05000325/LER-1981-034-01, /01T-0:on 810328,two Snubbers & Two Pipe Guides Were Found Damaged on HPCI Injection Line.Caused by Water Hammer in Sys.Supports Repaired & Strengthened

/01T-0:on 810328,two Snubbers & Two Pipe Guides Were Found Damaged on HPCI Injection Line.Caused by Water Hammer in Sys.Supports Repaired & Strengthened

ML19345H243
Person / Time
Site:	Brunswick
Issue date:	04/24/1981
From:	Poulk R CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19345H241	List: 05000325/LER-1981-034, Forwards LER 81-034/01T-0 05000325/LER-1981-034-01, /01T-0:on 810328,two Snubbers & Two Pipe Guides Were Found Damaged on HPCI Injection Line.Caused by Water Hammer in Sys.Supports Repaired & Strengthened
References
LER-81-034-01T, LER-81-34-1T, NUDOCS 8105010394
Download: ML19345H243 (4)

LER-1981-034, /01T-0:on 810328,two Snubbers & Two Pipe Guides Were Found Damaged on HPCI Injection Line.Caused by Water Hammer in Sys.Supports Repaired & Strengthened

Event date:
Report date:
3251981034R01 - NRC Website

text

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REPORT o ATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h l o 121 lWhile performing a review of the pipe supports on the HPCI iniection line, four i

lo lal l supports (2 snubbers and 2 pipe guides) were found damaged. As a result of this dis-l any other possible

.j I o 141 icovery, all ECCS lines on both units were inspected to identify la lsl Idamage. The enclosed table identifies the problems found.. Th:~

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g l All damaged supports were atributed either directly or indirectly to water hammer in i

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LER l-81-34 ATTAC10!ENT Facility: BSEP Unit Nos.1 and 2 Date: 3-28-81 Following the discovery of four supports on the HPCI injection line damaged due to a water hammer event, a decision was made.to examine the lines of all ECCS Systems on both units to verify the condition of the pipe.

During this inspection various supports and snubbers were found with deficiencies. All damaged supports were repaired and/or redesigned to provide additional strength. Damaged or nonfunctional snubbers were either rebuilt or replaced.

Additional NDE was performed in areas of suspected high stress supports.

Folicwing the completion of the inspection and repair work, all ECCS Systems were tested, with no excessive line motion noted, and declared fully operable and the units were returned to power operation.

The cause for these damaged supports and snubbers was one or several water hammer events on their respective system. These systems have been operated on a routine basis to perform operability checks and to perform designed operations (s/d cooling, HPCI injection on Low Level No. 2 following some scrams, etc.) No known or observed water hammer events have occurred on these lines during the operation of these systems.

It is believed that the keep-fill system which maintains the ECCS System lines full of water and possible system leakage is the cause for these events. In an effort to prevent future water hammer events and to correct the cause for the past events, several actions have been or are being taken:

1.

The Daily Surveillance Report for both units has been revised to require daily venting of all ECCS Systems to verify that the system is full. This periodicity may be changed depending on a review of the results of this venting.

~2.

Core Spray and HPCI operability periodic test have been revised to require observation of the lines when the pumps are started to detect any pipe

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movement. Also, after an auto initiation of an ECCS System, the lines will

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be inspected to assure no damage.

3.

Evaluate and modify as necessary the minimum flow valves on the ECCS Systems to ensure that they do not allow leakage which could create a water void in the system.

4.

Evaluate and modify as necessary the keep-fill system to promote its proper l

operation in maintaining the ECCS System lines full.

It is believed that these actions will provide assurance that water hammer events in the future will be prevected and ECCS line integrity assured.

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UNIT NO. 1 ECCS WALK-OFF SUPPORT NO.

LINE FAILURE DESCRIPTION REASON FOR FAILURE

CORRECTIVE ACTION

IE21-6SS42 12" CS Pump "B" Pipe clamp slipped Water hammer or system Fixed by maintenance, discharge transient IEll-18SS40 20" outlet from Insufficient weld Initial construction Redesigned and upgraded heat exch. "lA" (could have failed deficiency (added gusset plates) in seismic event).

No existing damage.

IE11-49SS 331 12" HPCI steam Slipped clamp Water hammer or system Repaired by maintenance.

cond. to RHR transient heat exch. "B" 1E41-60SS101 14" HPCI injection Broken shaft Water hammer / system Rebuilt and tested by transient maintenance IE41-60SS102 14" HPCI injection Anchor bolts pulled Water hammer / system Repaired and upgaaded per from wall transient redesign IE41-60PG55 14" HPCI injection Cracked weld on steel Water hammer / system Repaired transient IE41-60PG57 14" HPCI injection Damaged support steel Water hammer / system Repaired and upgraded per transient redesign

'1E11-2PG152 20" suction for Excessive gap between Initial construction Repaired (not a general shutdown cooling sliding surfaces on deficiency problem) steel and guide plates IE11-47CH325 12" HPCI cond.

Trapeze slipped from System transient Welded trapeze to support IE11-47CH327 to RHR heat underneath the pipe plate.

t (Spring trapeze) exch. "1A" 1E20-6PG35 CS pump "1-B" Pipe guide failed Water hammer / system Repaired and upgraded per discharge (elongated) transient new design 1E21-6PC37 CS pump "1-B" Cracked weld Water hammer / system Repaired and upgraded per discharge transient new design IE11-49PG420 12" HPCI steam Pipe clamp Clamp not tight and Repaired by maintenance.

cond, to "B" RHR slipped system transient heat exch It

UNIT NO. 2 ECCS WAI.K-OFF SUPPORT No.

l.I NE Fall.URE DESCRIPT20N REASON FOR FAII.URE

CORRECTIVE ACTION

Service condition Pumped up - not a generic 2 Ell-90SS283 4" llead Spray Low fluid problem.

2E11-95SS22 16" to RilR leat Broken bracket System transient Repaired exch. "2B" Repaired and upgraded per 2 E41-60SS102 14" llPCI injec-Bent steel Water hammer l

redesign.

tion 1

i Fluid reservoir Bad inacallation Repaired - no further action 2B32-SSB1 Recirc pump by vendor or necessary.

upside down maintenance.

Repaired and upgraded.

2 E41-60PG57 14" HPCI injec-Failed weld Water hammer (Rigid strut tion and bent pin initial weld lacked fusion.

restraint) 2E11-47CH325 12" liPCI cond.

Trapeze slipped System transient Welded trapeze to support i

plate.

line to RHR from underneath l

the pipe 2E11-47CH326 Spring supports 2E11-20FS29 20" RHR pump Approximately 3/16" Line movement during Added shim. No further action needed. Not a j

(Deadweight

disch, gap between support plant operation and steel or poor installation' generic problem.

support) 2E11-128PG358 16" x 12" Broken pipe guide Line vibration due Support repaired. Noise to F068A throttling reducing trim shall be Pipe guide reducer installed in F068A valve.

4 upstream of 2 Ell-F068A l

Water hammer / system Repaired and upgraded per 2E21-6P637 12" CS pump Bent steel redesign transient disch. "B" CS injection 12" CS pump Broken guide seal Water hammer / system Replaced 1

transient I

link seal disch. "B" in sleeve Water hammer / system Support was operable but re-2E21-6PG35 12" CS pump Slightly bent paired and upgraded per transient disch. "B"

}

redesign because Unit No. I support was inoperable.

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