Information Notice 1989-10, Undetected Installation Errors in Main Steam Line Pipe Tunnel Differential Temperature-Sensing Elements at Boiling Water Reactors

Undetected Installation Errors in Main Steam Line Pipe Tunnel Differential Temperature-Sensing Elements at Boiling Water Reactors

ML031180510
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
Issue date:	01/27/1989
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-89-010, NUDOCS 8901230427
Download: ML031180510 (6)

UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 January 27, 1989 NRC INFORMATION

NOTICE NO. 89-10: UNDETECTED

INSTALLATION

ERRORS IN MAIN STEAM LINE PIPE TUNNEL DIFFERENTIAL

TEMPERATURE-SENSING

ELEMENTS AT BOILING WATER REACTORS

Addressees

All holders of operating

licenses or construction

permits for boiling water reactors (BWRs).

Purpose

This information

notice is being provided to alert addressees

to potential problems from undetected

installation

errors in main steam line (MSL) pipe tunnel differential

temperature-sensing

elements at BWRs. It is expected that recipients

will review the information

for applicability

to their facilities

and consider actions, as appropriate, to avoid similar problems.However, suggestions

contained

in this information

notice do not constitute

NRC requirements;

therefore, no specific action or written response is required.Description

of Circumstances:

On July 27, 1988, Pennsylvania

Power and Light Company (PP&L) declared all of the differential

temperature (DT) instruments

in both Units 1 and 2, used for the detection

of leaks in the MSL pipe tunnel at the Susquehanna

Steam Electric Station (SSES) inoperable.

In both units the inlet and outlet temperature

detector (thermocouple)

locations

were found reversed such that the follower DT instrumentation

modules would sense a zero or negative DT in the event of a steam line leak. In Unit 2, the temperature

detectors

were found not only reversed, but installed

in the wrong location.

The Unit 2 detectors

were found in the vicinity of the air cooler units, a location that would have substan-tially reduced (non-conservatively)

the available

signal to the follower DT modules. As a result of these deficiencies, none of the DT protective

instru-mentation

would have detected a steam line leak, and thus they would have been unable to perform their design function.On June 24, 1987, Niagara Mohawk Power Corporation

declared two of four channels of the main steam tunnel DT instrumentation

at Nine Mile Point (NMP) Unit 2 in-operable.

The temperature-sensing

elements (thermocouples)

were improperly

located such that the cold leg thermocouples, which are supposed to monitor steam tunnel ventilation

inlet air temperature

were actually sensing steam tunnel ambient air temperature.

Operations

personnel

detected this problem 8901230427

7bh '// C

IN 89-10 January 27, 1989 while the reactor was at less than 2 percent power. They observed significant

differences

in the DT indications

for the four channels.

Two channels with properly located thermocouples

indicated

approximately

15 0 F DT and the other two channels with improperly

located thermocouples

indicated

approximately

0 DT.Discussion:

In both the SSES and NMP-2 plants, the steam tunnel is equipped with tempera-ture detectors

that are used to initiate steam line isolation

upon detection of a steam leak, based on either a rise in steam tunnel ambient air temperature

or an increase in the temperature

differential

between the tunnel ventilation

inlet and outlet. These steam tunnel differential

temperature

and ambient tem-perature instruments

provide redundant

methods for detecting

leaks and isolating the MSLs. The installation

errors described

above reduced the designed redun-dancy of the MSL leak detection

system.PP&L attributes

the root cause of DT thermocouple

location errors in both units to vague initial system descriptions

and design-basis

documents

that did not clearly establish

locations

for the DT thermocouples.

As a consequence, the installation

documents

for both units inappropriately

specified

the connection

of the thermocouples

to the DT instruments

in such a manner that the inlet and outlet device locations

were interchanged.

This reversal caused the follower DT instruments

to always read zero and downscale

when in fact they should have read above zero and upscale for both normal power operation

and in the event of a leak. The SSES-2 problem was further compounded

by the fact that the thermo-couples for sensing inlet air temperature

were not located in the air inlet but rather in the fan cooler room for the steam tunnel cooling system. As a con-sequence, even if the thermocouples

were connected

properly, the increase in DT in the event of a steam leak would have been substantially

less than the in-strumentation

trip set value. The scope of the PP&L start-up and surveillance

tests was too narrow to identify the location errors. Although these tests verified that the instrumentation

would respond to temperature

and DT, neither test verified that the inputs were of the proper magnitude

for a given steam leak or detected that they were reversed.

During these tests and during years of routine surveillance, neither the technicians

nor the operators

recognized

the zero or negative DT reading as being abnormal.Niagara Mohawk attributes

the root cause of the DT thermocouple

location errors for two channels to a design deficiency.

The two mislocated

thermocouples

were installed

away from the inlet air stream, and therefore

they sensed steam tunnel ambient air temperature

instead of ventilation

inlet air temperature.

This reading provided a non-conservative

input into the steam tunnel differential

temperature

isolation

logic.

IN 88-10--January 27, 1989 No specific action or written response is required by this information

notice.If you have any questions

about this matter, please contact the technical contact listed below or the Regional Administrator

of the appropriate

regional office.Charles E. Rossi, Irector Division of Operational

Events Assessment

Office of Nuclear Reactor Regulation

Technical

Contact: Carl H. Woodard, RI (215) 337-5261 Attachment:

List of Recently Issued NRC Information

Notices

IN 88-10 January 27, 1989 No specific action or written response is required by this information

notice.If you have any questions

about this matter, please contact the technical contact listed below or the Regional Administrator

of the appropriate

regional office.Charles E. Rossi, Director Division of Operational

Events Assessment

Office of Nuclear Reactor Regulation

Technical

Contact: Carl H. Woodard, RI (215) 337-5261 Attachment:

List of Recently Issued NRC Information

Notices*SEE PREVIOUS PAGE FOR CONCURRENCE

• OGCB:DOEA:NRR

PCWen 01/10/89*RI CHWoodard 01/10/89*PPMB:ARM TechEd 01/11/89*C/OGCB:DOEA:NRR

CHBerlinger

01/19/89 0123'89 IN 88-XX January xx, 1989 No specific action or written response is required by this information

notice.If you have any questions

about this matter, please contact the technical contact listed below or the Regional Administrator

of the appropriate

regional office.Charles E. Rossi, Director Division of Operational

Events Assessment

Office of Nuclear Reactor Regulation

Technical

Contact: Carl H. Woodard, RI (215) 337-5261 Attachment:

List of Recently Issued NRC Information

Notices OGCB:DOEA:NRR

PCWen 011o /89 RI CHWoodard 01/VO/89 4B AMC/OGCB:DOEA:NRR

TechEd YtHBerlinger

01////89 O1/1'/89 D/DOEA:NRR

CERossi 01/ /89 Document Name: MAIN STEAM LINE DETECTION

SYS Requestor's

ID: WERTMAN Author's Name: peter wen Document Comments: J17 IN main steam line detection

system installation

error a.