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Q December 28, 1984 C W (o o B f
Mr. Vincent S. Noonan Project Director Comanche Peak SES U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Ret TRT Civil / Structural Issues Summary of Planned Inspection and Testing Activities Dear Mr. Noonan.
Significant thought and effort has been devoted to the development of action plans for resolution of the TRT Civil / Structural issues. During this month. I have reviewed with your staff, the philosophy of our approach and important details of our third party initiatives. As you are aware, certain initiatives involve field inspection and testing activities. The following summary of these near term activities is provided to afford NRC the opportunity for timely review and observation as desired.
Item Number II.b - Concrete Compression Strength The Schmidt Hammer Test, a non-destructive test, will be conducted in accordance with ASTN-C805-79. " Standard Test Method for Rebound Number of Hardened Concrete" to verify the quality of concrete in questic'n (327 concrete placements betvcen January 1976 and February 1977). The relative strengths of concrete poured during this period in question and similar six concrete (the control) poured in a period of six months following the period in question will be compared utilizing statistical techniques. These techniques will be discussed under separate cover.
At Comanche Peak concrete placement quality procedures were based on required air entrainment and slump tests performed on each truck load. Test cylinders from the first truck load and every tenth truck load thereafter were required to verife quality.
Since the original quality control program was based on the unit of a truck load, the sampling plan uses a truck load as the unit to be tested in the present quality evaluation. This is consistent with the implicit assusption that a truck load represents the smallest unit of concrete with unif orm satorial properties. The area for testing is limited to the exposed surface area where the Schmidt Hammer Test can be performed. The determination of the number of truck loads which were placed as exposed testable concrete is determined as follows:
[p" Number of truck loads (slabs on ground) =
(l'0" depth X surf ace area) + 10 yd8/ truck
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1 Page 2 Number of truck loads (suspended slabs.
I columns, walls) = Total cubic yards i 10 8
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yd / truck i
l For deep slabs placed against the ground, a depth of one foot is assumed because during placement vibrators were used causing the concrete to flow and level out.
Thus only the truck loads placed the last foot of the slab would be exposed.
It has been determined, using the above assumptions, that the total number of L
truck loads corresponding to exposed surface of concrete in question is 1248. A i
similar number of truck loads is used to define the population of concrete not in question. Both concrete populations are randomly sampled to a minimum sample L
size of 100; thus, corresponding to a minimum of 200 test locations. This level of sampling may be adjusted consistent with statistical requirements for the comparison of the two populations.
The test program includes the following steps:
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1.
The areas where concrete was placed in Category I structures l
between January 1976 and February 1977 is determined.
2.
From these areas the number of concrete truck loads for which part of the concrete of that truck load is exposed and testable is determined.
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A grid of these truck load areas is drawn and each assigned a unique number.
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Grid areas are selected at randon to be tested.
5.
The concrete surface is prepared for testing per ASTM C805-79.
6.
The prepared areas are tested in accordance with ASTN C805-79.
7.
The above sequence is repeated for areas where concrete was placed in Category I structures between March 1977 and August 1977.
Brown and Root craft personnel will prepare the concrete surfaces for testing.
Southwest Research Institute (SWRI), a third party, will conduct the Schmidt Mammer Tests. The test results will be evaluated by TERA /TENERA. Jack Benjamin i
and Associates and Dr. Daniele Venesiano. M.I.T. with assistance fr om SWR 1 as required.
Surface preparation will be in progress during the first half of January 1985.
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Accordingly, these activities may be observed during the week of January 7.
f Testing will be conducted between January 14 - 21.
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Item Number I.c - Electrical Conduit Supports A series of engineering and inspection activities are in progress to document the basis for the CPSES Damage Study assumption that Train C, nonseismic conduit, two inches in diameter or less would be stable, such that reasonable assurance exists that unacceptable seismic induced interaction with safety related components is avoided.
The subject conduit have been field run; thus, isometric drawings and support details are not generally available. Accordingly, field verification of configuration of the installed conduit will be documented by CPP Engineering.
This data vill be utilized in subsequent seismic analyses by Gibbs and Hill.
All of these activities will be overviewed and evaluated by TERA, providing third party verification.
