ML20117M618
| ML20117M618 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Dresden |
| Issue date: | 07/02/1983 |
| From: | Rybak B COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20114G054 | List:
|
| References | |
| FOIA-84-616 6873N, NUDOCS 8505170141 | |
| Download: ML20117M618 (21) | |
Text
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['^'N Commonwealth Edison
)3 Tddress Reply to: Post Office Box 767 one First National Ptzt Ch cago. Ilknois O
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July 2, 1983 3;5[f'~IQ 7
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77 Mr.' James G. Keppler, Regional Administrator l'-
f 'l l Region III la Wint"2 6 U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
Dresden Station Unit 2 Main Steam Line Snubber Failure NRC Docket No. 50-237 References (a):
B. Rybak letter to J. G. Keppler dated May 13, 1983.
(b):
B. Rybak letter to J. G. Keppler dated May 24, 1983.
- (c):
B. Rybak letter to J. G. Keppler dated May 27, 1983.
(d):
- 8. Rybak letter to J. G. Keppler dated June 6, 1983.
Dear Mr. Keppler:
Per the request of Mr. Danielson of your staff-we are formally transmitting, as an attachment to this letter, the agenda and the handouts distributed at our April 22, 1983 and May 5, 1983 meetings on the subject issue.
All other information has been formally transmitted to you by the referenced letters.
The only outstanding material to be submitted is the final thermal growth evaluation as discussed in reference (d).
As concurred with by Mr.
Danielson, this evaluation will be submitted during the week of July lith.
If there are any additional questions regarding this matter, please contact this office.
Very truly yours, g51g1e40914 BARFIEL84-616 PDR B. R a
Nuclear Licens ng Administrator bg cc:
Resident Inspector - Dresden R. Gilbert - NRR g
61983 6873N
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/49 r, If P3 AGENDA 1.
PURP'0SE-II.
REVIEW CECO PROPOSED PROGRAM AS PRESENTED 4/22/83 III.
REVIEW lN-PLANT-TEST PESULTS IV.
REVIEW OUT-PLANT TEST RESULTS V.
CONCLUSIONS VI.-
FUTURE ACTION VII.- SAFETY l
5/5/83
-i' I.
PURPOSE
- A.-'
PROVIDE UPDATE OF SNUBBER FAILURE ASSESSMENT IN LIGHT OF THE IN-PLANT AND OUT-PLANT TEST RESULTS B.
PRESENT FURTHER. ACTION TO BE TAKEN
-8 II.. REVIEW 0F 4/22/83 CEC 0. PROPOSED PROGRAM A.
FAILURE MODES UNDERGOING ACTIVE CONSIDERATION 1.-
OVERLOAD 2.
INSTALLATION 3.
SNUBBER CAPABILITY B.
4/22/83 PROPOSED FURTHER ACTION 1.
EVALUATE IN-PLANT TEST DATA A.
DETERMINE WITHIN 48 HOURS IF A SAFETY CONCEPN 2.
EVALUATE RESULTS OF SNUBBER TEST PROGRAM 3.
FOLLOW TECH. SPEC. SURVEILLANCE A.
EXPERIENCE ON OTHER UNITS PROVIDES ASSURANCE THAT FAILURES WILL NOT OCCUR IN NEXT TWO MONTHS B.
TECH. SPEC, INTERVALS ARE DESIGNED TO ACCOUNT FOR UNKNOWN FAILURES 4.
TAKE FAILED SNUBBER TO PSCo. FOR FURTHER ANALYSIS OF FAILURE 5.
UPON COMPLETION OF AB0VE, PREPARE REPORT FOR SUBMITTAL TO NRC.
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III.
IN-PLANT TEST A.
TEST PURPOSE:
1.
IDENTIFY'HIGH LOADING CONDITION 2.
CONFIRM DESIGN BASIS RELIEF VALVE LOADS N
B.
TEST RESULTS f-1..
NO IMMEDIATE SAFETY CONCERN IDENTIFIED 2.
SNUBBERS AND SPRING CANS WERE FOUND TO BE WITHIN' EXPECTED LIMITS 3.
LINE MOVEMENT EVALUATION A.
LVDT READING USED IN CONJUNCTION WITH VISUAL RESULTS TO EVALUATE LINE MOVEMENT
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B.
MOVEMENTS BEYOND EXPECTED LIMITS WERE FOUND
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c.
ANALYSES PERFORMED INDICATE STRESSES ARE WITHIN CODE LIMITS
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4.
SNUBBER LOAD EVALUATION A.
IN 3 CASES, SNUBBER LOADS WERE AB0VE EXPECTED BUT WELL BELOW 22,500 (APPR0XIMATELY 4,500 LB.)
