ML17252A595

From kanterella
Jump to navigation Jump to search
Final Technical Evaluation Rept on Response from Comm Ed to Generic Ltr 88-01 Pertaining to Dresden Nuclear Power Station,Unit 3
ML17252A595
Person / Time
Site: Dresden  Constellation icon.png
Issue date: 08/31/1989
From: Bates R
VIKING SYSTEMS INTERNATIONAL
To:
NRC
Shared Package
ML17202U800 List:
References
CON-NRC-03-87-028, CON-NRC-3-87-28 GL-88-01, GL-88-1, NUDOCS 8908280066
Download: ML17252A595 (37)
v • d • e


Text

....

j i

/

.~..

'. ~*

. TECHNICAL EVALUATION REPORT ON RESPONSE FROM COMMONWEALTH EDISON TO GENERIC LE'ITER 88-01

-J>ERTAINING TO TIIE DRESDEN NUCLEAR POWER STATION, UNIT 3 Publishe~ August, 1989 prepared by Robert C. Bates

  • Armand Lakner Viking Systems International-2070 Wm. Pitt Way
  • Pittsburgh,- PA Prepared *for:

U.S. Nuclear Regulatory Commission

washington, D. C. 20555 under Contract No. NRC-03-87-028, Task Order OOS '

i;..*.,.,

ENCLOSURE 5 FINAL FINAL

r l

i.*

ABSTRACT This report contains an evaluation of the licensee **(Commonwealth Edison) submittal for Dresden Nuclear Power Station, Unit 3 which was submitted in response to the NRC Generic Letter 88-01 in which Commonwealth Edison was requested to: (1) Furnish their current plans relating to piping replacement and other measures to mitigate IGSCC, *inspection, repair~

and leakage detection.

(2) Indicate whether they plan to follow the NRC Staff positions, or propose alternative measures. CE's plans are evaluated in Section 2 of this report in terms of compliance to NRC Staff position13. Section 3 contains evaluations of an alternative pgsit:ion concerning a change to the Technical Specification *on ISI, alternatives to portions to the NRC Staff position ~n leakag*e detection, aii:d-an excepti~n. to the scope of Generic Letter 88-01

  • i

SUMMARY

ihe Licensee, Commonwealth Edison~ submitted a response to the NRC Generic Letter 88-01. CE's response pertaining to the austenitic stainless steel pipin~ in the* Dresden.. Nuclea~ P~ver Stati0n,* Unit 3 (a BWR nuclear power plant) was evaluated in terms. of: (1) Their,.

previous and planned actions to mi.tigate IGSCC to provide assurance of contiriued long-::term service. *~ (2) Their Inservice Inspection (ISI)

Program.

(3) Their Technical Specifications pe-rtaining to IS! and their pl~s to ensure that. le~ge" detection wil.l

  • be in conf oraiance

~tlt. the NRC Staff position.* (4) Their plans t~ noti.fy. the. NRC of... **

'

  • sign.ifican.t flaws identified (or changes in the condition of the welds
  • previously -known to b,e cracked) during ~11spection~*

Commonwealth Edison,endors.~s.* most *of the 13.NRC Staff positi()ns which

are outl~11ed in Generic Letter 88-01, but they applied provisious to..
  • their.endorsement of the NRC Staff position *on Cr~ck.Ev~l~ation.. and Repair Criteria and concerning IGSCC classifications of welds-between*.

~

~

~

castings.* They propo.sed alternative posifions concerning portions*

pf the. NRC: *St~ff position. on :leakage detectio~*.

Extensive programs of. J.>ipirig replacement, piping removal, and stress improvement have been* conducted at Dresden*3, so all except 11 of a total ~f 198 welds are IGSCC Cat~gorie~ A an:d.c *. Future mitigating

  • actions will be applied_. as necessar.y, and HWC is bei_ng *consid~x*ed.
  • An IGSCC ISI program proposed for Dresden 3 conforms with the.NJ:C Staff positions on schedule, methods and personnel,.and sample expansion, except* *t:hat RWCU ~elds out-board of. the. isolatici~ valves have been*

omitted.* Specific welds scheduled for-i.lispection ~uring the next two refueling outages were identified, but Commonwealth. Edison deelined to. amend the ~ecJviical Specification on.IS! to include a statement that the*Isi progr~ will conform With the NRC Staff po~ition. Rather, they proposed to include the required statement in the ISI Program

  • ABSTRACT..............................

SUMMARY

1. INTRODUCTION..................

~.......

2. :EVALUATION 01" RESPONSE TO GENERIC LETI'ER 88-01 2.1. Documents Evaluated

~:*....

2 *. 2 Review of CE' s Responses to Staff Posi tiolis and-Implementation of Those Positions 2.*3 Review of *Classification of Welds, Previous.

  • Mitigating Action~, *and Previo11s Inspections_

.. {

-2.3~1 Current IGSCC Gl~ssifica~ions

. 2'. 3. 2 Partial Replacement,, * * * ; * *....

~. **.*......

2.3.3 Piping Removal

    • j' ** ***

... ~

I!

~*.3~4 Summary of Mat~rials in IGSCC Category A W£,!lds*...

~*

2~3.5 Stress I~provement. -~ ****.*.".............

i ii 1

2 3

5 8

8

-_9 10

2. 3.* 6 Previous Inspecti~n
  • Prograai.s
  • * * *._,. * * * * * *
  • 11 2.3.7 Evaluation and-Recommendations '.. ".... ~..... *
  • 13 2.4 Current Plans for. Mitigating Actions

~

13 2.4.1 Commonwealth Edison's Position*... * * * * * * *

~ * *

  • 13 J

2.4.2 Evaluation of Conformance to Staff

,~'

Positions and Recommendation

  • ,; *.. * * * * *.. *
  • 13 2.5 Plans.for Future Inspections 14 2.5.1 Summary of Inspection Schedule
  • *. -. * * * * * * *
  • 14 2.5.2 Inaccessible Welds
  • * * * * * * * * * * * * * * *
  • iii

'*t'

i.*.

~*- ------

2.5.3 Methods and Personnel

  • * * * * * *... ~ -*. *..... 15 2.5.4 Sample Expansion
  • * * * * * * * * * * * * * * * *
  • 15 2.5.5 Evaluation 1µ1d.Recommendations
  • * * * * * * * * * *
  • 16 2.6 Changes in-the.Technical Specification Concerning ISI 2.7 Confirmation *of Leak Detection in the Techni~al Specification..........

