Information Notice 1985-37, Chemical Cleaning of Steam Generators at Millstone 2

Chemical Cleaning of Steam Generators at Millstone 2

ML031180249
Person / Time
Site:	Beaver Valley, Millstone, Calvert Cliffs, Davis Besse, Salem, Oconee, Mcguire, Palisades, Palo Verde, Indian Point, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Watts Bar, Sequoyah, Byron, Arkansas Nuclear, Braidwood, Summer, Prairie Island, Surry, North Anna, Turkey Point, Crystal River, Haddam Neck, Ginna, Callaway, Vogtle, Waterford, Farley, Robinson, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, McGuire, 05000000, Washington Public Power Supply System, Trojan, Marble Hill, Crane
Issue date:	05/14/1985
From:	Jordan E NRC/IE
To:
References
FOIA/PA-2005-0210 IN-85-037, NUDOCS 8505130034
Download: ML031180249 (3)

SSINS No.: 6835 IN 85-37

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D. C. 20555

'May 14, 1985 IE INFORMATION NOTICE NO. 85-37:

CHEMICAL CLEANING OF STEAM GENERATORS AT

MILLSTONE 2

Addressees

All pressurized water reactor (PWR) facilities holding an operating license

(OL) or a construction permit (CP).

Purpose

This information notice is being provided as notification of a potentially

significant problem pertaining to corrosion product buildup in the secondary

side of steam generators which may mask eddy current signals.

It is expected

that recipients will review the information for applicability to their facili- ties and consider actions, if appropriate, to preclude a similar problem

occurring at their facilities.

However, suggestions contained in this informa- tion notice do not constitute NRC requirements; therefore, no specific action

or written response is required.

Description of Circumstances

Millstone 2 is a two-loop, 2700 megawatt-thermal PWR that was licensed in 1975.

Secondary water treatment has been all-volatile since startup.

Northeast

Nuclear Energy Company (NNECo) had plugged 941 tubes in steam generator (SG)-1 and 759 in SG-2 and had sleeved 894 tubes in SG-1 and 1128 in SG-2 prior to the

current outage.

The deteriorating condition of the tubes has been attributed

to the buildup of sludge containing, principally, copper and iron.

Condenser

and feedwater heater tubes made of a copper-alloy are thought to be the source

of the copper. A sludge pile, the source of corrodants causing denting and

pitting, existed in the secondary side on the tube sheet and around the tubes

to a maximum depth of 13 inches.

Before cleaning the secondary side of the steam generators in early April 1985, NNECo conducted eddy current testing of all 8500 tubes in SG-2 and a statisti- cal sample of tubes in SG-1 and projected the need to sleeve 300 tubes in each

steam generator.

Sludge lancing removed about 300 pounds of sludge from each

steam generator.

Chemical cleaning of the secondary side removed about 300

pounds more of the sludge.

For the basic chemical process, NNECo selected the

Electric Power Research Institute's Steam Generator Owners Group Generic Process.

The concentration of the various chemicals in the solvents was adjusted to yield

the most efficient cleaning of the site-specific materials and configuration.

The procedure was designed to remove the sludge pile with few adverse effects

on the steam generators or internals.

8505130034

I

IN 85-37 May 14, 1985 The cleaning process involves the use of iron' and copper solvents in a specified

number of applications under controlled conditions.

The iron solvent uses an

inhibitor to protect the base metal, while the copper solvent has been virtually

noncorrosive to carbon steel and Inconel 600 in tests.

Coirosion of the Inconel

tubes has been less than 0.1 mil in sludge cleaning tests.

NNECo'had qualified

the specific solvents and processes for use at Millstone 2 before-their use.

Following chemical cleaning, eddy current testing of each of the steam generators

tubes was again performed.

NNECo reported that 1077 tubes in the cold leg and

552 tubes in the hot leg of SG-1 will be sleeved.

In SG-2, 1074 tubes in the

cold leg and 145 tubes in the hot leg will be sleeved.

This represents an increase

of nearly a factor of five in the number of tubes to be sleeved, compared to the

projections made based on eddy current testing prior to cleaning.

In addition,

19 tubes (12/7) will be plugged in the two SGs.

This is the first use of this cleaning process at any nuclear plant.

The tube

defects found after cleaning are thought to have been present prior to the

cleaning.

The copper and iron constituents of the sludge apparently generated

a signal which masked the signal of the smaller defects.

Pits of 0.075 inch

diameter and larger can be detected in the presence of copper.

After cleaning, smaller diameter defects were identified. Essentially all of these defects

were found in the region of the sludge pile; that is, within a height of 13 inches above the tube sheet.

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

If there are -Ay-4`uesti6ns regarding this matte-r, please contact the Regional

Administrator of the appropriate NRC regional office or this office.

a

iardctor

Divisit of Emergency Preparedness

and Engineering Response

Mary S. Wegner, IE

(301) 492-4511 Attachments:

List of Recently Issued IE Information Notices

1 NP-3009, Steam Generator Chemical Cleaning Process Development, Electric Power Research Institute, Palo Alto, CA, April 1983.

Attachment 1

IN 85-37

May 14, 1985

LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issue

Issued to

84-55 Sup. 1

85-20

Sup. 1

Seal Table Leaks At PWRs

5/14/85 Motor-Operated Valve Failures 5/14/85

Due To Hammering Effect

85-36

84-52 Sup. 1

85-35 Malfunction Of A Dry-Storage,

Panoramic, Gamma Exposure

Irradiator

Inadequate Material

Procurement Controls On

The Part Of Licensees And

Vendors

Failure Of Air Check Valves

To Seat

5/9/85

5/8/85

4/30/85

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All licensees

possessing gamma

irradiators

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

anOL or CP

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 power reactor

facilities holding

an OL or CP

t'

.

I

I

i

I I

i

85-34 Heat Tracing Contributes To

4/30/85

Corrosion Failure Of Stainless

Steel Piping

84-84 Rev. 1

85-33

85-32 Deficiencies In Ferro-

Resonant Transformers

Undersized Nozzle-To-Shell

Welded Joints In Tanks And

Heat Exchangers Constructed

Under The Rules Of The ASME

Boiler And Pressure Vessel

Code

Recent Engine Failures Of

Emergency Diesel Generators

4/24/85

4/22/85

4/22/85 OL = Operating License

CP = Construction Permit