United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for November 2, 2004

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Part 21 - 2004-0013 - Potential Nonconservative Swelling Model for Control Rods

Licensee/Facility:


FRAMATOME ANP

Dockets:

License No:
Notification:

MR Number: H-2004-0019
Date: 05/25/2004


Reviewer: Rich Laura

Discussion:

Framatome ANP, a vendor of power reactor control rods, reported that the model used to determine the amount of swelling in certain control rod assemblies may not be adequately conservative. The absorbers used in a variety of control rod assemblies supplied by vendors other than Framatome ANP have been observed to swell after many years in service. This swelling has caused incomplete rod insertion, loss of rod tips, and clad strain due to hard contact of the absorber against the clad followed by continued swelling. Affected assemblies include extended life control rod assemblies (ELCRAs) used in B&W-designed plants and the rod cluster control assemblies (RCCAs) supplied by Framatome ANP and used in numerous Westinghouse-designed plants for nine years or more.

Framatome ANP states that though no effect of absorber swelling has been observed on control rods supplied by Framatome ANP, the experience of other vendors and the lack of sufficient information to definitively judge the degree of the conservatism of the model indicate that the situation needs to be evaluated under the requirements of Part 21. Framatome ANP also states that no substantial safety hazard exists because the current operational exposure of all assemblies supplied by Framatome ANP is significantly less than the original design life.

Framatome ANP expects its evaluation of the swelling model to be complete by January 21, 2005.

Accession Numbers:

Accession No Accession Date
ML041490290 05/25/2004

Contacts:

Name Office Abbrev Phone No E-Mail
HODGE, VERNON NRR (301) 415-1861 CVH@nrc.gov

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Part 21 - 2004-0017 - GERS Correction for General Electric IAC66K Relay

Licensee/Facility:


SEISMIC QUALIFICATION UTIL GROUP (SQUG)

Dockets:

License No:
Notification:

MR Number: H-2004-0020
Date: 06/30/2004

Discussion:

On June 30, 2004, the Seismic Qualification Utility Group (SQUG) reported a typographical interchange of contact fragility values between operate and non-operate modes for the General Electric IAC66K relay (SQUG Advisory 2004-01: Relay GERS Corrections, ADAMS Accession Number ML041900058). This relay is used in circuit breaker control circuits in nuclear power plants. This error was found in the general equipment ruggedness spectrum (GERS) level provided in EPRI NP-7147, "Seismic Ruggedness of Relays," Volume 2: Addendum 2, April 1995. Depending on several variables, it is possible that this error can result in spurious switchgear operation. The consequences of this error depend on how SQUG relay test results were used in reviews related to Unresolved Safey Issue A-46, "Seismic Qualification of Equipment in Operating Plants." Issue A-46 is discussed in Generic Letter 87-03, "Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors."

On September 10, 2004, SQUG reported finding further errors of similar nature (SQUG Advisory 2004-02: Relay GERS Corrections, ADAMS Accession Number ML042610031).

Accession Numbers:

Accession No Accession Date
ML041900058 06/30/2004

Contacts:

Name Office Abbrev Phone No E-Mail
HODGE, VERNON NRR (301) 415-1861 CVH@nrc.gov
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