ML20216D611
| ML20216D611 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 03/12/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| References | |
| NUDOCS 9803170152 | |
| Download: ML20216D611 (4) | |
Text
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t UNITED STATE 3 y
j NUCLEAR REGULATORY COMMISSION 2
WASHINGTON, D.C. 20056-0001 i
i 23FETY EVALUATION BY THE OFFICE OF NUCl. EAR REACTOR REGULATION l
RELATED TO AMENDMENT NO.188 TO l
I FACILITY OPERATING LICENSE NO. NPF-6 j
l ENTERGY OPERATIONS. INC.
ARKANSAS NUCLEAR ONE UNIT NO. 2 DOCKET NO. 50-368
1.0 INTRODUCTION
By letter dated July 21,1997, Entergy Operations, Inc. (the licensee) submitted a request for changes to the Arkansas Nuclear One, Unit No. 2 (ANO-2) Technical Speci'ications (TS). The requested changes would revise the emergency feedwater (EFW) surveillance testing requirements in TS 4.7.1.2 for ANO-2. The proposed changes include a reduction in the minimum steam generator (SG) pressure required to perform the surveillance testing on the turbine-driven EFW pump, an extension of the EFW pump surveillance testing frequency, an ;
modifications to the EFW pump testing requirements. The proposed changes are generally consistent with the applicable surveillance requirements in NUREG-1432, Draft Revision 2 (ISTS), " Standard Technical Specifications for Combustion Engineering Plants."
The letter dated February 18,1998, clarified and added information provided in the TS Bases i
Sections associated with the EFW system and required surveillances. This submittal did not change the initial proposed no significant hazards consideration determination.
2.0 BACKGROUND
The EFW system consists of one electric-driven pump and one turbine-driven pump on two independent trains that are each capable of feeding either of the two SGs. The system has several functions, which include providing a safety grade backup source of feedwater to the SGs when needed to meet the cooling requirements for accidents analyzed in the Safety Analysis Report; providing feedwater to the SGs as necessary to assure that decay heat and residual heat can be removed at a rate such that the fuei design limits and the design conditions of the reactor coolant pressure boundary are not exceeded; and removing decay heat until the plant has been cooled and depressurized to permit the use of the shutdown cooling system.
l By letter dated October 2,1992, Entergy Operations received NRC approval for Amendment 136 to the ANO-2 TSs to reduce the minimum SG pressure requirements from greater than 865 psig l
to greater than 800 psia for the turbine-driven EFW pump surveillance test. TNs change was l
requested as a result of SG tubes being plugged, which required a lower reactor coolant system I
(RCS) hot leg temperature. The reduction in RCS hot leg temperature resulted in a significant reduction of the steam pressure in the SGs.
9803170152 980312 PDR ADOCK 05000368 i
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1 3.0 EVALUATION ANO-2 has continued to inspect and plug SG tubes when they meet the plugging criteria, which has caused a further decrease in SG steam pressure since the original RCS hot leg temperature reduction.- The licensee has proposed to decrease the minimum SG pressure required in TS 4.7.1.2.a.1 from greater than 800 psia to greater than 700 psia to allow for adequate steam pressure for testing the turbine-driven EFW pump. The licensee found that the expected performance curve for the turbine-driven EFW pump has an inlet steam pressure of 300 psia at the trip end throttle valve, which is sufficient to develop the full turbine horsepower for
' the required flowrate and discharge pressure. Based on a SG supply pressure of greater than 700 psia, minus the maximum head loss of 100 psi from the SGs to the trip and throttle valve, the steam pressure would exceed 600 psia at the inlet to the turbine-driven EFW pump.
Therefore, a 300 psia margin would exist between the TS minimum allowed SG pressure and the pressure required for the turbine to develop its required horsepower. The licensee concluded that the proposed reduction in the minimum allowed SG pressure would not affect the turbine-driven EFW pump's capability to deliver the required flowrate and discharge pressure during operation. ' in addition, the licensee stated that this change in steam pressure should be adequate to account for SG tube plugging that mcy occur until the SGs are replaced in the fall of 2000. The staff agrees with the licensee's conclusion, and finds it acceptable to decrease the minimum required SG pressure to greater than 700 psia for the surveillance test.
