ML20207J852
| ML20207J852 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 09/20/1988 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| IEB-88-008, IEB-88-8, ULNRC-1834, NUDOCS 8809280145 | |
| Download: ML20207J852 (7) | |
Text
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I901 G:soct 5'et Pest 0%:a &< 149 St icws. *.t nM 01EC 114 554 26$0 UVTON 8"" 8d""
Euscnuc
'd3 September 20, 1988 U. S. Nuclear Regulatory Commission ATTN:
Document Control Desk j
Mail Station Pl-137 Uashington, D.C.
20555 Gentlcment ULNRC-1834 I
DOCKET NO. 50-483 i
CALLAWAY PLANT i
THERMAL STRESSES IN PIPING CONNECTED l
TO RE.TCTOR COOLANT SYSTEMS l
References:
1)
NRC Bulletin 88-08, dated June 22, 1988 l
2)
NRC Bulletin 88-08, Supplement 1, dated l
June 24, 1988 3)
Supplement 2, dated August 4, 1988 NRC Bulletin 88-08, Action Item 1 required Licensocs to perform a review of plant systems and determine whether any unisolable sections connected to the RCS might be subjected to stresses from temperature stratification or temperature oscillations that could be j
induced by leaking valves.
This review has been performed and the results have been included as an attachment to thks letter.
N If there are any questions concerning this letter, please contact me.
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Very truly yours, r
t Donald F. Schnell
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Attachment t
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l 8809280145 880920 PDR ADOCK 05000483 Q
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STATE OF MISSOURI )
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Donald F.
Schnell, of lawful age, being first duly sworn upon oath says that he is Senior Vice President-Nuclear and an officer of Union Electric Company; that he has read the foregoing document and knows the content thereof; that he has executed the same for and on behalf of said company with full power and authority to do co; and that the facts therein stated are true and correct to the best of his knowledge, information and belief, m
By
/
Donald F.
Schnell Senior Vice President Nuclear SUBSCRIBED and sworn to before me this 88[ day of n/u; 1987 9 lAG FAk!3 ARA f'Fl AFF M g h0TARY cuatt;, STME CF WSSOURI MY CCMW;350N DP:RES APRIL 22, 1984 ST. Louis COUNTY
cc:
Gerald Charnoff, Esq.
Shaw, Pittman, Potts & Trowbridge 2300 N. Street, N.W.
Washington, D.C.
20037 Dr. J. O. Cermak CFA, Inc.
4 Professional Drive (Suite 110)
Gaithersburg, MD 20879 R. C. Knop Chief, Reactor Project Branch 1 U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 Bruce Little Callaway Resident Office U.S. Nuclear Regulatory Commission RRil Steedman, Missouri 65077 Tom Alexion (2)
Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 316 7920 Norfolk Avenue Bethesda, MD 20014 Manager, Electric Department Missouri Public Service Commission P.O. Box 360 i
Jefferson City, MO 65102 f
U.S.
Nuclear Regulatory Commission
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ATTN Document Control Desk Washington, D.C.
20555 l
I
Attachmont to ULNRC-1834 Page 1 of 4 NRC BULLETIN NO. 88-08 THERMAL STRESSES IN PIPING CONNECTED TO REACTOR COOLANT SYSTEMS A review has been performed of the Callaway Plant systems to determine whether any unisolabic sections connected to the RCS
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might be subjected to stresses from temperaturo stratification or temperature oscillations that could be induced by leaking valves (NRCB 88-08, Action Item 1).
Consideration was given to piping geometry, valvo configuration and lineup, and pressure and temperature differences betwoon the RCS and the connected system.
~
One potential location has been identified.
This connection is the auxiliary pressurizer spray line, BB-81-BCA-2", which is isolated from the normal RCS charging flow by a normally closed globe valve and a check valvo.
The operating conditions upstream of the globe valvo are approximately 516' E and 2300 psig (normal i
charging conditions) and the conditions downstream of the check valvo are the normal spray conditions, approximately 558' F and 2235 psig.
A situation could exist (similar to Farley Plant) where the pressure difference causes the isolation valve to leak i
and release cooler water (relative to the normal spray) past the i
check valvo creating a thermal stress.
Therefore, linc BB-81-BCA-2" will be inspected during the next refueling outage using non-destructive examinations (NRCB 88-08, Action Item 2).
NDE's of the nozzle area and the high stress location (wolds, j
heat affected zonc and base metal) will be performed.
NDE i
methods and techniques are being ovaluated to determine the most offective approach for this application.
For the long term, i
these NDE's will be performed during each refueling outage to provido assurance that no fatigue failure has occurred due to I
combined cyclic and static thermal stresses (NRCB 88-08, Action Item 3) and this line may be added to the Callaway ISI Program.
