ML20197G188
| ML20197G188 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 12/21/1983 |
| From: | Knight J Office of Nuclear Reactor Regulation |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-0718, CON-WNP-718 NUDOCS 8312290075 | |
| Download: ML20197G188 (7) | |
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DEC 211983 Distribution DCB-016 SGEB Reading Docket flunber:
50-397
!!Eh0RAriDUll FOR: Thomas fl. Novak, Assistant Director for Licensing Division of Licensing FROM:
James P. Knight, Assistant Director for Components & Structures Engineernig Division of Engineering
SUBJECT:
SAFETY EVALUATI0ft REPORT SUPPLEf!EllT, WPPSS i;UCLEAR PROJECT fl0 2 - RESCLUTICf4 0F C0i!TAlf!flEliT 00T-0F-RCUf;DfiESS ISSUE Plant flane: UPPSS !!uclear Project tio. 2 Occket flunocr:
50-597 Licensing Stage:
CL Review Responsible Branch and Project flanager:
LB-2, R. Auluck.
Our Safety Evaluation Report for Uf;P-2 was transmitted to you on February 19, 1982.
Subsequently, two safety evaluation report supplements were forwarded to you on August 5,1982 and December 16, 1983 respectively.
This safety evaluation report supplement is prepared to report the resolution of the WriP-2 containment out-of-roundness issue. Cur evaluation is provided in *.he enclosure.
This evaluation was perforned by K. C. Leu of Section A of the Structural and Geotechnical Engineering Branch.
James P. Knight, Assistant Director for Components & Structures Engineering Division of Engineering
Enclosure:
As stated cc:
R. Vollner J. Knight G. Lear A. Schwencer D. Jeng
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Enclosure Washington Public Power Supply System Nuclear Project No. 2 Docket No. 50-397 An Evaluation of " Containment Out-of-Roundness Issue" Structural and Geotechnical Engineering Branch Safety Evaluation Report Supplement I
1.
References i
1.
Memo from G. D. Bouchey to A. Schwencer, dated December 8,1982.
2.
Letter with attachment from Peyton Whitely to R. Auluck, dated April 16,1982, subject:
WNP-2 Containment Out-of Roundness.
3.
Memo from G. C. Sorensen to A. Schwencer, dated September 26, 1983.
t 9
4.
"As-built drawings and survey index, WPPSS Hanford No. 2, Contract 213 on Containment Vessel" provided by R. Auluck in May, 1982.
i 5.
Memo from G. D. Bouchey to A. Schwencer, dated June 1,1983.
===2.
Background===
(
The " containment out-of-roundness" issue was reicad by the contractor of contract no. 206 during a litigation following the defauic ut the l
No. 206 contract (Ref. 1). The contractor alleged that the problem of containment out-of-roundness led to difficulties in detailing, fabricating and installing the reinforcing steel for the exterior biological shield wall and delayed the construction schedule. There was a concern raised by a third party (Ref. 2) about whether the out-of-roundness issue had been adequately resolved by the NRC staff.
l l
t In order to resolve the concern, an evaluation of the issue was performed by the staff of the Structural and Geotechnical Engineering Branch. The findings and conclusions of the evaluation are reported in this supplement to the WNP-2 Safety Evaluation Report (SSER),
3.
Key Areas of Review and Findings (1) Biological Shield Wall In order to accommodate the as-built geometry of the containment shell, the biological shield wall was constructed by maintaining the outside wall radius at its design location while adjusting, as needed, the inside radius to be consistent with the "out-of-roundness" shell configuration.
In so doing, the wall thicknesses at some locations are forced to be thinner than the required thickness (i.e., S'-0").
This raised a concern as to the design adequacy of the wall sections with a reduced thickness.
In his effort to resolve the concern, the applicant performed an evaluation (refer to Ref 3) at critical wall sections.
The evaluation determined that the maximum wall thickness reduction was in the order of 3-3/8" and occurred at a wall location defined by Elevation 496.75' and Azimuth 90'.
It was further determined that the reduced wall section represents an as-built wall ultimate bending capacity M = 448 -ft K
as K t compared to the design capacity of M = 465
, 4,,,, 4 7, u
reduction in moment capacity.
However, since the actual required ultimate moment capacity at this critical section is M u
386 -ft, there still exists a design margin of 448/386 = 1.16.
K This is judged acceptable and the issue is deemed resolved.
During the process of review, it was found that non-contact reinforcing bar splices had been used in the biological shield wall.
The applicant stated that at elevation 446' in the biological shield wall, non-contact splices were used to accommodate the field-encountered rebar interference problems.
. The range of non-contact distances between #11 splicing rebars was from zero to five inches.
Since the applicable code (i.e.
ACI-318) allows such a practice, this issue is judged resolved by the staff.
(2) Containment Vessel - Evaluation of Conformance to ASME III, Div.
