ML20202D885

Summary of 970820 Meeting W/Westinghouse Owner Group in Rockville,Md to Discuss Reactor Internals Issues, Particularly Re Baffle Barrel Bolting.List of Attendees & Affiliations & Slides Used in WOG Presentation Provided

ML20202D885
Person / Time
Issue date:	11/26/1997
From:	Joshua Wilson NRC (Affiliation Not Assigned)
To:	Essig T NRC (Affiliation Not Assigned)
References
PROJECT-694 NUDOCS 9712050178
Download: ML20202D885 (30)

Text

_ _ - _ _

\\

naneep 3*

1 UNITED STATES I

s, NUCLEAR REGULATORY COMMISSION wAsMineroN, D.C. m

'e,

November 26, 1997 MEMORANDUM TO: Thomas H. Essig, Acting Chief Generic lasues and Environmental Projects Branch Division of Reactor Program Management, NRR FROM:

James H. Wilson, Senior Project Manager (L N.

h Standardization Project Directorate Division of Reactor Program Management, NRR

SUMMARY

OF PUBLIC MEETING HELC ON AUGUST 20,1997, WITH THE WESTINGHOUSE OWNERS' GROUP TO DISCUSS REACTOR INTERNALS ISSUES On August 20,1997, the staff held a public meeting at NRC headquarters in Rockville, Maryland with represe.. atives of the Westinghouse Owners' Group (WOG) to discuss reactor internals issues, particularly those related to baffle barrel botting. A list of attendees and their affiliations is provided as Attachment 1.

The purpose of the meeting was to present information on the status of the WOG's ongoing Baffle Barrel Bolting (B8) Program to evaluate and assess the impact of potential botting degradation on domestic Westinghouse reactors, should it occur. The WOG also provided a current assessment of baffle former botting degradatiore reported in European PWR plants. The slides used in the WOG presentation are rarovided as Attachment 2.

Baffle former bolt degradation was reportet uropean plants from 1988 to the present.

Although not fully understood, some tests on degraded botting suggest an age-related intergranular stress corrosion cracking process. Materials and fluence may also contribute to the aging process, in 1992, the WOG initiated a multi-phase program to evaluate and assess the impact of potential bolt cracking of WOG reactor vesselintemals baffle former bolts. Baffle bolt degradation has not yet been observed in domestic WOG plants, and Japanese utilities have not reported this type of bolt cracking. Sorr,a foreign utilities have performed UT inspections on baffle bolts while domestic plants rely on the visual ISI requirements of Section XI of the ASME Code. The cracking occurs at the juncture of the bolt head and shank, which is riot accessible for visual inspection. The WOG stated that due to the large nurnber of bolts (over a thousand), the potential failure of a few bolts may not have a significant safety impact.

CfQPi]

Tha WOG program includes: 1) Development of analytical methods and criteria for acceptable l

bolt analysis; 2) Performance of risk informed evaluations; 3) Performance of analysis for acceptable botting for three WOG lead plant groupings; 4) Participation in domestic and foreign related bolt activities; 5) Preparation of bid specifications for high production bolt inspection

//

equipment; and 6) Preparations for inspection and replacement site activities.

9712050178 971126 I

PDR TOPRP EPfWEST

'C PDR 3 e %. 7 ((Jd 3 C # "

n gjg 4 l

9

~

am wo

s....

2-The WOG suggested periodic meetings with the NRC to provide updates, and obtain feedback and approval on proposed licensing methodologies. The WOG program schedule calls for meetings and submittals in 1997 and 1998, with an NRC safety evaluation of the proposed inspection scope, inspection method and acceptance cr?eria and associated bases prior to perfoiming baffle botting inspection / replacement and testing on the initiallead plant (Point Beacn) during the last quarter of 1998.

Coordination of activities with the WOG on this issue would be similar to that conducted with the BWR Owners' Group on its Vessel Intemals Program on BWR intemals issues. The staff w?l also consider implications for B&W and CE PWRs.

Project No. 694 Attachments: As stated cc w/ atts: See next page s

I I

l

o 2-t'he WOG suggested periodic meetings with the NRC to provide updates, and obtain feedback i

and approval on proposed licensing methodologies. The WOG program schedule calls for meetings and submittals in 1997 and 1998, with an NRC safety evaluation of the proposed inspection scope, inspection method and acceptance criteria and associated bases prior to 1

performing baffle bolting inspection / replacement and testing on the initial lead plent (Point Beach) during the last quarter of 1998.

