Probability of Mark-I Containment Failure by Melt-Attack of Liner

362 Pages·1993·19.715 MB·English

NUREG/CR-6025
SAND93-0893
ANL/RE/LWR92-5
SAND93-0925
ANA-92-0143
II III
The Probability of
Mark-I Containment Failure
by Melt-Attack of the Liner
Manuscript Completed: September 1993
Date Published: November 1993
Prepared by
T.G. Theofanous, H. Yan,University of California at Santa Barbara
M. Z. Podowski, C. S.Cho, Rensselaer Polytechni Institute
D. A. Powers, T.J. Heames, Sandia National Laboratories
J. J. Sienicki, C. C. Chu, B. W.Spencer, Argonne National Laboratory
J. C. Castro, Y. R. Rashid, R. A. Dameron, J. S.Maxwell,D. A. Powers, ANATECH, Inc.
Department of Chemical and Nuclear Engineering
Center for Risk Studies and Safety
University of California at Santa Barbara
Santa Barbara, CA 93106
Department ofNuclear Engineering and Engineering Physics
Rensselaer Polytechnic Institute
Troy, NY 12180
Sandia National Laboratories
Albuquerque, NM 87185
Argonne National Laboratory
Argonne, IL 60439
ANATECH, Inc.
San Diego, CA 92121
Prepared for
Division of Systems Research
Office of Nuclear Regulatory Research
UW.Sas.hiNnugctolena,r DRCegu2l0a5to5r5y-000C1ommission M_SI[_ _,_
NRC FINs L2274, B0452, L1484, Ll135, L1897
• .d_,,''f'r :-_.
REPORT CONTENTS
PART I THE PROBABILITY OF MARK-I CONTAINMENT FAILURE BY MELT-
Aq'I'ACK OF THE LINER: THE PROBABILISTIC SYNTHESIS
T.G. Theofanous and H. Yan
University of California, Santa Barbara
PART II THE EFFECT OFHEATUP AND MELTDOWN OF REACTOR VESSEL UPPER
INTERNALS ON THE COMPOSITION OF CORIUM DISCHARGED INTO THE
DRYWELL OF A BWR MARK-I CONTAINMENT
M.Z. Podowski and C.S. Cho
Rensselaer Polytechnic Institute
PART Ill AUDIT CALCULATIONS WITH CORCON MOD3 OF THE DURATION OF
SUPERHEAT
D.A. Powers and T.J. Heames
Sandia National Laboratories
PART IV COMPARISON OF MELTSPREAD-1 CALCULATIONS OF CORIUM DEP'IH
NEXT TO THE MARK-I LINER WITH NUREG/CR-5423
J.J. Sienicki, C.C. Chu and B.W. Spencer
PART V CREEP-RUPTURE FAILURE IN A MARK-I CONTAINMENT
J.C. Castro, Y.R. Rashid, R.A. Dameron, J.S.Maxwell and D.A. Powers
ANATECH, Inc. and Sandia National Laboratories
APPENDIX I WORKING GROUP MEMBERS' COMMENTS ON THE INDEPENDENT
EVALUATIONS
APPENDIX II EXPERT PEER PANEL REPORTS AND AUTHOR'S _.ES'I_'O,,i._E,$
v NUREG/CR-6025
NUREG/CR-6025 1of 5
PART I: THE PROBABILITY OF MARK-I CONTAINMENT
FAILURE BY MELT-ATTACK OF THE LINER:
THE PROBABILISTIC SYNTHESIS
Abstract
This report is a followup to the work presented in NUREG/CR-5423 addressing early failure of
a BWR Mark I containment by melt attack of the liner, and it constitutes a part of the imple-
mentation of the Risk-Oriented Accident Analysis Methodology (ROAAM) employed therein.
