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, 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, Crane
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

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

heat exchangers in raw water systems.

The result of this fouling could affect

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

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

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

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

was 1480F 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'

Director

Divisi

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.

86-95

86-94

86-93

86-82 Rev. 1

86-92

86-91

86-90

86-89

86-05 Sup. 1

86-25 Sup. 1 Subject

Leak Testing I1dine-125 Sealed Sources In Lixi, Inc.

Imaging Oevices and Bone

Mineral Analyzers

Hilti Contrete Expansion

Anchor Balts

Issue

11/14/86

11/6/86 IEB 85-03 Evaluation Of

1W/3/B6 Motor-Operators Identifies

Improper Torque Switch

Settings

Failures Of Scram Discharge

11/4/86

Volume Vent And Drain Valves

Issued to

All NRC licensees

authorized to use

Lixii Inc. imaging

devices

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All PVR facilities

holding an OL or CP

All power reactor

facilities holding

an OL or CP; fuel

fabrication and

processing facilities

Pressurizer Safety Valve

Reliability

Limiting Access

Authorizations

Requests To Dispose Of Very

Low-Level Radioactive Waste

Pursuant to 10 CFR 20.302

Uncontrolled Rod Withdrawal

Because Of A Single Failure

Main Steam Safety Valve Tlst

Failures And Ring Setting

Adjustments

Traceability And Material

Control of Material And

Equipment. Particularly

Fasteners

11/4/86

11/3/86

1V3/86

All power reactor

facilities holding

an OL or CP

10/16/86

All 6WR facilities

holding an OL or CP

10/16/S6

All power reactor

facilities holding

an OL or CP

10/15/86

All power reactor

facilities holding

an OL or CP

OL a Operating License

CP

• Construction Permit

UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 2M55

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE $300

FRlST CLASS MAIlL

POSTAGE 6 FEES PAID

USNAC

WASH D.C

PERMIT No G

1

1 C

91 I

y 1

111 111

133575103600

NUS Co-P

L.FS

LYLE

3A

0E9 LICE\\ISING ENJINE_4

2536 COU\\NTRYrC ¢

iLV'

_L'

" AJA T-V

FL

3

7