Coordination of activities with the WOG on this issue would be similar to that conducted with the

' BWR Owners' Group on its Vessel Internals Program on BWR internals issues. The staff will also consider implications for B&W and CE PWRs.

i Project No. 694 i

Attachments: As stated ll cc w/ atts: See next page DISTRIBUTION w/ attachments:

PUBLIC Docket PGEB r/f SSheron RHerman AEL-Bassioni PTKuo

' Alee BElliott KWichman CCraig RWessman FGrubelich LLund Document Name: MEETSUM.820

• See previous concurrence OFC PGEB (A)SQ:PQE8 BC:EMCB BC:PGEB_

NAME JWilson:sw*

MJCase RWessman*

TEssig 48 i

DATE 11/20/97 11/k?

11/24/97 11/497 OFFICIAL RECORD COPY l

l 5

i

_,,w a

m..,

.._f,.,,m

...-,,4e.~.-v..y..

r

_,e.

-. ve

7 2

The WOG suggested periodic meetings with the NRC to provide updates, and obtain feedback and approval on proposed licensing methodologies. The WOG program schedule calls for meetings and submittals in 1997 and 1993, with an NRC safety evaluation of the proposed inspection scope, inspection method and acceptance criteria and associated bases prior to performing befne botting inspection / replacement and testing on the initial lead plant (Point Beach) during the last quarter of 1990.

Coordination of activities with the WOG on this issue would be similar to that conducted v.'th the BWR Owners' Group on its Vr ssel Intemals Program on BWR intemale issues. The staff will also consider implications for B&W end CE PWRs.

Project No. 694 Attachments: As stated cc w/ atts: See next page DISTRIBUTION w/ attachments:

PUBLIC Docket PGEB r/f BSheron RHerman AEL-Bassioni PTKuo Alee BElliott KWichman CCraig RWessman FGrubelich LLund i

Document Name: MEETSUM.820

• See previous concurrence OFC PGEB (A)SQ:PQE_B

'BC:EMCB BC:PGEB_

TEssig hA[E NAME JWilson:sw*

MJCS RWessman*

i l

jDATE 11/20/97 11M7 11/24/97 11/tif97 OFFICIAL RECORD COPY k

.~-

=..

Project No. 694 Westinghouse Owners' Group Mr. Nicholas Liparuto Westinghouse Electric Corporation Mail Stop ECE 4-15 P.O. Box 355 -

Pittsburgh, PA 15320-0355 Mr. Hank Sepp Westinghouse Electric Corporation Mall Stop ECE 4-07A P.O. Box 355 Pittsburgh, PA 15320-0355 Mr. Andrew Drake Westinghouse Electric Corporation Mall Stop ECE 5-16 P.O. Box 355 Pittsburgh, PA 15320-0355 l

LIST OF ATTENDEES AT MF.ETING WiTH WOG ON BAFFLE BARREL BOLTING lSSUES HELD IN ROCKVILLE, MARYLAND ON JULY 31,1997 NAfAE AFFILIATION J. Strosnidor NRC K. Wichman NRC B. Elliott NRC R. Wessman NRC A. El-Bassioni NRC W.Liu NRC P.Kuo NRC L.Lund NRC M. Shualbi NRC F. Grubelich NRC C. Grimes NRC R.Anand NRC J. H. Wilson NRC T. Greene WOG 1

T. Cloninger WOG J. Bailey WOG L. Liberatori WOG J. Bailey TVA R. Newton WEPCO C. Gallaway NEl R. Meeredy RG&E J. Gilbreath Duke W. Grsy Framatome G. Moffatt SCE&G K.Jacobs PASNY C. Tomes WPSC J. A. Wilson PSE&G A. Drake Westinghouse D. Forsyth Westinghouse D. Howe!!

Westinghouse R. Borsom FTl L Conner STS l

l

J.

~.

