ML20195G656

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Summary of 981105 Meeting with Public in Rockville,Md Re Containment Coating Failure & PWR Sump Blockage Studies
ML20195G656
Person / Time
Issue date: 11/13/1998
From: Serkiz A
NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
To:
NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
References
NUDOCS 9811230065
Download: ML20195G656 (102)
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NUCLEAR REGULATORY COMMISSION 2

WASHINGTON, D.C. 20555 4001

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November 13, 1998

SUBJECT:

SUMMARY

OF PUBLIC MEETING ON CONTAINMENT COATING FAILURE & PWR SUMP BLOCKAGE STUDIES The Office of Nuclear Regulatory Research (RES) conducted a public meeting on November 5, 1998, at NRC Headquarters for the purposes of describing recently initiated research programs and soliciting stakehoider input on program objectives, output, and expected application of findings. Detailed presentations were made by Savannah River Technology Center (SRTC) staff on the containment coating failure program and by Los Alamos National Laboratory (LANL) station PWR sump blockage studies (GSI-191). Attendees representing nuclear reactor licensees, containment coatings firms, nuclear inuustry engineering consulting firms and the Nuclear Energy Institute (NEI) and other public were present. The meeting agenda is provided as Enclosure 1, and a list of meeting attendees is provided as Enclosure 2. Presentation slides are provided as Enclosure 3.

The SRTC project team discussed the coatings failure model being developed, presented sample rasults of fini;e element modeling of a coating delamination problem, and also discussed initial benchmark testing of sample coatings using a videotape of sample latex and alkyd coatings subjected to vapor pressure loading in SRTC's environmental test chamber. Audience comments and questions were directed at achieving a better understanding of the program, the utility of program results to the nuclear industry and implications for coatings inspection, aging 7

effects, qualified versus unqualified coating implications and how does the end product fit into the resolution of this safety issue.

The LANL project team discussed recently initiated GSI-191 efforts, presented the program plan and some initial results. A constructive exchange of views and feedback was obtained with an identification of a need to clarify how reference plant information would be used and how risk perspectives would be applied.

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Attendees were asked to submit written comments or questions to the NRC project managers within 30 days of this meeting. NEl noted that an industry meeting had been scheduled for Novemb2r 6,1998, to discuss further industly views on the SRTC and LANL programs from which NEl would prepare a written response. Attendees were also requested to give consideration to formation of smaller technical working groups for containment coatings and PWR sump blockage that could interact with the NRC staff to exchange data and relevant information on a timely basis as was done on the BWR strainer blockage issue.

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Aleck W. Serkiz, Sr. Task Manager Generic Safety issues Branch Division of Regulatory Applications Office of Nuclear Regulatory Research

Enclosures:

1. Agenda
2. List of Attendees
3. Presentation Slides i

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I Summary 2

l Attendees were asked to submit written comments or questions to the NRC project managert:

within 30 days of this meeting. NEl noted that an industry meeting had been scheduled for t

November 6,1998, to discuss further industry views on the SRTC and LANL programs from which NEl would prepare a written response. Attendees were also requested to give consideration to formation of smaller technical working groups for containment coatings and PWR sump blockage that could interact with the NRC staff to exchange data and relevant i

information on a timely basis as was done on the BWR strainer blockage issue.

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Aleck W. Serkiz, Sr. Task Manager Generic Safety Issues Branch L

~ Division of Regulatory Applications Office of Nuclear Regulatory Research

Enclosures:

1. Agenda
2. List of Attendees i
3. Presentation Slides Distribution (hard coov w/all attachments) l

~ Central File PDR Distribution (Summarv. Aaenda & Attendees)

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N. lyer (SRTC)

D.V. Rao (LANL)

D. Moden (NEI)

J. Butler (NEI) l'

J.B. Hickman, NRR R. Elliott, NRR J. Davis, NRR R. Lobel, NRR C. Berlinger, NRR E. Sullivan, NRR D. Skay, NRR S. Richards, NRR

' A. Thadani, RES M. Federline, RES J. Craig, RES S. Duraiswamy, ACRS DOCUMENT NAME: H:\\SERKIZ\\MTGSUtti.WPD T'a voceive e cc >y of this document. Indicate in the boa; *C" = Copy without attachment / enclosure

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OFFICE GSIB/DRA:RES l GSIB/DRA:RES lG C:GSIB/DRA:RES l

l NAME ASerkiz:kj W MMarshall c/$ TMartin Gi h DATE 11/d/98 it / R /98 it/ p /98 l

OFFICIAL RECORD COPY L

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Enclosura 3, Prce:nttien Slideo i

11/5/98 Public Mtg j

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Coating Failure and PWR Sump Blockage Studies Safety Concern 1

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Tom Martin, Branch Chief U.S. Nuclear Regulatory Commission l

Office of Nuclear Regulatory Research Generic Safety issues Branch t

(301) 415-6201 Public Meeting on Cooting Failure and PWR Sump Blockage Studies i

Rockville, Marytand 4

November 5,1998 I

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PURPOSE OF MEETING

= Describe:

  • Background
  • Coating Failure Study

= Solicit the Views of Stakeholders I

  • Question and Answer Sessions
  • Open Discussions
  • Mail or Email Comments or Questions to A. Serkiz or M. Marshall i

Public Meeting on Cooting Failure and PWR Sump Blockage Studies Rockville, Maryland November 5,1998

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BACKGROUND

= Regulatory Guide 1.82, Rev. 0 (1974)

  • 50% Blockage of Screen or Sump

= USl A-43 (1981 - 1985)

= BWR Suction Strainer Blockage Study (1992 - 1996)

  • BarsebEck

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= PWR Sump Blockage Study (1998 -)

  • Risk informed I

l Public Meeting on Cooting Failure and PWR Sump Blockage Studies Rockville, Maryland November 5,1998

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4 REGULATORY and SAFETY CONCERN t

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= Regulation

  • 10 CFR 50.46, " Acceptance Criteria for Emergency C criteria. One of those criteria is long-term cooling.

