NUREG-0824, Safety Evaluation Concluding Util 831228,840111 & 0202 Responses to NUREG-0824,Section 4.12 Re Design Codes,Design Criteria & Loading Combinations Complete Except for Listed Issues Requiring Resolution

Safety Evaluation Concluding Util 831228,840111 & 0202 Responses to NUREG-0824,Section 4.12 Re Design Codes,Design Criteria & Loading Combinations Complete Except for Listed Issues Requiring Resolution

ML20207R224
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Site:	Millstone
Issue date:	03/10/1987
From:	Office of Nuclear Reactor Regulation
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ML20205T565	List: ML20205T561 NUREG-0824, Safety Evaluation Concluding Util 831228,840111 & 0202 Responses to NUREG-0824,Section 4.12 Re Design Codes,Design Criteria & Loading Combinations Complete Except for Listed Issues Requiring Resolution
References
RTR-NUREG-0824, RTR-NUREG-824, TASK-03-07.B, TASK-3-7.B, TASK-RR NUDOCS 8703160430
Download: ML20207R224 (5)

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SAFETY FVALUATION BY THE OFFICF 0F NUCLEAR REACTOR REGULATION RELATING TO NUREG-0822, SECTION 4.12 DESIGN CODES, DESIGN CRITERIA AND LOADING COMBINATIONS MILLSTONE NUCLEAR POWER STATION, UNIT ONE DOCKET NO. 50-245

1.0 INTRODUCTION

l i By letters dated December 28, 1983, January 11, 1984 and February 2,

! 1984 (Refererces 1,2, and 3), Northeast huclear Energy Company (NNECo),

licensee for Millstone Nuclear Power Station Unit No. 1 (Millstone 1) provided a respense to Sectico 4.12 of NUREG 0824 the Integrated Plant ,

Safet."AssessmentReport(IPSAR). This info *mation was revieweo by Franklin Research Center (FRC) under contract to the NRC. The results of the FRC review are provided in the attached Technical Evaluation Report (TER). Staff conclusions based on this review are presented below.  :

2.0 RACKGROUND PlantsreviewedundertheSystematicEvaluationProgram(SEP)wero l designed and constructed in accordance with criteria and codes which differ from those accepted by the NRC for new plants. Under SEP Topic Ill-7.B. the irract of safety margins in Seismic Category I plant structures was assessed considering the changes in design codes and criteria for load combinations.

The staff, with assistance from Franklin Research Center, evaluated l the design codes to identify areas where the code changes may have a

! significant impact on the margins of safety. In addition, loads and l loading combinations were reviewed to identify those of most signifi-cance for plant structures, which should therefore be reviewed for adequacy. This assessment was issued by letter dated August 11, 1982, (Ref. 4). Based on this review, the staff position was that NNEco should:

(1) review the specific areas of design code changes potentially applicable to Millstone 1 for which the current code requires substantially greater safety margins than did earlier versions of the code or for which no original code provision existed to determine their applicability; and i

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(2) perform on a sampling basis an evaluation of the code, design criteria, and load combination changes noted in the August 11, 1982 evaluation on existing as-built structures to assess their adequacy.

3.0 EVALUATION 3.1 Design Code Changes 3.1.1 Section 4 of the attached TER summarires the review findings for issues on design code changes. This section shows the old and new code sections, the licensee's approach to resolution, and FRC's evaluation of the response. For some entries, the

FRC review shows that the issue is resolved. The staff Concurs. j 3.1.2 Current Code Requirements for Compression Members (AISC 1980 vsAISC1985): The staff's concern is that the web of most standard tee sections when used as a compression member does not meet the current code requirements, i.e. buckling of the member would be expected, as discussed in the atached TER.

A sampling approach was chosen by the licensee to address this i issue and the evaluation results showed that one of the samples did not meet the code limit. Thu licensee argued that this non-conformance occurred in members used as manhole pit cover stiffeners which are not the main load carrying members and con-cluded that the applications of standard tee sections at Millstone Unit 1 are acceptable for this code change. The staff agreed that the sampling approach would be a reasonable way to address this issue. However, the details of sampling procedure, sampling basis, sample size, evaluation results, and basis for the conclusion should be submitted for review. In addition, the licensee should expand sample size to providu assurance that the '

remaining " standard tee section" compression mcmbers will satisfy the code requirements. As an alternative, the licensee nay demonstrate that the failure of these " standard tee section" com-pression members will not degrade the safety margins of structures.

