ML14149A001

NRR E-mail Capture - Draft Presentation

ML14149A001
Person / Time
Site:	South Texas
Issue date:	05/21/2014
From:	Pensado O - No Known Affiliation
To:	Balwant Singal Division of Operating Reactor Licensing
References
MF2400, MF2401
Download: ML14149A001 (16)

Text

1 NRR-PMDAPEm Resource From:

Osvaldo Pensado [opensado@swri.org]

Sent:

Wednesday, May 21, 2014 10:31 AM To:

Singal, Balwant; Stang, John; Geiger, Ervin; Smith, Stephen Cc:

Fong, CJ; Stuart Stothoff

Subject:

RE: Draft presentation Attachments:

May22_AlternativeMethods_R01.pptx CJ recommended some revisions of terminology. I incorporated those in the revised presentation.

The presentation does not contain any proprietary information.

I will need the bridge number to dial in.

Thanks Osvaldo From: Singal, Balwant [1]

Sent: Wednesday, May 21, 2014 7:55 AM To: Stang, John; Ervin Geiger; Smith, Stephen; Osvaldo Pensado

Subject:

FW: Draft presentation I need to pass on a copy to the members of the public calling in. Please confirm that the presentation does not contain any proprietary information.

Thanks.

Balwant K. Singal Senior Project Manager (Comanche Peak and STP)

Nuclear Regulatory Commission Division of Operating Reactor Licensing Balwant.Singal@nrc.gov Tel: (301) 415-3016 Fax: (301) 415-1222 From: Stang, John Sent: Tuesday, May 20, 2014 2:19 PM To: Cusumano, Victor; Singal, Balwant; Smith, Stephen; Klein, Paul; Fong, CJ; Yoder, Matthew

Subject:

FW: Draft presentation Please provide comments to Osvaldo. I did not know the staff/SWRI was making a presentation.

From: Osvaldo Pensado [2]

Sent: Tuesday, May 20, 2014 2:09 PM To: Stang, John; Fong, CJ; Geiger, Ervin Cc: Stuart Stothoff

Subject:

Draft presentation This is a draft presentation for Thursday.

2 I removed any critique. I will be happy to revise, if needed.

Osvaldo

Hearing Identifier:

NRR_PMDA Email Number:

1315 Mail Envelope Properties (5C3918AB5BDEEC44B7B718E15ACEC4BDD087471A)

Subject:

RE: Draft presentation Sent Date:

5/21/2014 10:31:17 AM Received Date:

5/21/2014 10:31:33 AM From:

Osvaldo Pensado Created By:

opensado@swri.org Recipients:

"Fong, CJ" <CJ.Fong@nrc.gov>

Tracking Status: None "Stuart Stothoff" <sstothoff@swri.org>

Tracking Status: None "Singal, Balwant" <Balwant.Singal@nrc.gov>

Tracking Status: None "Stang, John" <John.Stang@nrc.gov>

Tracking Status: None "Geiger, Ervin" <Ervin.Geiger@nrc.gov>

Tracking Status: None "Smith, Stephen" <Stephen.Smith@nrc.gov>

Tracking Status: None Post Office:

exch2.cnwra.swri.edu Files Size Date & Time MESSAGE 1493 5/21/2014 10:31:33 AM May22_AlternativeMethods_R01.pptx 1383839 Options Priority:

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Osvaldo Pensado Center for Nuclear Waste Regulatory Analyses Southwest Research Institute San Antonio, Texas May 22 2014 1

Objective Objective Show examples of graphic displays to Show examples of graphic displays to facilitate understanding of CASA Grande algorithms and outputs g

p Approach Exercise CASA Grande code with few realizations Exercise CASA Grande code with few realizations (5 frequency envelopes, 5 stochastic replicas)

Consider only case with 3 trains working (Case 1:

y g (

all pumps working)

