05000454/FIN-2010006-01
Finding | |
---|---|
Title | Manual Actions Not Explicitly Approved |
Description | An unresolved item (URI) was identified by the inspectors concerning manual actions which had not been explicitly approved by the NRC.
The inspectors identified that the licensee took credit for a number of manual actions to compensate for not having a train free of fire damage in non-alternative fire zones. Although some manual actions were described either in a safety evaluation report (SER) or licensing correspondence which was used as a basis for NRC approval in an SER, the majority of manual actions were not explicitly approved by the NRC. As an example, for Fire Zone 11.3-0, the safe shutdown analysis took credit for the following manual actions (not a full listing) to achieve a hot standby condition because one train would not be assured of being free of fire damage: Step 1 of Procedure BOP FR-1T10, 11.3-0; 364 Auxiliary Building General Area; 1D-17, 1D-40, 1S-59, 2S-54, directed operators to establish a flow path to the operating charging pump from the refueling water storage tank (RWST) because a hot short could cause a spurious closure of the volume control tank (VCT) outlet valve, part of the normal flowpath. If an alternate flowpath from the RWST is not established, spurious closure of the VCT outlet valve could result in a loss of suction to the operating charging pump and subsequent damage to the pump. Step 3 of Procedure BOP FR-1T10 directed operators to open eight breakers to prevent a fault from tripping an upstream breaker for a credited electrical bus. (See Section 1R05.6.b(1) for a related discussion.) Step 8 of Procedure BOP FR-1T10 directed operators to locally start the 1A and 2B essential service water (ESW) pumps because control cables for the pumps could be damaged due to fire. Step 11 of Procedure BOP FR-1T10 directed operators to verify ESW flow to the 2A charging pump. If ESW flow could not be verified, the procedure directed operators to stop the 2A charging and 2A auxiliary feedwater pumps until ESW flow could be restored. Step 21 of Procedure BOP FR-1T10 directed operators to locally open the power supply breaker for Motor Control Center 231X1 to allow local manual operation of Valve 2SX033, ESW Pump 2A Discharge Crosstie Isolation Valve. Step 22 of Procedure BOP FR-1T10 directed operators to locally open Valve 2SX033 using its handwheel. The crosstie valve was needed to be open because Unit 2 Train A components (such as the 2A charging pump and 2A auxiliary feedwater pump) relied upon essential service water for cooling. However, the Train A essential service water pump could not be credited because its power cable was in the zone. Consequently, the Train B essential service water pump was needed to provide cooling water for the credited Train A loads. Valve 2SX033 could spuriously close because control cables went through the zone. Procedures for a number of other non-alternative fire zones included similar manual actions. The inspectors noted that the licensee had informed the NRC of a number of manual actions as part of the licensing process. For example, by letter dated October 15, 1984, the licensee had identified a number of manual actions to address spurious operation of valves in response to Question 10.65. However, the majority of manual actions (including the examples listed above), were not explicitly identified during the licensing process and, as such, were not explicitly approved by the NRC. Amendment 3 to the Byron Station Fire Protection Report listed a number of assumptions for the safe shutdown analysis. Assumption 3, listed in Section 2.4.1.5 of Amendment 3, stated: For fires outside the control room, the operators are assumed to remain in the control room and to utilize the instruments and controls provided there to the greatest possible extent, in accordance with existing station procedures. When proper operation of equipment cannot be performed or confirmed from the control room, alternate procedures are utilized... Where the safe shutdown analysis shows that control cables from both redundant trains of equipment are located in the same fire zone, credit is taken for alternate shutdown via local operation of equipment as specified in various plant procedures... The inspectors noted that the licensee had used the term alternate to apply to procedures for fire zones other than those classified as alternative fire zones (i.e., other than the control room and the auxiliary electric equipment rooms). NUREG-0876, Safety Evaluation Report related to the operation of Byron Station, Units 1 and 2, documented the licensing basis approval by the NRC. Supplement 5 of NUREG-0876 relied upon Amendment 3 of the Byron Station Fire Protection Report for original licensing of Unit 1 for fire protection. Within the section titled Safe Shutdown Capability, of Section 9.5.1.4 of NUREG-0876, Supplement 5, the following statements were made by the NRC: Alternative shutdown capability in part, consists of local operation of equipment if the fire results in loss of redundant control capability. Local operations include local start and control of pumps and manual operation of valves and circuit breakers. For all local operation, accessibility of components and time restrictions were considered. These local operations are addressed in various plant procedures. Alternative shutdown capability also consists of utilization of diverse equipment as follows. To monitor reactor coolant hot leg temperature, the applicant ensured the availability of one of the following components, all of which provide an indication of hot leg temperature: reactor coolant wide range hot leg RTD\'s [resistance temperature detectors], core exit thermocouples, or heated junction thermocouples. Alternative shutdown capability also includes use of remote shutdown and instrument panels as discussed below. and Based on the above, the staff concludes that the post-fire safe shutdown capability for Byron complies with the guidelines of SRP [Standard Review Plan] Section 9.5.1, Position C.6.b subject to the following condition: The applicant shall complete the analysis of spurious operation of the pressurizer PORV\'s [power operated relief valves] and fully implement any necessary modifications prior to exceeding 5 percent power. The inspectors noted that sentences above describing local operation of equipment were located in the SER prior to the section titled Alternative Shutdown Capability. Based on the assumptions listed in Amendment 3 of the Fire Protection Report and the above SER language, the licensee had made the interpretation that the NRC had provided a general approval for the use of manual actions for non-alternative fire zones in addition to approval for alternative shutdown fire zones. The inspectors were not able to determine whether the SER language constituted a general approval of manual actions for non-alternative fire zones beyond those explicitly identified during licensing. This issue is a URI pending further review by NRC staff. |
Site: | Byron ![]() |
---|---|
Report | IR 05000454/2010006 Section 1R05 |
Date counted | Dec 31, 2010 (2010Q4) |
Type: | URI: |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.05 |
Inspectors (proximate) | R Daley R Langstaff R Winter A Dahbur L Kozak G Gulla N Mellya Dahburd Szwarc J Draper R Daley |
INPO aspect | |
' | |
Finding - Byron - IR 05000454/2010006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Finding List (Byron) @ 2010Q4
Self-Identified List (Byron)
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||