Should a flaw be detected, the piping will be repaired por ASME Section XI and the isolation valve will be leak rate tested and repaired if required.
i All other unisolabic RCS connections are considered to be precluded from the conditions of thermal stress as outlined in NRCB 88-08 by one of the following situations.
First, leakage is prevented by the use of double isolation valvos in some lines, contrary to the configuration at Farley where a single isolation valve 1 caked to establish thermal oscillations.
The second 1
situation is found in lines that have continuous flow during i
normal operation.
These lines have sufficient flow to climinate thermal cycling and stratification.
Third, some lines have f
insufficient pressure differential across the isolation valve to drive leakage of cooler water into the unisolabic section of l
pipe.
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The following table lists the Callaway RCS connections and l
the applicability of the Bulletin to cach.
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CALLAWAY RCS CONNECTIONS Potential NRCB 88-08 Description Location Justification Cold Leg Connections:
l Auxiliary pressurizer spray Yes Potential leak path line BB-81-BCA-2".
through one normally closed globe valve and one check valve from the regenerative heat exchanger to the main spray line with an approximate pressure difference of 65 psi and a temperaturo difference of about 40' F.
SIS boron injcetion lines BB-05-BCA-1 1/2" (loop 1),
BB-24-BCA-1 1/2" (loop 2),
BB-40-BCA-1 1/2" (loop 3),
BB-59-BCA-1 1/2" (loop 4),
- from BIT bypass (similar No Isolation provided by to Farley) 2 normally closed globo valves in line from the charging pumps to the RCS (compared to Farley Plant with only one isolation valve).
- from normal BIT path No Isolated by 2 normally clesed gate valves from the charging pumps.
CVCS normal charging, line No Continuous flow through BB-04-BCA-3" (loop 1),
normally open valves, therefore no cycling or stratification offect.
Safety injection accumulator No Insufficient driving head lines BB-02-BCA-10" (loop 1),
to inject into the RCS DB-22-BCA-10" (loop 2),
during normal operation; BB-39-BCA-10" (loop 3), BB pumps normally not BCA-10" (loop 4), from running; backflow from l
accumulator tanks, RHR pumps the RCS is provented by l
and SI pumps.
2 check valves in cach I
line.
l Pressurizer spray, lines No Continuous flow through BB-03-BCA-4" (loop 1) and normally open valves, BB-23-BCA-4" (loop 2).
therefore no cycling or stratification effect.
Page 2 of 4
CALLAWAY RCS CONNECTIONS (continued)
Potential NRCB 88-08 Description Location Arguments CVCS alternato charging, lino No Insufficient pressure BB-57-BCA-3" (loop 4), has difference (approximately 2 check valves and one 15 psi) to drive normally closed globe valvo
- leakage, from the cold leg to the regenerativo heat exchanger.
RTD manifold lines No Continuous flow through BB-16-BCA-2" (loop 1),
normally open valves, BB-34-BCA-2" (loop 2),
therefore no cycling or BB-50-BCA-2" (loop 3),
stratification offect.
BB-67-BCA-2" (loop 4).
Hot Lcq Connections:
Safety injection lines No Insufficient driving head BB-08-BCA-6" (loop 1),
to inject into the RCS BB-26-BCA-6" (loop 2),
during normal operation; BB-42-BCA-6" (loop 3),
pumps normally not BB-71-BCA-6" (loop 4).
running.
RHR lines No Insufficient driving BB-07-BCA-12" (loop 1),
head; RHR pumps are not BB-26-BCA-6" (loop 2),
running during normal BB-42-BCA-6" (loop 3),
operations; also, pump BB-70-BCA-12" (loop 4).
suction lines are isolated by 2 normally closed gate valves.
RTD manifold lines from No Continuous flow through the hot Icg.
normally open valves, therefore no cycling or stratification effect.
Crossover Leg _ Connections:
Reactor coolant drain tank No Isolated by 2 normally lines BB-20-BCA-2" (loop 1),
closed globe valves and BB-37-BCA-2" (loop 2),
one normally closed gato BB-54-BCA-3" (loop 3),
valve from the crossover BB-74-BCA-2" (loop 4).
Icg to the reactor coolant drain tank pumps.
I Page 3 of 4
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'.ALLAWAY RCS CONNECTIONS (continued)
Potential NRCB 88-08 Description Location Arguments CVCS lotdown line BB-54-BCA-3" No Normal lotdown flow path, from loop 3.
no cycling or stratification effect.
CVCS cxcess letdovn line No Isolated by 2 normally BB-74-BCA-2" from loop 4.
closed globe valves from the crossover leg to the excess lotdown heat exchanger.
RTD manifold lines No Continuous flow through BB-15-BCA-3" (loop 1),
normally open valves, BB-33-BCA-3" (loop 2),
therefore no BB-49-BCA-3" (loop 3),
cycling effect.
BB-66-BCA-3" (loop 4).
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