2.8 Plans for Notification of the NRC of Flavr;i 16 16 18

2. 8.1 Commonweal th Edison's Po~i ti on
  • * * * *.* * * * * *
  • 18 2.8.2Evaluatiori and Recommendation
  • * * * * * * * * * *
  • 18
3. ALTERNATIVE POSITIONS AND EXCEPTIONS
  • * * *. * * * * * * * * *
  • 18 3.* 1 Alternative Position Concerning ISI in the Technic.a.l SJ>ecification
  • * * *.* * * * * * * * * *****.. 18 3.1.1 Commonwealth.Edison's Positton * * * * *
  • . **.1
  • 18

. '3.1. 2 Evaluation and Recommend~tion

~....

,....... 19 3.2 Leakage Detection i~ the Technical Specification * * * * *

~....

3.2.2 Leakage Limits

  • *.. * * * * * * * * *. * *,~ * *
  • 23.

3.2.3 Frequency of LeakSge Monitoring 23 3.2.4 Definition of Unidentified Leakage.. * * * * * * * *

  • 24 3.2.5 Operability of° Monitoring Instruments
                • 24 3.2.6 Evaluation and Recommendations 3.3 Welds Exclused from IGSCC Program 3~3.1-Scope of Generic Letter 88-01 3.3.2 Commonwealth Edison's Position 3.3.3 Evaluation and Recommendation iv

~...

~ * * * *.. * *

  • 25
26.

26 26 27

'~.

'.!.-~

  • v

r j..

1. INTRODUCTION Intergranular stress corrosion cracking (IGSCC) near weldments in Boiling Water Reactor (BWR) piping has.been occurring for almost 20 years.

Substarit~al efforts in research and d~velopment have been sponsored by the BWR Owners Group for IGSCC Research, and the results of this program, along with other related work by vendors, consulting firms and co~firmatory research sponsored by the HRC, have permitted the development of NRC Staff positions regarding the IGSCC problems.

The technical basis for NRC Staff positions is detailed in Reference 1, and fur~her background is provided in Reference 2.

Th~ results, of these research. and devel~pment programs* *prompted the NRC*to issue ~neric*Letter 88-01.<see Reference 3) requesting all licensees of BWR's and holders of construction permits to:

    • (1) Furnish their current plans relating to piping replacement, inspection, repair~ an'd leakage detection.

(2) Indicate whether they:

(a) Plan to follow the staff positions, or *

(b) Propose.alternative measures.

Specifically, 'Generic Letter 88-01 stated that an acceptable licensee response would include the foilowing items:

(1) Current plans regarding pipe replacement and/or other measures*

taken or to be taken to mitigate *IGSCC and provide assurance of continµed long-term piping integrity and reliability *

. (2) An inservice inspection (ISI) program to be implemented at the next refueling outage for austenitic stainless steel piping.

(3) A change.to the Technical Specifications to include a statement 1

in the section o~_ISI that the inservice_inspection program for 'piping will be in conformance with the staff positions

~n schedule, methods and personnel, and sample expansion.

(4) Confirmation of plans to ensure that the Technical Specification related to leakage detection will be in conformance with the Staff position on leak detection.

(5) Plans to notify the NRC, i~ a~cordance With 10CFR50.55a(o),

of any.flaws identified that do not meet IWB-3500 criteria of Section XI of the ASME Code for continued operation without evaluation, or a change found in the condition of the velds previously known to be cracked, and an evalu~tion of the flaws for continued ~sed operation and/or repair plans.

This report.contains a technical evaluation of *the r.esponse which Commonweal~h Edison <sometimes called CE in.this report) submitted*.

  • fn response to the NRC Generic Letter 88-01 pertaining to the Dresden Nuclear Power Station, Unit' 3 (hereafter called Dresden 3).
2. EVALUATION OF RESPONSE TO GENERIC LETI'ER 88-01 This evaluation consisted of a review of the response to NRC Generic Letter 88-01.-of January 25, 1988 by Commonwealth Edison. pertaining f

. to Dresden 3 to determine if their performance and plans are in conformanc.e with the NRC Staff positio.ns or if proposed alternatives are acceptable. Proposed.inspection schedules and amendments :to.the Technical Specification were included in the review.

2.1 Documents Evaluated Review was conducted on the information pertaining to Dresden 3 2

r 1

prov;!.ded.by the Licensee in the following documents~

(1) "Dresden Station Units 2 and 3, Quad Cities Station Units 1 and 2, LaSalle County Station Units.1 and 2, (Response to) Generic Letter 88-01, Docket Nos. 50-237/249, 254/265, 373/374, License DPR-35," Commonwealth Edison, One First National Plaza, Chicago, Illinois 60609, July 29, 1988.

(2) "Dresden Station Unit 3, Response to Request for Additional

~*.

Information on Generic Letter 88-01, TAC No. 69~33, Docket

  • No. 50-237,".Commonwealth Edison, *0ne First National Plaza, Chicago, Illinois 60609, July ~l, 1989.

Hereafter, in this report, these documents*vill be referred to as CE Submittals No. 1 and No 2, respectively, and collectively

  • as the CE Submittals.

2.2 Review of Commonwealth Edison's Responses to Staff Positions

  • and Implementation of Those Positions *.

Generic* Letter 68-01 outlines thirteen NRC Staff positions pertaining to (l)' materials, (2) processes, (3) water chemistry, (4) weld overlay, (5) partial replacement, (6) stress improvement of cracked weldments, (7) clamping devices, cs>> crack evaluation and repair criteria, (9) inspection methods and personnel, (10) inspection schedules, (11) sample expansion, (12) leak detectio~,.

and (13) reporting requirements *. Generic Letter 88-01 states that the.licensee should indicate in their submittal whether they endorse these NRC Staff positions or propose alternative positions. Table l_ of this r~port, which is based o~ -a similar table in CE Submittal'.

No. 2 and discu~sion in both *~ Submittals, shows the CE position concerning the 13 NRC Staff positions.

3

~'J

~,*

'I"*,:..-

J r

. *~

Table 1 Summary of CE's Responses to Staff Positions CE Has/Will CE Accepts NRC Applied Consider for Staff Position Staff Position In Past Future Use

1. Materials
2.
  • Processes

?* Water Cheniistry

4. Weld Overlay
  • 5. Partial ~eplacement ~
  • 6. Stress Improvement of

,cracked. Weldments

7. Ci~ping Devices
8. Crack Evaluation an.d Repa+r*Criteria 9*. Inspection Method
  • *anq Personnel
10.,Insp~ction Schedul~
11. Sample 'Expansion*
12. Leak.Detection.
  • ., 13. Reporting Requirements yes( a) yes yes yes yes*.

yes.