= Safety Concern

  • The accumulation of debris on sump screens (or strainers) willincrease the resistanc drawing suction from the sum)p.across the screen (or strainer and thus red
  • The accumulation of debris at the sump screen or along the flowpaths on the con floor may form dams that prevent or impede the flow of water into the sump re available to the ECCS pumps.

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GOALS OF STUDIES

= Demonstrate That Debris Blockages in PWR Containments Will Or Will Not Prevent Or Impede The Operation Of The Emergency Core Cooling System.

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= Determine if There is A Need For Further NRC Action To Be Taken For PWRs Beyond That Taken During The Resolution of USI A-43.

= Coatings (which is one possible debris source) Has Been Singled Out For A Separate Study Because:

  • Lack of Information on Coating Debris Characteristics
  • Lack of Information on When Coating Failure May Occur Publ ng on Cooting Failure and PWR Sump Blockage Studies v* *'%

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USl A-43 RESOLUTION

= Generic Letter 85-22, " Potential For Loss Of Post LOCA Recirculation Capability Due To insulation Debris Blockage".

A Generic Solution Was Not Possible. Debris Blockage Effects Are Governed B Specific Design Features and Post-LOCA Debris Sources.

50% Screen Blockage Criterion Should Be Replaced With A More Comprehensive Requirement To Assess Debris Effects On a Plant-Specific Basis.

  • No New Requirements Were imposed Based On Regulatory Analysis (NUREG Rev.1).

Dealing With Modifications To Thermal Insulation Inside Containment.

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L Purpose and Schedule of Coating Failure Study Aleck Serkiz, Senior Task Manager U.S. Nuclear Regulatory Commission

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Office of Nuclear Regulatory Research Division of Regulatory Applications Generic Safety issues Branch l

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t OVERVIEW OF SRTC COATING FAILURE RESEARCH i

= Investigate NPP Coating Failure Mechanisms, Failed Coating I

Debris Characteristics And Time To Failure.

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= Employ A Combined Materials Modeling And Experimental i

s Verification Approach.

= Goal:

  • Develop Capability To Predict Failed Coatings Debris Characteristics And Time To FailI r

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i Public Meeting on Cemting Failure and PWR Sump Blockage Studies Rockville, Maryland November 5,1998 i

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OVERVIEW OF COATING FAILURE STUDY

= Contractor: Savannah River Technology Center

= Two Phase Program

  • Phase i Started in July 1998 l

i Develop Coating Model Develop NRR and RES i

Review Prelimanary Start Phase 11 Work Experimental and Analytical Program R

(DE 99)

Review Industry and I

Related Activities Public ee ing on Cooting Failure and PWR Sump Blockage Studies November 5,1998 f(

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.t Coating Failure and S

PWR Sump Blockage Studies i.

Purpose and Schedule of PWR Sump Blockage Study i

Michael Marshall, Task Manager I

U.S. Nuclear Regulatory Commission i

Office of Nuclear Regulatory Research Division of Regulatory Applications Generic Safety issues Branch i

mxm2@nrc. gov (301) 415-5859 l

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PURPOSE OF PWR SUMP BLOCKAGE STUDY

= Determine if the transport and accumulation of debris in ECCS in operating PWRs. containment following a LOCA will

= If it is shown that debris accumulation will impede ECCS operation, develop the technical basis for revising NRC's regulations or guidance to ensure that debris accumulation in containment will not prevent ECCS operation.

= If it is shown that debris accumulation

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will impede ECCS operation, provide NRC technical reviewers with safficient information on phenomena involved in debris accumulation and changes to plants that may be warranted.how it eff I

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I OVERVIEW OF PWR SUMP BLOCKAGE STUDY

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= Contractor: Los Alamos National Laboratory

= GSI-191, Assessment of Debris Accumulation on PWR Sump Performance 5

= Two Phase Program

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SELECTED PWR SUMP BLOCKAGE STUDY MILST Start Study September 1998 Complete Review of Current Studies, etc.

May 1999 Complete Prelimanary Transport Assessment June 1999 Complete Phase 1 Risk Assessment August 1999 i

Complete Phase 1 of Study i

September 1999 1

i Complete Phase 2 of Study September 2001 i

i Public Meeting on Cooting Falture and PWR Sump Blockage Studies Rockville, Maryland November S.1998 f* *'*%

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Degradation and Failure Characteristics of NPP Containment Protective Coatings Savannah River Technology Center 1

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Degradation-and Failure Characteristics of NPP Containment Protective Coatings i

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Program Overview and Technical Approach 1

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JSRTC Savannah RiverTechnologyCenter 11A)S)98 i

Degradation and Failure Characteristics of NPP Containment Protective Coatings Outline

  • Background
  • Overview of Program i
  • Program Objectives
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  • Program Team
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Savannah RiverTechnology Center l

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Degradation and Failure Characteristics of NPP Containment Protective Coatings.

