IR 05000336/1993021
| ML20057G052 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/11/1993 |
| From: | Chaudhary S, Gray E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20057G050 | List: |
| References | |
| 50-336-93-21, 50-423-93-22, NUDOCS 9310200126 | |
| Download: ML20057G052 (9) | |
Text
. _
l
.
.
l U. S. NUCLEAR REGULATORY COMMISSION
REGION I
]
REPORT NOS.:
50-336/93-21 50-423/93-22 DOCKET NOS.:
50-336; 50-423 LICENSE NOS.:
DPR-21 DPR-65 LICENSEE:
Northeast Nuclear Energy Company P. O. Box 270 Hartford, Connecticut 06141-0270 FACILITY NAME:
Millstone Units 2 and 3
<
INSPECTION AT:
Waterford, CT INSPECTION CONDUCTED:
August 24 - 27, 1993 hmM 9//o/43 INSPECTORS:
S. K. ChEd'hary, dr. Reactor Engr.
D' ate'
MS,DRS i
APPROVED BY:
'7N/ ff E. H. Gray, Section Chief, MS, EB Dste
[
D R
i Areas Inspected: Snubber and pipe support examination and surveillance progran? for ISI and IST requirements.
Results: The results of the inspection indicated that the snubber / pipe support inspection and l
surveillance program was acceptable in program scope and procedure implementation. No violation of regulatory requirements was identified.
i i
9310200126 931007 PDR ADOCK 05000336 j
G PDR.
'
i
__._
_
_
_
__
_ _ _
_
.
.
'
DETAILS 1.0 PURPOSE AND SCOPE OF TIIE INSPECTION (Inspection Procedure 70370)
The scope of the inspection was to determine through direct observation and independent i
evaluations of the licensee's program, if the control system was functioning properly for installation, modification, and maintenance and testing of safety-related supports and rutraints; and to determine that these supports and restraints were in compliance with NRC
requirements, applicable codes, and licensee's commitments.
2.0 FINDLNGS i
i 2.1 Unit 2 2.1.1 Program
,
,
Millstone Unit 2 is in the third " period" of the second " interval" of the inservice examination -
(ISI) program. The licensee's ISI program for the second interval was approved by the NRC in a letter, dated April 17, 1989, which granted relief from the ASME Code inservice test i
requirement, established in Section IWF-5000 of the Code. The relief request indicated that
-
the surveillance and examinations requirements established in the plant technical l
specifications meet or exceed the Code requirements in this area.
The snubber surveillance and inspection requirements are established in the Technical Specification (TS), Section 3/4.7.8. The TS requires that all safety-related snubbers be operable during plant modes 1,2,3,4; and in modes 5 and 6 for systems that are required for those modes. The operability of snubbers is to be assured by inservice inspection / examinations, and the service life is to be monitored to assure proper maintenance.
The frequency of inspection / surveillance and acceptance criteria have been clearly indicated in Section 4.7.8 of the TS, and Table 4.?.3 establishes the laspection intervals, based on the inspection results.
There are approximately 290 snubbers in Unit 2. They are of either hydraulic or mechanical type.
The inspcx: tion and surveillance requirements of the TS are implemented by approved surveillance procedures. Although there is no separate document to delineate the snubber surveillance program, the detailed description of the requirements in the TS itself is adequate to clearly establish the inspection and surveillance criteria, including the acceptance criteria i
and standards,
,
-.
-
-
,
.-,%
,ww-
.,c.---
.m<%m,,,,,--,--m.,.+mnw.
2.1.2 Procedures The inspector revkwed the following surveillance and maintenance procedures to determine their adequacy in fulfilling the intent of the TS requirements. These procedures were reviewed for adequacy of: technical requirements, procedural controls, and clarity of acceptance criteria. The following procedures were reviewed:
SP21149, Rev. 7:
Snubber inspection (mechanical and hydraulic)
.
21174, Rev. 5:
Snubber Functional Testing Based on the above review of procedures and discussion with cognizant personnel in this area, the inspector determined that the above procedures were adequate for implementing the inspection / surveillance requirements for snubbers in the plant Technical Specifications.
The inspector also reviewed inspection / surveillance visual examination data sheets for a selected sample of hydraulic and mechanical snubbers. These inspections had been performed in 1992. These data sheets were reviewed for procedural adherence, results of the inspection, and steps taken to resolve any identified deficiency. The inspector reviewed approximately 50 data sheets for various sizes of snubbers in different systems for hydraulic snubbers, and a similar number for mechanical snubbers. No deficiency was identified in these data sheets.
2.1.3 Walkthrough Inspection The inspector performed a walkthrough inspection and general visual examina. ion of accessible snubbers in the safety injection (SI) and the main steam (MS) systems. This examination was to assess the general condition of the installed snubbers, and any obvious
deficiency or degradation of the support / restraint that might affect their design function.
The inspector determined that the supports and snubbers were properly identified, and the identification matched the drawing description of the support. There were no obvious deficiencies that could hamper the functional capability of the snubber or the fixed support, and the general condition of the supports was adequate. The housekeeping of the plant areas, where the inspector visited, was also adequate to assure the safety functions of these supports.
