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 is1" 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

. 010.00 5 (n 0.00 10 .00 (in) 50.00*

/

to 1" Increase cover plate thickness 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 Bro*W rns Ferrv MST A Browns Ferry MSL A with Inserts

......... ____....... 0.7 25 0.5 -- IF2I..... .* ----..----

20 BF1

-- BF2 BF3 S06 -0 PIFi 15 ---------- ----

EI-

-- BF4

---

0.4 .. .

0 .. ..----. 7 --*

10 00..2 CLTP- - --------- -----------

5 0.- 0.05 0.1 0-15 0.2 0 0.15 0.2 0.25 0.05 0.1 Mach Number 0.25 0.3 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 10# IV, 10 -

S10" I BF - 1448 Hz Test W 353 Hz Plant 10ý S104 10*

10 -

10' 10, Frmquency.

M-FrequeM. If

Preliminary Data 1/5 Scale Testing Browns Ferry MSL B Browns Ferry MSL B 8 1.2

---

I

---

--- ------- .------.--. .---. .V 7 i - SRV2 BF1 0 1 6 BF2 V) - . .. SRV3 END 0 RV 0.8 N 5 EPU---

--- --- -- --- - --- - - ----- --- ----- ---- - EPU 4 C-1 0.6 ------- ----------

0 3 CLTP --------- --------- -------------

z 2

z 0.4 CLTP ----------------- ------ I------------

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

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

0.2 ---------------

11 ------

1 -. . --.. . .

0 0 0.05 0.1 0.15 0.2 0.25 0.3 0.. 0. 05 0.1 0.15 0.2 0.25 0.3 0.35 Mach Number Mach Number MSL B Has SRV 1, 2 in Steam Flow, SRV 3, 4 in Dead Leg All Blind Flanges in Dead Leg (w/o Inserts)

EPU EPU 01491COR~f16~dSOCXTP 10, 10, to0 Io'

• 10o*

I 1 IO0 .. .....

i I

A IE; I

lO~ 1e FrmquwCxy.W

Preliminary Data 1/5 Scale Testing fN91-6 Rerned to CUP 101 bf-491-0 Refeoemed to CLTP I- 1 R reET10,.

SRV - 450 Hz Test

... .. .zln to . ......... .............

. . ...... ~109 HzPlant C 0' - ..... ........ ............ BF.-900 HzTest

~.l4

.. .~.. . .218 Hz Plant

..1..

p10 ~ ~~~~~....

- - - - IC

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

---

--------- --- I------ S V 10 10 C)

I-I- 8 8 N

C)

I...

6 6 z I IV 4 4 2 2 I

A ý , I . . I . . . ý . I ý . . 0 t 0.0 5 0.1 0.15 0.2 0.25 0.3 0.05 0.1 0.15 0.2 0.25 0.3 Mach Number Mach Numnber EPU CLTP M = 0.087, EPU M = 0.1 EPU br-'491-15 Referenced t0 CLTP bFf49147 Referemcedto CUTP SRV2 ISRV3 SRV -450 Hz Test 10' '

BF- 900 Hz Test

~~~~~~ 218 Hz Plant ° " .... -

E z

10.... ... -

0*1:1*10* 10*

10' 10Frequency. 1z Frequency, M No significant effect seen on SRVs from Blind Flange Inserts