ML20247M086
| ML20247M086 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 05/21/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20247M065 | List: |
| References | |
| NUDOCS 9805260166 | |
| Download: ML20247M086 (2) | |
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NUCLEAR REGULATORY COMMISSION o
WASHINGTON, D.C. spee6410M k*****
I SAFETY EVALUATION BY THE OFFICE OF NUCI FAR REACTOR REGULATk").N l
CATAWBA NUCLEAR STATION. UNITS 1 AND 2 DOCKET NOS: 50-413 AND 50-414 SUPPLEMENT TO NUREG-0954 l
15.4.6 Fuel-Handling Accident By letter dated September 25,1997, Duke Energy Corporation (DEC, the licensee) submitted the 1997 revision to the Catawba Updated Final Safety Analysis Report (UFSAR). Among the changes made to the UFSAR, the revision added an analysis for a postulated accident involving dropping of a spent fuel pool weir gate onto spent fuel assemblies.
This postulated accident was not present in the Catawba FSAR submitted with DEC's application for facility operating licenses for the Catawba units. Likewise, the staffs Safety Evaluation Report (NUREG-0954) and supplements did not report the evaluation of such a postulated accident. Despite these facts, Catawba Technical Specification Section 3.9.7,
" Refueling Operations," has a requirement regarding movement of weir gates.
The licensee provided an analysis of the potential radiological consequences of moving the spent fuel pool weir gates over stored spent fuel. Moving the weir gates by crane over spent fuel that has decayed a minimum of 17.5 days is currently allowed by Technical Specification l
Section 3.9.7. However, the consequences of dropping a gate onto the fuel had not been i
previously analyzed in the FSAR or the UFSAR.
l The licensee's analysis of this accident assumes that seven fuel assemblies would be impacted by a dropped weir gate. The radioactive inventory in these fuel assemblies, the fraction of the activity released, as well as the other input parameters used in this analysis are consistent with
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those specified in Regulatory Guide (RG) 1.25, with one exception. Consistent with Catawba's current licensing basis, ventilation filtration removal efficiencies of 95 and 80 percent were assumed for the inorganic and organic species of iodines, respectively, in lieu of the 90 and 70 percent default assumptions in RG 1.25. Using the current design basis atmospheric diffusion factor (Chi /Q) of 4.78E-04 s/m*, the doses to an individual at the Exclusion Area Boundary (EAB) of.586 rem whole body and 66.7 rem thyroid were calculated. Because of the longer distances to the Low Population Zone and the same exposure time (2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />), the EAB doses are considered bounding.
l In addition to the preceding analysis that assumes the minimum decay and ventilation filtration I
l (Case 1), a second case was evaluated to determine what decay time would be necessary such-l-
that credit for ventilation filtration is not needed to maintain the consequences of the postulated l
accident within the acceptance criteria of the Standard Review Plan (NUREG-0800). Case 2 l
l 9805260166 990521 yDR ADOCK 05000413 PDR 3
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a i (30-day decay and no filtration) results in doses comparable to Case 1;.115 rem whole body and 71.8 rem thyroid. Therefore, only one train of filtration needs to be operable while moving the weir gates over fuel that has decayed for at least 30 days. Loss of this single operable train will not constitute a failure to meet the design basis commitment that a single active failure cannot result in a loss of the system functional performance capability (e.g., maintain dose consequences well within the criteria in 10 CFR Part 100). Technical Specification Section j
3.g.11 requires that at least one train of fuel handling ventilation exhaust system be operable j
. and discharging through a filtration unit whenever spent fuelis being moved or during crane operations with loads over storage pool.
The staff has reviewed the licensee's analysis methods and input assumptions. The licensee's l
analysis is consistent with the guidance in RG 1.25 and the results are well within the criteria in 10 CFR Part 100. The staff finds reasonable assurance that the plant design as described in l
the UFSAR revision meets the acceptance criteria in NUREG-0800 and is therefore acceptable.
l Principal Contributor: Roger L. Pedersen i
Dated:
May 21, 1998 i
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