05000325/LER-1981-032-03, /03L-0:on 810419,heat Exchanger,Model Ceu,Size 52-8-144,baffle Plate Was Discovered to Be Bowed.Caused by Excessive Differential Pressure Across Baffle Plate from Accumulation of Shells in Heat Exchanger.Plate Reinstalled

/03L-0:on 810419,heat Exchanger,Model Ceu,Size 52-8-144,baffle Plate Was Discovered to Be Bowed.Caused by Excessive Differential Pressure Across Baffle Plate from Accumulation of Shells in Heat Exchanger.Plate Reinstalled

ML19347F823
Person / Time
Site:	Brunswick
Issue date:	05/19/1981
From:	Pastva M CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19347F819	List: 05000325/LER-1981-032, Forwards LER 81-032/03L-0 05000325/LER-1981-032-03, /03L-0:on 810419,heat Exchanger,Model Ceu,Size 52-8-144,baffle Plate Was Discovered to Be Bowed.Caused by Excessive Differential Pressure Across Baffle Plate from Accumulation of Shells in Heat Exchanger.Plate Reinstalled
References
LER-81-032-03L, LER-81-32-3L, NUDOCS 8105260401
Download: ML19347F823 (3)

LER-1981-032, /03L-0:on 810419,heat Exchanger,Model Ceu,Size 52-8-144,baffle Plate Was Discovered to Be Bowed.Caused by Excessive Differential Pressure Across Baffle Plate from Accumulation of Shells in Heat Exchanger.Plate Reinstalled

Event date:
Report date:
3251981032R03 - NRC Website

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60 Gl DOCKET.NUMSER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h l [TITl l During a special inspection of 1B RHR heat exchaneer. as conunitted to in LER' 2-80-30. I (gl it was discovered that the heat exchanger, Model No. CEU, Size 52-8-144." baffle plate I l

@ l was partially bowed in the center at the bottom siere it fits into a eroove of the ITTTI I channel cover. As a result of this event, an inspection of the Unit No. 2 RHR heat I

l o Is l I exchangces was conducted which is being reported in LER 2-81-49.

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35 36 37 40 41 42 43 44 47 33 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h 1 o I Excessive differential oressure across the baffle nlate resultine from an accumula-1 1 1 l

tion of shells in the heat exchanoer enused the ninte to how and narefn11v cannenea I l

from attachment welds on each side of the plate. The heat exchanger tubes are I

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reinstalled to return the heat exchanger to operability.

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LER ATTACHMENT - RO #1-E -32

- Facility: BSEP Unit No. 1 Event Date: 4-19-81 During the inspection of IB RHR heat exchanger, it was found that the heat exchanger baffle plate was displaced approximately 9" at the bottom, which created a service water flow path from the inlet to the outlet, bypassing the tubes. The purpose of the plate is ~ t<i separate RHRSW. entering.the heat exchanger from RHRSW 1eaving'after-it has passed through the heat exchanger U-tubes. From the -inspection and an engineering evaluation of the plate failure,'

it was concluded that the failure occurred due to the failure of ;,lete attachment welds to within 8 - 10" of the heat ' exchanger tube sheet which' resulted from excessive differential pressure across the plate. The cause o.f the excessive differential pressure has been attributed to a blockage of the heat exchanger tube by shells (approximately 95Y, oyster) which accuciulated'in the heat exchanger when shells on the walls of the main service water piping became dislodged. The shall buildup apparently resulted from the service water chlorination system being out of service for an extended period.

4 l-During the repair of the IB RHR heat exchanger, a loss of cooling was" experienced immediately following the starting of a second. RHR service water pump on the 1A RHR heat exchanger., In establishing an alternate shutdown cooling line sp, it was decided to reject from the vessel with the RHR system through the fuel pool coolers and to the condensate storage tank (CST). To i

return water to the vessel, the Core Spray system would take a suction from the CST and provide makeup to the vessel at a throttled flow.of approximately 5000' gpm for level control. This lineup was later modified to delete the Core Spray system and the CST and return water to the vessel using the RHR system. Vessel temperature never reached 170*F. Using the Control Rod Drive system for vessel ~

l return was considered, however, it was felt that the low flow rate of this system would not provide sufficient cooling and mixing to maintain reactor temoarature below a desirable level.

To restore a normal shutdown cooling lineup as expeditiously as possible, temporary repairs were performed on the 1A heat exchanger and it was restored to service while permanent repairs were still in progress on the IB heat exchanger.

The baffle plate on the 1A heat exchanger was also found to be displaced at the bottom.

I An evaluation of the 1A heat exchanger baffle failure concluded that baffle displacement also occurred as a result of shell buildup. When the second RHRSW pur, was started, increased flow through the heat exchanger caused an excessive d__ferential pressure that displaced the baffle plate approyimately 9".

Permanent repairs for the la heat exchanger will follow the completion of work and the return to service of the IB heat exchanger.

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LER ATTACHMENT - RO #1-81-32 Facility: BSEP Unit No.1 Event Date: 4-19-81 o

A program is being pursued to monitor safety-related heat exchanger performance.

It will consist of using available temperature, flow and differential pressure instrumentation to determine the heat transfer rates and flow rates. This will help predict baffle plate degradation.

In order to prevent future similar occurrences, plant procedures will be revised to ensure the RHRSW system header is vented once per week and prior to opuration of the system. In addition, the heat exchanger tubes and service water piping will be cleaned to remove shell buildup. A design review of the divider plate will be performed to assure its adequacy.

These actions, along with the resumption of the service water chlorination program, will help eliminate future organism shell growth.

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