ML20057D074
| ML20057D074 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/21/1993 |
| From: | Rensen P ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY, ASEA BROWN BOVERI, INC. |
| To: | |
| Shared Package | |
| ML20046D604 | List: |
| References | |
| A-93-026, A-93-26, NUDOCS 9310010071 | |
| Download: ML20057D074 (4) | |
Text
!
i
. to A-93-026 Page 1 of-4 ARKANSAS NUCLEAR ONE UNIT 2. CYCLE 10 PROPOSED CHANGES TO INCORE DETECTOR TECHNICAL SPECIFICATION PREPARED BY:
21 y}3 J
y Si/ nature / Date PT L. J. Rensen Author VERIFICATION STATUS The information contained in-this document has been verified in accordance with the ABB Combustion Engineering Nuclear Fuel Quality Assurance Program.
/
Yes No j%l$lD A ED $
ABB Combustion Engineering Nuclear Fuel 9310010071 930924
't9 PDR ADOCK 05000368
- A P
PDR hp
- to A-93-026 Page 2 of 4 4
a Purcose This enclo:cce provides justification for the proposed (Reference 1) temporary changes to the ANO-2 Technical Specification operability requirements on in-core detectors. Attachment I contains the proposed change.
r l
Justification of Temocrary Chances to Technical Soecifications The following analyses have been performed in support of this revision.
First, a new analysis of the overall CECOR power peaking factor measurement uncertainties has been performed by Entergy Operations, Inc (Reference 2).
This analysis models the present instrument failures and combines them with various sets of additional postulated failures, so as to model up to 50% of the detectors as failed.
The additional element failures are randomly chosen, and each resultant failure pattern is analyzed for its impact on the CECOR measurement uncertainties. The analyzed patterns do not exceed the tilt estimate requirements of the Tech Spec or the 50% operable location Tech Spec.
From this analysis, the resultant overall uncertainty on CECOR measured Fxy
'ncreases by less than 0.5% compared to the value (6.92%) given in the Entergy CECOR Topical (Reference 3). Second, ABB-CENF has assessed the impact of up.
1 to 50% failed detector locations (including the increased CECOR Fxy measurement uncertainty) upon the calculations performed by the monitoring system (COLSS) and the protection system (CPCS). The impact is accounted for in revised values of certain addressable constants input to these systems as described in Enclosure I to this letter. For conservatism, a full 1.0%
increase in overall uncertainty on the CECOR Fxy measurement was assumed for the generation of these new constants.
Chance to Administrative Procedures Since the in-core detector system continuously monitors azimuthal tilt and axial shape, any unusual behavior will be detected immediately.
However, in-order to address past NRC concerns about changes which may occur between surveillance intervals, it is recommended that Entergy/ANO-2 administratively change its surveillance interval. The change is described below.
For the remainder of cycle 10, when the failure level of in-core detector locations exceeds 25%, Entergy/ANO-2 will check the planar radial peaking factor on a once per 15 day schedule, which is twice as often as the Technical Specifications now require.
Entergy/ANO-2 will incorporate the results of the new ABB-CENF analysis as embodied in the revised COLSS database constant K09, the revised COLSS addressable constants EPOL2, EPOL4, and UNCERT and the revised CPCS addressable constants BERR1, BERR2, BERR3 and BERR4, as required.
l -
u l
" to A-93-026 Page 3 of 4
References:
1 i
1.
A-93-025, " Proposal To Support Reduction of Operable Incore Detectors for ANO-2 Cycle 10 and Beyond", 8 September,1993, a letter from D. R. Earles (ABB-CE) to F. T. Philpott (Entergy Operations Inc).
2.
R. B. Lang, " ANO-2 Cycle 10 CECOR Reliability Factors",17 Sept, i
1993, File Nos.: 041-01;QR-220-18 and CE0-93/00367.
i 3.
MSS-NA3-P, " Verification of CECOR Coefficient Methodology for l
Application Pressurized Water Reactors of the Middle South Utilities System", August 1, 1984.
i f
l Attachments:
1.
Proposed Temporary Technical Specification Changes.
l l
l t
f i
t i
i l
l l
' to A-93-023 Page 4 of 4 ATTACHMENT 1 PROPOSED TEMPORARY TECHNICAL SPECIFICATIONS CHANGES INSTTUFENTATION YM!rTY YTTTCTMs f.YMitYt9 cmmfTffM Top errP ATf ont 3.3.3.2 na incere detection systaa shall be OPERABLE with SD a.
At Isast #5% of all incore detectors with at lasst one incors detsetor in each quadrant at sach level, and l
fo I
b.
At lasst d*% of all incere detector locations, and c.
Sufficiant operable incere detectors to pstform et Isant six ti.1t estiastas with at 1saat one tilt estimate at each of three levels.
An CPE1AILE incere detector location shall consist of a fool assembly containing either a fixed detector string with a minimum of three OPrratf2 rhodium detectors or an OPERABLE serable incore detector capable of mapping the location.
A tilt estimate can be onde from two sets.cf syssetric pairs of incore detectors. Two sets of symmetric pairs of incore detectors are formed by two pairs of diagemally opposite symmetric incore detectors, one incere i.etector per quadrant.
N YcAPff.YTY: Yban the incere detection systaa is used for moottoring the AIIrJTEAL PC7sT.R TILT. radial pe,aking factors, local power density or DK5 margin.
LEII21:
With the incere detection systes inoperable, do not use the systan for the j
above applicable monitoring or calibration functions. The provisions of Specifit.ations 3.0.3 are not applicable.
r"FYFrif3NN Trm377twmTM 4.3.3.2 no incere dessetion syntaa shall be demanstrated CaTEAliLE:
j a..
By performance of a CEADZL CEECK within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to its use and at least once per 7 days thereafter wben required for-monitoring the AZIEUTEAL POVER TILT, radial peaking factors, local power density or CKB margin.
b.
At laast once per 18 months by parformance of a CEAhdEL CALIERATION operation which areepts the neutros detectors but--
ineludas all electronic coeponents. The neutron detectors shall be calibrated prior to installation in the rasctor core.
l l
AIIANEAS - UNIT 2 3/4 3-28 Ameedmont No. U, 134