ML20204C436
| ML20204C436 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 07/22/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20204C432 | List: |
| References | |
| NUDOCS 8607310193 | |
| Download: ML20204C436 (4) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO FACILITY OPERATING LICENSE N0. NPF-6 ARKANSAS POWER AND LIGHT COMPANY ARKANSAS NUCLEAR ONE, UNIT 2 DOCKET NO. 50-368
1.0 INTRODUCTION
By letter dated February 27, 1986, Arkansas Power and Light Company (AP&L) submitted a request to revise the Technical Specifications, Appendix A to Facility Operating License No. NPF-6 for the Arkansas Nuclear One - Unit 2 (AN0-2) plant. The proposed Technical Specification revisions are necessary in order to implement the Core Protection Calculator (CPC) Improvement Program at AN0-2. The CPC Improvement Program has been developed by the CPC Oversight Committee, consisting of AP&L, Arizona Nuclear Power Project, Louisiana Power and Light Company and Southern California Edison, with Combustion Engineering (CE) as the technical consultant. Several goals of the program include the implementation of appropriate modifications and methodology improvements to reduce future reload efforts as well as to reduce unnecessary plant trips.
By letter dated April 21, 1986, AP&L also submitted responses to the NRC request for additional information concerning the proposed Technical Specification changes.
The staff's evaluation of these proposed changes follows.
2.0 EVALUATION The trip setpoint and allowable value for the local power density (LPD) high trip has been changed to 21.0 kw/ft. The change revised Table 2.2-1,
" Reactor Protective Instrumentation Trip Setpoint Limits," of Technical Specification 2.2.1 and its associated Bases. The LPD trip setpoint specifies the setpoint required to prevent the peak linear heat rate, in the limiting fuel pin in the core, from exceeding the value which corre-sponds to the centerline fuel melting temperature during anticipated l
operational occurrences.
It also assists in mitigating the consequences of accidents. The modification increases the trip setpoint from 20.3 kw/ft to 21.0 kw/ft, which is the linear heat generation rate corresponding to fuel centerline melting as determined by approved methods. Previously, the trip setpoint incorporated an adjustment for dynamic effects that i
l will now be accounted for elsewhere in the CPC algorithms. Also, the 8607310193 860722 PDR ADOCK 05000368 l
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21.0 kw/ft value has been previously approved for the San Onofre Units 2 and 3, the Palo Verde Units 1 and 2 and the CESSAR System 80 Technical Specification LPD trip setpoint. Based on this and on the fact that, effectively, the CPC LPD protection is not being changed, the modification is acceptable.
The Bases for Technical Specification 2.2.1 has been updated to reflect the appropriate CPC Improvement Program modifications and methodology documents which have been reviewed and approved by the NRC.
In addition, the CPC range limits have been modified to generic range limits specified by the CPC Improvement Program. The RCS Cold Leg Temperature-Low limit has been changed from 465 F to 490 F and the High limit from 605 F to 585*F. The Pressurizer Pressure-Low limit has been changed from 1750 psia to 1785 psia and the High limit from 2400 psia to 2415 psia. These changes will reduce the range of inputs (and, therefore, the calculational complexity) of the safety analyses and promote consistency between the software of CPC plants. The changes to the Bases of 2.2.1 are, therefore, acceptable.
The previous Limiting Condition for Operation (LCO) of Technical Specification 3.2.1, " Linear Heat Rate," has been replaced with two parts, 3.2.1.a and 3.2.1.b.
Specification 3.2.1.a is applicable when COLSS (Core Operating Limits Supervisory System) is in service and requires the COLSS calculated core power to be maintained less than or equal to the COLSS calculated Power Operating Limit (POL) based on linear heat rate. These words replace the old Figure 3.2-1 and state the same requirement. The change is, therefore, acceptable. Specification 3.2.1.b is applicable when COLSS is out of service and requires operation within the allowable region of the new Figure 3.2-1 using any operable CPC channel. The old Figure 3.2-1 has been deleted and replaced with the words of Specification 3.2.1.a which state the same requirements. The new Figure 3.2-1 is similar to the previous Figure 3.2-2 and gives the allowable peak linear heat rate as a function of burnup when COLSS is out of service. The linear heat rate limit value in this figure has been lowered from 14.5 kw/ft to 13.5 kw/ft in order to bound future cycles. Since this lower limit is more restrictive and in a conservative direction, the change is acceptable.