. '. ~

ye~

yes(e).

  • yes

... ye/a) yes'*

yes(e).

yes,.

  • yes yes(b)

'yes(b) yes no yes _*

yes<c>:

yes(b) yes(d)

(b) yeA.

no

.. (b) yes...

no

... (b) yes..

    • yes

{b)

.yes..

yes

._yes yes yes(b) no yes no yes

  • no*

y_e/b)

  • ca) C0mmonwealth Edison stat~d that they applied provisions to inspect}on* sch.edules, but* they were actually. applied to i;.:
  • materia:J.s (i.e., assignment of IGSCC class;l.fications tc)° welds between castings). See text for discussion.*.. *

(b) Common,_.ealth Edison will implement this item ~s necess~ry *

. ~:

~

'... (c) All*: weld,,ove*rlay repairs were removed during the piping re'p1acement prograni in 1985/1986.

(d) System removal has been used in addition to. an extensive piping replacement program.

(e) Provisions or exceptions applied. See text for discussion.

4

r 4..

Note that Commonwealth Edison endorses mos~ of the 13 *NRC Staff positions. They proposed alternative positions to portions of the item o~ leakage detection (discussed in Section 3.2). They also stated that they applied a provision on.inspection schedules, but it actually applies to IGSCC classifications of velds between castings and is discussed in Section 2.3.4. Finally, they applied a provision to the ~tem on Crack Evaluation aild Repair Criteria (i.e., they J>lan to in~orporate the favorable stress distribution for calculatfons for stress improved *welds)~-

This provi~ion is*

. acceptable and will not be discussed elsewhere in this report.

  • 2;3 Review of Cta~sification of Welds, Previous Mitigating Actions,.. and Previous. Inspections
  • 2.3.1 Current IGSCC.Classifications Welds in the RWCU that are outboard of.the isolation valves were omitted from the IG_SCC program. This action is discussed in.s~ction
  • 3.3.

-Hereaf.t~r, Sections.2.3 and 2.4 deal only with welds that are that are inboard of the isolation valves.

Table 2a,.. constructed from a similar table contained in CE.

Submittal No *. 1, provides a* summary ~f the number of welds at Dresden 3 in each of the IGSCC categories on a sy~tem-f by-system ha.sis.

IGSCC classifications of individual welds are not listed in CE Submittal No. 1.

CE Submittal No. 2 does* contain such a list which is summarized in Table 2b.

Differences between Tables 2a and 2b are:

.( 1) Two IGSCC Category G welds in the Isolation Condenser '

in are listed.in Table 2b and not in Table 2a.

(2) One weld 'in the Isolation Condenser ~ Supply which 5

  • f,'.

---~---_

.... _,,____ __ ~----

r*

t :..*

Table 2a Sunimary of IGSCC Class:i:fication of Welds (Based on CE Submittal No._ 1).

  • Dia.

No. of Welds of Indicated IGSCC Categor1 Sistem Inch ~

2- __£_

D

__:!._ _L __£ Total Retir\\llation Outlets 28

  • 22 0

0 0

0 0

  • o 22 Npz-SE 28 2

0 0

0 0

0 0

2

\\

12 10' 0

0 0

0 0

0 10

'22 4

0 0

0 o*

0

- 0 4

.. Risers

'12 24 0

0 0

o*

0

  • o
24.

Bypass 4

0 0

0 0

0 0

0 0

RHR

_LPCI 16

'20

. *.O 0

0 0

0 0

20 soc

16.

-7 0

0 0

0 0

o:

7 14 3

0 o-0 0-0

. 0,'

3

l.

Isolation Condensor.

Supply 14 O*

0

  • 23 0
  • o o*

1 24 12 0

0 15 0

  • o 0

0 15 l

Return 12 11 0

0 0

0 0

0 11 Core Spray 10 12 0

16 0

0 0

0 28 Jet Pump Inst*

4 2

0 0

0 0

0 0

2 RWCU*

8.

16_

0 0

0 0

0 o*

16

  • --6 1

0 0 '. 0 0

0 0

1*

N-18 A, B Nozzles 6

0 0

.0 4

0 0

Q.

4

  • "Head Vent 4

0

o.

.o _L 0

0 0

  • 3 Totals
  • 134 0

54 7

0 0

1 196 6

i'.

. i.

.i..

f

  • Table 2b
  • Summary of IGSCC Classification of Welds (Based on CE Submittal No. 2)

Dia.

No. of Welds of Indicated IGSCC CategorI System Inch ~

~ c -1L _!_

F

_Q._ Total Recirulation Outlets 28 22 0

0 0

0 0

0 22

'Noz-SE 28

  • 2 0

0 0

0 0

0 2

  • 12
10.

,0 o-0 0

0 0

10 Header

22.

4 0

0

  • o 0

0 0

4 Risers 12..

24 0

0 0

0

.0 0

24 RHR

.LPCI 16 20 0

0 0

0

  • O 0

20 SDG

. 16 7

.0 0

0 0

.o

.o 7

J4

.3

  • . 0 0

0 0

0 O*

  • 3 I.solation Condensor*

Supply 14 0

0

. 23 0

0

()

l 24

. 12 0

0 14 0

0

0.

3

'17 Return 12 11 0

0..

0 0

0 0

11 Core Spray 10 12 0

16 0

0 0

0 28 1.*

Jet ~uµip Inst 4

2 0:

p 0

0 0

0 2

RWCU 8

16 0

0 0

0 0

--o 16 p

1 o*

0 0..

0.

0 0

  • 1 N-18 A, B Nozzles*

6 0

0 0

4 0

0 0,.

4 Head Vent 4

()'

0 0

,.. _L o-0 0

3 Totals

  • ~.

134.

0 53 7

0 0

4* i98

..*.*No.te t9at *two 12" diameter IGSCC Category *G welds in *the*.

Is<:>lation Condensor - Supply.are listed in this table that*

were not listed in CE Submittal No. 1.

-~--

7

~-._

~ ~

~.. '.

is.. classified as IGSCC Category C in Table 2a (from CE Submittal 1) is classified as IGSCC Category G in Table 2a (from CE Submittal No. 2). Commonwealth Edison did not explain the reasons for the differences noted above, but hereafter, in this report, it is assumed that Table 2b is_:

~orrect (rather than Table 2a) because*Table 2b is based on the description of-welds contained in CE Submittal No.

2; whereas Table 2a was provided in the summary form in which*

it is contained in this report.

c CE Submittal No. 1 describe~ actions.that have been taken to mitigate IGSCC at Dresde~ 3.

