ML20077A698
| ML20077A698 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 04/29/1991 |
| From: | Richter M COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| GL-88-01, GL-88-1, NUDOCS 9105100337 | |
| Download: ML20077A698 (4) | |
Text
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Ctmmtnwealth Edistn
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j/E 1400 Opus Place
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> Downers Grova, Illinois 60516 J
April 29, 1991 Dr. Thomas E.-Hurley, Director Office'of Nuclear-Reactor Regulation U.S.. Nuclear-Regulatory-Commission Hashington, D.C, _
20555 Attn:
Document Control Desk
'I
Subject:
Quad Cities Nuclear Power Station Units 1 and 2 Response to Safety Evaluation Report for Generic Letter 88-01 NRCJo.c tatloL._50-15La.nL50-265 '
1
References:
(a)
--L. Olshan (NRC) letter to T. Kovach~
l (CECO), dated _ August 21, 1990.
-(b)
=H. Richter (CECO) letter to T. Murley (NRC),-dated October 19,-1990.
'Dr. Murley:
Reference (a) transmitted the Nuclear Regulatory Commission's (NRC) safety evaluation of_ Generic Letter _88-01 (Generic Letter), NRC Position of
'Intergranular Stress Corrosion Cracking (IGSCC) in BHR Austenttic Stainless Steel Piping,1for_ Quad Cities Station Units 1 and 2.
. Additionally, Reference (a) requested Commonwealth Edison _ Company-(CECO) to_ modify-theLInservice Inspection-(ISI) Program for Units 1 and 2 to address the Reactor Water Cleanup;(RHCU) System-pt. ping outboard-of the isolation valves.. Reference'(b)
~1nformed your staff that CECO.was evaluating the impact of incorporating!the RHCU System piping outboard of the isolation valves into_the ISI. Program.
-This letter presents'the results of'that evaluation, and the current plans for
=the RHCU_ piping for-Units 1_and 2?
For the evaluation, a study:was performed (specific to Dresden Station) to determine the optimum-IGSCC mitigation technique / alternative ~(based on cost and dose considerations) for-the RHCU piping outboard of'the isolation valves which is within the' scope of the. Generic Letter.
Although the current study wasL"Dresden-specific", the results al.so pertain-.to Quad Cities Station based on,the-similar.ity'of.the RHCU outboard-piping applicable to the. Generic. Letter.
.As shown on Figure 1, the sections of RHCU_ piping within the scope of.
the Generic Letter extend from outboard isolation valve 1201-5 up to and
-including the regenerative heat exchangers, the interconnecting piping-between
'the: regenerative-heat exchangers, and the interconnecting piping between the regenerative and non-regenerative-heat exchangers.
Additionally, the return
. piping from the. regenerative heat exchangers up to valve 1201-81 is included in'the scope of the applicable piping.
There are approximately=160 welds in this piping for each. unit.
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Dr ;T.E', Murley. April 29, 1991 Some of'the'IGSCC' mitigation alternatives which were evaluated included:
performance of IGSCC inspections in accordance with the Generic Letter; with expansion assumptions and anticipated weld repairs
'(utt11 zing the weld overlay technique) based on previous inspection results of.RHCU inboard piping.
performance of weld overlays on all welds over a two outage period, with no IGSCC inspections performed prior to application of the weld overlays.
J replacement of IGSCC susceptible piping, with no IGSCC inspections performed-prior to pipe replacement.
The;results of the study.("Dresden-specific" study) concluded _that pipe replacement was the optimum mitigation alternative (based on cost and dose
. considerations) for the RHCU piping.
Based on those results. CECO is pursuing the. replacement ofci-he subject RHCU piping (shown on Figure 1).
Additionally, CECO is investigating potential upgrades to the equipment (heat exchangers and val..ves) associated with the subject : piping. - At this time, _ the required company 1 assessments are being performed in order to budget the necessary funds for-the-pipe replacement project. - It is expected _that final budget approva; ifor this_ project will.be obtained by October 1991.
In the event that the required funding cannot.be obtained,-your staff will be notified and an inspectlon program will'be proposed,
'It.should be noted that the subject RHCU piping is not scheduled for
}IGSCC inspections prict to replacement.
The dose penalty factors, estimated-
- total exposure, and man-hour estimates which were utilized in the evaluation of:the pipe replacement alternative we.re_ predicated'on this assumption--(no JIGSCC.)nspections-prior to pipe' replacement). Although no IGSCC-inspections i
are planned pri.or to pipe' replacement,-existing instrumentation (area-temperature monitors)-is available to provide notification in the event of 3
=RHCU System leakage.
Based _on_ preliminary engineering, the'_RHCU piping replacement for each
~
unit-is_being scheduled over'a two refueling _ outage period.
At this time, pipe replacement between the refueling.-outages-is not' anticipated (due to dose-considerations); however, it.is expected that.in excess of thirty percent (307.) of the ~ piping will be' replaced during the first/ initial refueling'~
outage. 'The current schedule =for pipe replacement, which takes into account (the expected lead time required for engineering.and material-procurement, 1s-ipresented below for each unit.
It should be noted that the expected dates for these refueling outages may be subject to change.
Unit 1 - January 1994 refueling outage =(Q1R13)
Fall 1995 refueling outage-(Q1R14) r Unit 2 - Spring 1993 refueling outage (02R12)
Fall _1994 refueling outage _(Q2R13) l
{
-ZNLD/861/15
Dr. T.E' Murley April 29, 1991 Please contact this office should further information be required.
Respectfully, J
JJ.
M.H. Richter Nuclear Licensing Administrator figure 1:
Simplified Diagram of Reactor Hater Cleanup System cc:
A.B. Davis - Regional Administrator, Region III L.N. Olshan - NRR Project Manager T.E. Taylor - Senior Resident Inspector, Quad Cities ZNLD861/14-16 l
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l ZNLD/861/16 l
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FIGURE 1 Simplified Diagram of Reactor Water Cleanup Systen Drywell rron 1201-5 p
Filter p
g,._ n _p_-___.7-W _
_.enineralizers from i
e 8
Reactor Recire1f y
System J L A
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.g _.__ g _k___--_---__y- @ ---
---p<1><}---
c---
1201-81 8
Regenerative Ilon-Regenerative t
Heat Exchangers Heat Exchangers 8
to Feedwater I
________g_
p Systen e, _
t a
1 i
I 1r
's_-__ p --
><t><}--
,g
-s x
nup 1F to
,4 A
Filter Punp ranineralizers
><3 Cleanup Line Ilumbers of applicable outboard piping:
><l Recire W
1203-4"-A J205-4"-A 1206A-4"-A Punp 1203C-4"-A 1205A-h"-A 1206B-h"-A 1203D-h"-A 1205B-h"-A 1262-6"-A
--- : Outboard piping within the scope of 12121-h"-A 121?3-h"-A f
IiOTE : Diagram is applicable to Units 1 and 2.