ML20044B511

Summary of 920325 Meeting w/C-E Alloy 600 (Inconel 600) Working Group Re Update of Status of C-E Owners Group Inconel 600 Program.List of Attendees & Viewgraphs Encl

ML20044B511
Person / Time
Issue date:	05/05/1992
From:	Wiggins J Office of Nuclear Reactor Regulation
To:	Richardson J Office of Nuclear Reactor Regulation
References
NUDOCS 9205110002
Download: ML20044B511 (18)

Text

i a f %.

b-

' 7, UNITED STATES i.!'"'

i NUCLEAR REGULATORY COMMISSION

,. g f

WASMNGTON. D C. WA gv f MM 0 51991 MEMORANDUM FOR:

James E. Richardson, Director Division of Engineering Technology FROM:

James T. Wiggins, Acting Chief Materials and Chemical Engineering Branch Division of Engineering Technology

SUMMARY

OF MEETING WITH COMBUSTION ENGINEERING OWNERS GROUP (CE0G) CONCERNING PRIMARY WATER STRESS CORROSION CRACKING (PWSCC) 0F INCONEL 600 The staff met with the Alloy 600 (Inconel 600) Working Group of the Combustion Engineering Owners Group (CE0G) on March 25, 1992 for an update of the status of the CEOG Inconel 600 program.

Primary Water Stress Corrosion Cracking (PWSCC) of Inconel 600 is an emerging technical issue for the operating pressurized water reactors (PWRs) first identifed by reported cracking of pressurizet penetrations (thermal sleeves and instrument nozzles) in a number of domestic PWR plants. The CEOG had briefed the staff regarding this issue and its program status in two previous meetings.

Recently, cracking of Control Rod Drive Mechanism (CRDM) penetrations was found at several French PWRs.

The staff has raised concerns with various PWR owners groups regarding the potential of similar CRDM cracking at domestic PWRs.

In the meetings the CEOG reviewed the status of its Inconel 600 program, discussed the recent Inconel 600 cracking experiences and assessed the potential of PWSCC of CRDM penetrations in CE plants.

Based on the CEOG presentation, the staff continues to believe that the cracking found thus far does not result in the need for a more aggressive NRC response to this issue.

The CE0G's presentation is summarized below:

(1) Review of CE0G Inconel 600 Program The CEOG briefly reviewed its activities pertaining to the Inconel 600 penetration program.

The purpose of the program is to assess the PWSCC of Inconel 600 penetrations in pressurizers (heater sleeves and instrument nozzles) and other primary pressure boundary components of Combustion Engineering (CE) plants. The results of the program were documented in three CEOG reports: (i) CEN-393-P " Pressurizer Heater Sleeve Susceptibility To Primary Water Stress Corrosion Cracking" dated November, 1989, (ii) CEN-406-P "A Status Report On CE0G Activities Concerning Primary Water Stress Corrosion Cracking Of Inconel-600 Penetrations" dated May, 1991, and (iii) CE NPSD-690-P " Evaluation Of Pressurizer Penetrations And Evaluation Of Corrosion After Unidentified Leakage Develops" dated January, 1992.

These reports have already been transmitted to NRC for information.

Some of the program results were presented to NRC staff in previous meetings.

In report CE NPSD-690-P, the Owners Group recommended a detailed visual inspection of the pressurizer at least once every 1100 days.

The recommended inspection interval is sed on f

(? ~2 C 5 / / / D O fl

{3 h

q a

e o

r

+

i the predicted corrosion rate and on ASME Code reinforcement requirements.

Some CE0G members have used the program results to develop inspection plans or to ientify susceptible penetrations for orderly replacement. CE0G has also initiated another program in response to the French CRDM cracking experience.

This on-going program will be discussed separately.

(2) Recent Inconel 600 PWSCC Experiences in CE plants Leaking of Inconel 600 instrument nozzles was recently reported in the pressurizers of Palo Verde Unit I and Songs Unit 2.

There are seven instrument nozzles at each pressurizer with four in the upper steam space 'and three in the lower water space.

Nondestructive examination (eddy current test or liquid penetrant test) was performed on each instrument nozzle of the affected pressurizer. At Palo Verde, one nozzle at the steam space had leaked and 2 other nozzles (1 at steam space and I at water space) contained partially through-wall cracks. At Songs, two nozzles at steam space were found to be leaking. All reported cracks were short and axially oriented.

The cracked instrument nozzles were temporarily repaired. The licensees of those plants will replace all pressurizer instrument nozzles with nozzles made of Inconel 690 material during the next refueling outages.