B.
EVALUATION OF LOAD INDICATES LINE IS WITHIN CODE.
LIMITS c.
SUPPORTS EVALUATED F0P INCPEASED LOAD WEPE FOUND TO BE WITHIN CODE
IV.
NUTECH OUT-PLANT TEST A.~
-TEST PURPOSE 1.
DETERMINE CAPABILITY 0F PSA-10 TO SINGLE PULSE LOAD 2.
DETEPt11NE CAPABILITY OF. SNUBBER TO REPEATED DULSE LOADING 3.
DETERMINE CAPABILITY OF SNUBBERS TO LOADS WITH END
. MOMENT B. : TEST. RESULTS 1.
SNUBBER ~ ADEQUATELY PERFORMED WHEN SUBJECTED TO IMPULSE AND CYCLIC LOADING 2.
DEFLECTION OF APPROXIMATELY.2" RESULTED IN SNUBBER LOCK-UP' s
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SNUBBER DEGRADED PERMANENTLY s
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. CONCLUSIONS' BASED ON TEST PROGRAM RESULTS-A.
SRV LOADS ARE NOT OF A MAGNITUDE TO ALONE CAUSE SNUBBER FAILURE-B.
N0 KNOWN TRANSIENTiWHICH OCCURRED DURING UNIT 0PERATION CAN PRODUCE LOADS NEEDED TO FAIL SNUBBER
-C.
BENDING'IN SNUBBER CAN RESULT IN-SNUBBER LOCK-UP AND PERMANENT DEGRADATION
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VI.
PROPOSED FUTURE ACTION A.'
FOLLOW TECH SPEC. SURVEILLANCE
- 1.
TECH. SPEC, INTERVALS ARE DESIGNED TO ACCOUNT FOR UNKNOWN ~ FAILURE B.
PROVIDE MONITORING OF SNUBBER LOADS C.
TAKE SAMPLE OF FAILED SNUBBERS TO PSCo. -FOR FURTHER FAILURE ' ANALYSIS D.
DEVELOP ACTION PLAN PRIOR TO THE 62-DAY OUTAGE TO INSURE BINDING IS ELIMINATED 26 D j 4
. VII. - SAFETY CONCEM
- NO PROBLEMS ON QC-1, QC-2 AND D-3
- ANALYSES OF DESIGNED ~ EVENTS SHOW NO HIGH LOADS-
- OPERABILITY ANALYSES.
- SNUBBERS TO BE-REINSPECTED PER TECH. SPECS. (62 DAYS)
- INSPECTED STEEL:(COMPARED STEEL CAPACITIES TO POSSIBLE LOADS)
- INSPECTED PIPING HIGH STRESS WELDS (LOADS IMPOSED ON PIPE DID NOT OVERSTRESS PIPE)
- TEST INDICATED HIGH LOADING CONDITION DOES NOT EXIST
- PIPE CLAMPS WERE MODIFIED TO ALLEVIATE POSSIBLE BINDING u
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AGENDA
- 1.. PURPOSE II.
BACKGROUND III.
FAILURE ANALYSIS PROGRAM IV
'IN-PLANT TEST PROGRAM' GOALS V.
DUT-PLANT SNUBBER TEST PROGRAM G0ALS f7 'f 2 VI.
FUTURE ACTION p3 r.
VII.
SAFETY
. VIII.
NRC COMMENTS ON TEST PROGP.AM pz I.,estpa) 92.
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I.
PURPOSE A. 'PRESENT COMPREHENSIVE-PROGRAM BEING IMPLEMENTED TO ADDRESS SNUBBER FAILURE B.
DISCUSS EVIDENCE WHICH SUPPORTS D-2 CONTINUED OPERATION C.
RESOLVE SEVEN CONCERNS ON IN-PLANT TESTING PROGRAM
-II.
BACKGROUND A.
FIVE FAILED PSA-10 SNUBBERS ON MSL'S 1.
THREE ON C-LINE 2.
ONE ON.B-LINE 3.
ONE 0N D-LINE B.
THREE OF FOUR-SNUBBERS HAD SHAFTS STRIPPED THROUGH THRUST BEARING C.
INSPECTIONS ON D-3, QC-1, QC-2 SHOWED NO FAILURES 1.
PSA-10 MSL SNUBBERS STROKED 2.
CPS' CHECKED 3.
POSSIBLE BINDING CHECKED
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. III.
FAILURE ANALYSIS PROGRAM
. IDENTIFIED FIVE AREAS OF CONCERN A.. MATERIALS B. -VIBRATION C.
OVERLOAD D.
INSTALLATION E.
