ML20115B930
| ML20115B930 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 10/08/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20115B929 | List: |
| References | |
| NUDOCS 9210190020 | |
| Download: ML20115B930 (4) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.139 TO FACillTY OPERATING LICENSE NO. NPF-6 ENTERGY OPERATIONS. INC,.
ARKANSAS NUCLEAR ONE. UNIT N0. 2 DOCKET N0. 50-368
1.0 INTRODUCTION
By letter dated July 9,1992, as supplemented by letters dated September 11, and October 7, 1992, Entergy Operations, Inc. (the licensee), submitted a request for changes to the Arkansas Nuclear One. Unit No. 2 (AND ^) Technical Specifications (TSs).
The requested changes would revise TS 3.6.. 4 by revising the containment internal pressure, average air temperature, and relative humidity limits (TS Figure 3.6-1 and Bases), to incorporate values consistent with emergency core cooling system (ECCS) analysis assumptions and increase the allowable upper limits based on recent containment design-basis accident (DBA) analysis.
The Bases for TS 3.6.1.4 would be revised to ' clarify that operation in accordance with TS Figure 3.6-1 ensures the ECCS analysis assumptions are maintained and that containment peak pressure will not exceed the design pressure of 54 psig during design-basis conditions.
Ti allowable linear heat rate limit (TS Figure 3.2-1) would also be reduced to maintain a large-break loss-of-coolant accident (LBLOCA) peak clad temperature (PCT) within the 10 CFR 50.46 limit of 2200*F for ANO-2.
The September 11, and October 7,1992, letters provided clarifying information that did not change the initial proposed no significant hazards consideration determination.
2.0 BACKGROUND
in preparation for a reevaluation of the LBLOCA analysis in February of 1991, a discrepancy was found between the containment pressure and temperature conditions allowed by the TSs and the assumptions used for these parameters in the current ANO-2 ECCS analysis.
The Bases for TS 3.6.1.4 state that the limitations on containment internal pressure, average air temperature and relative humidity ensure that 1) the contair. ment structura is prevented from exceeding its design negative pressure differential with respect to the outside atm ohere of 5.0 psig, and 2) the containment peak pressure does not exceed the uesign pressure of 54 psig during LOCA conditions.
However, the-ANO-2 TSs do not ensure that the ECCS analysis assumptions for containment pressure and temperature are maintained.
'9210190020 921008 PDR ADOCK 05000368 P
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The ANO-2:r.ycle 1'ECCS analysis of record used initial containment. conditions of 90'F,14.7. psia, and 100% _ humidity.
TS 3.6.1.4 allows for a range of initial containment conditions from.11.7 psia to 16.1 psia, 50*F to 140*F, and-0% to 100% humidity. These lower containment temperatures and pressurer coupled with high containment humidities would result in a lower containment pressure (less conservative) following a DBA.- Yhe current ANO-2 ECCS analysis:
only. bounds plant operation with containment temperatures and pressures:above 90*F and 14.7 psia at any humidity as stated above.
An analysis done by the licensee for reduced containment parameters.of 12.8 psia and 60*F indicated that operation with these initial-containment conditions producer a PCT of 2170'F.
This is 92'F greater than the current analysis of recora af 2078'F for ANO-2.
In order to reduce the PCT closer to the original bounding value of 2078'F, the limit on peak linear heat rate (PLHR) was reduced from 13.5 kw/ft to 12.8 kw/ft.
This value of 12.8 kw/ft is being used for PLHR by administrative control for the _ remainder of the current operating cycle (Cycle 9).
The ANO-2 Cycle 10 core design has been developed by'the licensee.
Because of the desired longe'r cycle length for. the upcoming Cycle 10, the reload batch size-is significantly increased, resulting in.better power sharing among assemblies throughout the cycle length and a flatter overall power distribution.
This is advantageous for -the departure from-nucleate bciling ratio (DNBR) operating limit but has a negative impact on the PLHR power-
-operating limit..This effect was offset in-the Cycle 10 core design by a proposed reduction in the PLHR by 0.7 kw/ft., from 12.8 kw/ft to 12.1 kw/ft.
