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| Quarter | Site | Title | Description | |
|---|---|---|---|---|
| 05000341/FIN-2007006-07 | 2007Q4 | Fermi | NON-QUALIFIED TY-WRAPS Inside Primary Containment | The inspectors noted the use of Tefzel ty-wraps inside primary containment and, due to their abundance, the inspectors questioned the licensee about their tracking program for items that could become debris in the torus and potentially block the ECCS and RCIC pump suctions. The licensee stated the design specification did not cover the use of ty-wraps in the drywell. Upon further investigation, the licensee identified that the lead shielding installed during a previous outage had not been considered in the design specification. The inspectors reviewed specification 3071-389, Revision 3, Emergency Core Cooling System Suction Strainers, and noted that ty-wraps were not addressed in the specification. When questioned by the inspectors, the licensee stated the only program in place was to track paint in the drywell and torus. Upon further review, the licensee noted shield blankets had been installed in the drywell without modeling the debris loading on the strainers. The licensee-performed walkdowns revealed a total of 36 ft2 of ty-wraps inside the drywell. The licensee removed 20.6 ft2 of ty-wraps from the drywell following the walkdowns. Engineering personnel performed Engineering Functional Analysis (EFA) E11-07-0005, Revision A, Non-Qualified, Tefzel Ty-Wraps Inside Primary Containment, to analyze the effects of the remaining ty-wraps and the shield blanket debris on ECCS and RCIC suction from the torus. This analysis included the potential for the ty-wraps to be carried into the strainers via the torus for several different accident scenarios. The strainer hydraulic analysis performed in the EFA allowed for an increase in the load from fibrous debris and included the lead wool and ty-wraps. The evaluation concluded that only 7.1 ft2 of ty-wraps were available for transport to the strainers, which was less than the maximum allowable load of 13.75 ft2. For the design limiting case, the RHR and Core Spray pumps would have sufficient net positive suction head available thereby alleviating current safety concerns. Resolution of the past operability concern will be provided by incorporating the remaining material in the drywell into the plant design bases associated with strainer loading and the establishment of a program for control of materials inside containment. Pending further analysis of past operability by the licensee of whether the use of nonqualified Tefzel ty-wraps inside primary containment could have plugged the strainers, this is considered an Unresolved Item. URI 05000341/2007006-07: Non-Qualified Ty-Wraps Inside Primary Containment. |
| 05000341/FIN-2007006-02 | 2007Q4 | Fermi | Undocumented Technical Basis for Change to EOP | During one of the dynamic simulator scenarios, conditions were simulated during an Anticipated Transient Without Scram (ATWS) that required the operating crew to lower reactor pressure vessel (RPV) water level in accordance with emergency operating procedure (EOP) 29.100.01, Sheet 1A, RPV Control-ATWS. The purpose of lowering RPV water level is to reduce core inlet sub-cooling and thus reduce the potential for power oscillations. EOP 29.100.01, Sheet 1A, directs the operators to Terminate and Prevent all injection flow into the RPV except for flow from the CRD, Reactor Core Isolation Cooling (RCIC), and Standby Liquid Control (Boron) systems. Contrary to the BWR Owners Group (BWROG) Emergency Procedure Guidelines (EPG) and Severe Accident Guidelines (Revision 2) which states that failure to completely stop RPV injection flow (with the exception of CRD, RCIC, and Standby Liquid Control) would delay the reduction in core inlet sub-cooling, thus increasing the potential for flux oscillations the crew was observed to implement this step (FSL-10), in accordance with the licensees expectations, by turning OFF the low pressure Emergency Core Cooling Systems (ECCS) and Standby Feedwater pumps, reducing High Pressure Coolant Injection flow to 0 gpm, and reducing (i.e., NOT stopping) Feedwater system flow so that level decreased in a controlled manner. When asked why the licensees procedural steps deviated from the BWROG EPG, they stated that the deviation was necessary to allow time for bypassing of interlocks to prevent the loss of the Main Condenser heat sink, and to prevent dropping water level below the top of active fuel. The BWROG EPG states that reducing reactor power and preventing power oscillations is of greater importance than preventing loss of the main condenser. Technical Specification 5.4.1 requires, in part, that written procedures/instructions be established, implemented, and maintained covering the emergency operating procedures required to implement the requirements of NUREG-0737, Clarification of TMI Action Plan Requirements, and NUREG-0737, Supplement 1, as stated in Generic Letter 82-33. NUREG-0737 and the associated Supplement 1 required licensees to analyze transients and accidents, prepare emergency procedure technical guidelines, and develop symptom-based emergency operating procedures based on those technical guidelines. The BWROG EPG provides the technical basis for the development of the emergency operating procedures used by BWR licensees. Licensees are permitted to deviate from the BWROG guidelines provided they document the technical basis for the deviation. When asked to provide justification for the deviation from the BWROG EPG, the licensee was unable to do so. The licensee has initiated action (CARD 07-28195), through their corrective action program, to provide the necessary basis for the deviation. This issue is an Unresolved Item (URI) pending further NRC review and completion of the licensees actions to provide the necessary documentation to support the deviation: URI 05000341/2007006-02, Undocumented Technical Basis for Change to EOP ATWS Mitigation Strategy. |