SNUBBER CAPABILITY a
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MATERIALS A.
CECO MATERIAL TESTING VERIFIED CORRECT MATERIALS
-AND HEAT TREATMENT (SHAFT AND THRUST BEARING)
B.
ELIMINATED AS POSSIBLE CONCERN 2.
VIBRATION A.
REVIEW 0F AN EARLY STONE & WEBSTER REPORT INDICATED THAT.A HIGH CYCLE LOW AMPLITUDE-VIBRATION EXISTS B.
SNUBBER AUTOPSIES PERFORMED IN PRESENCE OF PSCo.,
WYLE AND OTHER SNUBBER EXPERTS c.
CONCLUDED SNUBBER FAILURE WAS OVERLOAD, NOT VIBRATION-(CAPSTAIN SPRING SHOWED NO SIGNS OF EXTENDED RAPID CONTACT OF TOROUE DRUM)
D.
ELIMINATED VIBRATION FROM ACTIVE CONSIDERATION
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' e 3.
OVERLOAD A.
SNUBBER AUTOPSY INDICATED OVERLOAD
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SENSITIVITY STUDY TO DETERMINE POSSIBLE MAXIMUM SRV LOAD - RESULTED IN LOADS MUCH LOWER THAN PREDICTED SNUBBER CAPABILITY c.
THIRD PARTY REVIEW 0F SEL ANALYSIS CONCLUDED LOADS TO BE LESS THAN PREDICTED SNUBBER FAILURE 10.
THERMAL-LOADS IDENTIFIED POSSIBLE CAUSE E.-
PIPE-INSPECTIONS OF PREDICTED HIGH STRESSED WELDS PROVIDED'LINE WAS NOT OVERSTRESSED F.
INSPECTION OF STEEL IN AREAS OF StluBBEP FAILURE INDICATES N0 YIELDING
- s. -REVIEWED CAPACITIES OF STRUCTURAL STEEL INDICATING STEEL WOULD YIELD AT SNUBBER MAXIMUM CAPABILITY H.
CONCLUDED HIGH LOADS IN 30-40 KIP RANGE COULD NOT HAVE OCCURRED 1.
OUT-OF-PLANT SNUBBER TESTING PROGRAM BEING PERFORMED TO ASSESS POSSIBILITY OF SNUBBER FAILUPE BELOW RATED CAPABILITY J.
IN-PLANT TEST BEING PERF0PMED l
1.
IDENTIFY HIGH LOADING CONDITION 1
2.
CONFIRM DESIGN BASIS RELIEF VALVE LOADS l
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4.
INSTALLATION A.
INSPECTION OF FAILED AREAS INDICATED POSSIBLE BINDING ON FAILED SNUBBERS B.
' PIPE CLAMPS MODIFIED TO INSURE CLEARANCE c.
PSCo. CONSULTED ON BINDING - BINDING SHOULD NOT CAUSE PROBLEM D.
NUTECH OUT-PLANT TEST PROGRAM 5.
SNUBBER CAPABILITY A.
.0VT-PLANT TEST TO DETERMINE POSSIBLE SNUBBER LIMITATIONS 1.
MISALIGNMENT 2.
HIGH IMPACT SRV LOADS
- 3. ' CYCLES OF HIGH IMPACT LOADS f
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4 IV,' fluT-PLANT SNUBBER TESTING PROGRAM A.
DETERMINE CAPABILITY OF PSA-10 TO SINGLE PULSE LOAD B,
DETERMINE CAPABILITY OF SNUBBER TO REPEATED DYNAMIC
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PULSE LOADING C.
DETERMINE CAPABILITY OF SNUBBER TO REPEATED DYNAMIC LOADS WITH AN END MOMENT-L o
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V.
IN-PLANT TEST PROGRAM A.
MONITOR.SRV ACTUATION B.
SRV - HIGHEST LOAD PRODUCING EVENT C.
TURBINE STOP-VALVE COULD BE COMPARABLE TO SRV BUT'DID NOT OCCUR D. -MSIV IS A NEGLIGIBLE EVENT 1.
VALVE CLOSING TIME THREE TO FIVE SECONDS 2.
SRV ON ORDER OF MILI.ISECONDS i
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VI.
PROPOSED FURTHER ACTION A.
EVALUATE IN-PLANT TEST DATA 1
1.
DETERMINE WITHIN 48 HOURS IF A SAFETY CONCERN B.. EVALUATE"RESULTS OF SNUBBER TEST PROGRAM C.
FOLLOW TECH. SPEC. SURVEILLANCE 1.