Background

. Service Level 1 Coatings Used on Exposed Surfaces within NPP Primary Containment Coatings Failure => Debonding and Fragmentation Coatings Debris Can Foul ECCS or Safety Related CSS Components

. Issues of ECCS and CSS Operability Time Dependent Accumulation of Debonded and Fragmented Coating Material DSRTC Savannah RiverTechnologyCenter 11N5/98

Program Objectives Develop Coatings Degradation and Failure Model Model Testable by Experimental Program Model Predicts Coating Failure Mechamsms j

. Failed Coating Characteristics

. Time to Failure i

Product:

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Particulate Source Term for Coating / Substrate System i

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t Degradation and Failure Characteristics of NPP Containtnent Protective Coatings Phase I:

  • Propose a Coatings Degradation and Failure Model
  • Develop Experimental Program
  • Characterization of Coatings Debris e Conduct Preliminary Scoping Tests to Guide Experimental Program e Review NPP Industry Coatings Activities s

Phase II:

  • Implement Experimental Program to Validate Model and Failed Coatings Characteristics JSRTC Savannah RiverTechnologyCenter 11NSB8 I

Degradation and Failure Charactenstics of NPP Containment Protective Coatings Program Team Natrallyer Program Manager NRC NPP Coatings Christine Sweeney Program Administration & Business Manager NRC NPP Coatings I

I Philip Zapp Eric Skidmore Co-Principallnvestigator Co-Principallnvestigator Failure Model Development and Validation Coatings Performance Evaluation i

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I Robert Sindelar Poh Sang Lam Elliot Clark Phil Zapp

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Model Concept & Logic Analytical Modeling Model Benchm arking Performance Evaluation l

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-Craig Stripling

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-Ross Lathrop

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Degradation and Failure Characteristics of NPP Containment Protective Coatings Key Deliverables and Dates Start Date: 7/15/98 Model Development Failure Model Logic Diagram Preliminary Failure Model Development Final Failure Model Benchmark Testing and Experimental Program Development Draft Phase II Program Plan (Dec. '98)

Phase II Program Plan Review ofIndustry and Related Activities Techmcal Review Memo gg s

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Review of Xuclear Power Plant Coatings-and Logic Tree for Degradation Modeling I

Philip Zapp Savannah River Technology Center i

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l Levels of XPP Containment Coatings l

e Qualified Coatings l

Safety-Related Required by Plant Licensing Basis Attested to Passing Simulated Design Basis Accident Test, etc.

Similar Designation to ' Service Level l' of ANSI N5.12 e Acceptable Coatings Safety Related Reviewed for Suitability

. Reasonably Assured not to Detach under Normal or Accident Conditions e

Unqualified Coatings Assumed to Form Solid Debris during DBA SavannahRiv TmSnologyCenter

I Service Level 1 Coatings i

I eEpoxy Based Polyamide Epoxy Epoxy Phenolic l

eIncrganic Zinc ePhenolic EPRI Report No: TR-106160 eVinyl eConstruction and Maintenance t

eConcrete and Steel Surfaces i

1 eUp to 70 psig,3400F, and 109 Rads i

Service Levell: Coatings used in areas where coating failure could adversely I

affect the operation of post-accident fluid systems and thereby impair primary l

containment.

Savannah RiverTechnology Center 11/1528

Protective Coating Qualification e " Qualified" vs. "Non-qualified" Coatings i

l e ASTM D3911 - DBA Testing (Qualitative Only) o ASTM D4082 - Radiation Exposure to 109 Rad l

e ASTM D5139/5144 - Sample Preparation Standards e ASTM D714 - Blister Evaluation e ASTM D4256 - Decontaminability l

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Applicable Coatings Experience at the Savannah River Site o Conventional Systems (Alkyd, Polyamide Epoxies, Zinc-rich Epoxies, Inorganic Zinc, Architectural Latexes) l e Secondary Containment (for Corrosive Solutions) l Epoxy-novolacs (High Solids)

Vinylesters Polysiloxane (High Temp, Acid Resistance) e DBA-qualified Systems in High Radiation and Contamination Areas e

Epoxies vs. Alkyds in Reactor Areas (1989-90, LOCA Issues) l e Site Engineering Standards & Guides for Above and Below Ground Applications i

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Technical Literature i

e EPRI Survey: " Coatings Handbook for Nuclear Power Plants"

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Report No: TR-106160 e

EPRI Report " Guidelines on Nuclear Safety-Related Coatings" Report No: TR-109937 e

BWR Owners' Group - Containment Coatings Committee i

e Journal of Protective Coatings and Linings Series by C. n Hare i

e Journal of Coatings Technology f

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Progress in Organic Coatings i

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L Degradation Modes and Mechanisms

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e Mechanisms That Could Result in ECCS Blockage i

l Delamination (Flakes, Sheets, Chips, etc.)

Blistering (Intact vs. Ruptured)

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Debris Characteristics Particle Size / Morphology and Distribution l

Mechanical Properties i

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Degradation Model Technical Considerations o

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Cohesion of Coating e InterfacialToughness j

e Internal (Curing) Stresses e HygrothermalStresses e

Water Permeation / Condensation j

e Radiation Agmg e Environmental Degradation o

Coating Mechanical and Physical Properties Tensile strength, Young's modulus, Coefficients of expansion, Glass transition temperature, Permeability, etc.