2.1.4 Loose Concrete Expansion Anchors The inspector noticed the Plant Information Report (PIR) No. 2-93-181, which identified loose "Hilties" (HILTI concrete expansion anchors) on hanger nos. 427046 and 427047 in the service water (SW) system. These supports were located in the intake pump house structure. The report was dated as August 23,1993, and the deficiency was noted by plant personnel while performing IST on pump "C" of the SW system.
l
\\
,
.
.
'
The inspector reviewed the licensee's follow-up actions in this matter, and noted that, after identifying the deficiency and documenting it on PIR, the licensee initiated a
,
walkdown/ visual inspection of all hangers and snubbers in both trains of the SW system to assess the condition of other supports, and to identify any other support with a similar deficiency. The above walkdown inspection identified one additional support (Hanger i
No. 60219) in the SW system with loose anchor nuts.
.
The operations / maintenance organization of the licensee forwarded the pertinent information
.
from these inspections to the licensee's engineering organization in Berlin, Connecticut for determination of the " operability" of the systems, and a technical evaluation and disposition of the deficiency. The licensee's engineering assessment and disposition of the problem was j
documented in the August 25,1993, memoranda Nos. MCE-SA-93-299, and MCE-SA-93-301. The evaluation of the supports was as follows:
!
'
Hanner No. 60219 An engineering assessment of this support concluded that the support remained operable j
during this deficiency, because:
!
1.
Suppon 60219 is a lateral support with a design 1oad of 500 lbs. A review of the structural members, weld sizes, base plate, and anchor bolt design
-
indicates that the support was originally designed for a load well in excess of 500 lbs.
2.
The gap between the base plate and the wall was approximately 1/8". This gap is considered to have a insignificant affect on the support function since the concrete wall limits displacement in compression. Support tension capability remains unaffected since the hilti bolts would carry the intended
.
design tension load.
,
-
3.
A field inspection of the support by plant personnel did not indicate any
'
'
irregularities. All welds were determined to be intact and were considered capable of sustaining the intended design load.
Hancer No. 427047
!
An engineering assessment of this support concluded that the support remained operable, because:
Support 427047 is a lateral support with a decign load of 5,450 lbs.
Base plate Nos. 9 and 14 appeared to be pulled away from the wall 1/16" to 1/8" around the corners due to the heat distortion from welding the I-beam to the base plate. The lower base plate 14 had 6 Hilti bolts versus 4 shown on the drawing. The 4 bolts had loose washers.
~ -. - -
- -,.
..
-
-
.
.<
~
.
.
1.
The revised support design load was 3,233 lbs. The support was designed well in excess (approximately 41%) of the required design load. The loose washers indicated that the Hiltis may have slipped slightly. However, the load-carrying capability of the base plate and anchor bolt was not considered to be significantly degraded since the embedment depth of the bolts remained essentially the same. As a result, the load-carrying capacity of the bolts were not degraded such that support design function would be impaired. The as-found conditions of the bolts were considered to be adequate to sustain a 3,233 lbs. load. The Hiltis had been reset and torqued.
2.
The gap between the base plate corners and the wall was approximately 1/8".
j This gap was considered not to have an adverse affect on the support function i
because the interior portion of the base plate provided sufficient bearing area for the applied load.
3.
A field inspection of the support by plant personnel did not indicate any irregularities. All welds were determined to be intact and were considered capable of sustaining the intended design load.
f Hanger No. 427046
)
Support 427046 is a lateral support with a design load of 6,100 lbs.
j Base plate appeared to have been pulled from the wall. Three bolts on the west side had a 1/8" gap between washer and base plate. Also, the nuts appeared to be run all the way down j
on Hilti-bolt threads.
An engineering assessment of this support has concluded that the support remains operable, because:
1.
Based on field inspection,3 Hilti bolts on the west side of the plate appeared to have pulled out approximately 1/8". This decrease in embedment depth slight;y reduced the load-carrying capacity of the bolts, however, the original Hilti bolt design factor of safety (FS) was 6. The small loss of embedment was not considered to liave reduced the FS below 4.
2.
The gap between the baseplate and the wall was approximately 1/8". This gap was considered to have an insignificant effect on the support function since the concrete wall would limit displacement in compression. Support tension capability remained unaffected since the Hilti bolts would carry the intended design tension load.
.
..
.
l l
'
3.
A field inspection of the support by plant personnel did not indicate any irregularities. All welds were determined to be intact and were considered i
capable of sustaining the intended design load.
The evaluation concluded that the subject supports were structurally capable of performing their intended function, and thus piping system remained operable. However, the licensee was still in the process of investigating if the problem of loose concrete expansion bolts in other systems also exist. A walkdown inspection of other systems was being planned at the time the inspector left the site. On September 1,1993, the licensee informed the NRC resident inspector that no other deficiencies were identified in other systems in the plant.
2.1.4 Conclusions Based on the above review of records, examinations of snubbers and supports, and discussions with cognizant personnel, the inspector concluded that the licensee's snubber and pipe support inspection and surveillance program was satisfactory, and was effective in identifying and resolving problems to assure plant safety.
