ML18033B069
| ML18033B069 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/11/1989 |
| From: | Michael Ray TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8912140193 | |
| Download: ML18033B069 (17) | |
Text
ACCELERATED D UTION DEMONSTRATION SYSTEM REGULATORY XNFORMATION DISTRIBUTXON SYSTEM (RIDS)
SUBJECT:
Discusses revised program for seismic qualification 'of CRDH piping sys.
DISTRIBUTXON CODE:
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TITLE: TVA Facilities Routine Correspondence NOTES:1 Copy each to: S.Black,D.M.Crutchfield,B.D.Liaw, R.Pierson,B.Wilson
.,S 05000260, /
ACCESSION NBR:8912140193 DOC.DATE: 89/12/1'1 NOTARIZED: NO DOCKET FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2,'ennessee 05000260 AUTH.NAME AUTHOR AFFILIATION RAY,M.J.
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TENNESSEE VALLEYAUTHORITY CHATTANOOGA. TENNESSEE 37401 5N 157B Lookout Place U.S. Nuclear Regulatory Comm)ssion ATTN:
Document Control Desk Hashington, D.C.
20555 Gentlemen:
In the Matter of Tennessee Valley Author)ty Docket No. 50-260 BRONNS FERRY NUCLEAR PLANT (BFN) UNIT 2 REVISED PROGRAM PLAN SEISMIC QUALIFICATION OF THE CONTROL ROD DRIVE HYDRAULIC (CRDH) PIPING SYSTEM This letter describes the revised program for the Seismic Qualification of the Browns Ferry Unit 2 CRDH Piping System, which includes the CRD insert and withdrawal piping, valves, and piping supports.
Enclosure 1 reflects the results of the July 7, 1989 NRC/TVA meeting on this
- topic, as documented by NRC's letter to TVA dated August 14,
- 1989, and the follow-up NRC/TVA meetings at the BFN site on October 16 through 27, 1989.
It serves to docket the basis for closure of NRC audit item Engineering Mechanics Group (EMG)-027.
This information supplements and updates the previous CRDH submittals dated March 17, 1988 and June 13, 1989.
Changes relative to the June 13 submittal are indicated by revision bars.
Enclosure 2 contains the commitment.
Please refer any questions regarding this submittal to Patrick P. Carier, Manager of Site Licensing, (205) 729-3570.
Very truly yours, TENNESSEE VALLEY AUTHORITY Enclosures cc:
See page 2
Manag r, Nucle r icensing and Regulatory Affairs
+91214O19 05000260 891211
@DR pQQCK pDC P
An Equal Opportunity Employer
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U.S. Nuclear Regulatory Commission cc (Enclosures):
Ms.
S.
C. Black, Assistant Director for Projects TVA Projects Division U.S. Nuclear Regulatory Commission One Hhite Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. B. A. Hilson, Assistant Director for Inspection Programs TVA Projects Division U.S.
Nuclear Regulatory Commission Region II 101 Marietta Street, NH, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Brogans Ferry Nuclear Plant Route 12, Box 637
- Athens, Alabama 35609-2000
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ENCLOSURE 1
TENNESSEE. VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT UNIT 2 (BFN-2)
SEISMIC QUALIFICATION OF THE CONTROL ROD DRIVE HYDRAULIC (CRDH) PIPING SYSTEM This report provides TVA's revised plan to qualify the BFN-2 CRDH piping system to seismic class I requirements.
It supplements and updates the Maxch 17, 1988, submittal from R. Gridley to US NRC entitled, "Seismic Qualification of Control Rod Drive Insert and Withdrawal Piping" and the June 13, 1989 submittal from M. J.
Ray to USNRC entitled "Seismic Qualification of the Control Rod Dx'ive Hydx'aulic (CRDH) Piping System".
An executive
- summaxy, located at the end of this report, provides a current overview of the BFN-2 CRDH Px'ogram.
BACKGROUND The CRDH piping system analysis has been the subject of significant discussions between TVA and the NRC staff since May 15,
- 1986, when TVA initially proposed specific guidelines fox'igorous analysis of the system.
A background summary in the referenced March 1988 submittal recaps the CRDH analysis history until that time.