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Logic Tree for Modeling Coating Degradation Modes & Mechanisms initial Material Properties and Condition (Film t, Surface Finish)

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Normal Ops. & LOCA Coating / Substrate Degradation Model Environmental n Input g,

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Criterion for Delamination 1

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GBond Energy (Adhesion)

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Measure G by ASTM Adhesion Test or Vapor i

nona energy Pressure Method; Use Finite Element Mechanics Model of i

Test to Evaluate G at Failure

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Bond Ener8y Develop "Look-Up" Tables of Values for Coating Systen: ' Exposure l

Evaluate G under Conditions of Interest l

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Criterion for Cracking / Flaking (Thin Coating) l coatingyield applied or 8 !auurc 8 appiicd e

Measure acoating yieia, e, and E Using ASTM Film Tension Test r

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o Develop "Look-Up" Tables of Values for Coatis 3 ystem/ Exposure S

o Evaluate c Under Conditions of Interest appiica JSRTC

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Coating / Substrate Degradation Model i

e Material Properties for Failure Mode Analysis G, a, E, a, v, e f

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G = G + AG(y, T, t, Film Moisture, Solution) o e Short-Term Aging Mechanisms (LOCA)

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G = G + AG(T,t,FilinMoisture; Solution) o e Use Degradation Models and Benchmark Testing i

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COATINGS DEGRADATION MODEL Poh-Sang Lam Savannah River Technology Center November 5,1998 JSRTC

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Outline l

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Model Considerations r

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Finite Element Model l

Effect of Thermal Expansion Mismatch I

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Effect of Vapor Pressure Loadmg

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Model Considerations Geometry Material Properties

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Loading Conditions (such as Temperature and Pressure)

Finite Element Methods.

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Finite Element Models (ABAQUS)

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- Delamination initiates at defects.

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- Temperature rises from 70 F to 340 F.

(bounded by BWR DBA temperatures)

Calculate the energy required to propagate the initial delaminated area (defect).

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r Fracture Mechanics Criterion for Delamination:

Energy Release Rate (Crack Driving Force?

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l 3-D Visualization of l

Vapor Pressure Loading

'i(Diameter = 3 8" at 340 F1 Assume No Defect Growth and No Coating Failure

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l Crack Opening Stress Distribution (3 A" Diameter,105 Q l

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Estimationof DelaminationTemperature andInterfacial BondEnergy (A Material Property) i i

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' Generic coating

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niister size Om pIOpeItieS Weie Dia=3/8-g Dia=l/8" ggg

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  • Interfacial bond Test Data l

221*F(105'C)

Prediction ODOI87 3 OSSUMOd Prediction 265 *F(129 *C) 327*F (164 *C) lO be a constant.

ga2 (filSt Old2r

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Postulated Interfacial Bond Energy o

f' 200 250 300 350 Delaminating Temperature ( F) 3 RTC Savannah RiverTechnology Center 11/5f)8 i

Methodology Applied to a PWR Containment SimplifiedLpper Comparurent CBA Temperature-Pressure Histories l

Estimated Calculation Data (MELCOR Code):

y j

For the first 20 seconds-3m c250-

.; so 7

lg g j

T=0 T=100 F P=14.7 psia g2m -

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Tmax = 285 F @ t= 5-10 sec.

50 i

-; 20 a j

(Rapid Rise)

- 10 o

o 5

io is 20 25 r

P= 45 psia @ t=10 sec.

Pmax = 46.5 psia @ t=15 sec.

(Rapid Rise) l P= 46 psia @ t= 20 sec.

i t CBA: Calculation Based Accident DSRTC Savannah RiverTechnology Center 11/5)98 I

,j

Determination of Threshold Defect Size

-i (PWR Containment Upper Compartment)

I I

Threshold Diameter " 15/32 in O

us v4 3/8 v2 5/8 3g,

Initial Defect Diameter (in) i 25 --

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15 '

STAllLE <

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10 --

SIZE C

en w

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Pressure Required for Delamination i

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(Vapor Pressure)-(Ambient Pressure) 2-Threshold

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Temperature

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203 210 220 230 240 250 260 270 280 290 303

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==

Conclusion:==

For initial defect diameters > 15/32", delamination at LOCA may occur.

l 3RTC Savannah RiverTechnology Center l

11/5)98 i

Multiple-Layer Model 4

Finite Mesh for a Three-Layer System te Thermal Buckling for a Three-Layer System 11 EEi

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<n sesmas

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+ : n. i + w -.

' E:E JSRTC Savannah RiverTechnologyCenter 11/5f)8 l

i

Conclusions Finite element method is employed for allowing parametric study of material properties with various loading conditions.

Fracture mechanics principle and elastic instability are utilized to investigate coating failure.

Energy release rate calculation enables prediction of the onset of delamination from an existing defect.

It has been demonstrated that the thermal expansion mismatch may cause the coating to buckle.

Delamination temperature and threshold defect size may be.

predicted in a LOCA as a result of vapor pressure loading.

]SRTC Savannah RiverTechnology Center II/5/93

Path Forward e

9 Model validation and refinement for predicting debris fragmentation and size.

Perform elastic-plastic analyses as the material properties become available.

Perform analyses pertinent to the LOCA and validate existing models with plant-relevant data (apply realistic temperature and pressure loading).

Investigate coating failure mechanisms during the heating and cooling cycle of LOCA.

1 1

i

]SRTC Savannah H!verTechnologyCenter q

71/5/98 l

i

?

I Benchmarking of Failure :Models and :Model Refinement i

I Robert L. Sindelar Savannah River Technology Center November 5,1998 JSRTC Savannah RiverTechnologyCenter l

11/5/98 l.