~

Baffle Barrel Bolting (B3) Program o

4 WOG Presentation to the NRC on the B3 Program 4*ggNGhoD e

WOG Executive Advisory Committee Chairman d

Ted Cloninger, Houston Light & Power

• WoD *

~

WOG Executive Advisory Committee Vice Chairman (o

g m-tm 4,

4 Jack Bailey, Tennessee Valley Authority

+

G*0 4 S WOG Chairman l

l Tom Greene, Georgia Power

?

O 8/lW

4 Baffle Barrel Bolting (B3) Program

~

AGENDA E Introduction / Meeting Purpose E Executive Summary E Current Assessment of Baffle Barrel Bolting E Planned WOG Programs E WOG/NRC Interactions E Discussion / Summary 8/lW7

s Baffle Barrel Bolting (B3) Program 1

Meeting Objective

_ 2

$0

~

E Provide background information/ current assessment 1

E Provide an overview of the WOG B3 program.

E Review WOG program plan schedule.

E Review WOG/NRC interactions for the program.

i E/1497

Baffle Barrel Bolting (B3) Program i

Baffle Plates, Former Plates and Bolting l

E2Il Base Bdts

[

ro,,.ier

. cW'W.,

/

,. N I

' /~'" fe,,,.Y"

,j syNnn)/

l

'dLIC

- A

(

y Form r.

?"PM "',

1%

S.

l b

-F-R--u i

f S:

~( %

s-s j

+

m 8% d LLL

/

W l

\\,

^

so n

(i%

d; -

h_ -

Aq

[

,.._.m.a 11/

'/

-FL

_g.

B#4 k Formes abt j

R/l W 7 MAM same = rar een

Baffle Barrel Bolting (B3) Program l

Background

E Indications of cracking in baflie/former bolts reported in some l

European plants from 1988 to present

- 90% of the indications from four reactors

- Percentage of bolts with indications versus total bolts inspected are l

relatively low

- No indications of cracking in bolts with former plate cooling holes E Indications of cracking reported in 316 CW stainless steel bolts

- WOG members were informed that no indications were found in 347 stainless steel bolts l

E Some tests suggest IASCC as a cause

- Age related degradation

- Contributing factors not specifically identified 8/I4/97 t

i m

ll

~

Baffle Barrel Bolting (B3) Program I

WOG/ Westinghouse Activities 2

~ [0 E Westinghouse informed of European experience early E In 1991, an initial assessment of safety significance performed concluded that the potential bolt degradation did not represent a substantial safety hazard for WOG plants.

E In 1992, the WOG initiated a multi-phase program to evaluate and assess the impact of potential bolt cracking on Westinghouse reactors, should it occur.

i fi/IV77

~

Baffle. Barrel Bolting (B3) Program

~ Current Assessment E Despite similarities with European reactors, there may be many design and operating differences which makes it difficult to generalize. In addition, there are design differences between individual WOG plants e.g.

- baffle / barrel region coolant flow direction

- neutron panel vs. thermal shield

- bolts with former plate cooling holes

- bolt design / manufacture j

- operating history

~

E Limited amount of bolt degradation following multiple inspections in European reactors

,,, n

l r

Baffle Barrei Bolting (B3) Program Current Assessment (Continued) g--

y L_

U

't E Baffle /former bolt degradation has not yet been observed in WOG plants and WOG members were informed by a WOG Japanese utility that no indications have been reported in Japan E Bolt slegradation is an aging elTect and, if it is occurring in WOG plants, it is expected to develop relatively slowly over a period of years.

E Analyses performed by the WOG to generically bound all WOG plants have not been able to eliminate the concern under postulated worst case assumptions.

- However, conservative acceptance criteria is met if half of the baffle /former bolts on each baffle plate at each former elevation are intact

- Application ofimproved analytical methods results in meeting the acceptance criteria with a more severe number and distribution of degraded bolts smm

n Baffle Barrel Bolting (B3) Program o

Overall Conclusions j

w

}

E Substantial conservatisms exist within the existing licensing basis and a large number of degraded bolts are required before challenging safety.

E Aging effects could potentially result in cracking of the baffle a

barrel bolts in WOG plants before the end of their current license.

E Additional aging management actions are warranted and are J

able to be implemented in a planned manner over the next several years.

E The WOG wishes to meet frequently with the NRC to provide

[

updates, obtain feedback and obtain approval oflicensing l

methodologies.

