IR 05000338/1978044
| ML19261A760 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 12/27/1978 |
| From: | Bryant J, Lenahan J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML19261A761 | List: |
| References | |
| 50-338-78-44, NUDOCS 7902080143 | |
| Download: ML19261A760 (9) | |
Text
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50-338/78-44 Docket No.:
50-338 License No.:
NPF-4 Category:
B2 Licensee: Virginia Electric and Power Company Post Office Box 26666 Richmond, Virginia 23261 Facility Name: North Anna Power Station, Unit 1 Inspection at: North Anna Power Station, Mineral, Virginia Inspection conducted: December 6-8, 1978 Inspectors:
J. J. Lenahan J. C. Bryant Reviewed by:
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ath J. C. Bryant, Chibf
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Engineering Support Section No. 1 Reactor Construction and Engineering Support.5 ranch Inspection Summarv Inspectionmon December 6-8, 1978 (Report No. 50-338/73-44)
Areas Inspected:
Special announced inspection of data collected on settlement of Units 1 and 2 service water pump house and of licensee action on previously identified item concerning settlement surveys. This inspec-tion involved 40 inspector-hours onsite by two NRC inspectors.
Results: Within the areas inspected, no items of noncompliance or deviations were identified.
7902080l(3,
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RII Rpt. No. 50-338/78-44 I-l DETAILS I Prepared by:
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^/2 7/7f J. J(/ IEnahan, uivil Engineer Date Engineering Support Section No. 1 Reactor Construction and Engineering Support Branch Dates of Inspection:
December 6-8, 1978 Reviewed by:21\\/l, Cow
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J. C. Bryant, Chief
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Dat6 Engineering Support Section
Reactor Construction and Engineering Support Branch 1.
Persons Contacted Virginia Electric and Power Company (VEPCO)
a.
- C. M. Robinson, Jr., Supervisor, Civil Engineering Services
- 0.
Schultz, Supervisor, Survey Services
- R.
C. Sturgill, Assistant Engineer, Unit 1 E. R. Bane, Supervisor, Construction QA
- P.
A. Slater, Resident QA Engineer
- E.
R. Smith, Jr., Supervisor, Engineering Services, Unit 1
- J.
D. Kellams, Superintendent Station.perations
- W.
F. Diehl, Engineer, Engineering Services
- D. C. Woods, VEPC0 NRC Coordinator b.
Stone and Webster Engineering Corporation (S&W)
D. Barry, Resident Engineer B. McIver, Soils Engineer (telephone conversations)
R. Allen, Field Engineer (telephone conversations)
c.
Moore, Hardee and Carrouth Associates (M H & C)
- M.
Croker, Party Chief
- G. Robertson d.
Nuclear Regulatory Commission Personnel (NRC)
- M.
S. Kidd, Resident Inspector
- Denote = those present at the December 7, 1978 exit interview.
- Denotes those present at the December 8, 1978 exit interview.
- Denotes those present at the December 7 and 8, 1978 exit interview *
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RII Rpt. No. 50-338/78-44 I-2 g
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2.
Licensee Action on Previous Inspection Findings T
(Open) Unresolved Item (338/78-37-04):
Settlement of Class I Structures.
Settlement survey requirements of Technical Specification 3.7.12.1 and
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enclosed Table 3.7-5 have not been met due to either the need to reset je survey points or due to establishment of some points prior to or af ter
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baseline dates. The inspectors examined survey field notebooks kept
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by Moore, Hardee and Carrouth Associates (engineering firm retained by
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VEPC0 to perform settlement survey), various settlement points, and
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settlement data. A review of the settlement data for points which
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have not been disturbed since the baseline date indicates that differ-
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ential and total settlements are well within the limits established in
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Table 3.7-5 for all structures except for the total allowable average
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settlement of the service water pump house. Differential settlements
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between structurer founded on rock or on fill concrete placed on rock
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are on the order of.005 to.010 feet.