Background-DBA Testing Requirements

" Pass / Fail" Only - No Mechanistic Explanation No Assessment of " Fresh" vs " Aged" Material Does Not Account for:

- Post-Irradiation Oxidation (thermoplastics)

- Surface Preparation

" Cold-Wall" - Immersion High Dose-Rate Testing Limitations JSRTC Savannah RiverTechnology Center 11/5/98

Purpose of Benchmarking Tests

  • Identify and Measure Relevant Coating Parameters for Failure Models
  • Measure Parameters for Degraded Coating Conditions j

= Establish Test Methodologies for Verification of i

Failure Models for Degraded Coating System r

JSRTC Savannah RiverTechnology Center t

11/5/98

{

Controls for Sample Preparation and Coating Properties Intrinsic Coating / Substrate Mechanical Properties

- tensile strength, modulus, elongation-at-failure, a, adhesion Coating / Substrate System Parameters

- surface preparation (surface profile, pH, moisture, contaminants), curing stresses Coating Formulation

- % solids, mix ratio, effect of VOC, thickness, application details (temp / humidity), pigment / color - Instacote Environmental Degradation Effects a

response to environmental conditions (temperature, radiation, moisture, etc.)

t JSRTC Savannah RintTechr' ology Center 11/5/98

,i

-i Relevant Test Standards and Methods

- Environmental Test Chamber (ETC)

  • ASTM D4541 - pull / adhesion test

- Elcometer adhesion tester, field application

  • ASTM D5162 - holiday / discontinuity testmg

- NDT/Bechtel construction

  • ASTM 4082 - radiation exposure

- SRTC gamma cell / pit sources JSRTC Savannah RiverTechnology Center 11/5/98 l

I

Proof of Principle -Initial Test G Bond Energy ( Adhesion ) - G oriving Force xwidth Benchmark Delamination Failure Analysis of Simple, Undegraded Coating Systems Calculate G and Compare to G applied driving force measured bond energy Use Published Values of E and o 1

i l

I JSRTC l

Savannah RiverTechnologyCenter o

11/5/98

-l

I Proof-of-Principle: Initial Test I

e C-Steel specimens n e u e g a,.;;r e.

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and alkydpaint Qi j lj ],

j e Initial delaminated i

regions j

i e Pressureloading-

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Savannah RiverTechnology Center II/5/98 I

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Environmental Test Chamber (ETC) 1

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  • S.S. Chamber - 75 cm diameter x 120 cm

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  • Fully-Automated Exposure Control & DAS me; l

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  • Remote Viewing & Recording Capability

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JSRTC Savannah RiverTechnologyCenter 11/5/98

V Material Characterizations Mechanical Properties (modulus, tensile strength, hardness, etc.)

Adhesion Chemical / Structural Changes Tg (TGA, DSC, DTA)

- crystallinity (XRD)

- composition (FTIR)

Size / Shape Distribution

- image analysis

- SEM examination JSRTC Savannah RiverTechnology Center 11/5/98 l

l t

l

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l Representative SRTC Characterization Facilities j

t t

[KTITW T Cqr nai 1, 7 7 ~

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,e Scanning Electron Microscopy (SEM)

X-Ray Diffraction (XRD) 3

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Fourier Transform Infrared Spectroscopy Thermal Analysis (FTIR)

(TGA, DSC, DTA)

Savannah RiverTechnology Center

-f 11/5/98 1

-l s

2m.

Model Refinements i

Refine Delamination and Cracking Failure Models e

Degradation Model Development and Application

- Radiation

- Moisture

- Thermal

- Low Cycle (Thermal) Fatigue Integrate Degradation Models with Failure Models to Predict Particulate Source Term JSRTC i

Savannah RiverTechnology Center t

11/5/98 f

l.

Path Forward t

I r

Philip Zapp Savannah River Technology Center i

h November 5,1998 i

i I

I l

l JSRTC Savannah RiverTechnology Center 11/5/98

{

t I

1 l

l Path Forward-Development of Failure Model e

Delamination and Cracking Models l

e Coating and Substrate Degradation Model e

EnvironmentalSub-ModelsLook-UpTables 1

e Develop Environmental Effects on G, o, E, a, v, er o

Prediction of Debris Size andTime to Failure 1

l e

Development of Phase II Test Plan l

JSRTC revannah RiverTechnology Center 11N588 1

Delamination and Cracking Models e Finite Element Calculations l

e Account for Multiple Loadings 1

i e HygrothermalStresses t

e Time Dependence

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i b

JSRTC i

Savannah RiverTechnology Center t

Coating and Substrate Degradation Model e

Compile Degradation Mechanisms e

Establish Functional Dependence of Properties on Degradation Mechanisms l

l l

e Establish Baseline Environmental Conditions l

e Establish Synergy 4nterdependence among Mechanisms e

Dependence on Particular Coating System JSRTC Savannah RiverTechnology Center l

11N5f]8 i

s e

Environmental Sub-Models and Look-U Tables 7

o Radiation Effects on Polymer Binder I

Cross-linking: Molecular WeightIncrease Chain Scission: Molecular Weight Decrease e Water Permeation / Absorption

- Effects on Properties: Swelling, Softening, Plasticizing Effects on Interface: Adhesion Effects on Substrate o Oxidation / Corrosion Effects on Coating and Interface Displacement from Corrosion Products Cathodic Disbondment e Thermal Aging i

DSRTC Savannah RiverTechnologyCenter l

' " ' ' ' ' ' ' ~

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Degradation and Failure Characteristics of NPP Containment Protective Coatings

.u Phase I Coating / Substrate Degradation Model Delamination / Cracking Model Experhuental Environmental Effects on Properties

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Validation

(

2' (PhaseII)

Product Characteristics JSRTC Savannah R Technology Center

. m

i Degradation and Failure Characteristics of NPP Containment Protective Coatings i

Phase HExperimental Validation Coatings Systems Environmental Product

()

Testing

( )

Characterization Application i

^

v Test methods for Assessing

/

ModelRefinement l

Coatings Characteristics N

l l

JSRTC i

Savannah RiverTechnclogyCenter 11/5/98 I

Encle:ure 3, 11/5/98 Public Mtg f a acc,"'o Presentation Slides o

i'n n$l',,s s.a e

PWR Sump Blockage Study:

{

Program Overview and Technical Approach i

B. Letellier andD. V. Rao t

Probabilistic Risk and Hazards Analysis Group Technology and Safety Assessment Division Los Alamos National Laboratory, NM satum.v,9'

.5 a

Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, MD

  • smi..#

Page No.: 1

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PWR Sump Blockage: Description g.-..-@-

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PWR Sump Blockage Concerns y m.>

t Loss of NPSH Screen Blockage 5

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a Fully Submerged Sump Not Fully Submerged Sump ECCS Failure Criteria:

ECCS Failure Criteria:

1

  • APac3,is > AH,,1;c 3

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Public Meeting on PWR Sump Blockage Study i

November 5,1998, TWFN, Rockville, MD j

Page No.: 3

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PWR Sump Blockage Concerns Potential Threats to ECCS Function t

Reduction or Elimination of NPSH Margin t

Blockage of Flow into Sump Important Factors that Influence Outcome

1) Debris Generation, 2) Debris Transport,3) Other Source of Debris l

(esp. Particulates), 4) Head Loss Across Sump Screen Major Unknowns l

i

- Sources, Characteristics and Quantities of Other Debris Paint / Coatings Debris (SRTC Research) l t

Likelihood of Debris Transport from Rupture Location to Screen 3-D Flow patterns and Turbulence Impact of Variability in Containment Design and Operator Action p->.v,

I/

1 Public Meeting on PWit sump Blockage study November 5,1998, TWFN, Rockville, MD q*ww*j Page No.: 4 C

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'g h,h,Yf,} Purpose and Programmatic Overview To Evaluate the Potential for Loss of ECCS Function Due to Accumulation of LOCA Debris on PWR Sump Screens and Blockage of Flow Passages.

Phase I Study Identify (and Explain) the Governing or Controlling Mechanisms (and Plant Features) that Effect PWR Sump Blockage. Develop Analytical Models Using Existing Knowledgebase.

Determine the likelihood of debris transport and risk significance of the overall problem. Identify Need for Further Research

- Collect Reference Plant Data Phase II Study (As Needed)

- Conduct Experiments / Tests to Fill Gaps in Understanding

- Refine Analytical Models

- Conduct Reference Plant and Parametric Analyses

  • """a' 3

Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, MD Page No.: 5

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Nf[f3 Phase I: Program Elements

...../

v s.,

1 Sump Screen Debris Blockage Source Book

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Review and Summarize International Knowledgebase Scaled to PWRs

1) Debris Generation,2) Postulated Accident Conditions,3) Operator Actions,4) Debris Sources,5) Short-and Long-Term Transport,
6) Debris Blockages and Accumulation,7) Head Loss 2

Methodology for Estimating Debris Transport t

Use Analytical Models with Modest Modifications that are Needed for Generic Plant Application Determine If Significant Quantities of Debris would Travel from Ruptured Pipe Location to the Sump Screen.

3 Review of Containment Design and Operation Information 4

Preliminary Risk Assessment Likelihood of Debris Blockage and Common Cause Loss of ECCS Risk Significance of PWR Sump Blockage Issue 3

s Public Meeting on PWR sump Blockage study November 5,1998, TWFN, Rockville, MD j

Page No.: 6 s-+.

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Program Plan: Phase I c

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N Debris Source Book Accident Pr sion

( Existing Knowledge Base \\

lp (Comprehensive Data (Pr, man _ly for BWRs) i o es

,/

Chemistry ar.d Precipitants Base for Use Later) 1 x~ _

NRC/SRTC Research on Paints

.'..... Y (Few Modifications) -

Task 3: Cont. Desian Data l

Exsiting Codes A

. Review to form composite plant V End Prvducts Important Operator Actions

.. '...-V 4 i

'x Tas( 2: Transport Ca cu ations (PWR Transport Methodology l

[BWR Transport Methodology \\

  • Blowdown and Floor Transport Composite Plant Application) i

+

Late Switchover (NUREGICR-6369),/

Flow into Inactive Sumps

~

Flow Patterns and Turbulence h

v 1P v

Major Gaps in Understanding Likelihood of Transport npt to s

s j

Need Additional Data or Controlling Cont. Features

' S ee of B P

pfbabI Analyses.

Dependence on Debris Type g

Guidance m USI A-43 C/C Loss of ECCS Mitigating Actions k

  • s Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, MD

. %w!

l Page No.: 7 i

i

,A id, 78fi election of Analytical Tools S

yv /

Decompose the Problem. Use Model:

tu calve individual Parts.

i j

Models must be capable of Modeling all antrolling phenomena to the i

i desired degree of accuracy.

i i

Existing Codes /Models. Limited Modifications.

TRAC: NRC Standard for PWR LOCA Blowdown. Boundary Conditions to Jet Models and Containment T/H Models FLOW-3D: CFD Standard for Free-Surface Flow. Turbulence Models.

Accuracy as good as Nodalization. Single Phase Flow. Time Intensive.

Jet Models: ANSI /ANS-58.2 and SNL/CSQ/2-$ Model.

MELCOR/CONTAIN: NRC Containment T/H Model. Quick R'unning. Bulk Vapor and Liquid Phase Movements. Best for Scoping out the Problem

,o.

T i

Public Meeting on 1*WR Sump 111ockage Study November 5,1998, TWFN, Rockville, MD Page No.: 9

%+o

lfLa RECg*%

b,1@ff,},Task 1: Technical Approach s

~... - -

x Task 1: Supportina Analyses

~

s Debr. Source Book Existing Knowledge Base x Accident Progression is

'\\

(Primarily for BWRs)

Pipe Rupture / Jet Models (Comprehensive Data

's

(,

j Chemistry and Precipitants Base for Use Later)

' ~-

NRC/SRTC Research on Paints 7

{

t i Scope of Supporting Analyses i

t i.

