ML20198H389
| ML20198H389 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 12/22/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20198H378 | List: |
| References | |
| NUDOCS 9801130273 | |
| Download: ML20198H389 (5) | |
Text
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t i'MTED STATES g
.j NUCLEAR REbdLATORY COMMISSION p
WASHINGTON, D.C. 3066Me01 1,
SAFE 1Y EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 202 TO FACILITY OPERATING LICENSE NO. DPR-70 E@LIC SERVICE ELECTRIC & GAS COMPANY PHILADELPHIA ELECTRIC COMPANY DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY SALEM NUCLEAR GENERATING STATION. UNIT NO. 1 DOCKET NO. 50-272
1.0 INTRODUCTION
By letter dated October 6,1997, the Public Service Electric & Gas Company (the licensee) submitted a request for changes to the Salem Nuclear Generating Station, Unit No.1, Technical Specifications (TSs). The requested changes would increase the allowable band for control and shutdown rod demanded position versus indicated position from i 12 steps to i 18 steps when the power level is not greater than 85% rated thermal power.
The changes have already been approved for Salem Unit 2 in Amendment No.183, issued September 10, 1997, as an exigent amendment.
2.0 [ VALUATION The analog rod position indication system (ARPI) system is designed to an accuracy of 12 steps.
Therefore, in order to guarantee a rod misalignment of less than 24 steps (12 steps misalignment plus 12 steps ARPI uncertainty), the individual ARPI readings must be no larger than 12 steps, in order to justify changing the misalignment limit to i 18 steps, the licensee did evaluations for misalignments of up to 30 steps (18 steps indicated plus 12 steps uncertainty) lowers.The TS limits on peaking factors F, and FBH increase as the power level The increase in the limit for F and FBH was used to accommodate the larger than 112 steps nisalignment al the reduced power levels. To justify the increase in allowable rod misalignment at a reduced power level, the following were evaluated:
1.
reactivity control 2.
control rod misoperation (dropped rods and static rod misalignmer.ts) 3.
rod ejection 4.
power operation with misaligned rods.
The principal tool used in the analysis was the Westinghouse PHOENIX-P/ANC core design system documented in References 2 and 3.
For this analysis the changes in peaking factors rather than the absolute values of the peaking NftTob d2 l
P
- - -___ A
. factors were of interest.
For each case, calculations were performed for misalignments of 124 and 130 steps and compared to the corresponding non-compared as a function of axial offset (Ab)for these cases were calculated and misaligned reference case. The FAH and F throughout the anticipated allowable range of operation. All calculations supporting this report used a Hot Full Power (HFP) A0 band of 115%.
The analysis was performed with two different models of the Salem core, the Unit 2 Cycle 10 core model and a " bounding" future cycle model. Applicability for each future cycle will be determined during the reload design process.
2.1 Reactivity Control To demonstrate that reactivity control was acceptable with the additional allowed misalignment, the reactivity effect of a misaligned bank by an additiond six steps was calculated for both core models at Hot Zero Power (HZP), HFP and part-power conditions. The change was found to be less than 100 pcm. These calculations were performed for End of Cycle (EOC) conditions since that represents the point in a cycle with the least available shutdown margin.
For future cycles, if a cycle-specific calculation is not performed, the rod insertion allowance calculated as part of the reload safety evaluation will be conservatively increased by 120 pcm.
2.2 RCCA Hisoperation Events The RCCA misoperation events (drcpped RCCAs and statically misaligned RCCAs) are initiated by the movement or displacement of one RCCA rod or bank from its normal position.
These events result in reactivity and power distribution anomalies. A change in the number of steps of misalignment allowed does not affect the results of these events since these events bound the misalignment cases.
2.3 Rod Ejection The rod ejection analysis is performed at HZP and HFP, Beginning of Cycle (BOC) and E0C conditions. The physics parameters of interest are the available trip worth following a rod ejection, the ejected rod worth, and the post-ejection F. Calculations were performed for both core models. The results of these calculations showed that the maximum increases in F and ejected rod worth were well within the margin on these parameters. forfuture cycles, if a cycle-specific analysis is not performed, the calculated ejected rod peak F, will be multiplied by 1.085 to bound the additional six steps of rod misalignment any time in the cycle.
Likewise, the ejected rod worth will be multiplied by 1.065.
In addition, the available trip worth following an ejected rod will be reduced by 100 pcm, which bounds the calculated values.
. 2.4 Power Operation with Misaligned Rod Power distributions with control rod misalignment of 30 steps (18 steps misalignment plus 12 steps for ARPI uncertainty) were evaluated.
To determine the misalignment cases to be analyzed for this TS change, an evaluation of the rod control system was performed, drawing from the Failure Mode and Effects Analysis. These analyses were performed to evaluate the impact of RCCA misalignment on steady state power distribution. Calculations were performed for both inward and outward misalignments from the demand counter positicn.
Multiple misalignments as well as single misalignments were analyzed. The cases analyzed included BOC, MOC and EOC cases for both core models. A total of over 'JGO cases were examined for A0s from -15% to +15%.
Comparisons were made between the peaking factors assuming the 18 ste) misalignment, the 12 step misalignment and the base case (control ban ( D at rod insertion limit (RIL)). The results indicate that the maximum tiicremental increase in F, and FM due to an additional misalignment of six steps is 3.6%
and 2.4% respectively.
Since the technical s>ecification limits on F and FM for 85% power are 18% and 4.5% greater than tioso at 100% power, the,small changes ir. F, and FM due to the larger misalignments are adequately accomodated.
2.5 Summary The proposed TS changes modify TS 3.1.3.1, 4.1.3.1, 3.1.3.2, and 4.1.3.2 and associated bases. The changes replace the rod misalignment value of 112 steps with 118 steps if RTP is not above 85%.
The bases have been modified to reflect tne new allowed rod misalignment.
RCCA misalignments of up to 30 steps (18 steps indicated plus 12 steps ARPI uncertainty) have been evaluated for impact on peaking factors and reactivity worth. The results with respect to reactivity control, RCCA misoperation events and rod ejection events have been shown to t,e acce) table.
For )ower o)eration with misalignment of 118 steps the results of tie analysis slowed t1at the incremental increases in the peaking factors were only a small fraction of the increase in the peaking factor limits for power levels less than 85%. Thus, it has been shown that the increase in peaking factors will be accommodated at or be?ow 85% of RTP and the change to the TS to allow misalignment of up to 18 steps is acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the New Jersey State official was notified of the proposed issuance of the amendment. The State Official had no comments.
4 4.0 ENVIRO?iMENTAL 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, r.nd no s
significant change in the types, of any effluents that may be released offsite, and that the e is no significant increase in individual or cumulative occupational radiation exposure. The Commisstori has found that the amendment involves no significant hazards consideration. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Parsuant 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 Com.11ssion has concluded, based on th..onsiderat..m e ed above, that:
(1) there is reasonable assurance
.at the he
'h sty of the public will not be endangered by operation in the p'
.....ner, (2) such l
activities will be conducted in compliance with the
, ission's regulations, L
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:
M. Chatterton Date:
December 22, 1997 L
L L
F
l 6.0 BEFERENCES 1.
E. C. Simpson, Public Service Electric and Gas Company, to NRC, dated August 19, 1997, 2.
T. Q. Nguyen, et al., Qualification of the PHOENIX-P/ANC Nuclear Design t
System for Pressurized Water Cores. WCAP-ll596-P-A, June 1988.
3.
Y. S. Liu, et al., ANC: A Westinghouse Advanced Nodal Computer Code, WCAP-10465-P-A, December 1986.
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