ML20059B196
| ML20059B196 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 10/22/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20059B195 | List: |
| References | |
| NUDOCS 9310280081 | |
| Download: ML20059B196 (2) | |
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NUCLEAR REGULATORY COMMISSION
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1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO FACILITY OPERATING LICENSE NOS. DPR-39 AND DPR-48 I
COMMONWEALTH EDISON COMPANY l
ZION NUCLEAR POWER STATION. UNITS 1 AND_Z DOCKET NOS. 50-295 AND 50-304 i
1.0 INTRODUCTION
In a letter dated September 13, 1993, Commonwealth Edison Company (CECO, the licensee) stated that it had performed a reanalysis of the fuel handling accident inside containment (FHA!C) for the Zion Nuclear Power Station. The licensee had previously performed this analysis and submitted it in a July 10, 1991, letter to support the transition to VANTAGE 5 fuel. A subsequent review j
of this analysis by one of the licensee's contractors identified the fact that j
a removal efficiency of 90% had been assumed for the charcoal adsorbers for organic forms of iodine. This value was inconsistent with guidance presented l
in Regulatory Guide (RG) 1.25, which specifies a value of 70%. Consequer.tly, the licensee reanalyzed the consequences of a FHAIC utilizing the value of 70%'
l and submitted its reanalysis for staff review in its September 13, 1993, i
letter.
The licensee also indicated that a reanalysis of the fuel handling accident I
inside the fuel handling building was not required because the analysis in the i
July 10,1991, submittal had been superseded by an analysis to support the l
installation of new spent fuel pool storage racks.
The latter analysis was submitted in support of the issuance of Amendment Nos.142 and 131 for Units 1 and 2.
l 2.0 EVALUATION The assumptions which were utilized by the licensee in its evaluation of a k
FHAIC were presented in Table 1 of the September 13, 1993 submittal. The staff independently calculated the doses to members of the public at the Exclusion Area Boundary (EAB). The staff's assumptions were similar to the licensee's with the following exceptions.
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1.
The staff assumed a power level of 3391 Mwt.
2.
The flooded reactor cavity pool decontamination factor used for i
elemental iodine was 22/23 of 100 to account for depth of water over the I
fuel being 22 feet rather than the RG 1.25 value of 23 feet.
3.
The flooded reactor cavity pool decontamination factor used for organic l
iodine was 1.
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DR ADOCK 0500 5
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! -l The staff's results indicated that the thyroid dose was approximately 110 ren.
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While the dose of 110 rem is greater than the criterion of Section 15.7.4 of NUREG-0800, the Standard Review Plan (SRP), it is within 10% of the value of l
100 rem thyroid which is the licensing basis for the Zion facility.
In the NRC's Safety Evaluation for Amendment Nos. 43 and 40 for Zion, Units 1 and 2, the staff stated that the results of a FHAIC were considered " appropriately l
within the guidelines of 10 CFR Part 100." At that time, the staff stated l
that " appropriately within the guidelines of 10 CFR Part 100 has been defined as less than 100 rem thyroid."
The staff considers the value of 110 rem thyroid to be acceptable because 'he staff utilized the licensee's Chi /Q for this calculation which is approximately a factor of 2 greater than the value calculated by the staff for the operating license safety evaluation. Use of the Chi /Q value normally utilized by the staff would, therefore, result in a dose of about 54 rem.
l Therefore, the staff considers 110 rem to be a conservative value.
3.0 CONCLUSION
The staff has concluded, based upon the considerations discussed above, that I
the consequences of a FHAIC would not result in doses which are unacceptable based upon the conservatism associated with the calculational assumptions and the fact that the dose is within 10% of the licensing basis for Zion Nuclear Power Station, yet significantly below 10 CFR Part 100 limits of 300 rem. The staff, therefore, finds the results of Ceco's analysis to be acceptable.
Principal Contributor: John Hayes Dated:
October 22, 1993 i
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