EXPERIENCE ON OTHER UNITS PROVIDES' ASSURANCE THAT-FAILURES WILL NOT OCCUR IN NEXT TWO MONTHS 2.
TECH. SPEC. ~ INTERVALS ARE DESIGNED TO ACCOUNT FOR UNKNOWN FAILURES D.
TAKE FAILED SNUBBER TO PSCo. FOR FURTHER ANALYSIS OF FAILURE
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E.
UPON COMPLETION OF ABOVE, PREPARE REPORT FOR SUBMITTAL TO NRC i
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O.. ;-
VII.. SAFETY CONCERN
- N0 PROBLEMS ON QC-1, QC-2 AND D-3
- ANALYSES OF DESIGNED EVENTS SHOW N0 HIGH LOADS
-.0PERABILITY ANALYSES
- SNUBBERS TO BE REINSPECTED PER TECH. SPECS. (62 DAYS)
- INSPECTED STEEL (COMPARED STEEL CAPACITIES TO POSSIBLE LOADS)
- INSPECTED PIPING HIGH STRESS WELDS (LOADS IMPOSED ON PIPE DID NOT OVERSTRESS PIPE)
- TEST WILL IDENTIFY lF HIGH LOADING CONDITION EXISTS
- PIPE CLAMPS WERE MODIFIED TO ALLEVIATE POSSIBLE BINDING l
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' July 6, 1983 DJS LTR. '#83-661 70:
E. R. Zebus Project Engineer SNED
SUBJECT:
Visual Inspection of the Main Steam and Safety Relief Valve Lines Inside the Drywell and X-Area of Unit Two
REFERENCE:
! C.A.L. to C. Reed dated 3-17-83 All attachments of the Main Steam Lines and the Safety Relief Valve Lines ~inside the drywell and X-area of Unit Two were inspected as part of
~the Dresden ISI program and as part of a special procedure. Included in
-these visual inspections.during the refueling outage and especially 4-23-83 and 4-26-83 were the MSL and SRV snubbers, spring cans, rigid restraints, hangers, pipe clamps, support beams, slides, bolting and anchors. There
. was one anomaly which was repaired after an evaluation by S & L that was minor'in' nature. Also included in the inspection were all the' pipe weld-ments, and in'some specific cases certain welds were liquid penetrant or magnetic particle tested per the ISI program.
All of the snubbers, rigid restraints, spring cans, etc. of the SRV lines'are in the proper condition..Also, the MSL upper springs, snubbers,
- mid-point-spring cans, slides, rigid restraints, pipe clamps and lower variable supports (which are immediately prior to the drywell to x-area penetration) are in proper working condition. Also the pipe clamps and supports in the x-area are in their proper working condition.
[1 Set-point readings were taken ig the cold condition of the MSL's L and when they reached a minimum of 450 F. to ensure proper movement of the piping within its' normal constraints. These inspections were performed by members of Dresden's Tech Staff and Quality Control Departments. Two
+
teams'of the groups, specifically Don Maxwe[11 of the Tech Staff and, Rich _Hylka of Quality Control were one team and Ben Schroeder of the Tech Staff and Ter m severson of Quality Control were the other team. Measurements and faspections of all restraints of the SRV and MSL's were made by the two-teams, independently ~of each 'other. and compared after the inspections were completed and no differences were found between any results. Both' inspection teams had at.least one examinee who is VT-3 and VT-4 certified as a visual examiner.
There was no evidence of structural steel failure.,There was no
~
local. warpage, no failed welds, and no signs of unusually large deflections,
'such as failures of small attachments to the structural steel.
If you have any questions, please call Don Maxwell at the Station on Ext. 489.
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- E. R. Zebus SNED July 6, 1983 M
M Prepared by D. C. Maxwell - Tech Staff A
Approved by V.
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D. J. Fcott Station Superintendent Dresden Nuclear Power Station DJS/DCM/jat cc:
J. D. Brunner J. W. Wujciga K. E. Davenport R. H. Mirochna J. E. Doyle File /SNED File /T.S. File File / Numerical G
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SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 s street. Box 15830, sacra,m%nfo California 95813; (916) 452 3211 l' l]
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=RJR 83-581~
August 8, 1983 J B MARTIN, REGIONAL ADMINISTRATOR.
REGION V 0FFICE.0F INSPECTION AND ENFORCEMENT U S NUCLEAR REGtJLATORY COMMISSION 1450 MARIA LANE SUITE 210 WALNUT CREEK CA 94596 DOCKET NO. 50-312 LICENSE N0. DPR-54 LICENSEEEVENTREPORTNUMBER;83-16F0LLOWUP}
In accordance with Rancho Seco Nuclear Generating Station Technical Specifi-cations, Section 6.9.4.2.b and Regulatory Guide 1.16, Section C.2.b(2), the Sacramento Municipal Utility District hereby submits a followup to LER 83-16.