.CE Submittal No. 2.lists

-. ~.

~

the justi~ication for the IGsCc classification for each of the* welds including materials used (base metal and weld metal)

  • *,~d mi~igating treatme'nt~. -Summaries are provid,_ed below.
  • 2. 3. 2 Partial Re.placement...

A major piping rf?placement program was completed at Dresden.

3 in 198.6 usin~ corrosion resist~nt.sta~nless steel (per NUREG

  • 0313, RevisiQn 2) *.

Shop wel,ds were solution treated *.

and energy i~put was controlled on field welds to minimize sensitization. Although it was not specifically stated,.

. descript_ions in the CE Submittal indicate that the welds

  • that ~ere ~eplaced in that program ar~ the 134 IGSCp welds iisted-in Tables 2a and 2b *. The materials contained0 in these welds are-'discussed in Section 2.3.4
  • 2.3.3 Piping Removal
. Several corrosion susceptible sections of stainless steel piping were permanently re~oved from the system including: *

(1) The Control Rod Drive Return Line from the reactor 8

~-:.

r J.

I l'

i.

vessel nozzle to the outboard check valve. A replacement safe end and cap were installed on the reactor nozzle.

(2) The 22 inch Recirculation discharge cross-tie.

(3) The 4-inch Recirculation discharg~ valve bypass lines.

2.3.4 Summary of Materfals in IGSCC Category A Welds Materials contained in velds that are classified* as IGSCC

    • Category A are B;S follows:
  • where:

Base Metal Pipe Pipe Casting Weld Metal Conf onning Conforming

. N on-Conf ormiilg Base Metal Pipe*.

Cas.ting Casting (I) All pipe is Type 316NG stainless steel.

(2) Castings contain > 0.035% carbon.

(3) Conforming weld metal is either: Type 316L ~tainless steel, Type 309L stainless steel, or Type, 308MoL.,,

stainless steel.

l

~

.(4) Non-conforming weld metal contains > 0~035% carbon.

Note that castir.gs and some weld metal (that used for welds whi~h join two casting) contain carbon contents > 0.035%.

Commonwealth Edison's justification for classifying.these*

9

  • t _*:*

i

  • ~

welds as IGSCC Category A is contained in CE Submittal No. -

2 which states:.

"Welds joining castings with,carbon content highe:i;- than.

  • 0.035%, such as cast pump body to cast elbow, are included in Category A.

The Staff Position on inspection schedules states that '.welds j~ini~g such castings (in the form of pump and valve bod.ies) to piping have been relatively

This may be attributable to a favorable stress distri.bution. ' " ~is good service experience includes ~oth cast and weld material with carbon. content

higher than 0.035% *. Therefore, it is logic~ to extend the Staff Position, which places high carbon cast material

_joined to resistant material in Category A, to also include cast material joined to cast material in Category A."

2.3.S Stress Improvement Stress improvement.tteatments using.the Mechanical Stress Improvement Process (MSIP) were applied t.o the A and B loops of the Core Spray system from the'inboard check valve to the drywell penetration and the Isolation Condenser steam

. supply line from the reactor vess.el nozzle, safe end to the

~solation Condenser inlet nozzles.

EPRI qualified.

pre-treatment and post-treatment ~ltrasonic*examinations were performed.

No flaws were f.ou~d.

All 54 of the welds that are classified as IGSCC Category C were included in those welds that received MSIP treatments.-

  • In addition, one weld classified as IGSCC Category G is shown in CE Submittal No. 2 to.have been included in those weids that was treated with MSIP and inspected as.~escribed above.

This is probably the weld that was classified as IGSCC 10

I 1 Category C in CE Submittal No. 1 and IGSCC Category G in CE Submittal No. 2, although that was not actually stated and no explanation for the change of classification of this weld was provided.

2. 3. 6 Prev~_ous Inspection Programs According to CE Submittal No. 2, all inspections p~rformed.

at Dresden 3 that.were conducted per NUREG 0313, Revision

2. (using methods and personnel qualified.under the NRC/EPRI/BWROG coordination plan as upgraded in September, 1985) w~re perf_ormed during Refueling Outages 9 and 10 which occurred during 10/85 thro~gh 7/86'and.3/88 through 6/88; respectively)* *. CE Submittal No. 2 contains a list of welds that were inspected during those outages. Those inspect~ons are sUlll.IDciri~ed in Table '3 of th~s report (which sl)ows the.

. number of welds" of each IGSCC category that.were inspected during. those outages) and in the fo'llowing paragraphs.

IGSCC Category A Welds: Pn*e of these welds. is inaccessible for ultrasonic.testing (UT) *. Of the *other 133.IGSCC Category A_welds, 131 were inspected during the Refueling

  • Outage No~ ~ (as mentioned previously, this was the outag~

during which the piping replacement program was completed).

A_ flaw was* fou~d in one weld (Weld No *.

f RRB-47F in the Recirculation System) which was determined*.

to have been cau~ed by l~ck of' fusion. That weld was repaired, reins.pected, 8.nd found to be acceptable.

IGSCC Category C and D Welds:.All of these welds were inspected.. dur:ing Refueling Outage No. 9. Nine of 53 IGSCC Categc;>ry C welds and 4 of the. 7 IGSCC Category.

D welds were reinspected during Refueling Outage No.

11

l

. IGSCC Categ.

A

-B c

'D E

Notes:

Table-3 SWlliilary of' Inspe.ction Schedules for Dresden 3 No. of Welds Categ.

No. Inspected/Scheduled During Indicated R.O.

Past Future 09 10

. 11 12 134(a)* 131 0

6' 6

53 53 9

37 16 '

7 4

7 o*.*

0 0

0 3.*

0-Required by Generic Letter 88-01 25% every.10 years* (at least 12% in 6 years) 50% every 10 years (at least.25% in 6.years)

A.11 within the next two refueling cycles, then all every 10 years (at 50 % in 6 years)*

All every 2 refueling cycles SO% next r~f~eling cycle, then all *every 2 refueling.

cycles All every. refueling outage,.

All*next refueling cycle (a) One of the IGSCC Category A welds is inaccessible for inspection.

(b) One of.the IGSCC Category.. G welds is inaccessible for inspection.

Acoustic emission monitoring of this weld is being evaluated.

  • Dates of refueling outages are:

R.0.#

Date R.0.#

Date 09 10/85-07/86 11 11/89-02/90 10

. 03/88-06/88 12

' 03/91-06/91.