Two independent samples of 2 inches and under diameter. Train C, non-seismic l
conduit are determined. One sample is randomly selected and the other sample is derived on an engineering basis using a profile of selected conduit against prescribed attributes that are physically important to seismic behavior.
The population of 2 inches and under diameter Train C, non-seismic conduit is represented by approximately 13,500 conduit runs where a run is defined as a single conduit running between origin and destination (e.g. junction boxes, panels, etc.).
Each run has a unique identifying conduit number. The percentage distribution of the population by conduit size breaks down approximately as follows:
3/4"6 - 551 1"$
171 1 1/2"6-19%
9%
313b
.2"9 The two independent samples are seleated from the lh and 2 inch diameter populations, representing a total of-3,438 runs. Sample selection has been restricted to this segment of the population because it is most significant from an engineering point of view due to its greater inertia. This is evident from the loaded weights of the conduit by size:
3/4"W - 1 pound / foot 1"6 2 pounds / foot 1 "6 4 pounds / foot 2"W 5 pounds / foot Supports fall into three general categories generic (specified on design document DCA-5106) specials, and seismic S-0910. representing approximately a 2/1/0.2 split respectively. The generic supports have several predetermined configurations with recommended dimension tolerances specified. The special supports are configured in the field, usually consisting of the generic support configuration with a variation to permit fitup under congested circumstances.
The seismic 5-0910
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l supports are seismically qualified for use on Class IE, Train A or B, conduit; however, these have been utilized on Train C, non-seismic conduit under limited circumstances. Individual supports may provide restraint for multiple conduit runs.
The sample plan is designed to provide 95 percent confidence that the sample l
will detect a defective rate of $ percent or greater, where a defective is defined as a run which fails to meet specified anchorage and support performance i
requirements. These requirements and acceptance criteria will be discussed under separate cover.
A random sample of 126 conduit runs from the 2 inch and 1 inch diameter populations will be evaluated, with an acceptance number of 2.
The random sample is selected from the population of 3,738 runs of th and 2 inch diameter l
conduit using a table of random numbers; thus, providing an equal chance than any single conduit run may be selected, regardless of its identity, physical l
attributes or quality. Runs, so selected, that are found in the field to be l
inaccessible for as-builting, will be excluded from the sample for practicality reasons.
The " engineering" sample of 126 conduit runs is selected for evaluation based l
upon engineering judgement. The intent of this selection process is to define a i
subset of the population of conduit ruas which is representative of an expected lower bound seismic performance behavior. An individual conduit run is a candidate for selection based upon its profile against specified attributes. As l
such, if $ of the following 9 criteria are met, a run may be selected:
Attribute Selection Criteria 1.
Significance to Safety Installed in Areas Containing Equipment Required for Hot Shutdown 2.
Conduit Size hl"$
3.
Total Length 120' 4
Span Length One Span 1 8' 5.
Unrestrained Length in 21$'
Longitudinal Direction 6.
Number of Conduit /
13 Supports 7.
Number of Special
&25% of Supports Supports on Run 8.
Congestion Unrelated Hardware Item within 6 Inches I
of Run
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9.
Elevation Upper Half of Su11 ding l
The statistically based, random sampling approach represents a singularly i
effective means of resolving the issue. It provides a clear statistical l
representation of the behavior of the total population; l
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s Page 5-however, the bias afforded by the engineering sample is judged to provide a more rigorous test of installed hardware. 'Thus, the engineering sample provides defense-in-depth evidence supporting conclusions to be reached.
All selected runs will be considered for interaction with safety related targets due to sway'or possible fall in circumstances, if any, where a run fails to meet anchorage and support performance requirements. This review will be accomplished through a walkdown by CPP Engineering. All identified interactions will be evaluated. Any conduit runs predicted to damage safety related targets to failure will be' considered as a reject in the random sample. The sample plan will be appropriately expanded utilizing the same,95 percent confidence level on the 5 percent defective rate criteria mentioned previously.
The as-built documentation is to be accomplished by CPP Engineering. Gibbs &
Hill is' conducting the seismic analyses. TERA /TENERA vill provide third party verification of all of these activities.