I Code NE Sections 4221 and 4222 The contract No. 213 (Ref. 4) stipulated that the tolerances for shell and head of a primary containment vessel shall be in accordance with the requirements of NE-4221 and NE-4222 of the ASME Section III Code.
With respect to subsection NE-4221.1, the code specifies that the difference between the maximum and minimua inside diameters at any cross section shall not exceed 1% of the nominal diameter at the cross section.
In table 1 of Ref. 3, the applicant provided a survey which showed that at all but one of the sixteen places, the above requirement was met.
The exception took place at elevation 564'-10" where the code limit was exceeded by less than 1/16 inch.
Since this deviation is rather insignificant and considering that the vessel is already built, the staff considers that the intent of the code is met and the vessel is acceptable.
With respect to subsection NE4221.2, the code specifies an allowable maximum deviation of vessel configuration from the true circular form of cylinders or the theoretical form of other shapes when subject to external pressure loads.
The applicant was requested to indicate if the above code provision was m t by WNP-2 containment. The applicant responded in references 3 t.nd 5 that no documentation of compliance with NE 4221.2 requirements existed, however, the plant Q/A program did require measurements of the deviation from design ge.onetry at locations of field-welded joints,
. The staff reviewed the pidnt Q/A program / criteria and other pertinent information and determined that the criteria adopted by the applicant for the Q/A program were sufficiently conservative to meet the requirements of NE-4221.2. Therefore, the provisions of NE-4221.2 are considered as fully met.
With respect to demonstrating confonnance with the requirements of NE-4222, which discusses and specifies the allowable tolerances for formed vessel heads, the applicant submitted a table (Table 2 of Ref. 3) for staff review, The review showed that based on the examinations performed for the drywell head, the specified shape at the skirt, the saucer plate, and the knuckle, the deviations found were smaller than those allowed by the code section.
Similar precedures were followed to determine the maximum differences in cross-sectional diameters in drywell head, and the results were found to be satisfactory in terms of complying with applicable code provisions. We conclude that the requirements of NE-4222 are fully met.
(3) Containment Plumbness The criterion governing the containment plumbness is specified as:
"For the overall vessel height, out-of-plumbness of the vertical centerline of the shell shall not exceed 1:800" (Ref.
4).
By the applicant's evaluation (Ref, 5), the actual out-of-plumbness of the containment vessel was determined to be 9/
1:1400(1 32 inches in 149 feet 9 inches of vessel height).
Since the above criterion for "out-of-plumbness" is fully met, the containment is judged acceptable.
. (4) Penetrations During the review of containment "out-of-roundness" issue, the staff requested the applicant to assess the impact on the construction and final stress analysis of piping system due to deviations in location and orientation of as-built penetrations from those defined in the design.
In his response (Refs. I and 5), the applicant provided results of a survey of 165 drywell and wetwell penetrations.
The survey showed that 9 penetrations exceeded vertical tolerance in centerline location by less than 1" and 18 exceeded tolerance on vertical alignment by less than l' as compared to pertinent criteria set forth in contract No. 213, Section 4.4 (Ref. 4).
It should be noted, however, that these as-built penetration geometries and orientations had been provided to the design organizations responsible for piping design, and had been used by design engineers for final approval of their design, fabrication, and stress analysis of piping. The applicant also provided an example of his procedures entitled, " Stress Analysis Procedure for Final As-Built Evaluation," which are used to accommodate and confirm the acceptability of the as-built penetration geometry.
The staff finds this applicant's approach acceptable and the issue is considered resolved.
(5) Containment Buckling As pointed out in Ref. 3, steel containment buckling analyses had been performed at WNP-2 for both perfect and imperfect shell cases. The imperfect shell analyses, referred to as the as-built conditions defined *and discussed in item (2) above, resulted in a factor of safety of 2.4 (i.e. the ratio of allowable stress for the imperfect shell divided by the actual stress).
The factor of
safety for the perfect shell was determined as 4.1.
Based on these safety factors computed by the applicant, we conclude that s
the containment buckling for WNP-2 vessel is of no concern.
4.
Conclusion The analysis, design and construction aspects of the WNP-2 containment pertair.ing to the "out-of-roundness" issue have been reviewed.
Based on the discussions and technical justifications provided above we conclude that the applicable code provisions or their intent have been met and the structural integrity and functionality of WNP-2 containment are not and will not be affected by the deviations of the as-built vessel from its design configuration.
We further conclude that the issue of the WNP-2 containment "out-of-roundness" is resolved.
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December 27, 1983
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' MEMORANDUM FOR:
Chief, Document Management Branch, TIDC FROM:
. Director, Divison of Rules and Records., ADM
SUBJECT:
REVIEW 0F UTILITY EMERGENCY PLAN DOCUMENTATION The submitter of the attached document has expressed no desire to withhold any information contained therein.
Therefore, this material may now be made publicly available.
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J. M. Felton, Director
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Division.of Rules and Records Office of Administration y
Attachment:
As stated 4
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