Review and Summarize Applicable International Knowledgebase i

e.g., BWROG, SRTC Research, European PWR Findings; OECD/lWG Database i

Judge Applicability of the Data to US PWRs f

Perform Accident Progression / Jet Model Arialyses to Develop PWR Scenarios i

Similarities and Differences between BWRs and PWRs i

i Re iew Acceptability of Test Conditions to PWR j-Scale Test Data, as appropriate, to PWR Accident Conditions j

...........................................................................................4 l

S. j g

.5 Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, MD Page No.: 10

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Task 1 Technical Approach (Example) f Debris Generation Data Scaling for PWRs: Existing Knowledgebase Extent of Insulation Study /Expen. ment Shape ZOI(UD)

Material Notes I

I i

ARUNRC (1984) 7 Jet FG/RMI Subcooled Water Jets USl A-43 7

Conical NUREG-0897; Based on subcooled Data Karlsham (1992) 8 n/a Mineral Wool Steam; No tests conducted beyond 8 UD Small Scale Studsvik (1993) 35 n/a Various Steam; Tests Conducted between 2 and 40 UD: small scale MlJIT (1995) 25 Jet Various Steam; 80 bar; no tests conducted beyond 25 UD; Large scale MlJIT/GE (1995) 25 Jet RMI Subcooled Water; 80 bar; No damage beyond 10 D.

BWROG AJIT (1996)

< 15 Sphere Various Air; 3" Nozzle; 28" Target-Pipe; Damage at > 50 UD for Jacketed Nukon Extensive Knowledgebase on Pacs, for Several Insulation Types Need to Scale it to PWR Conditions 5

a Public Meeting on PWit Sump Blockage Study November 5,1998, TWFN, Ilockville, MD j

Page No.: 11 wni

  • em

@v 9((,jTask 1 Technical Approach (Example)

DGM: Differences Between PWRs and BWRs Data obtained primarily for BWR Operating Conditions l

l

- Medium of testing mostly air or steam; limited data on saturated water Blowdown Significantly Different in PV/Rs

- Operating at 2250 psi and Atsub of 30 oF TRAC /MELCOR Analyses to Predict Blowdown History Saturated Blowdown at 1850 psi for t < 10 seconds

- Steam Blowdown at 1300-1100 psi for 20> t >10 seconds Jet Model Predictions for Target Pressure Isobars Saturated Water Blowdown (Steam continuum with water droplets)

Steam Blowdown (Steam core, very similar to BWRs) 1

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Public Meeting on PWR Sump Blockage Study Novemher 5,1998, TWFN, Rockville, MD p

j Page No.: 12 m

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Task 1 Technical Approach (Example?

j e

....+

BWROG Data for Pocs, for Nukon Incipient Damage for Target Pressure > 10 psi (0.68 bar) 1 Large Damage for Pressures > 14 psi Spherical Zone ofInfluence to account for Structural Congestion Conical Zone of Destruction for Undisturbed Jets

- Centerline Pressure > 10 psi for L/D < 50

- Exposure to High Pressures for up to half-minute Further Analyses: Is equivalent sphere concept valid for PWRs?

PWRs are not as congested as BWRs. Is Jet Deflection an Issue?

Icecondensor plants exception??

- PWR containments are compartmentalized. Unlike BWRs tastivm.yf

$[

Public Meeting on PWR Sump Blockage study Novemher 5,1998, TWFN, Rockville, MD

.p%+=j Page No.: 16 i

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Task 2: Technical Approach

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0 -1 see I -50 see 1 m -t,,ci,,

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Blowdown Transport h Long-Term Transport l Debris Generation 5

Large Debris Liquid & Vapor Phase ECCS+ Spray Rate Recirc. Flow Rote Small Debris Steam Flow Patterns Washdn. and Erosion 3-D Flow Rates i

To Upper Containment Non Directed Flow containment Layout To Inactive Sumps Residual Turbulence Turbulence Levels l

Debris Sourcebook Primary Tools Primary Tools Primary Tools MELCOR/CONTAIN MELCOR/CONTAIN FLOW-3D l

Parametric Analyses

  • FLOW-3D

{

Parametric Analyses j

Outcome Outcome Outcome Location and fraction

  • Location and fraction Fraction of debris at of debris.

of debris at t Boundary conditions recire-sump screen

. Boundary conditions for the later parts for the later parts g a.,,,,,

)

.8 3

l Public Meeting on PWR Sump tilockage Study Novemher 5,1998. TWFN, Rockville, MD Page No.: 18

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h<, $Yhe3Task 2: Tech ~ al Approach

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BWR Methodology Generic PWR

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NUREG/CR-6369 Methodology Phase I Evaluations

. Accident Progression

~ __ _

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Generic PWR Cont. Features t

x.

i bebris Transport Knowledgebase Flow Pattern Evaluations

i............................................................

1 l

y i

Plant Desion& Operation l

- ~ ~ '

Major Gaps m. Understanding Nukon & Cal-Sil Insulation Need for Additional Data Genen. Plant a.pplication Large and Medium Brakes l

c or Analyses.

Selected Parametrics Realistic Plant Geometry I

. Input from Tasks 1 & 3 l

T Transportation is not Possible fc. one or Input to Risk Large Breaks i

more cont. types Medium Breaks t

Non LBB Breaks M av

.f Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, Mo Task 2: Transport Methodology Development i

Page No.: 19

f. ~e ft s,A E:kN,f,}

cs.....