8/13/97 i

..r; i

Baffle Barrel Bolting.(B3) Program t

Agenda l

E Introduction / Meeting Purpose E Executive Summary E Current Assessment of Baffle Barrel Bolting E Planned WOG Programs E WOG/NRCInteractions E Discussion / Summary 9

8/13N7

Baffle Barrel Bolting-(B3) Program WOG Multi-Phase Approach - (1992-1997) l ll i

_U a Phase 1 - Plant Categorization (#, size, material of bolts) m Phase 2 - Evaluation using approved licensing basis 1

i assumptions and the limiting European UT data that was available at that time a Phase 3 - Decision analysis to assess alternative l

strategies / approaches l

m Phase 4 -Industry Participation a Phase 5 - Evaluation with more severe bolt degradation distributions with alternative assumptions l

i 8/13/97 I

d Baffle Barrel Bolting (B3) Program

~

WOG Phases 2 and 5 Results Summary m PHASE 2 (Typical 3 Loop Plant)

Conservative acceptance criteria is mot if half of the bolts on each former level of each bafne plate are intact.

m PHASE 5 (Typical 2 Loop Plant)

Conservative acceptance criteria can be met for more severe bolt cracking distributions.

Identified areas needing licensing basis methodology approval

• Break Opening Time Greater Than 1.0 msec

• Multinex Version 3.0

~

l

• Leak Before Break 8/13/97 e

-i h

Baffle Barrel Bolting (B3) Program l

1 WOG LCM / LR Program m Performed an Aging Management Evaluation for the Reactor Internals

- Identifies Baffle /Former and Barrel /Former Bolts as Requiring Additional Aging Management in the License Renewal Term

- Options for Managing Aging Effects to Maintain Intended Functions Are Provided i

t R/13S7

c l

Baffle Barrel Bolting (B3) Program l

?

Current Assessment-Industry Status

}

E

___l t m

E Four European plants represent most of the bolt indications experienced

(~ 90%) with a limited amount of bolt degradation following multiple inspections.

j E Cracking has been verified by metallographic testing and confirmed to be intergranular.

[

E Some tests have suggested IASCC as potential cause. Contributing factors I

have not been specifically identified (eg. water chemistry, load follow, fabrication differences).

I E European plants have continued to experience additional cracks, although few in number, with cracking now found on the bottom former level.

"I Foreign experience has not found indications of cracking in bolts with former plate cooling holes.

E WOG members were informed by a Japanese WOG utility that no indications of cracking in 347 SS bolts have been found.

t 8/13/97 t

E

i Baffle Barrel Bolting-(B3) Program 1

r Current Assessment - Impact on WOG Plants

_225]

E No indications of bafDe/former bolt cracking have been observed in WOG plants as determined by visual inspections.

E Visual inspections may not detect cracking due to the locking devices on the bolts. To date no domestic plant has performed UT inspections.

E The operating time at some WOG plants are higher than at plants that have already experienced cracking in Europe. Design and operating t

characteristics may be different than those European plants.

- cperating history

- baffic/ barrel region coolant ficw direction

- neutron panel vs. thermal shield

- bolts with former plate cooling holes

- bolt design / manufacture E UT inspection data is not available from WOG plants at this time.

E WOG plants are pursuing the availability of high production inspection / replacement equipment.

R/13/97 t

t

-~

Baffle Barrel Bolting (B3) Program 1

WOG June General Session E Formed WOG Working Group to manage B3 program E Authorized tasks totaling $2.14 million for 1997 E Directed additional tasks to be presented - l the October i

General Session I

I' 8/13/97

Baffle Barrel Bolting (B3) Program B3 Program Objectives m Maintain safety for WOG plants a Proactively manage the program with a systematic approach an3N7

Baffle Barrel Bolting (B3) Program Program Management WOG General Session I

B2 Exde m %, n, WOG 9eenng Cormonas Adasory Group g

e so--..cu.

namennascuedy MG4E Jesuemany srt*4 WOGS A..ree o d se, r -w Sons Pasusume-WWEP EFRifJoent Bame son WOG Bame Barret kweemmonaf Task Team (JoBB)

Boehng (83 Program lASCC Advisory Iban meensil Wortung Group Conurut*.ae co o enmen Jes Gdream.

