UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001

July 10, 2006

NRC INFORMATION NOTICE 2006-14: POTENTIALLY DEFECTIVE EXTERNAL

LEAD-WIRE CONNECTIONS IN BARTON

PRESSURE TRANSMITTERS

ADDRESSEES

All holders of operating licenses for nuclear power reactors, except those who have

permanently ceased operations and have certified that fuel has been permanently removed

from the reactor.

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this Information Notice to inform

addressees that ITT Barton Model 763 and 763A gage pressure transmitters and Model 764

differential pressure transmitters may have defective external lead-wire connectors that could

adversely affect the performance of the instruments during an accident. 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 are not NRC requirements; therefore, no specific action or written response is required.

DESCRIPTION OF CIRCUMSTANCES

On June 21, 2006, the Callaway nuclear power plant licensee submitted a Title 10 of the Code

of Federal Regulations Part 21 notification to the NRC that certain Barton pressure transmitters

may have defective external lead-wire connections (Event Notification 42658, Agencywide

Documents Access and Management System (ADAMS) Accession No. ML061770354). Prime

Measurement Products (Prime), formerly known as Barton Instruments or ITT Barton, currently

supplies these transmitters to the commercial nuclear power industry. The subject transmitters

are Barton Model 763 and 763A gage pressure transmitters and Barton Model 764 pressure

differential transmitters manufactured after May 1982 and shipped from the Prime factory prior

to April 1, 2006. 

The external lead wires are soldered to the glass-sealed pins of the hermetic seal. Epoxy

potting is used to structurally support the soldered wire connections and seal the solder

connections against potential shorting in an electrically conductive accident environment. The

defect is that the insulated portions of the wires in the connectors manufactured after May 1982

and shipped from the Prime factory prior to April 1, 2006, may not be embedded deeply enough

into the epoxy potting to provide such protection. Prime believes that the insulation was pulled

from the epoxy potting, leaving the conductors exposed directly to the environment because of

stress during either: (1) the normal manufacturing process; or (2) the installation of the

transmitters in the field. 

ML061870545
IN 2006-14

Page 2 of 2

During cleaning activities before shipping transmitters to a customer, Prime observed that one

transmitter had a severed lead. Prime inspected connector assemblies in the factory inventory

and identified some connectors with an exposed wire. Prime stopped shipment of all pressure

transmitters until the connector manufacturing process was modified and acceptable connector

assemblies became available. Prime instituted corrective actions, including improved connector

assembly manufacturing and inspection processes. These processes involve the use of

enhanced manufacturing fixtures and detailed assembly instructions.

DISCUSSION

On May 18, 2006, Prime recommended in an advisory letter to all affected licensees, including

the Callaway nuclear power plant that all connectors in transmitters manufactured after

May 1982 and shipped from the Prime factory prior to April 1, 2006, be inspected for exposure

of the external lead-wire conductors at the surface of the connector (instructions recommended

by Prime with illustrations are available at ADAMS Accession No. ML061860324). Prime stated

that gauge pressure and differential pressure transmitters manufactured before June 1982

were assembled with heat shrink tubing on the external lead wires at the location where they

were embedded into the epoxy potting. This configuration is not subject to the concerns of the

Prime advisory letter. Any connector assembly having heat shrink tubing individually applied to

each wire entering the epoxy potting is not considered susceptible to the condition described

herein. 

The Callaway licensee identified 39 gauge pressure and differential pressure transmitters of the

types described above as being installed in the plant and an additional 30 pressure transmitters

in its warehouse stock. Of these 30 pressure transmitters inspected from its spare parts

inventory, three connector assemblies were found to have one or more exposed conductors

external to the seal. One connector assembly had this defect on one of the two lead wires and

two connector assemblies had this defect on both lead wires. The licensee plans to inspect the

39 installed transmitters as conditions permit.

CONTACT

This information notice requires no specific action or written response. Please direct any

questions about this matter to one of the technical contacts listed below.

/RA/

Ho K. Nieh, Acting Director

Division of Policy and Rulemaking

Office of Nuclear Reactor Regulation

Technical Contacts: Chuck Paulk R-IV/DRS Kamalakar Naidu, NRR/DE

817-860-8236 301-415-2980

E-mail: cjp@nrc.gov E-mail: krn@nrc.gov

Vernon Hodge, NRR/DIRS Hukum Garg, NRR/DE

301-415-1861 301-415-2929

E-mail: cvh@nrc.gov E-mail: hcg@nrc.gov