12

f'

'i

10. _ No flaws were found. -

2.3.7 Evaluation and Recommendations As a t'esult of extensive piping replacement programs and MSIP treatments, all except 11 of the 198 velds at Dresden 3 are classified as either IGSCc Category A or IGSCC Category C, pr~viding that the IGSCC classifications that have been assigned are accepted. Acceptance of classifications of velds between two castings as IGSCC Category A (as discussed in Section 2.3.4) is recommended since it.is a natural

  • ext~nsion of the NRC StE!f:f position outlined in parag~aph*

( 2), page 5 of Gene.ric Letter 8~01. Classification of other welds follows NRC Staff guidelines and should be accepted.

  • Previous inspections also followed NRC.Staff guidelines.

2.4 Current Plans for M~tigating. Actions 2.4.1 Commonwealth Edison's Position The CE Submi.ttals do not list any spec:l.fic plans for future mitigating actions excep~ that implementation of Hydrogen Water Chemistry.is'belng considered and that (as indica~ed in Table.I) additioqal mitigating actions will be applied

-as nee.ded.

2.4.2 Evaluation of Conformance to Staff Positions and Recommendation Commonwealth Edison has followed the guidelines of Generic Letter 88-01 and NUREG 0313, Revision 2 with the extensive mitigating actions that have already been applied at Dresden

3. The result is that all except 11 of the welds have either 13

r.

been replaced _or stress improved. Hydrogen_ Wa_ter Chemistry, __

if it is implemented, will further reduce the possibility of IGSCC.

In addition, as discussed in Sections 2.3.6 and 2.5, an inspection program has been implemented that follovs the guidelines of Generic Letter 88-01 andNUREG 0313, Revision 2. Thus, acceptance of Commonwealth Edison's position is recommended.

  • ~ 2.5 Plans for Future Inspections Commonwealth.Edison stated that an augmented inspection program-will be conducted at Dr.esden-3 beginning in the December, 1989 Refueling Outage as.outlined below.
  • 2.S.l Summary of Inspection Schedule CE Submittal No *. :'1 st~tes that the inspection schedules for.

Dresden 3 are being revised to reflect the requirements.for inspection schedules as delineated* in* NUR,EG 0313, Rev:f,sion 2_ and Generic Letter 88-01 *with the exception of the one inaccessible IGSCC Category G weld that is discussed below.

Common~ealth Edison included a summary of the inspection plans.for the next two refueling outages (Refueling Outagell scheduled for 11/89 and Refueling Outage 12 sch~duled for 3/91) which is summarized_ in Table 3,along

  • with the past inspections discussed in Section 2.3.6. In addition, Table 3 contains the requirements for inspection schedules as delineated in Generic Letter 88-:-01 and NUREG 0313, Revision 2. Commonwealth Edison, in presenting these schedules; also included the following statement.in CE Submittal No. 2:

"It should be noted that future inspection schedules, 14

l j.

I.

I

  • ** may be subject to change.

However, at all times, Dresden Unit 3 will continue to meet the inspection schedules of the IGSCC categories as presented in Generic Letter 88-01."

Note that the number of velds of each of the various IGSCC Categories that are scheduled for inspection follows the guidelines presented in Generic Letter 88-01. This demonstrates that Commonwealth Edison has f ollo~ed 'the NRC Staff position on schedules in the development of the augmented inspection program for Dresden 3.

2.5.2 Inaccessible Welds Dresden.3 contains two inaccessible welds.

One of these (Weld No. RWC-09FN in the Reactor Water Cleanup System) is an IGSCC Category ~ weld.

The other (Weld No. 14-BN) is

      • an IGScc* Cat~gory G weld located inside the contaiIUJ!ent penetration assembly on the Isolation Condenser Supply piping.

Acoustic emission monitoring at this location is under

.investigation *

. 2.5.'3 Methods and Personnel

  • .I The augmented inspection pr.ogram will be conducted using methods and personnel in conformance.with the NRC Staff positions as delineated.in Generic Letter. 88-01 arid NUREG 0313, revision 2 *

-. 2. 5. 4 Sample Expansion CE Submittal No. 1 states that the Sample Expansion in the augmented inspection program will conform to the NRC Staff position as delineated in Generic Letter* 88-01.

15

  • .... )_

2.5.S Evaluation and Recommendations The inspection plan for Dresden 3, including schedule (as shown in Table 3), methods and personnel, sample expansion, and in~ccessible welds conforms with the NRC Staff position.

Thus, acceptance of Commonwealth Edison's plan is recommended.

2.6 Changes in the Technical Specification Concerning IS!

Commonwealth Edison proposed an alternative position to the NRC Staff posi*tion concerning a change to the Technical Specification.

This alternative position is discussed in Section 3 of this report.

2. i Confirmation of Leak Detection in the

- Technical Specification

'.~ ;

, *Table 4 of this *report, which was constructed from a similar table cqritained in CE Submittal No. 2, summarizes Commonwealth Edison's posit~ons on the various requirements for leakage detection as delineated in Generic* Letter 88-01.

Note that Commonwealth Edison stated that portions*of the J)resden 3 Technical Specification pertaining t9 leakage are in conformance with the NRC Staff position (or will be revised to be in* conformance with the NRC Staff position)', but they pro~osed alternaUve positions concerning other. -*

portions. * *Thus, discussion of leaka$e detection is* def erred. to Section 3 of this report, "Alternative Positions and Exceptions."

16

i.
  • ~--------*-*-- -*-------**

Table 4 Licensee Positions on Le~ge Detection Position

1. Conforms vi.th Position C of.

Regu~atory Guide 1~45 *

2. Plant shutdown should be*

initiated when:

(a) vit~in any _period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />

. or less, an increase is indicated in the.rate* of

. unidentified leakage in.

excess of 2 gpm, or

(~) the total unid~ntified leakage attains a.rate of 5 gpm.

3. Leakage monitored at four hour intervals or less.:

4.. Unidentified leakage includesa11*

_except:

(a) leakage into closed sys~ems, or (b) leakage into the *containment atmosphere from sources *that are located, do not interfere ll.'ith monitoring systems,.or not from throughwall crack.

5. Provisions for shutdown Within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> due to inoperable.measurement

. instruments in plants with Category D, E, F, or.G welds.

Already Contained in TS
  • ye~.

TS will be Changed to Include yes yes yes (a) See text for discussions concerning alternate proposals.

17 Alternate(a)

Position Proposed yes yes

. yes

'r.. -

l L

~;. *'

. 2.8-Plans--for Notification of the NRC of Flaws*

2.8.1 *commonwealth Edison's Position.

