05000410/LER-2013-005
| Nine Mile Point Unit 2 | |
| Event date: | 12-11-2013 |
|---|---|
| Report date: | 1-31-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 4102013005R00 - NRC Website | |
I. DESCRIPTION OF EVENT
A. PRE-EVENT PLANT CONDITIONS:
Prior to the event, Nine Mile Point Unit 2 (NMP2) was operating at rated reactor power.
B. EVENT:
On December 11, 2013 it was discovered that Nine Mile Point Unit 2 (NMP2) has not been reporting Secondary Containment inoperabilities to the Nuclear Regulatory Commission (NRC) in accordance with the administrative guidance in NUREG-1022 (Revision 3), and 10 CFR 50.72(b)(3)(v)(C) and 50.73(a)(2)(v)(C) as a condition that could have prevented the fulfillment of the safety function of a structure or system needed to control the release of radioactive material. This condition has occurred numerous times within the past three years when the Secondary Containment has been declared inoperable as a result of the Secondary Containment differential pressure (dP) dropping below the required Technical Specification (TS) minimum of negative 0.25 inches water gauge.
The direct causes of the Secondary Containment dP dropping below the required TS minimum value have been attributed predominantly due to changes in outdoor environmental conditions (changing wind direction and velocity) and secondarily due to changing of lineups or equipment failures associated with the normal non-safety related Reactor Building Ventilation System. In each case the required TS Limiting Condition for Operation (LCO) action was entered and subsequently exited once the Secondary Containment dP was restored to above the required TS minimum value. In all cases the TS required completion time was not exceeded.
Nine Mile Point Unit 1 (NMP1) was unaffected by the occurances of Secondary Containment inoperabilities at NMP2. While NMP1 Secondary Containment dP is impacted by similar changes in outdoor environmental conditions (changing wind direction and velocity) and the changing of lineups or equipment failures associated with the normal non-safety related Reactor Building Ventilation System, NMP1 does not have a TS Surveillance Requirement for Secondary Containment dP.
C. INOPERABLE STRUCTURES, COMPONENTS, OR SYSTEMS THAT CONTRIBUTED TO THE
EVENT:
There were no other inoperable structures, components, or systems that contributed to the event.
D. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES:
Over the past three years there have been numerous occasions when the NMP2 Secondary Containment has been declared inoperable, when the station was in a condition requiring it to be operable, due to the Secondary Containment differential pressure dropping below the required Technical Specification (TS) minimum of negative 0.25 inches water gauge.
E. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:
No other systems or secondary functions were affected.
F. METHOD OF DISCOVERY:
On December 11, 2013 during review of industry Operating Experience (OE) it was identified that NMP2 has not been reporting occurrences of Secondary Containment inoperability when the Secondary Containment differential pressure (dP) drops below the required Technical Specification (TS) minimum of negative 0.25 inches water gauge.
G. MAJOR OPERATOR ACTION:
No operator actions were required as a result of the identification of this condition.
H. SAFETY SYSTEM RESPONSES:
No operational conditions requiring the response of safety systems occurred as a result of this condition.
II. CAUSE OF EVENT:
The apparent cause of these occurrences is that training has not been effective in providing operations personnel the level of understanding required in order to consistently recognize when the failure of safety systems are reportable under 10 CFR 50.72(b)(3)(v)(C) and 50.73(a)(2)(v)(C).
This event has been entered into the Nine Mile Point Nuclear Station corrective action program as condition report number CR-20 I 3-010111.
III. ANALYSIS OF THE EVENT:
This event is reportable in accordance with 10 CFR 50.73(a)(2)(v)(C) as any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material.
There were no actual nuclear safety consequences associated with this event. The times when Secondary Containment was declared inoperable in the past three years, when required to be operable, were due to Secondary Containment differential pressure dropping below the required TS minimum value of negative 0.25 inches water gauge.
The direct causes of the Secondary Containment dP dropping below the required TS minimum value have been attributed predominantly due to changes in outdoor environmental conditions (changing wind direction and velocity) and secondarily due to changing of lineups or equipment failures associated with the normal non-safety related Reactor Building Ventilation System. In each case the required TS Limiting Condition for Operation (LCO) action was entered and subsequently exited once the Secondary Containment dP was restored to above the required TS minimum value. In all cases the TS required completion time was not exceeded.
In all cases, the Secondary Containment structural integrity, the ability to automatically isolate the non- safety related Reactor Building Ventilation System, and the Standby Gas Treatment System operability were not impacted. As a result, the ability of the Secondary Containment to perform its safety function was not impacted.
Based on the above discussion, it is concluded that the safety significance of this event is low and the event did not pose a threat to the health and safety of the public or plant personnel.
This event does not affect the NRC Regulatory Oversight Process (ROP) Indicators.
IV. CORRECTIVE ACTIONS:
A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:
In each of the occurrences within the past three years the Secondary Containment was declared operable following the restoration of the Secondary Containment differential pressure to at least the required TS minimum value.
B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:
L Senior Reactor Operators have been provided a briefing on the guidance in NUREG-1022 (Revision 3) associated with 10 CFR 50.72(b)(3)(v)(C) and 50.73(a)(2)(v)(C) reporting requirements relative to Secondary Containment inoperability.
2. Detailed training on 10 CFR 50.72(b)(3)(v)(C) and 50.73(a)(2)(v)(C) reporting requirements will be conducted for Senior Reactor Operators and Licensed Operator Training Instructors.
V. ADDITIONAL INFORMATION:
A. FAILED COMPONENTS:
There were no other failed components that contributed to this event.
B. PREVIOUS LERs ON SIMILAR EVENTS:
Nine Mile Point (NMP) has had previous LERs associated with not initially identifying reportable conditions under 10 CFR 50.72(b)(3)(v) and 10 CFR 50.73(a)(2)(v). Specifically at Nine Mile Point 1 (NMPI) LER 2012-003 was issued when Shutdown Cooling Primary Containment Isolation Valves were de-energized in an open position effectively defeating the isolation safety function. At NMP2, Isolation Instrumentation was defeated.
C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION
IDENTIFIER AND SYSTEM NAME OF EACH COMPONENT OR SYSTEM REFERRED TO IN
THIS LER:
IEEE 803 FUNCTION IEEE 805 SYSTEM
COMPONENT IDENTIFIER
IDENTIFICATION
Reactor Building (BWR) BLDG NG Reactor Building Ventilation System PDIC VA
D. SPECIAL COMMENTS:
None