3.1.3 Shear Load Capacity of Coped Beam Connections (AISC 1980 vsAISC1965): The licensee evaluated the significance i of this code change by a sampling approach. Based on the calculations performed (Ref. 2), the licensee concluded j that all of the bolted or riveted beam connections in the j plantwherethetopflange(orbothtopandbottomflanges)  !

i of steel beams was coped are adequate for the new code i provisions. However, the details of evaluation and basis for the conclusion are not clear to the staff.

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e In order to close this open iten, the licensee should submit its sampling procedure, sampling basis, sample size, evaluation results and basis for conclusion for review. In addition, the licensee should calculate the most severe shear loads imposed on the beam in the actual service condition and evaluate the adequacy of the connections.

3.1.4 Column with Spliced Reinforcements Subject to Stress Reversal (ACI 349-76 vs ACI 318-63): the licensee pre-sented a discussion of the "Fatique Environment" of con-crete columns in Seismic Category I buildings, expressing the opinion that fatique usage could be found small and concluded that column reinforcement splices designed to ACI 318-63 code will be adequate for alternating stresses. This is not acceptable to the staff. The licensee should evaluate the adequacy of the column splices for the most severe load reversal either by using the existing test data or by calculation.

3.1.5 Design of Containment Penetration Bellows: the licensee submitted Tube Turns Peport No. TT-1-66 (Ref. 5), for the qualification of containment penetration bellows assemblies X-7A through 70. As a result of review, two concerns were raised by the staff:

1. The procedure used in evaluating the bellows assemblies acceptable per NE-3365.2(e)(1) of the 1903 ASME Code, provided that the testing requirement made there to ensure validity of the calculations performed has been met. The statement made on page 6 of the report,

" Verification of these factors is found in Tube Turns Report No. 5.122-6." is not sufficient to ensure enm-pliance. The licensee should either provide a sumary of the report sufficiently detailed to determine that the requirements as to the number, type, and outcomes nf the tests are met, or provide the report itself for review. ,

2. The report does not include evaluation of the bellows assemblies for the seismic loads. Such evaluation should consider two factors: (1) the effect of the relative displacements of the bellows assembly ends resulting frcm the seismic response of the attached components (2)andtheeffectofsimultaneousdirect seismic responses of the bellows.

3.2 Loads and Leading Combinations 3.2.1 The effects of extreme environmental loads due to snow v on building roofs should be addressed; the snow load was ,

defined as 115 psf in the staff's March 30, 1981 Safety Evaluation on SEP Topic Il-2.A. '

3.2.2 The combination of safe shutdown earthquake and pipe break  ;

loads (e.g. LOCA) has not been examined except for drywell. !

The staff requires that this combination should be examined !

on a samplino basis to confirm the margin of safety in the  !

affected critical structures of the plant. [

4.0 CONCLUSION

S Based on the above discussions, IPSAR Section 4.12 is considered to be complete except for resolution of the folinwing six issues:

1. Current Code rtouirement for compression members (3.1.2)  ;

2. Shearloadcapacityofcopedbeamconnections(3.1.3)

3. Column with spliced reinforcements subject to stress reversal (3.1.4)

4. Design of containment penetration bellows (3.1.5) l r

5. The effects of snow loads on critical structures should i beaddressed(3.2.1) i C. The load combination of safe shutdown earthquake and -

pipe break loads should be examined (3.2.2) (

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l Principal Contributnes: T. Stilwoll (FRC):

P.Chen,T.Cheng,(NPC) f i

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5.0 REFERENCES

1) LetterfremW.G. Council (NNEco)toD.G.Eisenhut,(NRC) dated December 28, 1983.

2. Letter from W. G. Council to D. M. Crutchfield, dated January 11, 1984

3. Letter from W. G. Council and R. W. Bishop to D. M. Crutchfield, dated February 2, 1984.

4. Letter from W. G. Council to D. M. Crutchfield, dated August 11, 1982.

5, Report submitted by NNECO, "The Primary Containment Penetration Piping Expansion Joints Assemblies X-7A thru 70 for Millstone Nuclear Station." prepared for Impe11 Corporation by Tube Turns Division of Chenetrnn of Canada Limited, dated July 25, 1985.