ML080360067

Steam Dryer RAI 15 Status, Slides

ML080360067
Person / Time
Site:	Browns Ferry
Issue date:	01/25/2008
From:	Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation
Brown Eva, NRR/DORL, 415-2315
Shared Package
ml080360097	List: ML080360067
References
TAC MD5262, TAC MD5263, TAC MD5264
Download: ML080360067 (15)

Text

im TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT Steam Dryer RAI 15 Status January 25, 2008

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Finite Element Model Discrepancies "Differences Between Unit 1 FEM and Actual Configuration Cover Plate is 1 " thick vs. 1/2/" thick as modeled Cover plate has no man-way as modeled Outer hood vertical stiffeners have top covers that were omitted in model Dryer support restraint was modeled as bolted restraint - now revised to pin connection Support beam was disconnected from support ring (due to cracked welds) vs. modeled as attached to support ring

" FEM Verified G. Nelson2

I 0.00 10.00 (in) 5

. 010.00 (n

/

50.00*

Increase cover plate thickness to 1" Analyze with a 3/4" Fillet weld Remove Man way Revise Dryer support restraint Add top covers to vertical stiffeners Browns Ferry Unit 1 Finite Element Model

Finite Element Model Discrepancies

• Differences Between Unit 2/3 FEM and Actual Configuration The cover plate attachment welds to support ring and hood were not described as undersized welds in stress analysis The man-way attachment welds were not described as undersized welds in stress analysis The cover plate was not modeled with a 2" rise to the hood attachment

• Modifications to Unit 2 Steam Dryer in 2009 Replace and upgrade dryer tie bar design Reinforce cover plate and man-way welds

• Modifications to Unit 3 Steam Dryer in 2010 Replace and upgrade dryer tie bar design Reinforce cover plate and man-way welds

• FEM Verified G. Nelson 4

I 0.00 100.00 (in) 0.00 100.00 (in)

/

50.00 50.00

" Clarify that Cover Plate & Man-way welds to be reinforced from

'" to 3/8"

" Cover plate slopes up 2" from support ring, was modeled as flat

" Revise Dryer Support Restraint from fixed to pinned Browns Ferry Unit 2, 3 Finite Element Model 5

Potential for SRV Resonance 0 Potential for Resonance Onset Between CLTP and EPU Frequency range 105 Hz to 112 Hz most likely No demonstrated SRV resonance at CLTP velocities (135 - 142.25 ft/sec) from plant data 1/5 Scale Testing of A & B Main Steam Lines (preliminary data)

A MSL has 3 SRVs and 4 Blind Flanges B MSL has 2 SRVs in active steam flow region, and 2 SRVs and 2 Blind Flanges in dead leg 1/5 Scale Test Report to be completed on 1/30/2008 Testing shows SRV frequency (109 Hz) onset starting at CLTP and small increase at EPU Mach numbers Need to quantify SRV resonance through further testing J. Wolcott 6

Potential for SRV Resonance 1/8 Scale Testing for EPU Prediction Assess Stress Margins at EPU o Quantify the effects of potential resonance o Used to judge adequacy of CLTP stress margin o Used to determine the need for mitigation modifications Test circuit includes reactor vessel, dryer, nozzles, 4 MSLs and components through turbine high pressure inlet o Provides flow interaction and potential coupling between steam lines o Comparison of CLTP and EPU flows provides "Bump up" factor for steam dryer stress margin at EPU conditions BUMP UP Factor Applied to CLTP Results J. Wolcott 7

Bias and Uncertainty Issues RA

" FEM Inputs Still Under NRC Review Hope Creek 2 Dryer Benchmark Analysis (shake test)

Mesh Convergence Frequency Discretization Errors 75% Bias and Uncertainty Applied to the Peak Other - NRC discuss

" Issue Resolution Impacts BFN FEM Results and Schedule K. Spates 8

Margin Improvement IVA

• Noise Reduction and Margin Improvement FIV noise floor o Remove strain gage signals associated with minimal steam flow o 1000# data available for Unit 1 o 0# data available for Unit 2 0 1000# data will be taken for Unit 3 Will be incorporated in revised stress analyses J. Wolcott 9

Clarification of RAIs

" RAI 15 Questions 139/106 & 145/112

• Follow-up Discussion from NRC/TVA Meeting 12/10/07 Question, cannot be answered as written FEM Outputs in terms of displacement are not available

• Alternative Responses Discussion A. Bilanin 10

Schedule for RAI 15 Responses IRA

• Project Schedule Impacts Resolution of Bias and Uncertainty Issues Performance of Scale Model Tests Collection of Unit 3 Data Re-perform FEM Analyses F.E. Hartwig 11

Preliminary Data 1/5 Scale Testing rns Ferrv MST A Browns Ferry MSL A with Inserts Bro*W 25 EI-20 15 10 5

0 0.05 BF1 BF2 BF3 BF4 0.7 0.5 --

IF 2 I......* ----

S06

-0 PIFi 0.4 0.......

7 --

• 00..2 CLTP-0.15 0.2 0.25 0.-

0.05 0.1 0-15 0.2 Mach Number Mach Number CLTP M = 0.087, EPU M = 0.1 Significant effect seen from BF Inserts at the BF Chamber lfT t

P1-4T Referonc*4 to CLTP 0.1 0.25 0.3 I BF - 1448 Hz Test 353 Hz Plant 10#

W 10 S10" 10ý S104 10*

10 10' IV, 10, Frmquency.

M-FrequeM. If

Preliminary Data 1/5 Scale Testing Browns Ferry MSL B Browns Ferry MSL B 8

7 N

0z V) 6 5

4 3

2 1

00.

I

.---..V 0

i SRV2 SRV3 0

RV E PU---

CLTP ---------

0 z

C-1 1.2 1

0.8 0.6 0.4 BF1 BF2 END EPU CLTP I ------------

0 ----------------

11 0.2 0

0.

05 0.1 0.15 0.2 0.25 Mach Number 0.3 0..

05 0.1 0.15 0.2 0.25 Mach Number 0.3 0.35 MSL B Has SRV 1, 2 in Steam Flow, SRV 3, 4 in Dead Leg EPU 10, 10, All Blind Flanges in Dead Leg (w/o Inserts) to0 Io' 10o*

1 0 IO A

IE; 01491COR~f16~dSOCXTP EPU I

iI I

lO~

1e FrmquwCxy. W

Preliminary Data 1/5 Scale Testing 101 fN91-6 Rerned to CUP bf-491-0 Refeoemed to CLTP I-1 R

reET10,.

SRV - 450 Hz Test to

~109 HzPlant C

.zln 0' -

BF.- 900 HzTest

~.l4

.~..

.218 Hz Plant

..1..

p10

~ ~~~~~....

IC

Preliminary Data 1/5 Scale Testing Browns Ferry MSL A Browns Ferry MSL A with Inserts 12 N

z I-10 8

6 4

2 I--

S V I

IV C)

I-C)

I...

12 10 8

6 4

2 I

0.0 A ý I

I

ý I

ý 5

0 t 0.05 0.1 0.15 0.2 Mach Number 0.25 0.3 0.1 0.15 0.2 0.25 Mach Numnber 0.3 E

z CLTP M = 0.087, EPU M = 0.1 EPU EPU br-'491-15 Referenced t0 CLTP bFf49147 Referemcedto CUTP SRV2 I SRV3 SRV -450 Hz Test 10' BF-900 Hz Test

~~~~~~

218 Hz Plant

° 10....

0*1:1*10*

10*

10' 10Frequency.

1z Frequency, M No significant effect seen on SRVs from Blind Flange Inserts