Information Notice 1986-96, Heat Exchanger Fouling Can Cause Inadequate Operability of Service Water Systems

Heat Exchanger Fouling Can Cause Inadequate Operability of Service Water Systems

ML031250217
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
Issue date:	11/20/1986
From:	Jordan E NRC/IE
To:
References
IN-86-096, NUDOCS 8611180380
Download: ML031250217 (4)

L $ ESSINS No.: 6835 IN 86-96 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 November 20, 1986 IE INFORMATION NOTICE NO. 86-96: HEAT EXCHANGER FOULING CAN CAUSE INADEQUATE

OPERABILITY OF SERVICE WATER SYSTEMS

Addressees

All nuclear power reactor facilities holding an operating license or a con- struction permit.

Purpose

in

This notice is provided to alert recipients to the potential for fouling affect

heat exchangers in raw water systems. The result of this fouling could

be

the facility's ability to reject heat to the ultimate heat sink, which could

adverse under accident and post-accident conditions. It is suggested that

recipients review the information for applicability to their facilities and

consider actions, if appropriate, to preclude these conditions at their facili- ties. However, suggestions contained in this information notice do not consti- tute requirements; therefore, no specific action or written response is

required.

Description of Circumstances

Over an extended time period, the nuclear service water (NSW) system at McGuire

Nuclear Station was degraded by mud and silt buildup and corrosion. This

degraded the pathway to the ultimate heat sink (UHS), composed of Lake Norman

and its backup source, the standby nuclear service water pond. Therefore, the

heat removal capability assumed in the accident analysis could no longer be

satisfied.

The intake screens are too large to filter out the suspended solids and silt

from the lake. Over the years, a combination of organic and inorganic com- pounds fouled a number of heat exchangers, including the containment spray, component cooling water, and control room chiller heat exchangers. Adequate ii

performance of these heat exchangers is crucial for safely operating a unit

accident and post-accident conditions and for bringing it to cold shutdown

during normal operation or following an accident.

NRC inspections conducted at McGuire in 1985 and 1986 revealed significant

fouling problems with NSW system heat exchangers, indications of degraded NSW

flow, and inadequate flow balance tests to ensure system capability under design

accident conditions.

8611180380

IN 86-96 November 20, 1986 Additionally, the licensee notified the NRC that prior to January 27, 1986, the

NSW systems for Units 1 and 2 had not been tested under the most limiting

design basis accident configuration. Specifically, the system had never been

verified to supply the required flow concurrently to essential headers for both

units with the system taking suction solely from the common standby nuclear

service water pond rather than Lake Norman.

At Farley 1 on August 1, 1986, the licensee discovered that silt in the service

water system had caused overheating of gearboxes on two of three charging pumps

while the third pump was out of service for maintenance. In addition to their

normal function, these pumps function as part of the emergency core cooling

system. Service water is used to cool the lube oil coolers for the charging

pump gearboxes. One of the pumps was taken out of service when its gearbox

temperature exceeded 1550 F. The temperature of the gearbox on the other pump

was 1480 F and increasing. The vendor recommends operating the pumps with caution

above 140'F and not operating the pumps above 1550F. The lube oil coolers were

flushed to reduce the temperature of the gearbox lube oil below 140'F.

Discussion:

Service water systems are designed to meet General Design Criteria 44, 45, and

46 of 10 CFR 50, Appendix A. By these criteria, plant designs provide the

ability (1) to transfer heat from safety-related components under normal and

accident conditions to an ultimate heat sink; (2) to conduct periodic inspec- tions of the system to ensure integrity and capability; and (3) to test the

system under conditions as close to design as practical.

Fouling of service water systems has been recognized for some time as having

the potential for compromising system operability. IE Information Notice 81-21 and IE Bulletin 81-03 addressed the potential for fouling of safety-related

heat exchangers by Asiatic clams, mussels, and debris from other shell fish.

Duke Power Company responded with a program designed to monitor fouling of

several typical NSW supplied heat exchangers. Through this program and other

mechanisms the licensee identified numerous affected heat exchangers. However, because these data were not adequately evaluated to identify adverse trends, these programs were not totally effective. The affected heat exchangers included

containment spray, containment ventilation, control room air conditioning, reactor

coolant pump motor coolers, and component cooling water. In 1986 the licensee

identified several individual components, including containment spray heat

exchangers, which were not capable of meeting FSAR-specified performance require- ments. The containment spray heat exchangers were of particular concern since

they are normally inactive and gradual degradation from fouling can go unnoticed.

