ML20245D761
| ML20245D761 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 04/19/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20245D754 | List: |
| References | |
| NUDOCS 8905010153 | |
| Download: ML20245D761 (4) | |
Text
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UNITED STATES f
g, NUCLEAR REGULATORY COMMISSION g
<p WASHINGTON, D. C. 20555
/
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 44 TO FACILITY OPERATING LICENSE NO. NPF-30 UNION ELECTRIC COMPANY CALLAWAY PLANT, UNIT 1 i
DOCKET NO. STN 50-483 1.'
INTRODUCTION By letter dated October 25, 1988, Union Electric Company made application to modify the Technical Specifications (TS) for the Callaway plant to permit factors (F-delta H and Fq)gnificant changes incorporate increased peaking Cycle 4 operation. The si and a positive moderator temperature coefficient (MTC)
'Other changes include an increase in the boron concentration of the refuelitig water storage tank (RWST) and the reactor coolant system (RCS) accumulators, and an increased concentration of sodium hydroxide it. the spray additive tank.
The proposed Cycle 4 TS change values for the increased peaking-factors (F-delta H and Fq) and a positive moderator temperature coefficient (MTC) were used in the previous Cycle 3 reload safety analyses which were reviewed and
' accepted by the NRC staff. The proposed values, however, were not incorporated in the TS in Cycle 3.
The Cycle 3 core contained three different types of fuel: low (LOPAR), optimized fuel assemblies (0FA's) and Vantage 5 (V-5) parasitic It was the first application of V-5 fuel at the Callaway plant.
2.0 RELOAD DESCRIPTION The Callaway Cycle 4 reload will retain 9 0FA's and 96 V-5 fuel assemblies from the previous cycle and add 88 new,17 x 17, V-5 fuel assemblies. Sixty-four of the new assemblies will have a 3.6 percent enrichment of U-235 and 24 assemblies will have with an enrichment of 4.0 percent U-235. The 88 added assemblies will have 10,112 integral fuel burnable absorbers (IFBA's).
Axial blankets are part of the design of V-5 fuel assemblies. This design feature was approved generically via the staff review of Westinghouse Topical Report WCAP-10444-P-A (Reference 1 ).
The axial blankets were not used in the Cycle 3 reload and this will be their first use at the Callaway plant.
The reference cycle for this reload is Cycle 3.
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3.0 EVALUATION The Cycle 3 safety analysis, as a result of the hydraulic flow characteristics of three different fuel assembly types in the core, included a transition core departure from nucleate boiling ratio (DNBR) penalty of 2 percent for 0FA, and 12.5 percent for V-5 assemblies. This circumstance results from the tendency of an increased core flow to the LOPAR assemblies, which, of the three fuel assembly designs, have a relatively lower hydraulic. resistance.
LOPAR assemblies will not be in the Cycle 4 core. Therefore, the V-5 assemblies and the 0FA's will have less flow diversion and hence an improved performance with regard to DNBR and peak clad temperature (PCT). With a mixture of two fuel designs, no penalty in DNBR is assigned to the fuel of lower hydraulic resistance, OFA, in Cycle 4.
The 12.5 percent transition core DNBR penalty for the V-5 fuel is assumed in Cycle 4 and is conservative. The staff finds this penalty acceptable for addressing mixed core effects.
The licensee has also advised that debris-filter bottom nozzles (DFBN) will be used in Cycle 4.
The DFBN is a revised version of the current 17 x 17 nozzle
. design and includes an improved pattern of flow holes that:
- 1. Reduces the passage of debris into the fuel assembly,
- 2. Maintains the structural integrity of the current nozzle
- oesign,
- 3. Maintains the hydraulic performance of the current design.
The staff finds this use acceptable as the hydraulic performance of the current nozzles is maintained.
The Cycle 3 safety analysis included a full power enthalpy rise hot channel factor (F-delta'H) of 1.65 (with measurement uncertainty) for the V-b assemblies, a maximum heat flux hot channel facht (Fq) of 2.5, and a positive moderator temperature coefficient of +5 pcm/F from 0-70 percent power and decreasing linearly to O pcm/F at 100 percent power. This safety analysis was reviewed and accepted by the NRC staff in Reference 2.
