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

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.

1

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

Osvaldo 2

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: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

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

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

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

Consider onlyy case with 3 trains working g ((Case 1:

all pumps working)

Plot data from output text files 2

Debris Mass Balance in CG Debris types tracked independently Uniform mixing in 5 compartments 1 pool, 3 strainers, 1 core Mass transfer rates proportional to flows, Source mass in compartment, shedding time constant, t t and d filtration filt ti factors f t Particles and chips retained in strainers No particles in core Debris Bed Fibers shed away from strainers into the pool and core 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 Particle mass is weakly dependent on break size Red: failure by strainer buckling Blue: no failure 56,150 realizations 4

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

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

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

Failure by Boron Precipitation Failure (red dots) recorded when break occurs in cold leg and fiber > 7.5 g/FA Red: failure In majority of realizations, realizations Blue: no failure failure occurs at 35 minutes Recirculation R i l ti iinitiated iti t d after ft 30 minutes for large breaks Length of computer timestep i relevant is l t tto mass b balance l

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

8

Head Loss Computations Train A, Train B, Train C Train A, Train B, Train C 25 realizations with 31-in break size Most time functions are smooth and of Train A and Train B are identical narrow range Train C is different Only y head loss varies significantly Train A, Train B, Train C Train A, Train B, Train C in the 25 realizations Train A, Train B, Train C Minor variation Train C is different because the corresponding containment spray pump is assumed shut off 20 minutes after the LOCA event 9

Head Loss Versus Time (Examples from 4 Realizations)

T i A, Train A Train T i B B, Train T i C Train A, Train B, Train C Jump due to Small inflection containment spray due to hot leg pump shut off (2 switchover remaining pumps)

T < Tcrit, and Jump due to chemical effect System containment spray bump-up factor temperature pump shut off (2 dropping remaining pumps)

Chemical effects below Tcrit b

bump-up f t factor Train AA, Train B B, Train C Train A A, Train B B, Train C Decrease because T < Tcrit, and of inflection in T vs chemical effect time bump-up factor T < Tcrit, and chemical effect JJump due d tto b bump-up f t factor containment spray pump shut off (2 remaining pumps) 10

Sump Failure Criteria Are Not Independent Strainer Buckling Buckling failure:

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

H>approx pp 16 ft NPSH margin failure:

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

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

conventional head loss Failure if total HL > 9.35 ft 12

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

Strainer bed filtration and shedding gpparameters 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 Range of mass of particles is narrow Strainer buckling criterion (the 3 sump failure criteria are related) 13