At the civil/seismic criteria meeting of February 17, 1989, TVA indicated that the CRDH critexia was being finalized.
As requested by the NRC, this repoxt describes and justifies the new CRDH design criteria as well as TVA's pre-restart plan for implementing it for BFN-2. It reflects the results of the July 7, 1989 NRC/TVA meeting on this topic, as documented by NRC's letter to TVA dated August 14, 1989, and followup NRC/TVA meetings at the BFN site on October 16 through 27, 1989.
SCOPE The BFN-2 CRDH Pxogram encompasses all CRD insert and withdxawal piping,
- valves, and piping supports fox unit 2 from the point of piping attachment to the hydxaulic contxol units in the reactor building to the point of piping attachment to the contxol rod drive housings below the reactox vessel.
DESIGN CRITERIA.
The pxoposed long term criteria for analysis of CRDH piping and supports are BFN-50-C-7103,and BFN-50-C-7107, respectively.
The intexim operability criteria for CRDH piping and suppox'ts is BFN-50-C-7303.
Finally, the design criteria for evaluation of the equipment and" drywell interfaces are BFN-50-C-7105 for equiPment and BFN-50-C-7100 Attachments A and D for the drywe1 1.
The BFN-50-C-7303, BFN-50-C-7105, and BFN-50-C-7100 criteria have been previously reviewed by the NRC and they contain no special provisions for the CRDH piping system.
Tn addition, the NRC'has previously reviewed the BFN-50-C-7103 and BFN-50-C-7107 critex'ia,
- except, fox the special provisions for CRDH piping and suppoxts which are delineated in the next, two paragraphs.
0698c-77
The special provisions for CRDH piping analysis are contained in Table 8.0-1 of criteria BFN-50-C-7103 Attachment A.
The CRDH Portion of Table 8.0-1 defines load combinations and allowable stresses for rigorous analysis of the CRDH piping.
Note 10 of Table 8.0-1 identifies the requirement Eor analyzing representative lines in the CRDH pipe bundles and it defines the basis Eor designating support loads from those analyses.
Note 11 of Table 8.0-1 establishes requirements for defining and evaluating support and pipe loads due to seismic impacts where the pipe guides have been removed due to thermal-expansion considerations.
The special provisions for CRDH support analysis are contained in Notes 4 and 6 of Table 1.4.2.1, in Section 1.4.2.5.1, and section 1.4.2.13f of criteria BFN-50-C-7107.
Note 4 of Table 1.4.2.1 requires the normal scram thermal condition to be combined with the seismic events, and it defines additional load cases for analysis of abnormal scram (including leaking valve) thermal conditions.
Note 6 of Table 1.4.2.1 deEines special considerations for evaluating CRDH support stress and load effects, accounting for the fact that the peak seismic Eorces from the individual pipes in a CRDH bundle will not occur simultaneously.
Section 1.4.2.5.1 serves to enforce proper interaction of the CRDH piping analyst and support designer.
Finally, Section 1.4.2.13f establishes an overall. frame deflection limit for combined seismic and deadweight loads.
JUSTIFICATION FOR DESIGN CRITERIA SPECIAL PROVISIONS The provisions for CRDH piping analysis. load combinations and allowable stresses in BFN-50-C-7103 Attachment.
A Table 8.0-1 are consistent with the rigorous piping analysis philosophy in Appendix C of the BFN FSAR., FSAR Table C.0-6 sheets 7 and 9 will be revised in the next annual update to reflect this information.
This revision is justified because rigorous analysis to this design criteria is in accordance with FSAR Sections C.2.6 and C.3.2.1a, The provisions for rigorous analysis of representative CRDH pipes in BFN-50-C-7103 Attachment A Table 8.0-1 Note 10 ensure conservative calculation of pipe stresses and support loads, consistent with the standard requirements of this criteria for individual pipes.
The provisions for defining and evaluating seismic impact loads on CRDH support bars in BFN-50-C-7103 Attachment A Table 8.0-1 Note ll are justified because the impact forces are calculated conservatively, based upon the pipe velocity attained from a linear elastic analysis assuming no seismic restraint at the impact location.
The impact load effects are conservatively evaluated in the local pipe stress calculations per this note.
