ML20198M749
| ML20198M749 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 12/29/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20198M741 | List: |
| References | |
| NUDOCS 9901050342 | |
| Download: ML20198M749 (4) | |
Text
._
[f 40 0
4 UNITED STATES j
j
,j NUCLEAR REGULATORY COMMISSION
't WASHINGTON, D.C. 20066 4001
%...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.195 TO FACILITY OPERATING LICENSE NO. NPF-6 ENTERGY OPERATIONS. INC.
ARKANSAS NUCLEAR ONE. UNIT NO. 2 DOCKET NO. 50-368
1.0 INTRODUCTION
By letter dated July 28,1997 (2CAN079702), Entergy Operations, Inc. (the licensee) submitted a request for changes to the Technical Specifications for Arkansas Nuclear One, Unit 2. The requested changes would modify the actions associated with Technical Specification (TS) Table 3.3-1 for the Reactor Protective Instrumentation and TS Table 3.3-3 foi the Engineered Safety Feature Actuation System Instrumentation.
2.0 EVALUATION 2.1 Refuelina Water Tank Level-Low Sianal The recirculation actuation signal (RAS) is initiated by a 2 out of 4 logic for the refueling water tank (RWT) low level signal. The RAS system is designed to change the mode of operation of the emergency ccra cooling system (ECCS) from the injection phase to the recirculation phase during a loss-of-coolant accident (LOCA). At the onset of the recirculation phase, the RAS automatically stops the low pressure safety injection (LPSI) pumps and shifts the suction for the high pressure safety injection (HPSI) pumps and the containment spray (CS) pumps from the RWT to the containment sump. RAS is designed to actuate when the inventory of the RWT is nearly depleted, thereby ensuring the containment sump will have adequate inventory to supply the HPSI and CS pumps during the recirculation phase.
TS Table 3.3-3 Actions 10 and 11 allow one channel of RWT Level - Low to be placed in the tripped condition. With one channelin the tripped condition, a single failure of a second channel of RWT Level-Low could cause RAS actuation before the RWT level reaches the low level setpoint. If this were to occur during a LOCA, the HPSI pumps and CS pumps could have their suctions supplied by an inadequate suction source, possibly removing both trains of ECCS and CS from service.
l TS Table 3.3 3 Action 10 allows placing a channel of RWT Level - Low in the tripped condition until the end of the operating cycle (up to approximately 18 months). TS Table 3.3-3 Action 11 l
9901050342 981229 PDR ADOCK 05000368 P
I l
l
- allows placing one channel of RWT Level-Low in bypass and another channelin trip until the next channel functional test (up to one month). The proposed Actions 10 and 11 will reduce the 1
time a RWT Level-Low can be in the tripped condition to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. Additionally, proposed Actions 10 and 11 require that, if the inoperable channel of RWT Level-Low is not removed from the tripped condition within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, the unit be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
The 48-hour allowed time was selected because it is the current allowed outage time for other reactor protection system (RPS) and engineered safety features actuation system (ESFAS) instrumentation for conditions susceptible to a single failure following an initiating event. This time period is also consistent with the allowed time for a channel to be in trip for the analog ESFAS instrumentation listed in NUREG-1432, " Standard Technical Specifications for Combustion Engineering Plants." Operating experience has demonstrated the very small probability of a random failure of another RWT Level-Low channelin a given 48-hour period.
The requirement to be in at least HOT STANDBY witWn the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> is consistent with the requirements for other RPS and ESFAS instrumentation and is consistent with the actions in NUREG-1432.
The proposed changes do not modify the design or configuration of the plant. The proposed changes provide a more restrictive time limit for a channel of RWT Level-Low to be in a tripped I
condition than is currently allowed by the TS. By reducing the allowed time, the probability is reduced that a single failure of another channel would result in an early RAS actuation during the injection phase of a LOCA. The staff finds the proposed changes acceptable.
2.2 Steam Generator Differential Pressure Sianal The emergency feedwater actuation system (EFAS) is designed to provide emergency feedwater (EFW) to the steam generators (SGs), and to prevent feeding a faulted SG during a main steam line break (MSLB) event. EFAS is comprised of two trains: EFAS 1 controls EPW to SG 1 (A) and EFAS 2 controls EFW to SG 2 (B). EFAS starts the EFW pumps, determines whether the SG is intact, and opens the EFW valves to the intact SG.
Each train of EFAS is comprised of four channels and is actuated by a 2 out of 4 logic. Each channel monitors for low SG level, low SG pressure, and high differential pressure between the SGs (SG D/P). EFAS is initiated to SG 1 either by a low SG level coincident with no low pressure on SG 1, or by a low SG level coincident with a SG D/P with the higher pressure in SG 1 (the intact SG). An identical EFAS is generated for SG 2.
TS Table 3.3-3 Actions 10 and 11 allow the placement of one channel of SG D/P in the tripped condition. With one channelin a tripped condition, a single failure of a second channel of SG D/P could result in EFAS being unable to detect whether the SG is faulted. If this were to occur during a MSLB, it could result in the inappropriate feeding of a faulted SG.
TS Table 3.3-3 Action 10 allows placing a channel of SG D/P in the tripped condition until the l
end of the operating cycle (up to approximately 18 months). TS Table 3.3-3 Action 11 allows placing one channel of SG D/P in bypass and another channelin trip until the next channel l
l
o-l l.
3-functional test (up to one month). The proposed Actions 10 and 11 will reduce the time a SG I
D/P can be in the tripped condition to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. Additionall, proposed Actions 10 and 11 i
require that, if the inoperable channel of SG D/P is not removed from the tripped condition within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, the unit be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
l The 48-hour allowed time was selected because it b the current allowed outage time for other RPS and ESFAS instrumentation for conditions susceptible to a single failure following an initiating event. This time period is also consistent with the allowed time for a channel to be in trip for the analog ESFAS instrumentation listed in the NUREG-1432, " Standard Technical Specifications for Combustion Engineering Plants." Operati~
-ience has demonstrated the very small probability of a random failure of another SG D/P cha.
. in a given 48-hour period.
l The requirement to be in at least HOT STANDBY within the next u hours and COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> is consistent with the requirements for other RPS and ESFAS instrumentation and is consistent with the actions in NUREG-1432.
The proposed changes do not modify the design or configuration of the plant. The proposed changes provide a more restrictive time limit for a channel of SG D/P to be in a tripped condition than is currently allowed by the TS. By reducing the allowed time, the probability is reduced that a single failure of another channel would result in inappropriate feeding of a faulted steam generator during a MSLB. The staff finds the proposed changes acceptable.
2.3 Administrative Chanags l
TS Table 3.3-1 Actions 2 and 3 and TS Table 3.3-3 Actions 10 and 11 are applicable to functional units that are required in Modes 1,2,3 and/or 4. However, these actions only specify that STARTUP and POWER OPERATION, which are defined in TS Table 1.1 as Modes 2 and 1, respectively, may continue provided certain actions are satisfied which could be misinterpreted to excluae Modes 3 and/or 4 operations. The proposed actions will specify that
" operation in the applicable MODES" may continue provided certain actions are satisfied. This more clearly includes the range of applicable modes for each functional unit.
The proposed changes are administrative in nature and do not affect plant equipment or operations. These changes are consistent with the latest revision of the NUREG-1432. The staff finds the proposed changes acceptable.
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Arkansas State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no signi-
e ficant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no j
significant hazards consideration, and there has been no public comment on such finding (62 FR l
45456). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: S. Bailey Date: December 29, 1998 l
i l
i
-_