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NRC. Form 366 U.S NUCLE AR REGU6ATORY COMMISSION APPROVED OMB NO. 3160-0104* (6-87) E XPiRE S 4 /30 /02Estimated buroen per responsa to comply witn inns,

.. information conection roovest: 60.0 nrs. Sorware*comments regaroing burcen estimate to the Recorcs

LICENSEE EVENT REPORT (LER) ano Reports Managemoni Branen in-630i. u S Nuci.ar*

Regalatory Commission. WasNngton DC 20556, and tothe Paperwork Recoction Proiect (3160-0104 L Othee of iManagement and Baopet Wasnington, DC 20603, "

F ACILITY NAME (1) DOC *iT NVMbh4 (s'; PAM

Millstone Nuclear Power Station Unit 3 ol 5| o| of old 1213 1|OF| 0| 5"l '1 '') Both Trains of Containment Recirculation Pump Area Coolers Inoperable Due to an inadequate

Surveillance ProcedureEVENT DATE (51 LEP NUMBEP t61 REPORT DATE (7i OTHER F ACILITIES NVOLVED (81

MONTF DAY | YEAR YEAR MONTH DAY YEAR F ACILITY NAME S

01 sl of ol 01 | |

1|5 9 0 4 |0 0|2|3 0| 1 1|0 0|1 9| 0 olslololol | |0 6OPERATNG THS REPOF'T IS DEING SUBM;TTED PURSUANT TO THE REOuiREMENTS OF 10 CFR 0 (Check one or more of the following)(11)

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20 405 tal(11fivi 60.73(aH2i(in) 60 73(a)(2Hx)LICENSEE CONT ACT FOR THIS LER f12

NAMg TELEPHONE NUMBEA

ARE A CODtBarrett W. Nichols, Senior Engineer, X5493 2 0|3 4|4|7|-|1|7|9|1

COMPLETE ONE LINE FOR E ACH COMPONENT F AFLUAE DESCRIDED IN THS REPORT (131

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FACLTTY NAME (1) DOCKET NUMBER (2> ( F A NtMM A m ' PAGE (31

YEAR

Milistone Nuclear Power StationUnit 3

0| $| 0| 0| 0|4 |2 |3 9|0 0| 2| 3 0|1 0| 2 OF 0|5Text or mor. space is r.avir.o. us soon,one wee Form asr,A si on

1. Deerimion of Event

On July 5,1990 at approximately 2005 hours, while in Mode 1 at 80rc power, 580 degrees Fahrenheitand 2250 psia, a detailed engineering evaluation determined that both trains of ContainmentRecirculation Spray had been inoperable simultaneousl.y due to fouhng of the associated area cooler heatexchangers.

On June 18,1990 at 1300 hours, while in Mode 1 at 1008~c power, the *B" train ContainmentRecirculation Pump Area Cooler (3HVQ' ACUS 28) was found to be degraded when damage and foulingwas found in the heat exchanger head. On June 15,1990, at 1725 hours, while in Mode 1 at 80rcpower, similar damage had been found in the " A" Train unit 3HVQ' ACUS 2A. 3HVO* ACUS 2A wasrepaired and returned to sersice on June 16, 1990.

.

On June 13, 1900 the "B" train Residual Heat Removal Pump Area Cooler 3HVQ' ACUStB, had beenopened and substantial fouling found (reference Licensee Event Report 90-020). As part of thecorrective action, the opposite train unit and the Containment Recirculation Pump Area coolers weresubsequently inspected due to the similarity of design.

While cleaning each of the two Contamment Recirculation Pump Area Coolers, damage to the div' deriplate between the combined inlet and outlet head of the heat exchangers was found (see attachedfigure). The dwider plates developed holes (app.1* diameter in 3HVQ' ACUS 2A and app.13/8" by 13/4" b 3HVQ* ACUS 2B). The holes developed from a 1/4" drainage hole provided by the vendor. The3HVO'

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form 366AU.S. NUOLEAR REoVQToRY CoMMISSloN fro O 8N 60-0104

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F ACUTY NAME 0) ' DOCKET NUMDER (2) L F A NUMBFD to PAGE (3)

YEAR

Millstone Nuclear Power StationUnit 3 - -

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Based on the results of a detailed engineering evaluation which determined that the units wereinoperable, an immediate notification per the requirements of 10CFR50.72.(b)(2)(iii) was performed onJuly 5,1990.