The licensee has proposed, in TS 4.7.1.2.b.1, to revise the flow testing requirements for the EFW pumps from specific flows at defined test conditions on a monthly test interval to that testing required by TS 4.0.5 and the inservice testing (IST) program. Verifying each EFW pump's flow characteristics in accordance with the IST program ensures that pump performance i
has not degraded during the cycle and is an acceptable altamative to the current TS requirements. The proposed change will also revise the testing interval from monthly to the interval defined by the IST program (currently the IST defines a quarterly test interval). A comprehensive examination of surveillance requirements in TS was performed by the NRC staff and was documented in NUREG-1366," improvements to Technical Specification Surveillance Requirements," dated December 1992. Based on the results of the evaluations documented in NUREG-1366, the NRC issued Generic Letter 93-05, "Line-Item Technical Specifications improveme_nts to Reduce Surveillance Requirements for Testing During Power Operation," dated September 27,1993. The change proposed by the licensee regarding an increase in the EFW pump surveillance interval from monthly to quarterly is consistent with the recommendations in NUREG-1366. In addition to the studies referenced in NUREG-1366, the licensee provided data' specific to ANO-2. The staff finds the operating history of the pumps at ANO-2 to be compatible with the recommended intervalin NUREG-1366. Therefore, the staff finds the proposed change to the EFW surveillance requirements to be acceptable.
The proposed TS 4.7.1.2.b.1 also eliminates the need for an exception from TS 4.0.4 (currently in TS 4.7.1.2.a.1) pertaining to performing surveillances prior to entering an operating mode in which the subject system is required to bs operable. The exception to TS 4.0.4 was previously required to allow the surveillance of the turbine-driven EFW pump to be deferred until steam generator pressure was above the test pressure. The proposed revision to TS 4.7.1.2.b.1 defines a maximum period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> within which the surveillance of the turbine-driven EFW pump is required to be performed once the defined test conditions are reached. Based on the O
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expected heat removal requirements present during the 24-hour period in which the testing of the turbine-driven EFW pump can be deferred, the availability of attemate heat removal systems (including the motor-driven EFW pump) during this period, and engineering judgement, the staff finds it acceptable to perform the surveillance of the turbine-driven EFW pump within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of establishing plant conditions that can support the test. Therefore, the staff agrees that the exception from TS 4.0.4 contained in TS 4.7.1.2.A.1 can be deleted.
In the proposed revision of TS 4.7.1.2.c, the licensee has removed the words "during shutdown" for the 18 month surveillance requirements for the EFW system since the words are not defined within the ANO-2 TSs. Although the references to "during shutdown" are removed from the surveillance requirement, the proposed Bases Section associated with the revised TS describe that the 18 month frequency is based on the need to perform the surveillances under the '
conditions that apply during a unit outage and also states that performance of the tests when the reactor is at power could lead to an unplanned transient. The staff finds that the proposed TS change and enhanced Bases Section clarify the description of the testing conditions and are therefore acceptable.
In proposed TS 4.7.1.2.d, the licensee has revised the current 18 month surveillance requirement for verifying the turbine-driven EFW train flow path (currently TS 4.7.1.2.b.4) to include verification of the electric-driven EFW train flow path. This change corrects a deficiency in the current TS in that the routine verification of the electric-driven EFW train flow is not included in the current TS 4.7.1.2 as a required surveillance activity. The proposed surveillance requirements would also revise the frequency of flow path verification from at least once per 18 months (during shutdown) to whenever the plant has been below mode 3 for greater than 30 days and prior to entering mode 2. This change would continue to require the verification of the EFW flow paths (now for both EFW trains) following refueling outages and would add the requirement to verify the EFW flow paths following any outage that involves extended operation in those modes most likely to affect the EFW flow path configuration. The proposed flow path verifications further ensure that the EFW system is properly aligned following extended outages.
The staff finds the proposed changes to be acceptable.
The licensee has proposed new revisions to bases for TS 3/4.7.1.2 and has added information to the revised surveillance requirements. The staff agrees with the proposed changes to the bases i
for the EFW TS. Also, the licensee has proposed administrative changes to renumber the TSs in accordance with the changes described above. The staff finds these changes to be acceptable.
- The staff reviewed the licensee's proposed changes that would revise the EFW surveillance testing requirements in TS 4.7.1.2 for ANO-2. Based on its review, the staff concludes that the l
licensee's proposed change to reduce the minimum SG pressure required to perform the surveillance testing on the turbine-driven EFW pump is adequate to demonstrate the pump's performance, and it is acceptable. Also, the staff concludes that the proposed changes to extend the EFW pump surveillance testing frequency and modify the EFW pump testing requirements are acceptable.
4.0 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.
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e f 5.0 ENylRONMENTAL 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 and changes surveillance requirements. The NRC staff has determined that the amendment involves no significant.
Increase in the amounts, and no significant change in the types, of any effluents that may be
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released offsite, and that there is no significant increase in individual or cumulative occupational l
radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public l;
comment on such finding 62 FR 43367. 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.
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6.0 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.
j Principal Contributors: V. Ordaz W. Reckley l-
- Date: March 12,1998 i
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