The staff finds the proposed peaking fr: tors and positive MTC acceptable for the Cycle 4 reload.
With a positive MTC, the reactor coolant system (RCS) boron concentration is expected to increase. The Cycle 3 safety analysis included a reanalysis of the boron oilution transient to incorporate this increase. For the Cycle 4 reload, the licensee reanalyzed the boron dilution transient. This reanalysis incorporates a revised methodology that includes the effects of density compensat' ion on the l
dilution flow rates. The licensee stated that the applicable safety criteria were met.
The staff finds this approach acceptable and further notes that 1.his iniprovement would not have affected Cycle 3 as this cycle's T5 for the MTC was not changed.
7 i To support longer. cycles. and the implementation of a positive MTC while retaining the required shutdown margin, it has'been proposed that the TS for the RWST and the RCS accumulators boron concentration ranges be increased to 2350-2500 ppm and 2300-2500 ppm, res Analysis Report (FSAR)pectively. The accident analysis in the Final Safety was evaluated for the above-mentioned increased boron concentrations. The licensee determined that there was no adverse effect on the FSAR results caused by increasing the RWST and the RCS accumulator boron concentration bands. The staff-has reviewed the evaluation and agrees with the conclusion.
The containment spray system reduces the iodine and particulate product inventories in the containment post-LOCA atmosphere.
A minimum pH 'f 8.5 in the containment' o
sump is necessary to ensure long-term retention of iodine in solution. On the
-basis of, the increased boron concentrations, higher sodium hydroxide concentrations (31-34 percent by weight) are needed to achieve the minimum long-term post-LOCA containment sump pH of 8.5.
The licensee has considered the post-accident effects of the increased sodium hydroxide on the following:
. Hydrogen generation in containment Environmental qualification of electrical equipment in containment Radiological consequences Potential precipitt. tion of boric acid It was determined that the increased sodium hydroxide did not adversely affect these considerations. The staff has reviewed the evaluation and find it acceptable.
l 4.0 TECHNICAL SPECIFICATION CHANGES The TS proposed changes are described below:
TS 3.1.1.3 is revised to include a positive MTC.
TS 3.1.2.5 and TS 3.5.5 are revised to include a new minimum boron concentration for the RWST of 2350 ppm.
TS 3.1.2.6 is revised to include a new boron concentration range for the RWST.
i TS 3.2.1, TS 3.2.2, TS Fig 3.2.2 TS 4.2.2, TS 4.2.2.2, TS 4.2.2.3 and TS 4.2.2.4 are revised to include the increased heat flux hot channel factor, Fq.
TS 4.2.1.4 is revised to include 6 calculated value, rather than zero value, at the end-of-cycle life in determining axial offset. The use of the calculated value is more realistic and represents a small change.
-4.
TS 3.2.3 is revised to include the~ increased F-delta H.
TS 3.5.1 is revised to include a new boron concentration range for each
. reactor coolant system accumulator.
TS 3.6.2.2'is revised to reflect a new weight percent range of sodium hydroxide in the spray additive tank.
l 1
The proposed TS are consister.t with the safety analyses and'are therefore acceptable.
a 5.0
SUMMARY
The staff has reviewed the accident analysis evaluation presented in the Callaway Cycle 4 reload submittal and has concluded that the proposed reload and i
associated TS are acceptable.
6.0 ENVIRONMENTAL CONSIDERATION
This-amendment involves a change to a requirement with respect to the instal-lation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and a change to a surveillance requirement. 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 issued a proposed finding that this amendment involves no significant hazards-consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forthin10CFR51.22(c)(9). Pursuantto10CFR51.22(b),noenvironmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
7.0 CONCLUSION
The staff has concluded, based ca the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by o' eration in the proposed manner; and (2) such p
activities will be conducted in compliance with the Connission's regulations and the issuance of this amendrent will not be inimical to the connon defense and' security or to the health and safety of the public.
3.0 REFERENCES
.1.
Davidson,S.L.andKramer,W.R.;(Ed.)"ReferenceCoreReportVANTAGE5 Fuel Assembly, WCAP-10444-P-A, September 1985.
P-License Amendment No. 28, dated October 9, 1987.
j Principal Contributor:
D. Katze, SRXB l
Dated: April 19, 1989-f i
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