These apparent movements are a
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result of the limits of the accuracy of surveying.
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After the baseline dates had past, NRC requested that the licensee a
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establish additional settlement points.
Settlement of these points
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can not be referenced back to the Technical Specification baseline
dates. Other settlement points were established by the licensee prior
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to Technical Specification baseline date.
Settlement of these points
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was recorded prior to the baseline dates.
The.icensee will submit a letter to NEC requesting permission to amend the Technical Specifications
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to clarify baseline dates.
Six points have been reset since Technical
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j Specification baseline date. This was either due to construction
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activities which resulted in points being destroyed or erection of
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i permanent facilities which have made pcints inaccessible.
The licensee
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has reconstructed the settlement histor-- of points which have been
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.H reset from the settlement records of oth r points on the same structure e
and from settlement points on adjacent st uctures which have similar f,
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l foundation and loading conditions.
The li:ensee is evaluating methods
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to protect settlement points from construc ion and other activities.
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The inspectors discussed requirements of a (\\ program with the licensee's
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representatives to audit the settlement suri ry program and the results
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of surveys performed by M H & C.
On occasieas, up to 4 months have
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ij elasped between the time the M H & C survey were made and data was gi f
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Tae licensee was informed
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In cases where the limits approach 75% of the allowable e ;}+
values listed in Table 3.7-5, this time lapse should be on the order of one to three days to insure prompt reporting as required by the
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Technical Specification.
This item remains open pending NRC review of
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RII Rpt. No. 50-338/78-44 I-3 3.
Unresolved Items No new unresolved items were identified during this inspection.
4.
Independent Inspection Effort There was no independent inspection conducted during this inspection.
5.
Scope of Special Inspection On April 28,1978, the 1*censee notified RII that survey readings taken on March 30, 1978, indicated that the average settlement of the service water pump house (SWPH) exceeded 75% of the maximum allowable value of 0.15 feet.
The licensee submitted a special report regarding the settlement of the SWPH to NRC RII on May 31, 1978.
This special inspection was performed to review the settlement data collected at the site and determine the following:
a.
When 75% of the maximum allowable service water pump house settlement was attained.
b.
If settlement surveys are being performed at frequency required in Technical Specifications.
c.
If the licensee had reported to NRC within 60 days of when 75% of the allowable settlement of the SWPH was detected.
d.
Amount of differential settlement between the SWPH and the north side of the flexible joint in the service water lines.
The inspectors attended a meeting held in Bethesda, Maryland on December 5, 1978, between NRR, VEPC0 and Stone and Webster to receive background on settlement history of the North Anna Site.
6.
Findings a.
VEPC0 Service Water Pump House Settlement Surveillance Program-The licensee contracted with HH&C to perform the surveys for the settlement surveillance program required by Technical Specification 3.7.12.1.
Settlement survey requirements of the Technical Speci-fications are to determine elevations of points listed in Table 3.7-5 to the nearest 0.01 foot at least once every six months.
The elevation of the points is to be determined by precise leveling (surveying) with second order Class 2 accuracy as defined by U. S. Department of Commerce, National Oceanic and Atmospheric Administration (NOAA). The inspectors reviewed MH&C survey fie'd data and field data reductions and discussed survey techniques used in the settlement surveys with MH&C personnel.
The inspectors
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RII Rpt. No. 50-338/78-44 I-4 examined the settlemert points in the service water pump house (SWPH) and on the north side of the expansion joint in the service water lines, and benchmarks (Reference Monuments A and B) used in the settlement survey. Reference Monuments A and B consist of steel casing drilled and grouted into rock.
Settlement points in the SWPH are brass markers grouted into the concrete floor.
Settlement points on the service water lines are painted on the pipes.
The procedure used by MH&C in the settlement survey for the SUPH is to run a level line from Reference Monument A along the dike of the service water reservoir to Reference Monument B, estab-lishing a temporary benchmark (TBM) in the vicinity of the SWPH.
