ML022460183

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Undated FENOC Slides: Subject: Agenda - Assurance Davis-Besse Safe to Operate
ML022460183
Person / Time
Site: Davis Besse Cleveland Electric icon.png
Issue date: 08/29/2002
From:
FirstEnergy Nuclear Operating Co
To:
Office of Nuclear Reactor Regulation
References
BL-01-001, FOIA/PA-2002-0229
Download: ML022460183 (28)
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AgenU da Introduction/Background Deterministic Model Dave Geisen Probabilistic Risk A 3ment Ken Byrd Inspection Pl*ý-

" Mark McLaughlin

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Closing Summary..

Steve Moffitt

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Today's OGilective Provide Reasonable Assu rance that Davis-Besse is safe to operate until February 16, 2002,

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2 FENOC

BacA'ground:

% NRC Bulletin 2001-01 response provided Telephone call received on September 28 r Teleconference on October 3

&- Brief drop by visit o.

ctober 11

&- Meeting with'NRR Staff on Q:.tqber 24 SNRR Staff andlA,*,*Rm nNovember 8 & 9 t Meeting with NRRS.taff on.November 13 STeleconference on November 26 3

FENOC

Ioetfrminiistic Aspects DBNPS's evaluation is based on visual inspections performed in 10, 11, and 12 RFO (May 1996, April 1998, and April 2000).

The inspection results afford us assurance that all but 4 nozzle penetrations were inspected in 1996, all but 19 inspected in 1998, and all but 24 penetrations inspected in 2000.

The limiting nozzle populatl n is those nozzles that could not be inspected in 1998-or 200*11.

It is conservativel s

,ee penetrations, an axial through-weld flaw occurs immediately upon startup from 10 RFO (May 1996).

FENOC 4

InitifiuFlaw Size Initial flaw depth of 0.5 mm, 1720 around the nozzle, is assumed to exist immediately upon achieving a full penetration axial flaw.

BASIS:

This is a conservative flainitiation site size.

SIt is further conservativel:yasSum.edd,.'

at multiple starting flaws could exist and#iat thee wo ntua~y link together.

7Ar It is conservative inthat b,' assumgp'gthis starting point, we also are assuming that We"'havea iready had several years of flaw propagation axially through the Alloy 182 weld material.

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Use ofModified Scott Model The Modified Scott Model is still deemed credible as a mean curve for crack growth rates.

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Data received to date does not negate the curve.

Numerous curves have been developed and to a certain degree, they all rest on eng ering judgement.

SThe data from OTSGs for"Iloy 600 is relevant for developing the CGR curves andi.nI-fact i

in that the Alloy properties are still re~ler,4 y cold-working of the tubes at the tube support shseetouwlduicn"crease the failure rate over non-worked Alloy 60:0,il;

1. make this conservative.

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Risk-InifurmedfEvluation SDavis-Besse risk assessment provides a bounding estimation of risk. Bounding or conservative assumptions were used to resolve uncertainties.

70 Studies of sensitivity.

parameters.

I Results indri incr(

in the "small" categ.v per RG 1.174.

IM-. w

/as performed for all significant

  • riiA woulld be bounded b "very small" Incremental LERF and Public health risk is expected to be negligible.

7 TIOM oFENOC

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Risk-InformeldEvhIfalationl Nozzle Leak Freffeqicy The Davis-Besse plant specific PSA has used the method from the generic Framatome analysis which applies a constant leak initiation f. quency.

SThe constant. rte ovepredictdhe early cycles...

  • k Impact of inspection on conditional leak at a future date is not quantified.

8 number of leaks in probability of a FENOC

Risk-InformedEvialutionl Nozzle Leak Freuenicy Other approaches have assumed that the onset of leakage can be approximated by a two parameter Weibull cumulate probability distribution.

-The Davis-Besse ris sessment was modified to apply a Weibull distributi,,.

  1. Studies were pe'Q600r, t,

Ra ate the sensitivity to the Weibull scale and,shape parameters.

rThe conditional probability of a leak by a future date given no leak now can be calculated if a nozzle has been inspec6ted aTno leakage detected.

of01 FENOC I

Iisk-IinfurmedfEvuluation Nozzle Lea' FrHequeny "

Predicted Leaks for various Weibull Leak Initiation Models Expected Number of Leaking CR-DM Nozzles Davis-Davis-EPRIsUMRPrE*

P Besse Davis-Besse Upper Median EPRI MRP Shape Refueling EFPY Corrected Projection Projection Weibull Parameter Outage to600F 1.5Shape 1.5 Shape Model Modified Parameter Parameter Protection Scale rParameter 10 10.56 12.91 5.0 1.0 9.5x10 5 0.02 11 12.33 15.07 6.3 1.3 1.7xlO-3 0.36 12 14.06 17.18 7.6 1.6 1.9x10-2 4.00 13 15.81 19.32 8.9 1.9 0.17 28.3

-_16.37 20.00 9.3 2.0 0.32 43.7 0K FENOC 10 C*

Risk-InformedfEvulufatio Paistlnspectioins SInspections were assumed to have a failure probability of 1.00 if boron inhibited detection of nozzle leakage.