With'a PLHR of 12.1 kw/ft, there is a slight increase in the PCT to 2086*F for.
Cycle 10 as compared to the current analysis of record of 2078'F.
The licensee has also reviewed all the limits on containment conditions allowed by Figure 3.6-1.
From this review, it was-determined-that changes have occurred in the containment DBA analysis since_the Bases for Figure _3~6-1 were developed.
There are three major changes which-affect the: peak pressure;
- 1).a reduction in the air cooler performance; 2) an increase in the gap _
conductance between the containment liner and concrete; and 3) the-use.of'a-later version of Bechtel's containment analysis code (C0PATTA).
The current-analysis also indicates that the main steam line break (MSLB), rather than a LOCA. is the most limiting with respect to peak containment: pressure.
The licensee's evaluation of these changes indicates that the net effect is at
.least a 0.1: psi margin in the allowable initial containment pressure. The licensee has generated six data. points to support new upper limits for TS Figure 3.6-1 using the COPATTA_ code.
The six sets of input data projected d
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PCTLvalue of 2086*F.
This _ is well below the limit of 2200*F. _11herefore, we -
find this change to be acceptable, n
4.0:.S1 ATE' CONSULTATION In accordance.with_ the Commission's regulations, the Arkansas St at e official 1 was notified of the proposed issuance of the amendment.
The s'-
official had no comments.
5.0 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 and changes surveillance requirements. The NRC staff has determined that the-amendment--involves no signifierat' 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, issued a-proposed finding that the amendment involves no significant hazards consideration,_and there has been no public' comment on such-finding (57 FR 34582). 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.
6.0 CONCLUSION
The Comntission 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:
H. Balukjian-
.Date: October.8,-1992 i
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.. peak containment pressure _in _each case to be below the TS basis value of_54 psig.- These six data points are:-
Initial Initial Initial Containment Containment Containment Case Pressure Temperature Humidity (psia)
(Deg,F)
(%)
1 15.9 100 0
2 14.116 140 0
3 16.05 100 50 4
14.46 140 50 5
16.19 100 100 6
14.8 140 100 3.0 EVALUATION l
The licensee made the following changes to the ANO-2 TSs: 1) revised the Region Of Acceptable Operation of TS Figure 3.6-1, " Containment Internal Pressure vs. Containment Average Air Temperature," and 2) revised the PLHR limit of TS Figure 3.2-1, " Allowable Peak Linear Heat Rate vs. Burnup."
The licensee revised TS Figure 3.6-1 to include a lower pressure bound of 12.8 psia and a lower temperature bound of 60*F.
These are the values used in the LBLOCA analysis performed, as-discussed in Section 2.0 above. -In the revision-of TS Figure 3.6-1, the licensee incorporated the effects of changes
- that have occurred in the. containment DBA analysis sincs the Bases for Figure
- 3. 6-1 were developed.
This includes the-three major changes which affect peak-pressure as discussed in Section 2.0 above using the six data points with the--
COPATTA code. These changes affected.the_ upper limits _of_-the curve in_ Figure-3.6-1.
The_ licensee stated that the proposed changes to the: upper region of TS Figure 3.6-1 still ensure-that-the-peak containment containment DBA is.less than the 54.psig design pressurpressure.following the e_ of the containment.
The. lower rig 5t hand: portion of the curve, which'is derived from the analysis.
of.an inadvertent spray actuation, remains unchanged, as this portion of the curve is considered bounding. _ We find these changes-to-be acceptable as they are based on reanalysis using the-current version of the COPATTA code with data representing current design conditions and,resulting in values within acceptable = limits.
The' licensee revised TS F_igure 3.2-1.to reduce the PLHR from 13.5 kw/ft to-12,1 kw/ft, which should remain ~ bounding for future-cycles.- The' licensee-stated that the PLHR limit has _never impacted the: operation of-AN0-2 (DNBR-is
- typically limiting):so-the proposed limit was chosen to make the PLHR power-operating limit approximately equal to, but~ still greater than, the DNBR _ power operating limit. This' limit, when used in the present ECCS evaluation model-to' determine the acceptability for Cycle 10' core design, was found to yield-a-l s
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