CE Submittal No._ l states that.the NRC Will be notified of flaws in.accordance.with the NRG Staff position as delineated in Gen~ric Letter 8$.;-01 *. -Additionally, notification will be provided of the evaluation by the Commonwealth Edison Engineering.. D_ep~rtment.for the* con(litions for continued

_c operation and/or the necessary corrective action to be taken *.

. ; Notifica.tion will be madE!! by the Consolidated E.d.ison Nucl_~ar Licensing Depa.rtment -to the--appropriate NRR project *manager.

. 2. 8. 2 Evaluation. and Recommendation *:

The Commonwealth Edison plans_ to comply:with the NRC Staff position, so it* is rec.o!Dniended that th~ plans for report;lng

~.:,.

of f l~ws should be accepted.

3. ALTERNATIVE POSITIONS AND EXCEPTIONS *.

. 3.l:Alternative Position Concerning ISI in -the Technical Specification 3.1. 1 Commonweal th Edison's* Position The CE Submittal states that since the Station is currentiy --.

reviewingand revfsing the Technical, Specifications under the Dresden Station I~provement Program.:__ Technical Specification Action Plan, that a statement _insuring compliance with.the IS! provisions of Generic Letter 88-01 will. be *included in the Dresden 3 !SI program.*

18

  • -~

.. ' -~ ~.

'1_,.,

~,.,-.. ~.. _

l J I..

3.1.2 Evaluation and Recommendation Generic Letter 88-01 discloses that the Inservice Inspection and Te~ting Se~tions may be removed from the Technical Specifications and included in the Inservice Inspection Program in the future (as proposed by Commonwealth Edison).

. Despite this consideration, the NRC Staff~ specifically included a reqpirement in Generic Letter 88-01 to change the Technical Specification to include a stateme~t that the section on ISI will conform with the NRC Staff position on schedule, methQds and personnel, and sample expansion. Thus rejection of the Commonwealth Edison position is recommended.

It is further recommended that Commonwealth Edison should amend the Technical Specification on ISI for Dresden 3. to include a statement that the ISI program will conform with the NRC Staff pos~tioq as delineated in Generic Letter 88-01.

3.2 Leakage Detection in the Technical Specification CE Submittal No. 1 states that certain exceptions concerning the NRC Staff position on leakage detection are.needed to avoid unnecessary.plant modifications or unnecessary restrictive operating_

  • conditions at Dresd.en 3. These* exceptions:, as stat~d in CE Submittal No. 1, are as follows:

(1) "Individual identified leakage is not flow-metered, but all identified leakage is collected and conducted to a separate collection system from unidentified leakage. Total identified leakage is monitored via the drywell'equipment drain sump pump discharge flow totalizer meter....

(2) "Sump operability is defined by the statio~ as the ability to.measure reactor coolant leakage rather than strictly 19

r i

J

  • -.')'.

.. depending on the operability of a*leakage measurement instrument. Since only one channel exists for unidentified leakage monitoring, strict compliance with the staff

  • positions wili 1;1ot occur."

(3) "Increase in unidentified leakage shall be 2 gpm over the previous 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average will preclude shutdown due to variations in measured coolant leakage between 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> intervals."

In response to a Request for Additional Information (RAI) concerning alternate methods of measuring reactor coolant leakage rather than strictly depending on leakage measurement instrument, Commonwealth Edison replied in.CE Submittal No. 2 as follows:

"The abilif.Y to measure reactor coolant leakage can be accomplished by using sump pump flow recorder, timing the

.duration of pump operation or monitoring the input.into Rad Waste."

"Each sump pump's flow rate is recorded in the main control room on a chart recorder.

By integrating the area under the pen trace over time~*the total.flow can be calculated. The accuracy of this determination.will be less than 90%; however,.

the integraFion can be conservatively performed to d~termine a bounding value for leakage."

"In a similar way, the duration of sump pump operation* can 1 be timed.

A flow rate can be multiplied by the eiapsed time to determine flow~ The flow rate can be chosen to bound previous.~flow rates recorded on the control room recorder."

"The sump pumps input into the Waste Collector Tank in the' Rad Waste system.

By reading the tank level increase at the 20

i

    • time of -sump-pump operation, t:}le-leakage can *be-.dett=fnilined.

Because the relative error of this method.is greater than 20%,

this method could be used to ~ubstantiate the two methods previously described. u*

  • Commonwealtl) Edison's. response to the RA! (CE Submittal No. 2) also included information used to construct Table 4 of this report which shows that s_ome of the r_equiremerits concerning leakage

... detection as delineated in Generic Letter 8~01 are currently

.contained in the_Dresden'3 Technical Specificati_ons, others viil be i~corpo~ated into the Tecllliical* Specifications,- and th~y pr.oposed alternative positions (exceptions) concerning9thers. Additional discussion concerning leakage detection.. arE!. conta_ine.d in the *

  • f ollorlng sections. :

... ~.,2.1 Coriformance'With Regulato~y Guide 1.45

~* _..

  • <:;,eneric*'Letter 8~01 !iltates:

'~Leakage* detection syste~ should be in ~onforinance with Position. C of Reg~lat~ry.Gui<<ie 1. 45 'Reactor C~olant gressure Boundary -~eakage

  • d~tection Systems., ', or* as
  • otherwi,se previously ~pproved by the NRC~"

CE.Submittal.No. 2 contains the following.statements:

"Reg. Guide 1.45 Position. C.S states: 'The sensitivitt and response time of each leakage detection system in

  • : regulatory positio~ 3 above *e1Dp~oyed for unidentified

'leakage ~hould be ad~quate to detect. a leakage rate,.

or* its equivalent, of one gpm in less ~ban one hour.'

_The.discussion regarding this position further clarifies this point. It states in part: 'all det~ctor systems should respond to a one gpm, or its equivalent, leakage 21.

.. *~.

j increase in one hour.or less.'"

"Identified and unidentified leakages are measured by

.determining the amount of water pumped from the Drywell Equipment Drain Sump and Dryweil Floor Drain Sump from flow totalizers. The amount of water pumped divided

  • by the time interval between pumpdowns equals the leakage rate. Pumpdowns occur.at four hour intervals by manual P.ump actuation. The other detection methods th~t fulfill regulatory position 3, airborne particulate radioactivity monitoring and monitoring of airborne gaseous radioactivity, are also accomplished by.manual actions."*

"The leakage detection systems are not able to detect

  • a one gpm,leakage increase in ~me hour or less. However, indirect.indications such as priinary containm~nt temperatur~.and.pressure have short. response tim~s to React<?!. Coolant Pressure Boundary le~ge.".
  • ']Reg.* Guide.Position 6 states: *'~!! leaka$e detection.

systems sho.uld be capable* of.performing their functions following seismic events that do not require plant shutdown.

