05000352/FIN-2015001-03
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Finding | |
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| Title | Operability of High Pressure Coolant Injection and Entries into Operational Conditions at Low Reactor Pressures with High Reactor Water Level Trip Actuated |
| Description | On February 23, 2015, LGS Unit 1 automatically shut down and remained in the hot shutdown operational condition (i.e. mode 3) for equipment repair and restart. Based on a lit overhead annunciator and indicating light in the main control room, the inspectors noted that the HPCI high reactor water level trip (Level 8, trip setpoint 54 inches) was actuated with normal reactor water level being maintained using the reactor water level narrow range instruments (35 inches). This annunciator provided indication that HPCI was potentially inoperable. The inspectors noted that Exelon had been tracking the HPCI system as operable. The inspectors questioned the ability of the high drywell pressure instruments to fulfill the function required by TS to actuate the HPCI system with the high water level trip actuated. Technical specification 3.3.3 requires that the emergency core cooling system actuation channels shown in Table 3.3.3-1 be operable. Table 3.3.3-1, trip function 3.b, drywell pressure high, requires four operable channels during operating modes 1, 2, and 3 (Power Operation, Startup, and Hot Shutdown) when reactor pressure is greater than 200 psig. With more than one channel inoperable, the HPCI system must be declared inoperable. With a Level 8 trip present, the logic circuitry prevents actuation of the HPCI system by tripping its urbine stop valve closed. In addition, to prevent undue cycling of the HPCI system, when the reactor water level drops below the Level 8 trip signal setpoint, a sealin circuit prevents actuation of the HPCI system until the Level 8 trip relays are reset, either by a manual reset pushbutton or when reactor water level drops to the reactor vessel water level low-low (Level 2, actuation setpoint -38 inches) actuation setpoint. The operators did not declare HPCI inoperable because procedure GP-2, Normal Plant Startup, contained a note that stated HPCI systems have been determined operable by engineering evaluation with a high level trip setpoint actuated. Exelon determined that the note was added to Revision 56 of GP-2, approved on December 18, 1995. However, Exelon was unable to find the referenced engineering evaluation that justified this conclusion. The inspectors determined that at normal operating reactor pressure the TS required the high drywell pressure channels be declared inoperable when the channels were incapable of automatically actuating the HPCI system and the procedural note was not supported by an associated evaluation. Therefore, the lack of an adequate evaluation supporting the procedural note represented a performance deficiency and violation of regulatory requirements. However, in consultation with staff from the Technical Specifications and Reactor Systems Branches in the NRC Office of Nuclear Reactor Regulation, the inspectors determined that Exelons conclusion that the operability and safety function of the HPCI system was maintained at lower reactor pressures with the Level 8 trip actuated required further information in order to determine if that issue of concern was a performance deficiency and violation. |
| Site: | Limerick  |
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| Report | IR 05000352/2015001 Section 1R20 |
| Date counted | Mar 31, 2015 (2015Q1) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.2 |
| Inspectors (proximate) | F Bower M Fannon R Montgomery R Nimitz S Rutenkroger B Lin E Burket E Dipaolod Schroederh Gray H. Anagnostopoulus J Brand J Kulp M Fannon S Rutenkroger |
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Finding - Limerick - IR 05000352/2015001 | |||||||||||||||||||||||||||||||||||
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Finding List (Limerick) @ 2015Q1
Self-Identified List (Limerick)
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