The as-built physical configuration documentation process will be concluded in early January,1985. Accordingly, this activity may be witnessed the week of January 7.'
Item Number II.c - Maintenance of Air Cap Between Concrete beructures Inspections will be conducted to assess the current as-built condition and available documentation to determine the extent and cause of the existing condition. Engineering evaluations will follow to determine the design I
significance of the as-built condition and to document its acceptability.
Details of these evaluations will be addressed in the future. The following key steps will be implemented:
1.
QC inspections of the seismic gaps between Category I structures and between Category I and Non-Category I structures for both Unit 1 and Unit 2 will be reperformed and documented. CFF Engineering and QC will identify access points to the craft for seal or flashing removal. With the use of temporary lighting and special video equipment. QC will then inspect the existing separation. These inspections will verify gap width, and will locate and identify sise and type of materials in the separation areas to the extent practical and a sufficient level of detail to support an evaluation of cause of the existing condition and to support a decision to remove or analyse the existing condition. Video tapes will be available documenting the inspections. SWRI and TERA /TENEgA will overview this process.
2.
The new as-built inspection documentation will be reviewed with available construction documentation and past inspection records to assess the sequence of events leading to the existing condition and the cause.
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Based upon the as-built inspection. a decision'will be made to either remove any debris encountered in the separation space through vacuuming or other methods by the craf t or evaluate the significance of the as-built condition to the design basis.
4.
As necessary based upon the results of the previous three steps, an analysis will be performed by Gibbs & Hill to document the acceptability of the final as-built condition.
5.
QC will document the final as-built conditions and SWRI and TERA /TENERA will overview this process.
6.
TERA /TENERA will review conclusions reached on cause and applicability to other areas as well as the acceptability of the final as-built condition.
The air gap inspections will be conducted between January 14-21.
Item Number II.c - Rebar in the Fuel Handling Building in addition to providing an assessment of the acceptability of the as-built condition, initiatives under this action plan include an assessment of the work of the construction crew that may have cut an additional rebar without proper authorization, a review of selected cases where rebar cutting is requested for Hilti bolt installation, as well as a review of controls governing rebar cutting for both Hilti bolt and core bore installations. Accordingly, plans include inspections of actual length of Hilti bolts installed where a potential exists for rebar cutting in addition to that approved. Documentation evaluations for approximately 150 cases identified are in progress. To date, potential deviations have not been identified. Accordingly, inspection plans are currently indeterminate. The NRC will be notified in advance of any such inspections, should these be required. SWRI will overview these inspections and TERA /TENERA will evaluate the significance of any findings.
Item Number II.a - Reinforcing Steel in the Reactor Cavity Field inspection or testing activities are not contemplated as part of this action plan. Details of the plan will be documented at a later time.
Item Number II.d - Seismic Design of Control Room Ceiling Elements Engineering walkdown of architectural features and items above the control room ceiling are contemplated. These will be overviewed by TERA to provide third party verification. However, plans have not progressed to the point where a definitive schedule is available at this time. NRC will be notified when a schedule is more firm.
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.e-Page 7 In addition, TERA is evaluating the full scope of the CPSES Damage Study with particular emphasis on assumptions utilized as input to the Study. Selected areas will be walkdown by TERA /TENERA to verify implementation of CPSES Damage Study procedures. These details will be documented at a later time.
All of the aforementioned activities will be governed by procedures, either applicable Comanche Peak procedures or CPRT procedures, depending upon the party executing the work.
It is important to note that the preceding summary focuses primarily upon field inspections and testing activities and therefore does not, represent the full scope of initiatives contemplated under the CPRT Civil / Structural issues action plans. These initiatives, including details of methodology, acceptance criteria and plans for documentation will be documented in the next revision of the issue specific action plans.
Please do not hesitate to call if you have questions or if I can be of assistance in coordinating NRC observation of site CPRT activities.
Sine ely.
Howard A. Levin Comanche Peak Response Team Civil / Structural Review Team Leader cc:
L. Shao, NRC/TRT D. Jeng, NRC/TRT R. Phillao, TRT T. Langowski, TRT C. Hofmayer, TRT J. Cummins, NRC Resident Inspector L. Fikar, Chairman CPRT SRT 1
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