The airborne. particulate radioactivity

.monitoring syste~*should remain functional when subjected.

to the* SSE."'

.I "The piping* system from the dr~ell sumps to RAD Was~e is not seismically designed.

  • The airborne particulate radioactivity monitor and the gaseous radioactivity
  • monitor are.seismically designed. The monitors are part of th.e High Radiation Sample System implemented* to meet NUREG 737 item II.B~3."

22

.~.

r

~*

J

.:.3.3.2 -Leakage Limits.

Generic Letter 88-01 states:

_i "Plant shutdown should be initiated for inspection and.

correc;tive action when, within any period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or iess, any leakage detection system indicates an increase in rate of unidentified leakage in excess of i gpm or* its equivalent';* or when the total unidentified leakage attains a rate of *s gpm or equivalent, whicllever occurs first."

Note from Table 4 that the Dresden.3 Technical Specifica~ion contains requirements that conform with th.e NRC Sti!ff positiol'!

concerning the 5 gpm total unidentified leakage. However, both. of. the CE.,Submittals contain the folloWing state11,1ent:

  • ~'The increase in. un~dentifi~d leakage shall* be 2 gpm

.over the'previou~ 24. hour averag~. The :24 hour average Will preciude u~it.shutdo\\fll. due to* variations in measured reactor coolant *leakage betwe*en 4 *hour,, intervals."

3.3.3 Frequency of Leakage Monitoring Gen~ric tette~ 88-01 states:

"For sump level monitoring sys.tems with fixed-measureme~t-

  • i~terval methods, the level should be monito.red at appro~iinately 4-hour intervafs;or less."

Note from Table 4 that Commonwealth Edison proposes an alternative position on this,item.

CE Submittal No. 2 states the following:

23

,.. *~

I

  • ~

"Leaicage-wiil be monitored at approximately four hour

  • inte~vals; a sinall interval tolerance will avoid technical...

specification violations while still maintaining a conservative surveillance interval.".

3.3.4 Definition of Unidentified Leakage

. Generic Letter 88-01.states:

"Unidentified leakage should include all leakage other.

that\\:* {a)- leakage into closed systems, such as pump seal or.valve pack~ng leaks that are* captured, flow metered, and conducted to a sump or collection tank, or (b) le~ge into the~ containment_ atmosphere from:sources that_ are both specifically located and known e_ither not to i~tetf ere with the operations of unidentified leakage

  • monitoring systems or not.to be from a :~hroughwall crack ip the piping within the.re~ctor coolant pressure boundary."

As. indicated* in Table 4,. the Dresden 3 Technical Sp.ecification conforms.with this position. CE Submittal *.No. 1 contains the following clarifying remark:

  • '. ~-.

"Individual identified leakage is not flow~metered, but all identified leakage iscqllected and conducted to a separate c<:)llection system from unidentified leakage~..

  • *Total identified
  • ie~kage is monitored via the. drywell equipment drain sump p_ump discharge-flow totalizer meter."

... 3. 3. s. Operability of Mo_ni toring Instruments

.~

l:

  • *Generic. Letter 88...,0l states:

24

r.:-"

- "For plants operating With any IGSCC Category D, E, -F, or G welds, at least one of the leakage measurement instruments associated with each sump shall be operable, and the outage time for inoperable instruments shall be limited to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or immediately initiate an orderly shutdown."

As indicated in Table 4, tjle Di-esden 3 T~chnical Specification will be amended to include* this requirement.

3.2.6 Evaluation and Recommendations Commonwealth* Edison's.position concerning compliance with Regulatory Guide L45 is dictated by limitations of plant facilities, so acceptance of this position is recommended.

Commonwealth Edison's positions concerning limits on the total unidentified leakage of 5 gpm, description (or definition) *of unidentified leakage, and operability of leakage monitoring instruments are in compli.ance (or will be changed to be in,.compliance) with the NRC Staff positions *.

Thus, acceptance of these positions are recommended.

Commonwealth Edison's position concerning frequency of leakage measurements is within the intent of.the NRC Staff position, so acceptance of Commonwealth Edison's position on this item is recommended.

However, concerning the requirement for limiting the increase of the unidentified leakage to 2-gpm

over a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period, Commonwealth Edison's proposal to use the 24.hour average is less restrictive than that required in Generic Letter 88-01. Thus, rejection of this position is recommended.

Commonwealth Edison should amend the Dresden 3 Technical Specification to limit the increase of unidentified leakage to 2 gpm over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (rather than 25

r over the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average)~

j 3.3 Welds Excluded from IGSCC Program

  • --=

3.3.1 Scope.of Generic Letter 88-01 Generic Letter 88-01 defines.the extent of its applicability as follows:

"This Generic Letter applies to all BWR piping made of austenitic stainless steel that is {our inches or lareger in nominal diameter and contains reactor coolant at a temperature above 200°F during power operation regardless of Code classification. It also applies to react0~ vessel attachments 8n appurtenances such as j*e~ pump instrumeri.tati_on penetration assemblies and head spray arid "ven~- components."

3.3.2 Commonwealth Edison's Position In response*_ to a question in a Request for Additional Information (RAI)' concerning whet~er any welds within* this scope of applicability had been omitted from CE Submittal No. 1, the following statement was*.provided in CE Sµbmittal..

No. 2:

"The submittal in response to Generic Letter 8&-01 for Dresden Unit 1 included all ASME Code class i, 2, 3.Piping.

welds made of,austenitic stai~less steel that are four (04) inches or larger in n.omin~l *diameter ~d contain reactor coolant at a temperature above 200 degerees* F during power operation."

26

  • r.

\\...

t.1.

I.

i. i

  • "Non-'ASME Code stainless steel piping-velds were NOT included in the submittal b~cause they were considered to be outside the defined scope of Generic Letter 8801.

The phrase'regardless of Code classification' used in Generic Letter ~l (on page 2) is interpreted to limit the scope of applicability to piping which has been classified as ASME Code Class 1,2, or 3 for Inservice Inspection. The stainles~ steel velds in the Reactor-Water Clean-Up (RWCU) system aownstream of the outboard isolation valve are NON-4SME Code and Non-safety related."

3.3.3 Evaluation and Recommendation Commonwealth Edison had incorre~tly interpr~ted the scope

  • .. of welds covered by Generic Letter 8~1. The phrase, "regardless. of Code clas~if ication" means that neither code related nor non-code related welds should be.excluded unless they are excluded by the size or temperature requirements.

Thus,.rejection of Commonw~alth Edison's.position is.