In response to a Containment Recirculation Pump start the associated Containment Recirculation Pumpand Area cooler starts to provide cooling to the pump cubicle. The cooler ensures that the Containmentrecirculation pumps, motors and associated electrical components do not over heat.

'If a design basis loss of coolant accident (LOCA) were to occur with the two area coolers in a degradedcondition, the Containment Recirculation Pumps could potentially fail due to overheating if no othercompensatory measures were taken and worst case design conditions existed.' An alarm would annunciateto alert control room personnel of a high area temperature condition. Other compensatory measures(opening doors to increase ventilation) could prevent temperatures in the area from exceeding the designbasis conditions.

Neither of the Containment Recirculation Pump and Area Coolers had exhibited any sign of highdifferential pressure, which is the parameter measured in the surveillance program. This was due to flowbypassing the heat exchanger tubes through the hole in the divider plate.

IV. Corrective Action

When fouling was identified, each heat exchanger was immediately cleaned of debns and the differential-pressure at design flow verified to be acceptable.

The divider plates on 3HVQ' ACUS 2A and 2B units were repaired using a monel patch. A 1/Pdiameter drain hole was drilled in the patch to maintain consistency with the original design. By utilizingmonel for the repair, the galvanic impact of a different material was minimized. Monel is not susceptibleto the same flow erosion as the original copper nickel material.

During the upcoming refueling outage (tentatively scheduled for February,1991) 3HVQ' ACUS 2A and2B will be visually inspected per the requirements of NRC Generic Letter 89-013 " Service Water SystemProblems Affecting Safety Related Equipment". Additionally, the existing surveillance program will bechanged to measure additional parameters to better assess the condition of the Semce Water Systemheat exchangers.

All of the Containment Recirculation Pump Area and Residual Heat Removal Pump Area cooler heatexchangers have been put on a twice an operating cycle preventive maintenance program to inspect andclean the units as required. A visual inspection of the heat exchangers will be performed by October 30,-1990, to determine if fouhng or damage to the divider plate is occurring. ,

!

Due to the generic implications, all of the heat exchangers in the Service Water System have beenreviewed for similar problems. All other heat exchangers subject to this type of fouhng have beeninspected within the past six months.

V. Additional Information

Generic Letter 89-013. " Service Water System Problems Affecting Safety-Related Equipment"specifically addresses the loss of heat transfer capability of heat exchangers in the Service Water System.Millstone 3 has committed to test or mspect all heat exchangers in the Service Water System by the endof the third refuehng outage (tentatively scheduled for February,1990). The existing surveillance programwill continue to be used m conjunction with inspections recommended in the Generic Letter.

A review of the Institute of Nuclear Power Operations (INPO) Nuclear Plant Rehabihty Data System(NPRDS) data base did not reveal any other failures of this type. The heat exchanger manufacturer isGraham Manufacturing Company Inc.

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c'"ommen'*s"regardinom.roen estimate io ine n.aro .t coroTEXT CONTINUATION ano n.noris uanao nt Branen to saon u s. Nucisarnepuistory Commission Wasnington. DC 20565. and totne Paperwork Recueten Protect 13150-01NL Office ofManagement and Budget. Washington DC 20603.

FACILITY NAME (1) DoCFJT NUMBER (2) LEA tamAFFA f61 PAGE (3)

YEAR W NMillstone Nuclear Power StationUnit 3 - ~

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A similar event of heat exchanger fouling is discussed in Licensee Event Report 90-020. The eventdiscussed in this Licensee Event Report was identified as a result of the corrective actions of LER90-020. ,

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Ells Codes

System Comnonents

Containment Recirculation Heat Exchangers - HXSpray System - DE

H orm 366

NRO Form 366A U.S NUCLEAR REGULATORY COMMISStON APPROVED OMB NO. 3160 01(4M 69) EXPIRES d/30/02, ' #

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F ACUTY NAME (1) DOOFIT NUMBER (2, (FA Nuunto 481 PAGEi31

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