The TBM is usually either settlement marker 5 or 6.
A level line is then run into the SWPH to check the elevations of settlement points.
MH&C employs Precise Level Rods (solid one piece yard rods) and a Zeiss NI-2 relf leveling level in the survey.
These instruments meet the requirements specified by NOAA for second order, Class 2 surveys. Examination of survey methods, equipment and reduced field data indicated that the survey accuracy attained is equal to that required for second order, Class 2.
Surveys are being performed at the frequency required by the Technical Specifi-cations (at least once every six months).
MH&C survey data indicated the following average service water pamphouse settlements.
(Note:
Complete MH&C data not tabulated below.
Data shown is that which brackets readingt when 75% of allowable SWPH settlement was attained.)
Percent ci Allowable Settlement Date Average Settlement (Feet)
(0.15 Feet)
12/1/75
.000
7/11/77
.063
12/12/77
.103
3/15/78
.121
3/30/78
.119
4/25/78
.106
5/10/78
.110
8/3/78
.117
The above data indicate that 75% of the maximum allowable total average SWPH settlement was exceeded on March 15, 1978, and March 30, 1978. However, MH&C surveys made prior to March 15,
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RII Rpt. No. 50-338/78-44 I-5 1978, indicated settlement was less than 75%.
Based on the above data, the licensee sent a Licensee Event Report to NRC on April 28, 1978, that SWPH settlement exceeded 75% of the allowable value.
A detailed special report was submitted to NRC on May 31, 1978.
b.
Construction Settlement Survey Program - Settlement of the SWPH along with other structures was monitored by Stone and Webster during construction. This was not a requirement of the PSAR, FSAR, or the Technical Specifications but was done in accordance with standard engineering practice to confirm design assumptions.
The requirements of the S&W settlement surveillance program were determined by their Geotechnical Engineers.
This program was not rigid project requirement, and at times surveys were not made a
due to higher priority work.
However, the frequency of the construction survey program was adequate to obtain a good settle-ment history of SWPH.
From the results of the S&W surveys, the licensee determined and reported to NRC in April 1975 that the SWPH settlement exceeded the PSAR estimates. Additional design studies were made by S&W to investigate settlement of the SWPH and determine stresses in the service water lines at their connections to the SWPH. As a result of these studies, S&W estimated that total average addi-tional settlement of the SWPH would be approximately 0.15 feet after December 1975 and flexible couplings were installed in the service water lines at their connection to the SWPH.
The inspectors reviewed the survey field book in which the S&W SWPH settlement survey data was recorded and discussed survey techniques with S&W engineers.
S&W surveys were made from a variety of benchmarks, including Reference Monuments A and B, and several temporary construction benchmarks.
S&W engineers stated that the procedure they used on their settlement survey was to run a level line from one of the benchmarks to the SWPH, establish a TBM in the vicinity of the SWPH, and close the loop by either tying back into the originating benchmark or one of the other benchmarks on the project. However, the survey loop closure was not documented in the field book for each SFA settlement survey.
Loop closures documented in the field book were closed within acceptable accuracy.
The rods used in the S&W survey did not meet the requirements of the type specified by NOAA for use in second order, Class 2 differential leveling.
There was some discussion that one of the S&W rods might have been slightly damaged. The S&W engineer estimated errors of up to.01 foot.
S&W survey data was incomplete for readings made from August 3,1977, through January 5,1978,
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RII Rpt. No. 50-338/78-44 I-6 because settlement point SM-8 was inaccessible to S&W surveyors though MH&C surveyors did record data for this point in December, 1977. The missing data for point SM-8 can be interpolated f rom the other data to the nearest.01 foot.
In comparison of MH&C data with S&W data, the inspectors noted that S&W data consistently indicated approximately.01 feet more settlement than the MH&C data.