  • recommeded. It is further recommended that Commonwealth Edison should'revise their IGSCC.program to include the RWCU welds. that are downstream o~ the isolation valves that are 4 inches or larger in diameter. and operate.at temperatures a.hove 200°F. * -
4. CONCLUSIONS AND RECOMMENDATIONS Concerning the thirteen NRC Staff positfons: l,!S delineated in Generic Letter 88-0f:* Commonwealth Edison*endorses. most of t]:ie thirteen NRC Staff positions, but they applied.provisions to the NRC Staff positions concerning ma.terials (specifically, the IGSCC classif !cations of welds between castings and inspection schedules for those wel~s) and concerning crack evaluation and repair criteria (that a favorable stress 27

~**

~

L distribution_resultin~ from stress improvement would be incorporated in calculations for stress improved welds).

In addition, Commonwealth Edison proposed alternatives,to some of the provisions outlined in Generic Letter 88-01 pertaining to leakage detection.

Commonwealth Edison excluded certain welds ~rom their IGSCC program.

Specifically, the portion of piping in the RWCE that is outboard of the isolation valves was omitted.

An incorrect interpretation of the scope of Generic Letter 88-01 (i.e., that.the scope is restricted to.

code related pipi~g) was the basis for that oiDission.

Extensive programs of piping replacement programs and application of stress improvement (utilizing MSIP) have been conducted at Dr~sden 3 with the result that ail-except 11 of the welds within the scope of Generic Letter 88-01 are classified as either IGSCC Category A or IGScc* Category C.

Pla~s for future mitigating actions incl~.de *possible.:

implementation of Hydrogen Water Chemistry and* replacemen_t and/or repair of welds (usirig NRC Staff approved processes) as needed. In the assignment of the IGSCC classifications.to welds between castings; Commonwealth Edison interpreted the guidelines of Generic.Letter ~~Ol to apply IGSCC Cate~ory A classifications to these welds.even though

.. they contain > 0.035% carbon. The.assignment of IGSCC classifications has followed the guidelines of Generlc Letter 88-01.

An Inservice Inspection program (ISI) has been developed for Dresden 3 which complies with the requirements of.Generic Letter*BS-01 pertaining to schedule, methods and personnel, sample expansion, reporting of flaws, and plans for inaccessible welds. The specif.ic welds sd1eduled for inspection during the next two refu~ling. outag_es were listed, although Commonwealth Edison stated that.these schedules*

were.. only tentative and may change as circumstances dictate. In the event of schedule changes, however, Common~ealth Edison stated that.

they would still follow. the_ guidelines of the NRC Staff position as delineated in Generic Letter 88-01~

28

"tr --

L Commonwealth Edison declined to change the Technical Specification on ISI to include, as required by Generic Letter 88-01, a statement that the IGS program will-follow the NRC Staff position on inspection schedules, methods and.personnel,_and sample expansion. Rather they proposed to include such a statement in the ISI Program.

Such action

.was specifically rejected in Generic Letter 88-01.

The Dresden 3 Technical Specification c9ntains (or will be changed

    • to contain) the provisions recommended *by the NRC *staff pertai~ing to limits on.the total :unidentified leakage of 5 gpm, descriptions

(_or definition) of unidentified leakage, and operability of leakage monitoring instruments. Commonwealth presented an alternate proposal concerning frequency of leakage meas.urements (i.e.; that they will monitor leakage at approximate).y 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> intervals)._* This is actually

. within the intent of the NRC Staff.

. *. ~.. '

Commonwealth Edison p~oposed tw_o o.ther alternati~e position~- concerning leakage :detection: (1) *.Concerning the NRC Staff position on liiiliting '

any increase of unidentified leakage to 2 gpm_during a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period l

or less~ they prop9sed using the average oyer a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period). This is un~cceptable because it is less restrictive than the* NRC Staff.

positio:n *. (2) Devia~ions from stri~t complianc*e *with some items _in Regulatory_Guide 1.45 were proposed by Commonwealth Edison. These deviations are dictated:by *limitations of plant facilities.

I

. *: ~....

  • _/.

-As a result of this technical evaluation, the-foiiowing recoinmendations are made.

-(1)' Rejection of Commonwealth Edison's position which excludes

  • welds iri piping in the portions of the RWCU that is'outboard of the isolation valves. Commonwealth Edison should revise the IGSCC program for Dresden 3 (includ.ing inspection schedules) to include this portion of piping.

29

L J

I j

  • (2) Acceptance of Commonwealth Edison's IGSCC classifications of -

welds at Dresden 3 that are inboard of the isolation valves.

(3) Acceptance of Commonwealth Edison's position on the IGSCC. ISI Program for welds at Dresden 3 that are inboard of the.isolation valves,* including schedules, methods and personnel, and sample.

  • expansion.

(4) Tentative a,cceptance of Commonwealth :Edison's plan for acoustic*

emission monitoring of the inaccessible weld, pending finalization of their plan.*

(5) Rejection of Commonvealth Edison's position concerning changes to the Technical Specification on ISI~ The Technical Specif~cation.should.be amended to include the statement on IS! as required by Generic Letter 88-01.

(6) Rejection of CommQnwealth Eqison's position concerning

. liniitations of an increase of unidentified leakage *.. The Technical Specif !cation should be amended. to includ~

req~ir~ments f.or plMt shutdown when, wit:Jiin My.period of 24 h~urs or l~ss'. a~y leakage detection system indicat_es an.

increase in r~te of unidentified leakage i~ exces~ of 2 gpm or its equivalent (rather than the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average as proposed *

. by Co,mmonwealth Edi~on).

( 7.) Acceptance of other p0,rti9ns of Commonweal th Edison's position

. -._ ~.

on leakage detection...

(8) Acceptance. of the rema*ining portions of the CE Submittals *.

30

J I

1

  • I I;

i *.

/;

I

~

5.
  • REFERENCES
1. "Technical report on Material Selection and Processing Guidelines for BWR Coolant Pressure Boundary Piping," NUREG 0313, Revision 2, U.S. Nuclear Regulatory Commissi()n, Of.fice of Nuclear Reactor Regulati_on, January, 1988.
2. "Investigation iµid Evaluation of Stress-Corrosion Cracking in Piping of Light Water Reactor Plants," NUREG.0531, U. S. Nuclear Regulatory Commission, February, 1979.

3 *. "NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping,"

Generic Letter 88-01, U.S. Nuclear Regulatory Commission, January 25, 1988.

31

Retrieved from "https://kanterella.com/w/index.php?title=ML17252A595&oldid=5111289"