As noted above, the licensee at Farley 1 determined that charging pump gearbox

lube oil coolers are also important heat exchangers that can be affected by

silting.

To ensure minimum NSW component flows, including adequate flow to the contain- ment spray heat exchangers during design LOCA conditions, the normally throt- tled valves associated with each NSW component were set during preoperational

IN 86-96 November 20, 1986 testing of the NSW system. These throttled positions were to be incorporated

into operating and surveillance procedures for future operations. In some

cases, the throttled valve positions listed in the licensee's NSW operating

procedures and locked valve verification procedures were not consistent with

earlier preoperational "as left" data. Flow balance tests of the system had

not been performed from the initial preoperational test in 1982 until December

1985, even though the positions of established throttle valves were changed and

some heat exchangers exhibited fouling problems. The test conducted in 1985 revealed that flow rates through several safety-related heat exchangers were

below FSAR values.

IE Bulletin 81-03 does not by itself provide a high degree of assurance that a

long-term resolution has been achieved. The NRC also is formally studying this

subject under Generic Issue 51, "Proposed Requirements for Improving Reliabil- ity of Open Cycle Service Water Systems." This project depends on a research

program now well under way. Task 1 (of 4), determining the applicability of

documented biofouling surveillance and control methods to open cycle water

systems in nuclear power plants, is complete (NUREG/CR-4626, Vol. 1)*. The

resulting recommendations of Task 1 include: (1) a thorough system evaluation

to focus surveillance and control efforts for the best return on plant safety

and efficient operation, (2) revision of plant technical specifications to

reflect improved procedures, (3) monitoring the effectiveness of control

procedures as part of the surveillance program, and (4) including biofouling

K. surveillance in the routine maintenance program.

No specific action or written response is required by this information notice.

If you need any additional information regarding this matter, please contact

the Regional Administrator of the appropriate regional office or the technical

contact listed below.

6'

Divisi

Director

of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Technical Contacts: C. Vernon Hodge, IE

(301)492-7275 Frank Jape, Region II

(404)331-4182 Attachment: List of Recently Issued IE Information Notices

• A copy of this document is available in the NRC Public Document Room, 1717 H

Street N.W., Washington, DC 20555 for inspection and copying.

bt1- - nt 1 IN 86-96 November 20, 1986 LIST OF RECENTLY ISSUED

IE INFORMATION POTICES

InTorMation

Notice No. Subject Issue Issued to

86-95 Leak Testing I1dine-125 11/14/86 All NRClicensees

Sealed Sources In Lixi, Inc. authorized to use

Imaging Oevices and Bone Lixii Inc. imaging

Mineral Analyzers devices

86-94 Hilti Contrete Expansion 11/6/86 All power reactor

Anchor Balts facilities holding

an OL or CP

86-93 IEB 85-03 Evaluation Of 1W/3/B6 All power reactor

Motor-Operators Identifies facilities holding

Improper Torque Switch an OL or CP

Settings

86-82 Failures Of Scram Discharge 11/4/86 All power reactor

Rev. 1 Volume Vent And Drain Valves facilities holding

an OL or CP

86-92 Pressurizer Safety Valve 11/4/86 All PVR facilities

Reliability holding an OL or CP

86-91 Limiting Access 11/3/86 All power reactor

Authorizations facilities holding

an OL or CP; fuel

fabrication and

processing facilities

86-90 Requests To Dispose Of Very 1V3/86 All power reactor

Low-Level Radioactive Waste facilities holding

Pursuant to 10 CFR 20.302 an OL or CP

86-89 Uncontrolled Rod Withdrawal 10/16/86 All 6WR facilities

Because Of A Single Failure holding an OL or CP

86-05 Main Steam Safety Valve Tlst 10/16/S6 All power reactor

Sup. 1 Failures And Ring Setting facilities holding

Adjustments an OL or CP

86-25 Traceability And Material 10/15/86 All power reactor

Sup. 1 Control of Material And facilities holding

Equipment. Particularly an OL or CP

Fasteners

OL a Operating License

CP

• Construction Permit

UNITED STATES FRlST CLASS MAIlL

NUCLEAR REGULATORY COMMISSION POSTAGE 6 FEES PAID

USNAC

WASHINGTON, D.C. 2M55 WASH D.C

PERMIT No G

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE $300

133575103600 1 1 C 91 I y 1 111 111 NUS Co-P

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