The CEOG concluded that the subject cracking has very low significance because the reported cracking is consistent with previous experience.

(3) Cracking Experience of French CRDH Penetrations The Owners Group briefly described the cracking of the French CRDM penetrations at three 900 MW plants. The available information pertaining to these cracking events is limited and the root cause of the cracking is not yet known as the French have not yet completed a failure analysis or published its findings.

In response to the French CRDM cracking experience, CE0G has initiated a program to compare the CRDM penetrations in CE plants to that of French EdF plants.

Penetration materials (form and properties) and fabrication techniques, as well as key operational and water chemistry factors I

will be examined.

The program will also catalog materials and fabrication data for each penetration for CE plants and establish a qualitative susceptibility ranking.

The Owners Group did not provide a completion date for this program because it is not known when the results of the French failure analysis and its root cause determination would become available.

The CEOG believes that, because of the potential differences in the fabrication of CRDM penetrations including their susceptibility to PWSCC, it is premature to assume that the French CRDM problem will also occur at domestic plants.

The staff will continue to monitor and evaluate the adequacy of each PWR Owners Groups' (Westinghouse, Combustion Engineering and B&W) and EPRI's action plans regarding PWSCC of Inconel 600. The staff continues to believe that the cracking of Inconel 600 penetrations in domestic PWRs will not impose a major safety concern, because all the reported Inconel 600 cracking in French reactor vessels and in domestic PVRs are short and axially oriented.

Short axial cracking does not threaten the structural integrity of the affected components and, therefore, are not currently considered to be a significant safety concern.

t J. Richardson A list of the meeting attendees and a copy of the CEOG presentation materials are attached.

WWW James T. Wiggins, Acting chief Materials and Chemical Engineering Branch Division of Engineering Technology

Enclosures:

(1) A List of Meeting Attendees (2) CE0G Presentation Mat 6 rials ccc: B.D. Liaw W.T. Russell T. Murley DISTRIBUTION Central Files EMCB R/F DET R/F WHKoo RHermann JTWiggins

• SEE PREVIOUS CONCURRENCE DET:EMCB DET:EMCB S [C:EMCB A

h,g/t'/92

• WHKoo:wk:adi

• RHermann TWJggins file name:ceog-2 04/22/92 05/04/92 J

under "g" i

l

t List of Attendees for Meeting with CEOG Alloy-600 Working Group i

March 25, 1992 NAME COMPANY TELEPHONE P. Richarson ABB 203-285-5643

(

Keith Resser SCE 714-368-6138 R. O. Hardies BG1E 410-260-6511 Mike Mecton APS 602-340-4623 Dan Sachs APS 602-393-5261 John F. Hall ABB 203-285-4762 r

Geoff Hornseth NRC 301-504-2756 Jim Cirill NU 203-665-4675 Steve Collard FPL 407-694-4175 George Kalman NRC 301-504-1367 James T. Wiggins NRC 301-504-2796 William H. Koo NRC 301-504-2706 Don Wright BG1E 401-787-5519 i

B i

l l

1

?

F

1 I

l l

1 List of Attendees for Meeting with CEOG Alloy-600 Working Group j

March 25, 1992 NAME COMPANY TELEPHONE P.

Richarson ABB 203-285-5643 i

Keith Resser SCE 714-368-6138 l

R.

O.

Hardies BG&E 410-260-6511 Mike Mecton APS 602-340-4623 i

Dan Sachs APS 602-393-5261 John F. Hall ABB 203-285-4762 Geoff Hornseth NRC 301-504-2756 Jim Cirill NU 203-665-4675 Steve Collard FPL 407-694-4175 i

George Kalman NkC 301-504-1367 i

James T. Wiggins NRC 301-504-2796 William H.

Koo NRC 301-504-2706 l

Don Wright BG&E 401-787-5519 f

i h

I f

i i

i l

CE0G ALLOY 600 WORKING GROUP

SUMMARY

REPORT TO THE NRC STAFF MARCH 25, 1992 1

AGENDA OPENING REMARKS DON WRIGHT (BG&E),

CHAIRMAN CEOG ALLOY-600 WORKING GROUP BOB HERMANN / BILL KOO, USNRC STAFF t

ALLOY 600. PENETRATION PROGRAM CEOG l

REVIEW OF CEOG PROGRAMS RESULTS APPLICATIONS l

l PRESSURIZER INSPECTION RECOMMENDATIONS CEOG/NRC STAFF L

l~

RESULTS_

STAFF-QUESTIONS CEOG I 60f 1

-n-r--.w---w

n. - - ~ - -.,. _,. - - - -, -.