Pomer noyer messon. vuEP m-KadJeeses MVPA e.r:,

1 i d Pw.

.,d -

Lead Place 2 ftsk Harmed Evahsanon Lead Piart ?

Laconseg & Ane yas s

B/13/97

Baffle Barrel Bolting (B3) Program WOG Working Group Program Plan Tasks

_7 9 License enhanced analytical methods and criteria for acceptable bolt analysis.

O Perform risk informed evaluation of the bame/ barrel region to show that the core damage frequency resulting from assumed bame/ barrel region bolt failure pro 3 abilities is low when compared to other l

contributors to overall plant risk.

O Perform acceptable bolt analysis for three WOG lead plant groupings.

9 Participate in domestic and foreign activities related to B3 9 Determine availability of B3 as-built information..

O Prepare bid specification for high production inspection and replacement site activities.

t 4

b I

.t Baffle Barrel Bolting (B3) Program F

Identification of Lead Plants E Lead Plant Group 1 (347 SS) - Point Beach Unit 1 or R. E. Ginna Plant E Lead Plant Group 2 (316 CW SS) - Three Loop Plant E Lead Plant Group 3 - To be Based on Program Results E Implementation Schedule

- Group 1 Point Beach 1 (Fall 98) or R. E. Ginna (Spring 99)

- Group 2 Three Loop Plant

- Group 3 To be based on prograni results t

savn i

a

4 4

Baffle Barrel Bolting (B3) Program Proposed Licensing Schedule,

j i

E Initial Methodology Meeting - September 1997

-[

' E NRC Periodic Meetings E " Justification for Increasing Postulated Break Opening

}

Times in Westinghouse PWRs" WCAP report submitted -

9 January 1997 3

E Subinittal of Bolt Analysis Methodology and NIultiflex 4

Version 3.0 WCAP Reports - January 1998 E Submittal of Lead Plant Group application of bolt analysis results - March 1998 E NRC Approval of Methodology (including WCAP for BOT) and Lead I'lant Group 1 Results - September 1998 (Supports Outage Schedule) i

+

i I

1 Baffle Barrel Bolting (B3) Program Program Schedule l

T t et - and sw.

P l

De s.pm.ne.,2.'.nd 4 % te op.e.

I I

Tw. L, eid sp.enewi.n -

l 1

---

--~rm 1-. q _ ~ =, =..m 1.... _

- =. -.. pm t d 4.o

,1

'Y

~

-~o

.<- y-amme aacm.a f-

==mmm ac -

y = = = = =i

..o (

P.e. An.syni..nd thst.eles

. o,.w v. 4 L d Pwe Gr.ap 1 r,,

lunc a.=4 l

ac,,

+

1 m

n-i t d e i

y,,

-n t

Baffle Barrel Bolting (B3) Program

SUMMARY

o li u

E To date, no domestic WOG plant has observed baltic /former belt cracking using visual inspection techniques.

E Visual inspections may not detect cracking due to the locking devices on the bolts.To date no domestic plant has performed UT inspections.

E Based on current data, baffle / barrel region bolt degradation does not represent a safety concern for WOG plants.

E Aging effects could potentially result in cracking of the haf11c barrel bolts in the US l

Westinghouse plants before the end of their current license. The WOG report on the l

aging management of reactor internal components identifies these bolts as requiring additional aging management for license renewal.

E A proactive program plan has been initiated by the WOG which includes WOG/NRC interaction relative to the bolt analysis methodologies.

E A lead plant ha volunteered for inspection and/or replacement activities with the lead t

plant ficid work scheduled for the Fall of 1998 or the Spring of 1999.

m yn l

l L_

Baffle Barrel Bolting (B3) Program CONCLUSIONS l

_ __L~l

~~~

E Substantial conservatisms exist within the existing licensing basis and a large number of degraded bolts are required before challenging safety.

E Aging effects couid potentially result in cracking of the bafHe barrel bolts in the US Westinghouse plants before the end of their current license.

E Additional aging management actions are warranted and are able to be implemented in a planned manner over the next several years.

E Tiae WOG wishes to meet frequently with the NRC to provide updates, obtain feedback and obtain approval oflicensing methodologies.

B/IV97

.