PWR Sump Blockage Study: Progress To Date k

i B. Letellier and D. V. Rao Probabilistic Risk and IIazards Analysis Group Technology and Safety Assessment Division Los Alamos National Laboratory, NM E'!?<<.

Public Meeting on PWR Sump Blockage study November 5,1998, TWFN, Rockviile, MD

f%,,

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i Overview of Preliminary Analyses sp i

Use Existing Containment Codes to Draw Insights Regarding:

1 LOCA Accident Progression in a Composite Containment Portions of the Accident that Merit 3-D Flow Analyses

(

Evaluation Process Building rudimentary models for several unique containment configurations j

Identify features, physics and configurations desirable for

?

detailed analysis in a reference plant i

t Use nodal (control volume) models to establish boundary I

conditions for 3-D analysis Example Problem Using MELCOR Illustrates:

i

- Appropriate level of detail for scoping calculations

- Plant specific data requirements s.o 3

Pui>lic Meeting on PWR Sump lilockage Study November 5,1998, TWFN, Rockville, MD i

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w posite Containment Features

....+

1 Volume typical of Large-dry PWR containment Two SG compartments

- simulate inactive sumps and flow obstructions ECCS begins low pressure injection at RCS pressure of 150 i

psi and switches to recirculation at 4 ft pool height

{

1 i

ECCS 11cw rates:

Low Pressure Injection

= 7,500 gpm

- Recirculation

= 7,500 gpm Fan coolers turned on at containment pressure of 22 psia 3

Sprays turned on at containment pressure of 38 psia and operated at 3000 gym i

Decay heat typical of 1-yr operation at 1100 MW-th i

Fixed-temperature recirculation heat rejection

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i Public Meeting on PWR Sump Blockage Study i

November 5,1998, TWFN, Rockville, MD I

+ w.-

Att Hf CO s

s t-rs (mja?$g/Composite PWR Containment Geometry Containment 3

2 I

Specifications RPV ;

R9 = 25 m Cavity j I

R2"46m 4

,, ' + ',

1 gg,,

R3== 4.8 m fi2' n'

R4 = 3.0 m

, ng RI 5 R6

'06 RS = 3.3 m S

/

R6 = 42.7 m 0'

Hj = 67.1 m 5

RPV Sump Recirculation H2 = 14.0 m Hsump = -2.5 m j

to RPV and Sprays PRPV = 2248 psia 6

7 TRPV = 600 *F g

g 3

VRCS = 425.0 m RWST I

Upper Containment o

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\\thq>a ;j Important Results from MELCOR Analyses S

General Accident Progression Vapor Phase Movement Global Flow Patterns on the Containment Floor l

Thermodynamics of the Pool

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Pressure and Temperature Traces Consistent with Large-l Dry Containments for Large LOCA (30"-Pipe) 1 High Pressure Blowdown Completed in Approx. 30 seconds and low pressure injection begins

- Initially Saturated Water Followed by Vapor Continuum i

Containment Pressure Increases Precipitously f

Containment Pressure and Temperature Drop quickly due to Fan Coolers (3.2 seconds) and Sprays (12.4 seconds)

- ECCS switches to sump recirculation from RWST at pool

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height of 4 ft (3400 seconds) j i

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RCS Conditions During 30-in LOCA

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Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, MD

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Initially Containment is Characterized.by High Velocity Vapor Flows 1

- It is highly likely that debris would be carried and distributed through out the containment (include upper containment)

After about 1-2 minutes only regions close to the break and fan coolers have large velocities. Otherwise debris would likely settle down on (or captured by) surfaces g=ilm,

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  • g Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, MD

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()e.3*h,3Bulk Water Movement on the Floor Initial Sloshing and Turbulence

- May transport debris to the proximity of the sump screen depending on relative location Will maintain debris in suspension Quiescent Pool Movement

- Settling Possible? (MELCOR neglects local turbulence) l

- Potential must be evaluated for other containment configurations Do sprays and drainage add flow patterns?

Pool moves slowly despite sprays Switchover Approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to reach 4' containment flood level (7500 gpm ECCS and 3000 gpm spray)

Velocities beyond sump are very small for this recirculation g.y,;,,

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November 5,1998, TWFN, Rockville, MD

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Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, MD

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  • 3 Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, MD

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Pool Behavior Similar Across Containment Collapsed Liquid Levels

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  1. -[f]iPool Thermodynamic Conditions y s.s Flashing in the pool when sprays operate to reduce containment pressure may provide a source of turbulence MELCOR cale did not account for bubble physics properly Use of single-phase hydro code to simulate recirculation i

flow on the containment floor is reasonable because long term pool and atmosphere temps reach equilibrium j

l.

What if the sprinklers do not function? Is this an important accident progression?

- Future analyses will address this issue.

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Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, MD

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Pool and Atmosphere Temps Near Sump Containment Sector 8 Temperatures 430 g

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Summary of Preliminary Analyses s,

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MELCOR models of simplified geometry are useful to identify global flow patterns and thermodynamic conditions l

- More work needed to investigate potential for flashing i

High vapor velocities and initial pool turbulence are sufficient to transport debris throughout containment

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l MELCOR suggests a potential for some settling before recirculation, but it cannot account for local turbulence j

Single-phase hydrodynamic models will suffice for post-spray pool transport I

Future work:

- Add more complexity to containment

- Simulate a more realistic containment layout i

Different types of containments: Ice Condenser and Large-Dry t

Medium and Large LOCAs (Range of Break Areas) 5

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Public Meeting on PWR Sump Blockage Study November 5,1998, TWFN, Rockville, MD

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