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

boiling water

All holders of operating licenses or construction permits for

reactors (BWRs).

Purpose

to potential

This information notice is being provided to alert addressees line (MSL) pipe

problems from undetected installation errors in main steam

at BWRs. It is expected

tunnel differential temperature-sensing elements to their

that recipients will review the information for applicability

to avoid similar problems.

facilities and consider actions, as appropriate, do not constitute

However, suggestions contained in this information notice

is required.

NRC requirements; therefore, no specific action or written response

Description of Circumstances

declared all of

On July 27, 1988, Pennsylvania Power and Light Company (PP&L) and 2, used for

the differential temperature (DT) instruments in both Units 1 Steam Electric

the detection of leaks in the MSL pipe tunnel at the Susquehanna temperature

Station (SSES) inoperable. In both units the inlet and outlet the follower

detector (thermocouple) locations were found reversed such that

the event of

DT instrumentation modules would sense a zero or negative DT in found not only

a steam line leak. In Unit 2, the temperature detectors were were found

reversed, but installed in the wrong location. The Unit 2 detectors have substan- in the vicinity of the air cooler units, a location that would follower DT

tially reduced (non-conservatively) the available signal to the instru- modules. As a result of these deficiencies, none of the DT protective

they would have been

mentation would have detected a steam line leak, and thus

unable to perform their design function.

of four channels

On June 24, 1987, Niagara Mohawk Power Corporation declared two Unit 2 in- (NMP)

of the main steam tunnel DT instrumentation at Nine Mile Point were improperly

operable. The temperature-sensing elements (thermocouples) to monitor

located such that the cold leg thermocouples, which are supposed steam

steam tunnel ventilation inlet air temperature were actually sensing

this problem

tunnel ambient air temperature. Operations personnel detected

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. 0 Two channels with

properly located thermocouples indicated approximately 15 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

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

Carl H. Woodard, RI

(215) 337-5261 Attachment: List of Recently Issued NRC Information Notices

• SEE PREVIOUS PAGE FOR CONCURRENCE

• OGCB:DOEA:NRR *RI *PPMB:ARM *C/OGCB:DOEA:NRR

PCWen CHWoodard TechEd CHBerlinger

01/10/89 01/10/89 01/11/89 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

Carl H. Woodard, RI

(215) 337-5261 Attachment: List of Recently Issued NRC Information Notices

OGCB:DOEA:NRR RI 4B AMC/OGCB:DOEA:NRR D/DOEA:NRR

PCWen CHWoodard TechEd YtHBerlinger CERossi

011o /89 01/VO/89 01////89 O1/1'/89 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.