Inspections were assumed to have a failure probability of O:16,if no bor s present.

% Sensitivities we re performed to effect of various leakage detection I1 investigate the probabilities.

FENOC

Risk-InformedfEvuluution Prolbubility of Circu~mfereniahl Crack ing SEvidence from recent B&W plant inspections has indicated that not all axial cracks have resulted in initiation Qcircumferential B&W plants.have xpere.iced 27 and 6 circumfer.ntial *rac, cracking.

axial cracks Probability of the initiation of a circumferential crack is estimated to be 0.22 based on B&W evidence.

FENOC 12

Risk-informhfdEvilua'tioni Nozzle Failure Prouabfility r Probability of CRDM nozzle failure is determined by performing a Monte Carlo simulation on the Scott deterministic crack growth model.

SConservatior b;oundri umptions w(

used when data ta able.

Studies were performed to investigate the sensitivity to all significant inputs.

13 FENOC ere

Iisk-IniformedfEvuluatfion No111e Failure Pruobaullty-Consefativauve Ass uiojpos SInitial crack size - Applied a uniformr distribution from O-1O degrees.

Stress Profile - U C rack Gro*:

.. R growth rate coeb it s the worst case stresses.

t4 Iit -Applies crack S.--

0,

FENOC 14

Risk, qome Nozzle Failure ProaiuluiM.- Sensiftivry Studies

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Initial crack size Initial crack depth Temperature;

~ Stress Profile"',

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Crack Growth Rate Coefficient FENOC 15

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FENEOC 1/1LL117.

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Iisk-Iinformedlfvuluaioni Conditionail Core Dhmagefl/Release ProNability Davis-Besse conditional core damage probability for a ft2 medium LOCA is 2.7 x 10-3.

Conditional large early elease probability for a medium LOCA is about 4. x 10-6.

r The conditional

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o illty for this analysis is less than applied in thePSA because the medium LOCA range i-n the PSA is 0.02 ft2 - 0.5 ft2.

FENOC 16 0.1

Risk-InformefdEvaluatggion ROSHIIS L

Constant Initiation Frequency Bounding Best Estimate Upper (95%)

Projection 1.5 Shape

_ Parameter if ounding Best Estimate EPU.RP Shape Parameter Modified Scale

.Parameter Bou idihg Best Estimate CDF 1.8 E-6 9.9 E-8 1.1 E-6 6.3 E-8 3.3 E-7 1.9 E-8 LERF 2.6 E-9 1.5 E-10 1.7 E-9 9.4 E-11 4.9 E-10 2.8 E-11 Person REM 0.16 9.2 E-3

.11 5.9 E-3 3.1 E-2 1.7 E-3

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FENOC 17 737 cc-.

Iisk-inf~ormfdfEvhIuation Uniquei Aspects of Davis-Besse iisAssessmenit SInspection Information - Davis-Besse inspections do not indicate evidence a nozzle leaks.

Material Heat Informn nozzle material circumferential hea ts ha\\

le; at ol

-64 of 69 Davis-Besse hOi_ yofaxial or

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Risk-Iufuormedfvulufation ConcIusions SOCDF - The plant specific risk assessment conservatively estimates a bounding incremental core damage frequency to be in the range which is categorized as "small" per RG 1.174.

The actual incremental core damage frequency would be categorized as "very small,,,

er RG 1.174.

SLERF - The plant specific8risk asse$sment conservatively estimates a boundi~ngwincrernental-early release frequency which is cat 1'1'F**'s "very small" per RG 1.174.

The actual incremental re se frequency is negligible.

SPublic Health Risk - The plant specific risk person rem per year is negligible.

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Inspection PlaNs r 13RFO:

S100%

qualified visual

ý 100% NDE Flaw

  • Data dustry use.

Vessel Head Replacement.altfirst available opportunity FENOC 20

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"-4 FENOC L.

Ravis-Besse Specific Feaufres andiActinis rRecord of inspection from last three outages.

rOnly B&W plant with a continuous head vent which provides high confidenc n temperature measurements.

&-Reduce reactorvessel[Ifread te. perature from 605F 598AF.

-i nr trainin s9, e r

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-i~Additional training for,0Operators on issues raised in to Bulletin 2001-01.

&-Maximize availability of redundant critical safety systems.

