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A self-revealing noncited violation of Tec … A self-revealing noncited violation of Technical Specification 5.8.1.a was identified for the failure to have an adequate procedure for plant cooldown. Specifically, on June 10, 2008, the plant cooldown procedure allowed the control room staff to unexpectedly draw an approximately 2700-gallon steam void in the reactor coolant system. The procedure failed to provide guidance to ensure the reactor vessel head and steam generator u-tubes were sufficiently cooled down before depressurizing the reactor coolant system. Contributors to the event included: 1) the failure to institutionalize related operating experience from NRC Generic Letter 81-21, Natural Circulation Cooldown, dated May 5, 1981; and 2) the failure of plant operators to implement related training intended to avoid void formation. After voids formed, operators recognized the void indications, raised system pressure to collapse the steam voids, and then cooled the vessel head and steam generator u-tubes before reducing system pressure again. The licensee entered the issue into their corrective action program as CR 2008-4131. The failure to have an adequate cooldown procedure was more than minor because, if left uncorrected, it could become a more significant safety concern. Specifically, the same procedure would be used during natural circulation operations. Voiding in the steam generator u-tubes under these conditions could challenge the use of the steam generators as a heat sink. Using the NRC Manual Chapter 0609, Appendix G, Shutdown Operations Significance Determination Process, and Attachment 1 to Appendix G, Shutdown Operations Significance Determination Process Phase 1 Operational Checklists for Both PWRs and BWRs, the inspectors determined that the finding was of very low risk significance because it did not: 1) result in non-compliance with low-temperature-over-pressure technical specifications; 2) increase the likelihood that a loss of decay heat removal would occur or affect the ability to recover decay heat removal; 3) increase the likelihood of a loss of reactor coolant system inventory or affect the ability to terminate a primary system leak; 4) increase the likelihood of a loss of offsite power or affect the ability to recover from a loss of offsite power; nor 5) affect containment integrity. Also, this finding had a cross-cutting aspect in the area of human performance related to the decision making component because control room personnel failed to use conservative assumptions when deciding to proceed with plant depressurization, considering the unusual circumstance of excessive residual heat in the steam generators and reactor vessel head (H.1(b)generators and reactor vessel head (H.1(b)

Discovered date

23:59:59, 30 June 2008 +

Docket

05000285 +

Event date

23:59:59, 30 June 2008 +

Finding integer

4 +

Finding type

Non-cited violation +

Generic letter

NRC Generic Letter 81-21, Natural Circulation Cooldown +

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INPO aspect

DM.2 +

Identified by

Self-revealing +

Inspection Manual Chapter

NRC Inspection Manual 0609, Appendix G +

Inspection procedure

IP 71153, Event Followup +

Inspection report

IR 05000285/2008003 +

Inspector

D Stearns +, L Ellershaw +, John Hanna +, Paul Elkmann +, John Kirkland +, Shiattin Makor +, T Pate +, Matt Young + and Webb Patricia Walker +

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>.

03:05:21, 30 May 2018 +

Person