[Federal Register Volume 80, Number 148 (Monday, August 3, 2015)]
[Notices]
[Pages 46061-46062]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-18997]


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NUCLEAR REGULATORY COMMISSION

[NRC-2015-0183]


Testing of Open Secondary Window-Type Current Transformers--Test 
Plan

AGENCY: Nuclear Regulatory Commission.

ACTION: Draft test plan; request for comment.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing for 
public comment a proposed draft test plan, ``Testing of Open Secondary 
Window-Type Current Transformers--Test Plan.'' The purpose of this 
testing is to better understand the following scenario: Will open 
circuiting of the secondary circuit of a current transformer (CT), 
which is operating within its rated continuous primary current limits, 
result in an excessively high voltage in the secondary circuit 
sufficient to start a fire in the form of explosion or arcing in the 
circuit's insulation at the location of the CT itself or at some other 
location in the secondary circuit?

DATES: Submit comments by September 2, 2015. Comments received after 
this date will be considered if it is practical to do so, but the 
Commission is able to ensure consideration only for comments received 
before this date.

ADDRESSES: You may submit comments by any of the following methods 
(unless this document describes a different method for submitting 
comments on a specific subject):
     Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2015-0183. Address 
questions about NRC dockets to Carol Gallagher; telephone: 301-415-
3463; email: [email protected]. For technical questions, contact 
the individual listed in the FOR FURTHER INFORMATION CONTACT section of 
this document.
     Mail comments to: Cindy Bladey, Office of Administration, 
Mail Stop: OWFN-12-H08, U.S. Nuclear Regulatory Commission, Washington, 
DC 20555-0001.
    For additional direction on obtaining information and submitting 
comments, see ``Obtaining Information and Submitting Comments'' in the 
SUPPLEMENTARY INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: Shivani Mehta, Office of Nuclear 
Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001; telephone: 301-415-0860, email: [email protected].

SUPPLEMENTARY INFORMATION:

[[Page 46062]]

I. Obtaining Information and Submitting Comments

A. Obtaining Information

    Please refer to Docket ID NRC-2015-0183 when contacting the NRC 
about the availability of information for this action. You may obtain 
publicly-available information related to this action by any of the 
following methods:
     Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2015-0183.
     NRC's Agencywide Documents Access and Management System 
(ADAMS): You may obtain publicly-available documents online in the 
ADAMS Public Documents collection at http://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``ADAMS Public Documents'' and 
then select ``Begin Web-based ADAMS Search.'' For problems with ADAMS, 
please contact the NRC's Public Document Room (PDR) reference staff at 
1-800-397-4209, 301-415-4737, or by email to [email protected]. The 
proposed draft test plan, ``Testing of Open Secondary Window-Type 
Current Transformers--Test Plan'' is available in ADAMS under Accession 
No. ML15203A228.
     NRC's PDR: You may examine and purchase copies of public 
documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555 
Rockville Pike, Rockville, Maryland 20852.

B. Submitting Comments

    Please include Docket ID NRC-2015-0183 in your comment submission.
    The NRC cautions you not to include identifying or contact 
information that you do not want to be publicly disclosed in your 
comment submission. The NRC will post all comment submissions at http://www.regulations.gov as well as enter the comment submissions into 
ADAMS. The NRC does not routinely edit comment submissions to remove 
identifying or contact information.
    If you are requesting or aggregating comments from other persons 
for submission to the NRC, then you should inform those persons not to 
include identifying or contact information that they do not want to be 
publicly disclosed in their comment submission. Your request should 
state that the NRC does not routinely edit comment submissions to 
remove such information before making the comment submissions available 
to the public or entering the comment submissions into ADAMS.

II. Discussion

    The NRC is issuing for public comment a proposed draft test plan. 
The purpose of this test program is to better understand and obtain 
information to form a technical basis for assessing the propensity of a 
secondary fire or damage to the secondary side circuit or components as 
a result of an open-circuited current transformer (CT) secondary 
winding. Specifically, the test program will allow investigation of the 
high-voltage in the secondary circuit to determine if it is sufficient 
to induce a fire in the circuit's insulation at the CT location or 
within the secondary circuit.
    The NRC is seeking public comment in order to receive feedback from 
the widest range of interested parties and to ensure that all 
information relevant to developing this document is available to the 
NRC staff. This document is issued for comment only and is not intended 
for interim use. The NRC will review public comments received on the 
documents, incorporate suggested changes as necessary, and make the 
final test plan available to the public through ADAMS and http://www.regulations.gov at Docket ID NRC-2015-0183, and will be documented 
in the final test report. No responses will be provided to specific 
commenters in regards to the disposition of their comments.
    Current transformers (CTs) are widely used to monitor the current 
at strategic locations of electrical power distribution systems in 
nuclear power plants (NPPs). The CTs provide isolation from the high-
voltage primary, and step-down the magnitude of the measured current to 
a value that can be safely handled by the monitoring instruments. Thus, 
they are designed to measure the current in alternating current (AC) 
power systems (generally three-phase systems) in their primary winding 
and transform this current into a representative low secondary current 
for instrumentation used for remote readout of the current. An open-
circuit in a CT's secondary winding can cause high voltages on the 
secondary circuit as the CT attempts to maintain the current 
relationship dictated by the transformer's winding turns ratio. The 
resulting high voltage condition in the secondary circuit from an open-
circuited CT introduces a potential failure mode that warrants further 
investigation as part of the final resolution of circuit failure issues 
associated with the fire protection strategies at nuclear power plants. 
Specifically, an open circuit on a high voltage CT circuit may result 
in secondary damage, possibly resulting in the occurrence of an 
additional fire in the location of the CT itself or at a location 
remote to the CT. This potential event is described in Section 3.5.2.1 
of the NEI 00-01, Revision 2 (ADAMS Accession No. ML091770265), and 
endorsed by Regulatory Guide 1.189, Revision 2 (ADAMS under Accession 
No. ML092580550).
    Accordingly, the purpose of this test program is to better 
understand and obtain information to form a technical basis for 
assessing the propensity of a secondary fire or damage to the secondary 
side circuit or components under an open-circuited CT secondary 
winding. Specifically, the test program will allow investigation of the 
high-voltage in the secondary circuit to determine if it is sufficient 
to induce a fire in the circuit's insulation at the CT location or 
within the secondary circuit.

    Dated at Rockville, Maryland, this 27th day of July 2015.

    For the Nuclear Regulatory Commission.
Felix Gonzalez,
Acting Chief, Fire Research Branch, Division of Risk Analysis, Office 
of Nuclear Regulatory Research.
[FR Doc. 2015-18997 Filed 7-31-15; 8:45 am]
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