In particular, it expands the quantification to include four independent evaluations carried out at
Rensselaer Polytechnic Institute, Argonne National Laboratories, Sandia National Laboratories
and ANATECH, Inc. on the various portions of the phenomenology involved. These indepen-
dent evaluations are included here as Parts II through V.The results, and their integration in Part
I, demonstrate the substantial synergism and convergence necessary to recognize that the issue
has been resolved.
iii NUREG/CR-6025
Acknowledgments
This work was supported by the U.S. Nuclear RegulatoryCommissionunder Contract No. 04-
92-055. The cooperation and supportof ourprojectmanager,Dr. S. Basu, isgratefully acknowl-
edged.
iv NUREG/CR-6025
Contents
Page
Abstract .......................................... iii
Acknowledgments ..................................... vii
1.0 Introductionand Background .............................. 1-1
2.0 Resultsof IndependentEvaluationsand Discussions ..................... 1-7
3.0 Probabilistic Synthesisof theSequence .......................... 1-13
4.0 Extrapolation toOther MarkI Plants ........................... 1-14
5.0 Concluding Remarks .................................. 1-15
AppendixA:ConsiderationofFuel-CoolantInteractions ..................... A-1
Figures
1.1 Illustrationof the Mark-Ilinerattackproblem ....................... 1-2
1.2 Illustrationofthe phenomenologyinvolvedintheMark-Ilinerattackproblem .......... 1-3
1.3 Theprobabilisticframeworkfor addressingMark-Ifinerattack ................ 1-3
1.4 The enveloping,splinterscenariosconsidered........................ 1-4
1.5 The MELTSPREADresults forScenarioI showninrelationto the
NUREG/CR-5423quantification(CR1) .......................... 1-9
1.6 The MELTSPREADresultsforScenarioII("peakrelease")showninrelationto the
NUREG/CR-5423quantification(CR1) .......................... 1-9
1.7 The MELTSPREADresultsforScenarioII("averagerelease")shownin
relation to theNUREG/CR-5423 quantification(CR1) .................... 1-10
1.8 The variationof criticalsuperheatwith superheatdurationtimeandlinersubmergencefor
ScenarioImelts, inthepresenceofwater,foralinerfailurecriterionof 1260 *C ......... 1-12
1.9 The variationof criticalsuperheatwithsuperheatdurationtimeandlinersubmergencefor
ScenarioI melts,inthepresenceofwater,for alinerfailurecriterionof 1200 °C ......... 1-12
A.1 Illustrationof pressuredistributionattwodifferenttimes(0.5and1.0msaftertriggering)
as aresultof ahypotheticalbig explosionin the middleof thepedestalarea.(z = distance
measuredfromthe floor,r = radialdistance,initialwaterdepth= 50era, andnote the
changeof scalefortheplotat z= 37.5cm,42.5cm and47.5cm) ............... A-5
v NUREG/CR-6025
Tables
Page
1.1 The mainresults ofNU'REG/CR-5423.Numbersto beinterpreted onthe
basisof theprobability scale showninTable 2 ....................... 1-5
1.2 Definitionofprobability levels .............................. 1-5
1.3 Comparisonof APRIL.Mod3auditresultswith the NUREG/CR-5423
quantificationof melt release conditions .......................... 1-8
1.4 Summary of theCORCON-MOD3Results in Relation to theQuantification
Employedin NUREG/CR-5423 ............................. 1-11
1.5 Definitionof theIkvoEnvelopingScenario ICalculations ofLiner Failure
Probability ...................................... 1-13
1.6 Final Conservative Estimates ofLiner FailureProbability ................... 1-13
NUREG/CR-6025 vi
1.0 Introduction and Background
This report is written as a sequel to NUREG/CR- the respective working group that recommended
5423, and together they are intended to address and the work, and the results of these reviews are
resolve the so-called "Mark I Liner Attack" issue, documented in Appendix I to this report. The
NUREG/CR-5423 represents the first step in the results ofthe review ofthis final report, asawhole,
Risk Oriented Accident Analysis Methodology are documented in Appendix II.