Then the impact load effects are combined with other seismic load effects on the supports according to BFN-50-C-7107 Table 1.4.2.1 Note 6.
(2) 0698c-18
The provi,sions fox CRDH piping support thermal load combinations and allowable stresses in BFN-50-C-7107 are in compliance with x'igorous analysis philosophy of Appendix C of the BFN FSAR.
The thermal conditions are consistent with BFN FSAR Figure 3.4-10 and other pertinent FSAR sections.
The abnormal scram condition (envelope of leaking scxam valve and multi.-scram cases) has been defined as an upset thermal condition based on the following: 1) the li.kelihood of a multi.-scxam condi.tion is extremely low due to scram discharge modifications made on ECN P0392 and,
- 2) the plant records indicate no past problems with scram outlet valve leakage.
1n addition, leak detection systems and associated operation instructions provide added assurance. that the probability of scram outlet valve leakage is extremely low at any given time during plant operati.ons.
The provisions fox evaluating CRDH support stress and load effects in BFN-50-C-7107 Table 1.4.2.1 Note 6 axe justi.fied because the criteria for combining seismi.c inerti:a load effects from the multiple individual pipes on a xack and bax are consistent with the results of a special calculation, which is reference 1.5.2 of the criteria.
This calculation justifies 0.5, 0.75, and 1.0 multiplication factors for the absolute sum (ABSUM) of seismic inertia load effects from CRDH pipes which axe restxained by the racks and individual baxs of a support frame. It determines the relationship between the number of xestrained pipes and the multiplication factors, on the basis of time history analysis of BFN CRDH pipes.
Compaxi.sons to an alternate frequency separation (RG 1.92) technique are presented to demonstrate the appropriateness of the multiplication factoxs.
In addition, this calculation demonstrates the conservatism of the CRDH support frame structural qualification when the factoxed piping reaction loads from response spectrum analysis are applied.
The Note 6 provision for combination of the pipe seismic inertia load effects with the individual pipe seismic impact load effects by the square root of the sum of squares (SRSS) is justified by the random nature of the impact load occurrences and the manner in which the impact loads are calculated.
The Note 6 provisions for combining, by ABSUM, the seismic support.
load effects. from frame self-weight exitation, from different orthogonal directions, and from multiple racks on a frame are conservative.
The Note 6 provisions for calculating static load effects, combining static and seismic load effects, and evaluating the combined effects are consistent with the basic support design requirements of the BFN-50-C-7107 criteria.
The ovexall frame deflection limit provision in section 1.4.2.13f is justified as it represents a x'easonable basis for design and is an accepted industxy practice for othex facili.ties.
Attachment 1 summarizes major technical provisions of the proposed criteria and the planned 1989 CRDH analysis.
Attachment 2 summarizes the comparable provisions of the 1986 CRDH analysis which resulted in the 1987 CRDH modifications (Attachment 3).
(3) 0698c-19
PRE-RESTART IMPLEMENTATION PLAN The representative CRDH pipes inside and outside of the drywell will be analyzed and nozzle loads/valve accelerations will be evaluated using the proposed criteria.
Long-term pipe stress, nozzle load and valve acceleration allowables are expected to be satisfied for CRDH pipes both inside and outside the drywell.
All 20 suppoxt frames (10 inside the drywell and 10 outside the drywell) will be analyzed to the proposed criteria. It is 'expected that additional support frame modifications will be required in order to satisfy the intexim operability criteria and the long term criteria.
Design of these additional modifications will be completed before restart.
Modifications will be installed in accordance with the following Executive Summary.
Post, restart activity is expected to be minimal, if any.
EXECUTIVE
SUMMARY
The cxitexia and pxogram plan fox the BFN-2 CRDH Progxam have been revised to address concerns identified by the NRC during the NRC/TVA meeting of "July 7, 1989, and resolved during NRC/TVA meetings at BFN from October 16 through 27, 1989.
Major CRDH modifications were previously installed, in 1987 (Attachment 3).
Additional support frame modifications are anticipated in order to satisfy the revised criteria.
Although TVA plans to complete installation of the additional support frame modifications befoxe restart from the current outage, the BFN-2 CRDH Program licensing commitment remains as follows:
1)
Compliance with interim operability criteria before restart from the current outage.