FENOC 21

Comparisui uflinspection Bates December 31 st February 16th

- Two Shutdowns Required

- Single Shutdown for inspection (One Inspection, One Refuel)'and refueling.

- Approximately 30 REM addition'J

-.Normal refueling outage dose.

exposure to employees.,,,..

- Limited NDE Full NDE and flaw characterization.

No significant difference in risk (incremental CDF).

'ENOC FENOC Pony 2.....

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Sufmmamry Based on Conservative Analysis:

Davis-Besse is Salo. to Operate until February 16, 2002>'

23 FENOC

Heat 59 Crack Growth - Constant Int itiatIuion Frequency

,RAl t 13 1.1 4

6.38E-02 1.25E-05 2.70E-03 2.22E-01 NA NA NA 4.78E-10 7.08E-13 4.44E-05 12 1.1 4

6.38E-02 1.25E-05 2.70E-03 2.22E-01 NA NA 1

4.78E-10 7.08E-13 4.44E-05 11 1.1 4

6.38E-02 9.65E-03 2.70E-03 2.22E-01 NA 1

1 3.69E-07 5.46E-10 3.43E-02 10 1.1 4

6.38E-02 4.43E-02 2.70E-03 2.22E-01 1

1 1

11.69E-06 2.51E-09 1.57E-01 2.06E-06 3.05E-09 1.92E-01 13 1.1 15 2.39E-01 1.25E-05 2.70E-03 2.22E-01 NA NA 1A 1.79E-09 2.65E-12 1.67E-04 12 1.1 15 2.39E-01 1.25E-05 2.70E-03 2.22E-01 NA 1A 1

1.79E-09 2.65E-12 1.67E-04 11 1.1 15 2.39E-01 9.65E-03 2.70E-031 2.22E-01 NA 1

1 1.38E-06 2.05E-09 1.29E-01 10 1.1 15 2.39E-01 4.43E-02 2.70E-03 2.22E-01 0.05 1

1 3.17E-07 4.70E-10 2.95E-02 1.70E-06 2.52E-09 1.58E-01 13 1.1 5

7.97E-02 1.25E-05 2.70E-03 2.22E-01 NA NA NA 5.97E-10 8.85E-13 5.55E-05 12 1.1 5

7.97E-02 1.25E-05 2.70E-03 2.22E-01 NA NA 1

5.97E-10 8.85E-13 5.55E-05 11 1.1 5

7.97E-02 9.65E-03 2.70E-03 2.22E-01 NA 0.05 1

2.31E-08 3.42E-11 2.14E-03 10 1.1 5

7.97E-02 4.43E-02 2.70E-03 2.22E-01 0.05 0.05 1

5.29E-09 7.83E-12 4.91E-04 12.95E-08 4.38E-1 1 2.75E-03 13 1.1 45 7.17E-01 1.25E-05 2.70E-03 2.22E-01 NA NA NA 5.38E-09 7.96E-12 5.OOE-04 12 1.1 45 7.17E-01 1.25E-05 2.70E-03 2.22E-01 NA NA 0.05 2.69E-10 3.98E-13 2.50E-05 11 1.1 45 7.17E-01 9.65E-03 2.70E-03 2.22E-01 NA 0.05 0.05 1.04E-08 1.54E-11 9.64E-04 10 1.1 45 7.17E-01 4.43E-02 2.70E-03 2.22E-01 0.05 0.05 0.05 2.38E-09 3.52E-12 2.21E-04 1.84E-08 2.73E-11 1.71E-03 1.75E-06 2.60E-09 1.63E-01 FENOC.

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Heat 6" Crack reowit - Low Weibul$loSape Factor 11 3.92E-03 4

7.84E-03 9.65E-03 2.70E-03 2.20E-01 NA 1

1 4.49E-08 6.66E-11 4.18E-03 10 1.51E-02 4

3.03E-02 4.43E-02 2.70E-03 2.20E-01 1

1 1

7.96E-07 1.18E-09 7.40E-02 8.41E-07 1.25E-09 7.82E-02 13 4.50E-03 15 3.37E-02 1.25E-05 2.70E-03 2.20E-01 NA NA NA 2.51E-10 3.71E-13 2.33E-05 12 4.18E-03 15 3.13E-02 1.25E-05 2.70E-03 2.20E-01 NA NA 1