As the District committed in our original submittal of LER 83-16, dated April 28, 1983, the District has completed its testing and reworking of'all snubbers required to meet SP 201.108 criteria. This followup serves to pro-vide a final list of those snubbers that required rework and their failure modes as Attachment I.
The District also committed to perform SP 201.10A, the visual inspection of the snubber fluid reservoirs.
SP 201.10A was per-formed on the-inaccessible snubbers, which was the intent of that commitment in the original LER.
The District performed SP 201.10A on the accessible snubbers on March 9, 1983, so that, in fact, all snubbers have' received their SP 201.10A inspection during this outage.
In addition, as part of the maintenance procedure that reinstalls the snubbers tested under SP 201.108, the functional test,'the fluid reservoirs are refilled and adjusted as the snubbers are returned to their proper locations in the plant.
. The District believes the above actions meet the commitments of the original LER and that this event should be considered closed out. Any questions concerning this event should be directed to Mr. Ron Colombo at the Rancho
.Seco Nuclear Generating Station
/Mk John J. Mattimoe General Manager and Chief Engineer cc:
INP0 DCD, Washington l
FILE COPY w.
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s Ah riffTRit tytTtM A f t y t N r.
i.e n s t Twag Ann nnn #N fut uraet nr a oser
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,s ATTACI;HEUT I FOR LT.R C3-lEF0LLOWUPJ Equip. I.D.
/ System Manufacturer Failure Mode Cause IS E 3626-I I ~Grinnelf - ~~
Iiouldn't stroke smoota-Valve out of adjustment
/SIM ly at rain. velocity on ext. stroke.
75W-30305-2 Crinnell Uouldn't stroke smooth-Valve out of adjustment
/ MSS
~
ly at min. velocity on cxt. stroke.
7SW-30300-8 Crinnell Wouldn't stroke smooth-Valve out of adjustment
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/ MSS ly at min. velocity on ext. stroke.
4SW-26025-43 Bergen-Patterson Exceeded Retraction Dcfective valve body,
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DifS Bleed Velocity limit poppet seat was scored.
4SW-53520-3 Bergen-Patterson Exceeded Extension Lock-Water in fluid. Valve
/FVS up Velocity Limit corrosion in body & parts.
9SW-30709-4 Bergen-Patterson Exceeded Extension Lock-Not known--snubber was re-
/ MSS up Velocity Limit worked then function tested, acceptable.
45W-26101-2 Bergen-Patterson Wouldn't stroke smooth-Leakage was caused by
/DilS ly at min. velocity on defective seals.
retraction stroke.
Leaked oil.
ISW-50063-2A Bergen-Patterson Exceeded Retraction Unknown--snubber was re-
/;ISW Bleed Velocity limit.
worked then function tested. )
acceptable.
9SW-307CS-5A Bergen-Patterson Exceeded Extension Unknown--snubber was re-
/i!SS Bleed Velocity limit.
worked then function tested, acceptable.
I
!!S-20521-SWil Bergen-Patterson Wouldn't stroke smooth-Unknown--snubber was re-
/ MSS ly on extension stroke, worked then function tested,i
. acceptable.
ISW-32141-2 Bergen-Patterson Wouldn't stroke smooth-Unknown--snubber was re-
/FWS ly on extension stroke.
worked then function tested, acceptable.
10SW-20553-1A Crinnell Wouldn'tstrokesmoNh-Valve out of adjustment
/ MSS ly in retract on exten-sion stroke.
SSW-20529-4A Grinnell No physical failure.
No cause--the snubber was
/llSS This snubber was tested tested to verify acceptable because of a violation function only.
a violation of the test procedure caused its status to be in question.
Page 1 of 2 WT )? ^ Q ~
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- - - -. - - - - - - - - - ~ _ - - - - - - - - - - - - - - - - - - - - - - - -
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/ATTACliME T - I.
I JIFOR LER 831165F61[LONUPd.(Cont'd)
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T Equip. I.D.
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~_ Manufacturer Fa,ilure Mode Cause 4
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Gritinell Wouldn't stroke scooth-Valve out of adjustncnt and/
p.
'/SFC --
ly in extension on or old scals.
retraction.
Ecrgen Patterson.
Wouldn't lock up.
Scored piston cylinder and
/ MSS piston.
,1SW-50050-6A Grinnell Wouldn' t' stroke s:nooth.
Seals worn.
/IISW -
ly in extension direc-tion; locked up at minimuti velocity.
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Page 2 of 2 L"