Plot data from output text files 2

Debris Mass Balance in CG Debris Mass Balance in CG

Debris types tracked independently

Uniform mixing in 5 compartments

Uniform mixing in 5 compartments

1 pool, 3 strainers, 1 core

Mass transfer rates proportional to flows, mass in compartment, shedding time t

t d filt ti f

t urce constant, and filtration factors

Particles and chips retained in strainers

No particles in core So Debris Bed

Fibers shed away from strainers into the pool and core

Fibers retained in the core Debris Bed

Fibers retained in the core

Mass in strainers used to compute head loss through strainers

Fiber in core used to compute the fiber load per fuel assembly 3

Total Mass as Function of Break Size Total Mass as Function of Break Size Particle mass is weakly dependent on break size Red: failure by strainer buckling Blue: no failure 56,150 realizations 56,150 realizations 4

Mass Balance Mass Balance Variability due to on on Fiber Fiber 25 realizations plotted Variability due to uncertainty in filtration and shedding rates Break size = 31 in Constant total fiber mass (dependent on mass (dependent on break size)

Majority of fiber Majority of fiber retained in strainer debris bed Plateaus fixed by the maximum mass in the system Minor amount of fiber shed to pool and core 5

Fiber in the Core Fiber in the Core 25 realizations plotted Variability due to Break size = 31 in Variability due to uncertainty in filtration and bed shedding rates Failure recorded when fiber > 7.5 g/Fuel Assembly Assembly After hot leg switchover Realizations above 7.5 g/FA are recorded as failure After hot leg switchover, fiber is assumed not to accumulate anymore in accumulate anymore in the core 6

Hot let switchover

Failure by Boron Precipitation Failure (red dots) recorded when break occurs in cold leg and fiber > 7.5 g/FA In majority of realizations In majority of realizations, failure occurs at 35 minutes R

i l ti i iti t d ft Red: failure Blue: no failure Recirculation initiated after 30 minutes for large breaks Length of computer timestep i

l t t b l is relevant to mass balance No failure occurs after 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, because of hot leg g

switchover 7

Head Loss in Strainer Head Loss in Strainer

8

Head Loss Computations

25 realizations with 31-in break size

Most time functions Train A, Train B, Train C Train A, Train B, Train C are smooth and of narrow range

Only head loss Train A and Train B are identical Train C is different y

varies significantly in the 25 realizations Train A, Train B, Train C Train A, Train B, Train C Minor variation Train A, Train B, Train C Train C is different because the corresponding 9

Train C is different because the corresponding containment spray pump is assumed shut off 20 minutes after the LOCA event

Head Loss Versus Time (Examples from 4 Realizations)

T i

A T i

B T i

C Small inflection due to hot leg switchover Jump due to containment spray pump shut off (2 remaining pumps)

Train A, Train B, Train C Train A, Train B, Train C System temperature dropping below Tcrit Chemical effects b

f t

T < Tcrit, and chemical effect bump-up factor Jump due to containment spray pump shut off (2 remaining pumps) below Tcrit bump-up factor Train A Train B Train C Train A Train B Train C T < Tcrit, and chemical effect bump-up factor T < Tcrit, and chemical effect b

f t

Decrease because of inflection in T vs time J

d t

Train A, Train B, Train C Train A, Train B, Train C bump-up factor Jump due to containment spray pump shut off (2 remaining pumps) 10

Sump Failure Criteria Are Not Independent Buckling failure:

H>9 35 ft Strainer Buckling Failure H>9.35 ft Degassing failure:

H>approx 16 ft Failure pp NPSH margin failure:

H>approx 21 ft Degassing Failure Red: buckling failure Blue: no failure Red: buckling failure Blue: no failure Degassing Failure 11 Blue: no failure

Scatter Plots to Understand Sump Failure Model in CASA Grande Failure Model in CASA Grande Step 2: compute the bed thickness a function of the Step 1: estimate mass given a break size fiber mass Step 3: compute the conventional head loss Step 4: apply enhancement factors.

Failure if total HL > 9.35 ft 12

Conclusions Conclusions Important elements of boron precipitation failure model model Fiber limit (7.5 g/FA)

Strainer bed filtration and shedding parameters g p Computer timestep length Important elements of sump failure model Conventional head loss (HL) empirical equation Chemical bump-up factor and crank-up HL factor Uncertainty in the amount of fiber Uncertainty in the amount of fiber Range of mass of particles is narrow Strainer buckling criterion (the 3 sump failure criteria are related) 13