2-----,-a-,.--...,,-.--.-vm

.w- -,,, - <..

-e-.-

u.n.c~.-ar--.--,-+-+--,--a.w.+,+.-----

.-m~., -, - - -.

v-no-,,--,----,

---

e--,>,.

+--

,a-

CE0G ALLOY 600 WORKING GROUP

SUMMARY

REPORT TO THE NRC STAFF MARCH 25, 1992 i

l AGENDA (CONT)

RECENT CE0G PWSCC EXPERIENCE CEOG

' eof CRDM PENETRATION CRACKING CEOG/NRC STAFF STATUS OF ISSUE IN FRANCE CEOG PROGRAM REGULATORY STATUS OF THE ISSUE WRAP-UP / QUESTIONS / COMMENTS CEOG/NRC STAFF CEOG I+60(

2 i

t 4

4

.,...:.--_,.--_._____m.

--,.-..re.

--,-.--*-~-E-,-_--

.-,,...~.re>=

5=--%.-.-..,.--.

.e.

-.e..s r--,--

rw-~.

.ww-.

---

,...-c4-m-..

w.-~

..m-.

.' P q

<T, ALLOY 600 PENFTRATION PROGRAM e

MULTI TASK EFFORT TO DETERMINE i

CAUSES OF CRACKING IN PENETRATIONS OTHER LOCATIONS WHERE IT COULD OCCUR SAFETY SIGNIFICANCE OF ITS OCCURRENCE CEOG'I-60(

i m

me-, - - - - - - --

e a.~e-e.- a

-m-.. - - -

--we

.---a w

we.

e-w~.

a.m-

-s--

v-.,-w e<

w.,~ - - -, -..

~v-.

.e-n-m.v v w e-..m,

,-+w,w-..-r-

>,as w - r e.

---

mm, n-v,,--s

ALLOY 600 PENETRATION PROGRAM REVIEW OF CE0G ACTIVITIES DETAI!E9 ALLOY-600 WORKING GROUP PROGRAM PLAN PRESS!uIZER HEATER SLEEVE EVALUATION, THERMAL

ANALYSIS, AND TESTING PRESSURIZER NOZZLE & PENETRATION EVALUATIONS ECT TECHNIQUES QUALIFICATIOr PRESSURIZER SHELL CORROSION TESTING PRESSURIZER INSPECTION RECOMMENDATIONS CRDM PENETRATION CRACKING EVALUATION ALLOY-690 MATERIAL PROCUREMENT CEOG I-60 4

Am-

___.__.__m_________________________,__.w_,.7

___...,,_m.,...,,..,m,#m.,

,.m.

,,,-,,c_,,,,e.,w_,,,.

,,...,m.,

,,m,,,,,,

e ALLOY 600 PENETRATION PROGRAM (CONTI STATUS CEN-406-P "A STATUS REPORT ON CEOG ACTIVITIES CONCERNING PRIMARY WATER STRESS CORROSION CRACKING OF INCONEL-600 PENETRATIONS" WAS ISSUED TO THE STAFF ON JUNE 6, 1991 CRDM EVALUATION-& MATERIAL PROCUREMENT TASKS ONGOING i

RESULTS j

PRELIMINARY INSPECTION RECOMMENDATIONS USED BY SEVERAL MEMBERS TO DEVELOP' INSPECTION PLANS i

ONE MEMBER USED RESULTS OF ALLOY-600 PENETRATION DATA TO IDENTIFY PARTICULARLY SUSCEPTIBLE PENETRATIONS AND PLAN THEIR~ ORDERLY REPLACEMENT CEOG 1760 5

-,.,..--_-m.--.~,--,--,,.--.-----e,-~w,

,.,--v vv..-...e.

. + _, -.

-..,-#m.-..~.

.-.....-....w,.,.=

w.-.v+v..-.

,. - -. -.. -mv.--

.-E,.,

s.

m o r

,. s<r,

PRESSURIZER INSPECTION RECOMMENDATIONS CEN-393-P " PRESSURIZER HEATER SLEEVE SUSCEPTIBILITY TO.

t PRIMARY WATER STRESS CORROSION CRACKING" PROVIDED PRELIMINARY INSPECTION RECOMMENDATIONS FOR HEATER SLEEVES MORE EXTENSIVE TESTING AND ANALYSIS PROGRAM PURSUED i

ISSUED TO NRC STAFF. NOVEMBER 17, 1989 CEOG I-60 6

,+,.

-.e,,

---r.-.a a-..--e,,

--i.-r-m.m,, -

-ww* * - - -..-- -,,.

--..m.w+-

-.e.-

~-.--,-,,e--,,

, +...

e#,

-t--,ya

.,+e.