| 05000341/FIN-2007003-05 | 2007Q3 | Fermi | INRUSH CURRENT OF SPRING CHARGING MOTORS NOT CONSIDERED (Section 1R21.3.b.5) | The inspectors identified an unresolved item concerning calculation DC-0213, Sizing of 130/260V Batteries, for not considering the inrush current of the spring charging motors associated with closing mechanism of 4160V and 480V switchgear circuit breakers. The licensee recognized this condition in 2003 and issued a CARD to incorporate the inrush current of spring charging motors into the calculation and re-evaluate the batterys 1 minute rating. However, four years later the licensee has failed to revise the calculation. At the end of the inspection, the licensee was still evaluating the impact of the inrush current on the batterys 1 minute rating and had not completed their final assessment. The inspectors needed this information to complete the assessment of this issue. Description: During a review of battery sizing calculation DC-0213, the inspectors identified that the calculation used average current values instead of inrush current values of spring charging motors associated with closing mechanism of 4160V and 480V switchgear circuit breakers. Per IEEE Standard 485-1997, IEEE Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications, momentary loads such as the switchgear operations and inrush currents should be used when determining batterys 1 minute rating. Momentary loads could occur one or more times during the duty cycle, but would be of short duration, not exceeding 1 minute at any occurrence. Although momentary loads may exist for only a fraction of a second, it was common industry practice to consider that each load would last for a full minute because the battery voltage drop after several seconds often determined the batterys 1 minute rating. Sizing for a load lasting only a fraction of a second, based on the batterys 1 minute performance rating, would result in a conservatively sized battery. When several momentary loads occur within the same 1 minute period and a discrete sequence cannot be established, the load for the 1 minute should be assumed to be the sum of all momentary loads occurring within that minute. During the minute, depending on how many momentary loads occur, the inrush current pulls the battery voltage down and therefore it would be necessary to ensure that the battery was adequately sized to provide the required voltage to the loads. Because of the failure to consider the inrush 15 Enclosure current in sizing the batteries, the inspectors were concerned that the batteries might not have been adequately sized to provide the required voltage to the loads. The licensee recognized this condition in 2003 and entered this issue into their corrective action program, CARD 03-16683, which called for revising the calculation based on inrush current of the spring charging motors. This CARD was assigned a low priority level of four and closed out to Technical Service Request 34807. As a result, four years later, this calculation had not been revised. The licensee tested three spring charging motors to determine their inrush currents because the information was not available. Out of the three motors tested, one motor registered twice the inrush current of the other two. The licensee had the breaker manufacturer (Asea Brown-Bovari) conduct tests on Ametek charging motors in Kline 800 amp breakers. At the end of the inspection, the licensee had not finished their assessment, but took some temporary compensatory measures to reduce load on the batteries as part of operability determination, EFA R32-07-002. The compensatory measures consisted of turning off power to the spring charging motors associated with breakers feeding non-safety-related loads. However, the inspectors noted that the licensee did not follow the 10 CFR 50.59 process for implementing compensatory measures as required. The licensee performed 10 CFR 50.59 screening 07-0162 that concluded a safety evaluation was not required. The inspectors review of the licensees operability determination and 10 CFR 50.59 screening did not identify any concerns with their conclusions. Since the licensee had not finished their assessment and had not validated the battery sizing calculation based on incorporating the inrush current of the spring charging motors, the NRC concluded that additional review and evaluation were required to assess whether or not the batteries were adequately sized for the application. Therefore, this issue is considered an unresolved item (URI 05000341/2007003-05) pending the licensee completion of an analysis to assess the battery sizing and subsequent NRC review. |