2)
Compliance with long-term criteria before restart from the next (Cycle 6) refueling outage.
(4) 0698c-80
ATTACHMENT 1 1989 CRDH ANALYSIS O
~ RIGOROUS ANALYSXS FOR ALL FSAR LOADS
, LOAD COMBINATIONS PER FSAR PHILOSOPHY ALLOWABLE STRESSES PER PROPOSED CRITERIA CLOSE-FIT HOUSNER SEISMIC INPUT TO BUILDING MODEL SEISMIC SPECTRA FROM MULTI-BRANCH BUILDING MODEL BROADENED SPECTRA + 10 PERCENT ENVELOPED SPECTRA OR INDEPENDENT SUPPORT MOTZON VERTICAL SPECTRA CORRESPONDING TO HORIZONTAL SPECTRA REPRESENTATIVE PIPE MODELS INSIDE/OUTSXDE DRYWEL L 0.5 PERCENT DAMPING FOR DBE ANALYSIS 2 DIMENSIONAL EARTHQUAKE ABSUM COMBINATION FOR DIRECTIONS AND R.G. 1.92 FOR MODES RIGID RESPONSE (ZPA) ANALYSIS BY MISSING MASS OBE RESPONSE
= 1/2 DBE RESPONSE SEISMIC IMPACT LOADS WHERE GUIDES/CLAMPS REMOVED FRICTION LOADS CONSIDERED, F = 0.3 SCRAM AND LOCA THERMAL ANALYSIS FACTORED ABSUM SEISMIC PIPE LOAD EFFECTS COMBZNATION FOR SUPPORTS SEISMIC/DEADWEIGHT LOAD SUPPORT DISPlACEMENT LIMIT = 1/8 INCH 0698c-81 (5)
S
ATTACHMENT 2 1986 CRDH ANALYSIS RIGOROUS ANALYSIS FOR ALL FSAR LOADS LOAD COMBINATZONS PER FSAR PHILOSOPHY ALLOWABLE STRESSES PER BFN-50-D707 CRZTERIA EI CENTRO SEISMIC INPUT TO BUXLDING MODEL SEISMIC SPECTRA FROM 3-BRANCH BUILDING MODEL BROADENED SPECTRA + 10 PERCENT ENVELOPED HORIZONTAL SPECTRA VERTICAL SPECTRA - GROUND LEVEL REPRESENTATIVE PIPE MODELS INSIDE/OUTSIDE DRYMELL 5 PERCENT DAMPING FOR DBE ANALYSIS 2-DIMENSIONAL EARTHQUAKE SRSS COMBINATION FOR MODES AND DIRECTIONS RIGID RESPONSE (ZPA) ANALYSIS OBE RESPONSE
= 2/3 DBE RESPONSE SEISMIC IMPACT LOADS WERE GUIDES/CLAMPS REMOVED FRICTION LOADS CONSIDERED, F
~ 0.3 SCRAM AND LOCA THERMAL ANALYSIS (ABSUM + SRSS)/2 SEISMIC PIPE LOAD EFFECTS COMBINATION FOR SUPPORTS SEISMIC LOAD SUPPORT DISPLACEMENT LIMIT = 1/8 INCH
,(6) 0698c-82
ATTACHMENT 3 1987 CRDH MODIFICATIONS REQUIRED TO SATISFY 1986 ANALYSIS GUIDELINES/CRITERIA 800 LOCAL STRUCTURAL MODIFICATIONS TO SUPPORTS ADD STRENGTH/STIFFNESS TO SUPPORT FRAMES PRIMARILY BRACES AND CONNECTION REINFORCEMENTS 300 INSIDE DRYMELL 500'OUTSIDE DRYMFLL 3000 PIPE GUIDES/CLAMPS REPLACED ENSURE REQUIRED LOAD CAPACITIES AND GAPS PROVIDE QUALITY INSTALLATIONS A FEM PIPE GUIDES REMOVED ALLOW THERMAL EXPANSION OF PIPES/DRYWELL 0698c-83
Enclosure 2
Control Rod Drive Hydraulic (CRDH) Piping Program Plan Commitments Final Safety Analysis Report, Table C.0-6, sheets 7 and 9 will be revised in the next annual update to current CRDH piping criteria.