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Loss of Power Instrumentation TS 3.3.8.1 A … Loss of Power Instrumentation TS 3.3.8.1 Applicability Following Bus 64C Potential Transformer Fuse Failures Introduction. The inspectors opened an Unresolved Item to further evaluate the applicability of TS 3.3.8.1, Loss of Power (LOP) Instrumentation, following the failure of potential transformer fuses that caused half of the bus 64C LOP and degraded voltage relays to de-energize. Description. On April 24, 2016, a loss of output from the line to neutral potential transformers occurred on 4160 volt AC busses 64A and 64C. This resulted in the loss of bus indications, loss of automatic control of station transformer 64 load tap changer, and actuation of half of the LOP and degraded voltage relaying for safety-related bus 64C. The licensee subsequently discovered all six of the primary side fuses to the potential transformers had blown. Although the actual cause for the blown fuses was not conclusively determined, the most likely cause was attributed to an intermittent low energy transient on the secondary side of station transformer 64 or a transient on the 120 kilovolt electrical grid supplying the transformer. The inspectors noted the licensee did not consider the de-energized LOP and degraded voltage instrument channels to be inoperable, and therefore, did not enter the applicable action requirements of TS 3.3.8.1. The licensee had concluded the affected LOP and degraded voltage instrument channels remained operable since their safety function was believed to have been satisfied while they were de-energized and tripped. The inspectors raised several questions with the licensee concerning the operability of the affected LOP and degraded voltage instrument channels. The questions included whether the potential transformers were part of the LOP and degraded voltage instrumentation described in TS 3.3.8.1 and whether applicable surveillance requirements had been satisfied for the instrumentation prior to and during the event. The licensee entered this issue into its corrective action program as CARD 1625194 for further evaluation. This issue of concern is considered an Unresolved Item pending additional review by the inspectors to determine whether the licensee had correctly applied the TS limitations and satisfied applicable regulatory reporting requirements (URI 05000341/201600203, Loss of Power Instrumentation TS 3.3.8.1 Applicability Following Bus 64C Potential Transformer Fuse Failures). 64C Potential Transformer Fuse Failures).

Discovered date

23:59:59, 30 June 2016 +

Docket

05000341 +

Event date

23:59:59, 30 June 2016 +

Finding integer

3 +

Finding type

URI +

Has query"Has query" is a predefined property that represents meta information (in form of a <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Subobject">subobject</a>) about individual queries and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.

CL.4 +

IP 71111.15, Operability Determinations and Functionality Assessments +

Inspection report

IR 05000341/2016002 +

Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.

04:24:00, 22 February 2018 +

2016Q2 +

Green +

Fermi +

23:59:59, 30 June 2016 +

TS

TS-3.3.8.1 +

Title

Loss of Power Instrumentation TS 3.3.8.1 Applicability Following Bus 64C Potential Transformer Fuse Failures +

Violation of

Pending +

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