From examination of the field data and the discussions with S&W engineers, the inspectors concluded that the S&W survey did not meet the requirements of a second order, Class 2 survey, and that the SWPH settlements shown for the period from August 3, 1977, through January 5, 1978 were based on incomplete data. The survey made for purposes of meeting the requirements of the Technical Specifications was that made by MH&C.
In cases of conflict between the MH&C data and the S&W data, the MH&C data would be accepted as cocrect since it was obtained from a survey which was better controlled and more accurate than the S&W survey.
c.
Differential S-ttlement Between SWPH and North Side of Service Water Piping Expansion Joint - The inspectors reviewed the results of surveys perfetmed by MH&C to measure settlement of the service water lines north of the expansion joints.
Settlement of the service water lines was compared to the settlement of SWPH settle-ment point SM-7, which is located on the northeast corner of SWPH. This is the location where the service water lines enter the pumphouse. The settlement of point SM-7 versus the settlement of the service water lines is tabulated belcw.
Differential Differential Settlement Between Between Date of SM-7 SM-15 SM-7 & SM-15 SM-18 SM-7 & SM-18 7/11/77
.000
.000
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.000
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12/12/77
.039
.051
.012
.058
.019 3/15/78
.059
.071
.012
.081
.022 3/30/78
.057
.072
.015
.077
.020 4/25/78
.045
.060
.015
.066
.021 5/10/78
.043
.064
.021
.071
.028 8/3/78
.058
.066
.008
.069
.011 NOTES:
(1) July 11, 1977 is date when initial survey was performed on service water lines.
(2) SM-15 is settlement point on east pipe.
(3) SM-18 settlemen point on west pip,
RII Rpt. No. 50-338/78-44 I-7 (4) Complete MH&C data not tabulated in above table.
(5) Settlements shown are in feet.
The above data indicate that differential settlements between the service water lines north of the expansion joint and the northeast corner of the SWPH has been insignificant since July 1977.
The data also indicate that the service water lines have settled more than the SWPH. The expansion joints in the service water lines are located where the height of fill in the dike is the greatest.
The expansion joints in the service water lines were installed in March 1976.
An estimate of how much the service water lines have settled since the expansion joints were installed can be made by comparison of SWPH settlement data with the available service water line settlement data.
Settlement point SM-7 settled.046 feet between December 1975 and July 1977.
This is approximately the same magnitude SM-7 settled between July 1977 and May 1978 when the largest differential settlement between the service water lines and the point SM-7 is indicated.
Therefore it is conceivable that an equal amount of differential settlement between SM-7 and the service water lines occured between March 1976 and July 1977 as occured between July 1977 and May 1978.
This would mean that a maximum of approximately one-half inch of differential settlement may have occured between the SWPH and the service water lines since the expansion joints were installed in March, 1976. The expansion joints are designed to tolerate up to three inches of differential settlement between the SWPH and the service water lines. The inspectors examined the expansion joints during the inspection and detected no problems.
d.
Conclusions Based on the results of examination of settlement data and survey procedures and discussions with responsible engineers the inspectors concluded:
The survey performed to meet the requirements of Technical a.
Specification 3.7.12.1 indicated that the average pumphouse settlement exceeded 75% of the maximum allowable value in March, 1978.
b.
Settlement surveys are being made at the frequency required in the Technical Specification r..
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RII Rpt. No. 50-338/78-44 I-8 The licensee notified NRC within 60 days (time period specified c.
in the Technical Specifications) of when 75% of the allowable settlement of the SWPH was detected.
d.
The amount of differential settlement occurring between the SWPH and the service water lines is well within tolerance.
No deviatians or items of noncompliance were identified.
7.
Exit Interview The inspectors net sith the licensee representatives denoted in paragraph I on December 7, 1978 and on December 8, 1978 to discuss the results of the inspection. The inspectors summarized the scope and findings of their examinatian of data collected on settlement of the SWPH and of action on previous inspection findings concerning settlement surveys.
No deviations or items of noncompliance were identified.