2.2 Unit 3 2.2.1 Program Millstone Unit 3 is in the third " period" of the first " interval" of the inservice inspection / examination (ISI) program. Detailed requirements for the inservice inspection / examinations for snubbers and pipe support are included in the licensing basis in l
the approved plant Technical Specifications (TSs). Section 3/4.7.10 of the TS describes these requirements, including: acceptance criteria, transient event inspection, functional test i
failure analysis, and sampling plan and frequency. The licensee has implemented these requirements through approved procedures.
2.2 2 Procedures The inspector reviewed the following surveillance and maintenance procedures to determine their adequacy in fulfilling the intent of the TS requirements. These procedures were reviewed for adequacy of: technical requirements, procedural controls, and clarity of acceptance criteria. The following procedures were reviewed:
SP31138, Rev. 0:
Snubber Visual Inspection MP3710FD, Rev. 5:
Mechanical Snubber Removal and Installation SP31140, Rev. 0:
Snubber Functional Testing
-
.
-
--
. - -.
_ _ - _ _ _ _ _ - _ _ _ _ - _ _ _ -
.
SNPS-TST-1.1, Rev. 0:
Functional Testing of Pacific Scientific Mechanical Snubbers SPC-CAL-2.2, Rev. 3:
Snubber Test System ST-002 Calibration Verification Based on the review of the above procedures and discussion with cognizant personnel in this area, the inspector determined that procedures were adequate for implementing the inspection / surveillance requirements established in the plant technical specifications.
The inspector also reviewed the Unit 3 snubber list, dated August 16,1993. The list showed the status of examinations performed on the snubbers and the results of the examinations.
Out of the 973 snubbers listed, approximately 878 snubbers were safety-related. The list also indicated that over 95% of these snubbers had been inspected in the current refueling outage, and the inspection results were under review to determine any adverse trend disclosed by the data. The inspector reviewed the historical snubber functional test data.
The data indicated that there had been 66 (sixty-six) failures in the functional test of snubbers from the inception of the testing in 1986. Out of the above, approximately 58% of the failures were clustered in the 1/4" size of the Pacific Scientific mechanical snubbers, and most of these were due to drag and the " boot" failure. The licensee, however, has initiated a program of replacement of these snubbers to improve reliability. The inspector visually examined some failed snubbers, and the snubbers which had been installed in auxiliary.
feedwater system trains A, B, C, and D. These snubbers were 3FWS-4-PSSP-0200,201, 202, and 203, and were located in the main steam valve building. These snubbers were replaced under PDCR-M3-93-016. The inspector reviewed the PDCR package to determine the adequacy of engineering analysis and evaluation supporting the replacement of these snubbers, and found them to be adequate.
2.2.3 Walkdown Inspection The inspector performed a walkthrough inspection and general visual examination of accessible snubbers in the auxiliary feedwater system, the main steam valve building, and other accessible areas of the plant. This examination was to assess the general condition of the installed snubbers and any obvious deficiency or degradation of the support / restraint that might affect their design function.
The inspector determined that the supports and snubbers were properly identified, and the identification matched the drawing description of the support. T1.cre were no obvious deficiencies that could hamper the functional capability of the snubbers or the fixed supports, and the general condition of the supports were adequate. The housekeeping of the plant areas, where the inspector visited, was also adequate to assure the safety functions of these supports.
'
.
l
..
_ _ _ _ _ _ _ _ _ _ _
. _ - _ _ _ _ _ _ _ _ _ _ _ _.
- _ - _ - _ _ _ _
.
.
2.2.4 Conclusions Based on the review of records, examinations of snubbers and supports, and discussions with cognizant personnel, the inspector concluded that the licensee's snubber and pipe support inspection and surveillance program was satisfactory, and was effective in identifying and resolving problems in this area to assure plant safety.
3.0 EXIT INTERVIEW i
The inspector discussed his findings at the exit meeting at the conclusion of the inspection on August 27,1993, where the inspector summarized the scope and the findings of the inspection. The licensee acknowledged the findings. The list of attendees at the exit meeting is shown in Attachment 1.
,
m,-.
w,--
,
.,
.
. ATTACIIMENT 1 Persons Contacted i
Northeast Nuclear Energy Comnany R. Blanchard, ISI Coordinator, Unit 2
J. Keenan, Director, Unit 2 W. Loweth, ISI Coordinator, Unit 1
P. Parulis, ISI Supervisor, Unit 2 J. Resetar, Engineering Supervisor, Unit 2
,
S. Stadnick, Unit 2 Engineering S. Sudigala, Engineering Supervisor, Unit 3
i R. Wells, PSD Engineering Supervisor, Unit 2 NUSCO L. Bigalbal, Licensing Engineer D. Harris, Licensing Engineer
U. S. Nuclear Regulatory Commission i
K. Kolaczyk, Resident Inspector, Unit 2 In addition, other personnel from both units from engineering, operations, and maintenance were contacted as the inspectors' work interfaced with their responsibilities.
Persons marked * attended the exit nieeting on August 27,1993.
- l
. -..
.
., -