(ROAAM) employed for this purpose, while the
present report is intended to represent thelast step. To avoid unnecessary duplication, this report is
Inparticular, in NUREG/CR-5423 one can find: designed to be read in conjunction with NUREG/
CR-5423. The connection ismade bythevery brief
• a complete definition of the problem; remarks inthe next twoparagraphs, one devoted to
• a description of the methodology; the technical approach and the other to the
• the probabilistic framework employed; conclusions and recommendations of the four
• a quantification, including use of all prior working groups.
work;
• the results of the probabilistic synthesis, i.e., Very briefly, the problem is concerned with the
the overall quantification; possibility thatthemolten corium released from the
• two rounds of comments by experts in a 19- reactorvessel (inalow-pressure unmitigated severe
member peerreviewpanel; and accident in a BWR with a Mark I pressure
• authors' responses, suppression containment) willcome incontact with
thecontainment linerand cause abreach initshortly
AlsoinNUREG/CR-5423onecanfindtheinitiation thereafter. This liner is the containment pressure
of a second step in the ROAAM process: that of boundary, and such a breach would constitute an
focusingthetechnicalissuesraisedduringthereview "early" containment failure. The situation is
into four areas requiring further, and independent, illustrated in Figure 1.1. The important
evaluation. This focusing took place through the phenomenology is sketched in Figure 1.2, which
work of four working groups (including members also notes the key terminology employed in such
not in the original panel) and is documented in discussions. The objective is to determine the
NUREG/CR-5423 (Appendix L) by respective likelihood ofsucha linerbreach (conditional onthe
summaries of the work and sets ofconclusions and occurrence of anunmitigated severe accident), and
recommendations. The actual second step took especially to consider the effect of flooding (by
place in implementing these recommendations water) of the drywell floor. The problem was
which resulted in four independent research/audit decomposed inthemanner illustrated inFigure 1.3,
efforts (to be described shortly below). The third along with the definition of several melt release
step, initiated bythe present report, involves theuse scenarios forconsideration inthemanner illustrated
ofthe results of these independent evaluations into in Figure 1.4. The quantification (of the pdf's and
an updated quantification, and is expected to be the CRs inFigure 1.3)employs aprobability scale,
completed through theinvolvement ofa peerreview andtheresults, summarized inTable 1.1,interpreted
panel. The four independent evaluations are docu- bythe samescale (see Table 1.2)indicate that inthe
mented in Parts II through V of thisreport. Each of presence of water such liner failure is "physically
these parts has been reviewed by the members of unreasonable."
1-1 NUREG/CR-6025
Introduction and Background
Blowout Blowout
Panels Panels
Refueling Bay
iI.-
-,-
; Reactor
I ieo_
i [:;.: Vessel
I1:;;]
i,ltl
TuPnipneel _-:-.'_ Drywell
Reactor Cavity
Hatch
/ Torus
Suppression _ Suppression
Pool Pool
Figure1.1.IllustrationoftheMark.Ilinerattackproblem.
NUREG/CR-6025 1-2 .
IntroductionandBackground
Release
Liner Submergence (_ (_ 0
%
I r
ff,
Pedestal
Spreading Front
Sump Drywell Floor
Figure1.:2.UlustrationofthephenomenoioginyvolvedintheMark-Ilinerattackproblem
, .i iiiiiiiiiiiii
Quantityof Melt LinerSubmergence ZirconiumContent InitialMelt
Released Versus inMelt Superheat
pdfl MeltQuantityReleased pdf3 pdf4
ii
I I
TM
SuperheatDurationTime
Versus
ZirconiumContent,Initial
LinerSubmergence Depth
pdf2
Iii I CRS2uperheat,and MeltPool
Critical(Failure)Superheat InitialSuperheat,Superheat
Versus DurationTime, andLiner
SuperheatDurationTime Submergence
andLinerSubmergence pdf5
CR3
I LinerFailure IP_
FigureL3. TheprobabilistficrameworfkoraddressinMg ark.llinerattack.
1-3 NUREG/CR-6025