The previous LC0 of Technical Specification 3.2.4, "DNBR Margin," has been replaced with four parts, a, b, c, and d.
Specification 3.2.4.a is applicable when COLSS is in service and at least one Control Element Assembly Calculator (CEAC) is operable and requires the COLSS calculated core power to be maintained less than or equal to the COLSS calculated POL based on DNBR.
This is consistent with the previous requirement except that Figure 3.2-3 has been deleted and replaced with words to the same effect. The change is acceptable. Specification 3.2.4.b is applicable when COLSS is in service and neither CEAC is operable and requires the COLSS calculated core power to be maintained less than or equal to the COLSS calculated POL based on DNBR decreased by a penalty factor of 13% of rated power.
The 13% penalty factor is calculated based on a single group 6 CEA withdrawal event and accounts for the power rise and increased core power peaking during the event.
It provides sufficient margin for CEA misoperation events during periods when neither CEAC is operable and the CPC system does not have CEA position information and is, therefore, acceptable. Specification 3.2.4.c is applicable when COLSS is out of service and at least one CEAC is operable.
In this case, the CPC cal-culated DNBR is maintained within the limits of a new Figure 3.2-2.
This is identical to the old Figure 3.2-4 and the change is acceptable.
Specification 3.2.4.d applies when COLSS is out of service and neither CEAC is operable.
In this case, the CPC calculated DNBR is maintained within a new Figure 3.2-3.
This new figure accommodates the increased margin required when both CEACs are inoperable and the change is, therefore, acceptable. The staff also concludes that it does not matter which of the four CPC channels is chosen to monitor DNBR when COLSS is out of service since appropriate uncertainty allowances are already imple-mented in the CPC system calculations and trip setpoints. The four redundant CPC channels are still required for protection purposes to ensure appropriate protective action during transients and accidents.
Action 5 of Table 3.3-1 in Technical Specification 3.3.1 has been revised.
Action 5 provides conditions under which operation may continue for various operability conditions of the CEACs. Action 5.a is revised to allow operation with one inoperable CEAC to continue after 7 days provided Action 5.b is met. Since Action 5.b addresses operation with both CEACs inoperable, it requires more restrictive actions to be taken. The change is, therefore, acceptable.
In addition, Action 5.b is revised to reference the appropriate requirement of Specification 3.2.4, as described and approved above, and to clarify the setting of the "RSPT/CEAC Inoperable" addressable constant in the CPCs. These changes are also acceptable.
The resistance temperature detector (RTD) response time of 6 seconds for a CPC channel, shown in the footnote to Table 3.3-2 of Technical Specifi-cation 3.3.1, has been revised. The CPC Improvement Program and related accident analyses now assume effective response times of 8 seconds for the RCS cold leg temperature RTDs and 13 seconds for the RCS hot leg temperature RTDs. The footnotes to Table 3.3-2 are revised accordingly.
Figure 3.3-1 is also revised to give the DNBR and linear heat rate penalties to be applied if the effective cold leg RTD response time falls between 8 seconds and 13 seconds. Table 3.3-3 is deleted since the analyses now assumes response times up to 13 seconds and adjustments are no longer required for RTD response times less than this. These changes are acceptable.
3.0 EVALUATION
SUMMARY
I The staff has concluded, based on the considerations discussed above, that the proposed changes to the ANO-2 Technical Specifications are acceptable.
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4.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The 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 released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously published a proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, the amendment meets the eli for categorical exclusion set forth in 10 CFR 951.22(c)(9)gibility criteria Pursuant to 10 CFR 551.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
We have 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, and (2) such activities will be conducted in compliance with the Commission's regulations, and 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 to this SE was L. Kopp Dated:
July 22, 1986 i
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