ENS 42386
ENS Event | |
|---|---|
23:00 Mar 3, 2006 | |
| Title | Reactor Building Ventilation Flowpath Inoperable |
| Event Description | This notification is being made in accordance with License Condition 2.F for Nine Mile Point Unit 2 which states in part 'report any violations of the requirements contained in Section 2.C of this license in the following manner: initial notification shall be made within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to the NRC Operations Center via the Emergency Notification System, with written follow-up within 30 days in accordance with the procedures described in 10 CFR 50.73(b), ( c), and (e).' License Condition 2.C (2) states in part 'Nine Mile Point Nuclear Station, LLC shall operate the facility in accordance with the Technical Specifications.' This notification describes a licensee identified condition where both redundant Standby Gas Treatment (SGT) trains were apparently inoperable in violation of Technical Specifications. The condition has been corrected.
At 1800 on 3 March 2006, while operating at 91 % power (coast down to refueling), Nine Mile Point Unit 2 identified a condition in which both trains of SGT were apparently rendered inoperable for intermittent time periods of a few hours in length, starting from 17 February 2006 through about 1900 on 28 February 2006. This was not recognized at the time; as such the requirement to initiate a plant shutdown per LCO 3.0.3 was not performed. The condition was caused by use of a heavy-duty tarp and associated cargo net supporting it from underneath, installed across the Unit 2 Reactor Building Hoist Well. Installation of the tarp and net across the hoist well occurred between the above dates, for time periods of a few hours each, in order to support refueling preparations, thereby avoiding spread of contamination during rigging activities. The blockage of the Reactor Building Hoist Well would have obstructed or significantly degraded the design flow paths of both trains of SGT if called upon to perform their safety functions in a design basis accident. Therefore current information indicates this tarp installation configuration renders the SGT system inoperable. The tarp and net were permanently removed at about 1900 on 28 February 2006 when a supervisor questioned if tarp installation was allowed while the reactor was at power. Although removal of the tarp and net typically required only a few minutes effort by plant workers, its installation and continued blockage of the ventilation flow path would have resulted in declaration of the [SGT] safety systems to be inoperable if not removed. Workers were not sensitive to the safety function of the open ventilation flow path provided by the hoist well, and no programmatic training or administrative requirements were identified which prohibited the configuration at conditions other than cold shutdown. Nine Mile Point is in the process of taking compensatory measures to preclude installation of the tarp when SGT is required to be operable by briefing operations, radiation protection and refuel worker crews on ventilation requirements and sensitivity to safety functions. Operations took physical control (lock and key) of the tarp. Corrective actions to provide administrative controls on the tarp installation are in process. Detailed evaluation of the safety significance of the condition is ongoing. Initial review of plant records indicate that this configuration was also installed intermittently around July 2003. It was recognized as undesirable but was not identified as an operability or reportability issue at the time. Corrective action to prevent its recurrence was not effective. More detailed information on specific dates and durations when this configuration existed will be provided in the 30 day written LER report, after a detailed review. The instances noted above and any similar conditions identified will be explained in detail in the follow-up LER that will be submitted as required by 10CFR 50.73(a)(2)(i)(B) - 'Any operation or condition which was prohibited by the plants Technical Specifications .'" Unit-1 is not affected since they have a different method to control use of this tarp. The licensee notified the NRC Resident Inspector.
At 1800 on 3 March 2006, while operating at 91% power (coast down to refueling), Nine Mile Point Unit 2 identified a condition in which both trains of the Standby Gas Treatment (SGT) system were apparently inoperable for intermittent time periods of a few hours of length, starting from 17 February 2006 through about 1900 on 28 February 2006. This was not recognized at the time; as such the requirement to initiate a plant shutdown per LCO 3.0.3 was not performed. The condition was caused by use of a heavy-duty tarp and associated cargo net supporting it from underneath, installed across the Unit 2 reactor Building Hoist Well. Installation of the tarp and net across the hoist well occurred between the above dates, for time periods of a few hours each, in order to support refueling preparations, thereby avoiding the spread of contamination during rigging activities. The blockage of the reactor Building Hoist Well would have obstructed or significantly degraded the design flow paths of both trains of SGT if called upon to perform their safety functions in a design basis accident. Review of plant records indicate that this condition was also installed intermittently around July 2003. A subsequent evaluation of the safety significance of this condition has been performed. This evaluation considered actual area of flow path remaining with the tarp in place, as well as bounding outside temperatures during the times the tarp may have been installed. The evaluation has concluded that the secondary containment function, and therefore the SGT system, remained operable and would have performed its intended safety function during a design basis accident during the time periods the tarp may have been installed during the last three years. This evaluation provides the basis for retraction of the ENS report of March 4, 2006. The licensee notified the NRC Resident Inspector. The R1DO(Cook) has been notified. |
| Where | |
|---|---|
Nine Mile Point  New York (NRC Region 1) | |
| Reporting | |
| Other Unspec Reqmnt | |
| Time - Person (Reporting Time:+15.85 h0.66 days <br />0.0943 weeks <br />0.0217 months <br />) | |
| Opened: | Chris Skinner 14:51 Mar 4, 2006 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Mar 28, 2006 |
| 42386 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (91 %) |
| After | Power Operation (91 %) |
WEEKMONTHYEARENS 493862013-09-25T19:30:00025 September 2013 19:30:00
[Table view]Other Unspec Reqmnt Environmental Impact During Service Water Mollusk Biocide Treatment ENS 432862007-01-11T16:11:00011 January 2007 16:11:00 Other Unspec Reqmnt Initiation of Invalid Primary Containment Isolation Signals ENS 423862006-03-03T23:00:0003 March 2006 23:00:00 Other Unspec Reqmnt Reactor Building Ventilation Flowpath Inoperable ENS 415002005-03-17T22:55:00017 March 2005 22:55:00 Other Unspec Reqmnt Other Unspecified Requirement - License Condition 2.F ENS 407492004-05-14T13:17:00014 May 2004 13:17:00 Other Unspec Reqmnt, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Change in the Methodology Used by Ge/Gnf to Demonstrate Compliance with Eccs Performance Requirements ENS 404872004-01-28T20:30:00028 January 2004 20:30:00 Other Unspec Reqmnt 24-Hour Condition of License Report Due to Inoperable Division II Control Room Special Filter Train 2013-09-25T19:30:00 | |