation and reporting in accordance with 10 CFR 50.55a (b) (2) (x) (A) were observed.
Also, the alternative to IWE-2430 permitted by 10 CFR 50.55a (b) (2) (x) (D) was not used following examinations performed on items other than those indicated in this report during this inspection.
Condition #1 Portions of Moisture Barrier Inspection Item
- E05.30.0036 (sealant) were observed to be missing from surfaces along the vertical interface between the Fuel
McGuire Nuclear Station, Unit 2 Class MC ISI Summary Report Refueling Outage EOC12 Page 4 of 8 Transfer Tube Radiation Shielding Concrete and the exterior of the Steel Containment Vessel at azimuths j
247 and 270 degrees, between elevations 725'+0" (nom.)
and 742'+1" (nom).
Item #E05.30.0036 also includes sealant along the horizontal interface between the top of the Fuel Transfer Tube Radiation Shielding Concrete and the Steel Containment Vessel exterior, but this portion was not missing and was considered acceptable.
- 1. Description of each flaw or area, including the extent of degradation, and the conditions that led to the degradation.
Moisture barrier materials identified as missing had apparently never been installed and therefore, were not damaged or degraded.
However, because the initial Inservice Inspection Plan had identified these locations as having been sealed with moisture barrier materials, the condition of the Item
- E05.30.0036 was deemed recordable because of rejectable conditions (i.e. missing material) which are specified in our examination procedures.
Locations where moisture barrier material was missing
)
are identified above.
I Please note the following:
(a)
The initial inspection plan conservatively identified these locations as having been sealed i
with moisture barrier materials to eliminate the need for field examinations that would have been necessary to confirm the existence and location of every moisture barrier.
It was expected that initial inservice inspections would confirm whether all identified locations such as these l
were sealed so that additional moisture barrier l
materials could be added to protect the Steel j
Containment Vessel from potential future moisture intrusion.
i (b)
The design basis of the Steel Containment Vessel does not require the installation of moisture barrier materials, and these materials are not addressed in the applicable Construction Code.
McGuire Nuclear Station, Unit 2 Class MC ISI Summary Report Refueling Outage EOC12 Page 5 of 8
- 2. The acceptability of each flaw or area, and the need for additional examinations to verify that similar degradation does not exist in similar components.
A VT-1 visual examination was performed on locations where moisture barrier materials were missing to determine whether there was evidence of any moisture intrusion, and whether the condition of adjacent Steel Containment Vessel surfaces met the acceptance standards specified in our VT-1 examination procedures.
These examinations detected no unacceptable conditions on Steel Containment Vessel surfaces at these locations.
As such, the condition of the Steel Containment Vessel was determined to be acceptable and did not require reporting and evaluation in accordance with 10 CFR 50.55a (b) (2)
(x) (A).
- 3. A description of necessary corrective actions.
New moisture barrier material (sealant) was added to seal these locations from potential future moisture intrusion.
This work was completed during the refueling outage, prior to returning the unit to service.
- 4. The number and type of additional examinations to ensure detection of similar degradation in similar components.
All moisture barrier materials identified in the inspection plan on the exterior of the Steel Containment Vessel were examined during the inspection.
1 Please note that the inspection plan identifies other locations where moisture barrier materials are installed on the interior of the Steel Containment Vessel.
These moisture barriers were not examined during this inspection for the following reasons:
(a)
Nearly all of the moisture barrier materials installed on the interior exist along vertical interfaces between the Steel Containment vessel and interior concrete structures.
These locations do not permit the accumulation of moisture, and the risk of moisture intrusion at L
McGuire Nuclear Station, Unit _2 Class MC ISI Summary Report Refueling Outage EOCl2 Page 6 of 8 4
these locations is minimal,'even if moisture barriers at these locations are missing or degraded.
(b)
Nearly all of the remainine moisture barrier materials installed on tre interior are located at or near the Steel Containment Vessel embedment zone. -These materials were replaced or were added in the past two years and do not justify examination at this time.
(c)
The McGuire procedure'for IWE-2500, Examination Category E-A, general visual examinations requires that accessible moisture barriers on
-the interior and exterior of the Steel Containment Vessel be exar.2 ned.
IWE-2500, Examination Category E-A, general visual examinations are scheduled to be performed during the next refueling outage.
As a result, 100% of all moisture barriers will have received a general visual or VT-3 visual examination by the end of the next refueling outage.
Condition #2 Portions of Moisture Barrier Inspection Item
- E05.30.0035 (sealant) exhibited conditions which could have allowed the possible intrusion of moisture against inaccessible (embedded) surfaces of the Steel Containment Vessel.
Item #E05.30.0035 consists of sealant installed at the embedment zone between the Steel Containment Vessel exterior and the Annulus concrete floor.
- 1. Description of each flaw or area, including the extent of degradation, and the conditions that led to the degradation.
Several isolated locations were noted where conditions such as the following were observed:
Sealant separated from the Steel Containment
=
Vessel l
McGuire Nuclear Station, Unit 2 Class MC ISI Summary Report Refueling Outage EOCl2 Page 7 of 8 At some locations, the sealant did not maintain good contact with the Steel Containment Vessel so that a water-proof seal was obtained.
These conditions did not appear to be the result of degradation, but appear to be the result of inadequate application of the material.
Some locations on the moisture barrier were coated, making examination difficult.
Please note that most of this moisture barrier satisfied the acceptance standard of IWE-3513 and the inspection procedure, and that deficient areas were noted only at limited locations.
- 2. The acceptability of each flaw or area, and the need for additional examinations to verify that similar degradation does not exist in similar components.
A VT-1 visual examination was performed on suspect moisture barrier locations to determine whether there was evidence of any past moisture intrusion, and to determine whether the condition of adjacent Steel Containment Vessel surfaces met the acceptance standards specified in our VT-1 examination procedures.
These examinations detected no unacceptable conditions at these Steel Containment Vessel to concrete interfaces.
In addition, no evidence of past moisture intrusion was observed.
As a result, the condition of the Steel Containment Vessel was determined to be acceptable and did not require reporting and evaluation in accordance with 10 CFR 50.55a (b) (2) (x) (A).
- 3. A description of necessary corrective actions.
At locations where coatings covered portions of the moisture barrier, the existing sealant was removed and replaced so that effective future examinations can be performed.
At other affected locations, the moisture barrier sealant was repaired or replaced as needed to meet the acceptance standard of IWE-3513 and our inspection procedures.
1 McGuire Nuclear Station, Unit 2 Class MC ISI Summary Report Refueling Outage EOC12 Page 8 of 8
- 4. The number and type of additional' examinations to ensure detection of similar degradation in similar components.
Additional moisture barrier examinations were deemed unnecessary for the following reasons:
(a)
All moisture barrier materials identified in the inspection plan on the exterior of the Steel Containment Vessel were examined during the inspection.
(b)
Nearly all of the horizontal moisture barriers on the interior of the Steel Containment vessel were replaced or were added in the past two years and do not justify examination at this time.
(c)
Our procedure for IWE-2500, Examination Category E-A, general visual examinations requires that accessible moisture barriers on the interior and exterior of the Steel Containment Vessel be examined.
IWE-2500, Examination Category E-A, general visual examinations are scheduled to be performed during the next refueling outage.
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