ML20040B386
| ML20040B386 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 12/21/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20040B384 | List: |
| References | |
| NUDOCS 8201250506 | |
| Download: ML20040B386 (3) | |
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UNITED STATES g
g NUCLEAR REGULATORY COMMISSION O
j WASHINGTON, D. C. 20555 3
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION i
SUPPORTING AMENDMENT N05. 63 AND 45 TO
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FACILITY OPERATING LICENSE NOS. DPR-53 AND DPR-69 BALTIMORE GAS AND ELECTRIC COMPANY CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-317 AND 50-318 Introduction By application dated October 6, 1981, the Baltimore Gas and Electric Company (BG&E)requestedachangetotheTechnicalSpecifications(TS) for Calvert Cliffs Units 1 and 2.
The proposed change would increase the maximum allowable enrichment for fuel storage in the fresh fuel.
storage racks from 4.0 to 4.1 weight percent as stated in TS 5.6.2.
Discussion and Evaluation In order to accomodate the extended burnup due to an 18-month operating cycle for the Calvert Cliffs units, fuel of higher enrichment is required.
The actual enrichment is expected to be within an envel' ope from 3.95 weight percent (w/o) to 4.05 w/o U-235.
A proposed modification to TS 5.6.2 has, therefore, been proposed by BG&E in order to increase the fresh (new) fuel storage rack maximum fuel assembly enrichment from the currently approved 4.0 w/o U-235 value to 4.1 w/o U-235.
'The new fuel storage facility is not affected by the proposed TS change.
New fuel for Calvert Cliffs 1 and 2 is stored in a common area adjacent to the spent fuel storage pools, in the Auxiliary Building. The new fuel storage facility provides dry storage for approximately 2/3 of a core which is approximately 144 fuel assemblies. The facility consists of two rows of storage modules, each of which consists of a double row of six storage locations. Fuel. assemblies are centered in each storage locat'on.
the storage facility is enclosed by a concrete wall that is one foot thick. The floor is v :oncrete, but there is no concrete structure immediately above the r.icility.
The two by six arrays of fuel assembly: storage racks are separated by aisles that are two to three feet wide end the center-to-center spacing cf assemblies within each two by six array is approximately 17 inches.
One-quarter inch thick full-length, stainless steel angles, two inches by two inches, are at.the corner of each storage rack.~
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We have reviewed the revised new fuel rack criticality analysis to determine whether margin exists to permit storage of these higher ;
i enrichment fuel assemblies. The analysis included assuming the ':
i inundation of the fresh fuel rack, containing fuel with 4.1 w/o U-235, in unborated water having effective densities in the range of 0.04 to 1.0 gram /cc.
The low density water moderation could conceivably arise during fire-fighting operations through the use of fire hoses and aqueous foam generators._ We. find the range of;moderatortwater density investigated adequately covers all conceivable values and is,'therefore, acceptable.
f Criticality (keeffective) calculations were performed with the Monte Carlo code KENO-IV using' neutron cross-sections generated by the CEPAK code. These are analytical techniques that have been used in the past and are, therefore, acceptable.
The KENO-IV calculations field a K-effective of 0.89 for full density water and 0.75 for a secondiry peak at a water density of about 0.08 gm/cc.
These values provide a 10% margin to the limiting value of 0.98 required by TS 5.6.2.
We consider this margin to be adequate to conservatively allow for calculational uncertainties. Accordingly, we find that neither I
the probability nor the consequences associated with criticality of the-new fuel storage facility have increased as a result of an increase.from 4.0 w/o to 4.1 w/o enrichment of stored fuel. We, therefore, conclude i
that the Calvert Cliffs Units 1 and 2 new (fresh) fuel storage racks can safely accommodate 4.1 w/o U-235 14x14 fuel assemblies.
Based upon the above, we find it appropriate to increase the maximum allowable new fuel storage enrichment from 4.0 w/o to 4/1 w/o as provided by TS 5.6.2.
In addition, it is appropriate,to indicate in TS 5.6.2 that, for supporting calculations, "...various densities of unborated, water are assumed, including aqueous foam moderation."
Environmental Consideration We have determined that the amendments do not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendments involve an action which is insignificant.from the standpoint of
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environment'al impact and, pursuant to 10'CFR 551.5(d)(4), that an environmental impact statement or negative declaration and environ-mental impact appraisal need not be prepared in connection with the
. issuance of t.hese amendments.
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C 3-Conclusion
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We have concluded; based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase i
in the probability or consequences of accidents previously considered i
and do no: involve a significant decrease in a safety margin, the amendments do not i'nvolve a significant hazards consideration, (2) there is reasonable assu' ance that the health and safety of the public r
will not be endangered by operation in the proposed manner,' and (3) such activities will be conducted in ecmpliance with the. Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of th'e public.
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.1 Date:
December 21, 1981 O
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