2.33E-10 3.45E-13 2.16E-05 11 3.98E-03 15 2.99E-02 9.65E-03 2.70E-03 2.20E-01 NA 1

1 1.71E-07 2.53E-10 1.59E.-02 10 1.51E-02 15 1.14E-01 4.43E-02 2.70E-03 2.20E-01 0.05 1

1 1.49E-07 2.21E-10 1.39E-02 3.21E-07 4.75E-10 2.98E-02 13 4.50E-03 5

1.12E-02 1.25E-05 2.70E-03 2.20E-01 NA NA NA 8.35E-11 1.24E-13 7.76E-06 12 4.18E-03 5

1.04E-02 1.25E-05 2.70E-03 2.20E-01 NA NA 1

7.75E-11 1.15E-13 7.21E-06 11 3.98E-03 5

9.95E-03 9.65E-03 2.70E-03 2.20E-01 NA 0.05 1

2.85E-09 4.22E-12 2.65E-04 10 1.51E-02 5

3.79E-02 4.43E-02 2.70E-03 2.20E-01 0.05 0.05 1

2.49E-09 3.69E-12 2.31E-04 5.50E-09 8.15E-12 5.11E-04 13 4.50E-03 45 1.01E-01 1.25E-05 2.70E-03 2.20E-01 NA NA NA 7.52E-10 1.11E-12 6.99E-05 12 4.18E-03 45 9.40E-02 1.25E-05 2.70E-03 2.20E-01 NA NA 0.05 3.49E-11 5.17E-14 3.24E-06 11 3.98E-03 45 8.96E-02 9.65E-03 2.70E-03 2.20E-01 NA 0.05 0.05 1.28E-09 1.90E-12 1.19E-04 10 1.51E-02 45 3.41E-01 4.43E-02 2.70E-03 2.20E-01 0.05 0.05 0.05 1.12E-09 1.66E-12 1.04E-04 3.19E-09 4.73E-12 2.97E-04

_"_'_____11.13E-06 1.67E-09 1.05E-01 FENOC'E

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Hest ag Crack Growth - High Weibpull Shape Factor 13 3.52E-01 4

7.03E-01 1.25E-05 2.70E-03 2.20E-01 NA NA NA 5.22E-09 7.73E-12 4.85E--04 12 5.30E-02 4

1.06E-01 1.25E-05 2.70E-03 2.20E-01 NA NA I

7.86E-10 1.17E-12 7.31E-05 11 4.97E-03 4

9.94E-03 9.65E-03 2.70E-03 2.20E-01 NA 1

1 5.70E-08 8,44E-1 1 5.30E-03 10 3.OOE-04 4

6.01E-04 4.43E-02 2.70E-03 2.20E-01 1

1 1

1.58E-08 2.34E-11 1.47E-03 7.88E-08 1.17E-10 7.32E-03 13 3.73E-01 15 2.80E+00 1.25E-05 2.70E-03 2.20E-01 NA NA NA 2.08E-08 3.08E-11 1.93E-03 12 5.32E-02 15 3.99E-01 1.25E-05 2.70E-03 2.20E-01 NA NA 1

2.96E-09 4.39E-12 2.76E-04 11 4.97E-03 15 3.73E-02 9.65E-03 2.70E-03 2.20E-01 NA 1

1 2.14E-07 3.17E-10 1.99E-02 10 3.00E-04 15 2.25E-03 4.43E-02 2.70E-03 2.20E-01 0.05 1

1 2.96E-09 4.39E-12 2.75E-04 2.40E-07 3.56E-10 2.23E-02 13 3.73E-01 5

9.33E-01 1.25E-05 2.70E-03 2.20E-01 NA NA NA 6.93E-09 1.03E-11 6.44E-04 12 5.32E-02 5

1.33E-01 1.25E-05 2.70E-03 2.20E-01 NA NA 1

9.88E-10 1.46E-12 9.19E-05 11 4.97E-03 5

1.24E-02 9.65E-03 2.70E-03 2.20E-01 NA 0.05 1

3.56E-09 5.28E-12 3.31E-04 10 3.00E-04 5

7.51E-04 4.43E-02 2.70E-03 2.20E-01 0.05 0.05 1

4.93E-11 7.31E-14 4.59E-06 1.15E-08 1.71E-11 1.07E-03 13 3.73E-01 45 8.40E+00 1.25E-05 2.70E-03 2.20E-01 NA NA NA 6.24E-08 9.24E-11 5.80E-03 12 5.32E-02 45 1.20E+00 1.25E-05 2.70E-03 2.20E-01 NA NA 0.05 4.45E-10 6.59E-13 4.13E-05 11 4.97E-03 45 1.12E-01 9.65E-03 2.70E-03 2.20E-01 NA 0.05 0.05 1.60E-09 2.37E-12 1.49E-04 10 3.OOE-04 45 6.76E-03 4.43E-02 2.70E-03 2.20E-01 0.05 0.05 0.05 2.22E-11 3.29E-14 2.06E-06 16.44E-08 9.55E-1 1 5.99E-03 I-13.32E-07 4.92E-10 3.09E-02

." FENOC ".

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