...w-,w,

.,...-%e-.ms-.-ere, ew

-wr

PRESSURIZER INSPECTION RECOMMENDATIONS (CONTl RESULTS OF SEVERAL TASKS FOLDED INTO CE NPSD-690-P

-INCLUDED SHELL CORROSION TEST DATA LOCALIZED CORROSION RATES ESTABLISHED REINFORCING CALCULATIONS DEMONSTRATED ADEQUACY OF 1100 DA,Y INSPECTION INTERVAL (HOT)

REMOVAL OF INSULATION NOT REQUIRED CE NPSD-690-P ISSUED TO NRC' FEBRUARY 26, 1992 e

CEOG I-60r 7

m

-..m- -

i.-.-...

c... -. -.. - - -...

.-.*,.r.--

..e.

. * + rs e-4--.----.

.e-

..m--.

m

RECENT PWSCC EXPERIENCES

)

.CEOG MEMBER INPUT ALL FAILURES CONSISTENT WITH PREVIOUS CONCLUSIONS AXIAL-ORIENTATION LITTLE' CORROSION HIGH TEMPERATURE NO SAFETY SIGNIFICANCE CEOG'I-608 8

...,-.-~w

-+

+

e--,-

+-----**--~*e*-*

- * -- - - - * - + -- * - - ' * ' ' - - ' * ' ~ " = - "' ** ' ' ' ' " ' ' - '--- **' ' ' ' ' * ' " ' ' ' ' " ' ' ' ' " " " - - ' ' - " - ~ ~

' ' ~ ' " ' " " ' " ' "'

. RECENT PWSCC EXPERIENCES CE0G MEMBER. INPUT ALL-FAILURES CONSISTENT WITH PREVIOUS CONCLUSIONS AXIAL-ORIENTATION LITTLE CORROSION HIGH TEMPERATURE NO SAFETY SIGNIFICANCE CEOG I-600-1

~

..-,.._,..,.-,.........-...,-_...,,.......~.m-.........,.,....,...,,,.......,,.,-,.,.,-w, m,.,

_.,,.,,~,,,

,,_.m

,r.

y EDF CRDM. PENETRATION' CRACKING STATUS OF ISSUE IN FRANCE (AS CE0G' UNDERSTANDS IT)

DISCOVERED 1991 THREE AFFECTED PLANTS IDENTIFIED AXIAL CRACKS ONLY 900 MW PLANTS 80,000 - 100,000 HOURS OF OPERATION 0

TEMPERATURE UNDER HEAD: 599 F ONE 1300 MW PLANT INSPECTED NO CRACKS l

< 50,000 HOURS OPERATION SAME TEMPERATURE l

1 l

CEOG I-608 9

EDF CRDM PENETRATION CRACKING (CONT)

CRACKED PENETRATIONS PERIPHERAL LOCATIONS FORGED ALLOY 600 SHRINK FIT + PARTIAL PENETRATION WELDS OVALIZATION NO FAILURE ANALYSIS RESULTS YET

)

9 4

1 CEOG I-600 0-t

.,.,,,--,e-.

. ~.....

4,-

-.,r.,,.

,. ~... -,,, -. ~.,.. -. ~,. _.. _

...._,~-...,.........-~._..,,...,-.-s

- -. -,... _, - - -... ~. _ -. _

EDF CRDM PENETRATION CRACKING (CONT) 1 i

CE0G PROGRAM INITIATED COMPARE CEOG CRDM PENETRATIONS WITH eof MATERIALS (FORM, PROPERTIES)

FABRICATION TECHNIQUES (SIMILARITIES, DIFFERENCES)

CATALOG MATERIALS AW FABRICATION DATA FOR-EACH PENETRATION FOLLOW ' eof ACTIVITIES, INCLUDING REVIEW OF FAILURE ANALYSIS COMPARE KEY OPERATIONAL AND WATER CHEMISTRY. FACTORS QUALITATIVE SUSCEPTIBILITY RANKING CEOG'I-600..

.1

~.. -,......,.....

....._..-,.~.,~...........,.._-..,,.....-.._,,,,,,...~............m.....-

....~........,m

....e..

......4..

EDF CRDM PENETRATION CRACKING '(CONT)

PRELIMINARY REVIEW SHOWS THAT eof HEADS ARE SIMILAR TO DOMESTIC 'PWR HEADS CONFIGURATION MATERIALS

~

MANUFACTURING i

CEOG 1 600, 2

_ o.

s.

u m

_.,.._,._.....,...,,,,_,4,,,

... ~,.

4

...