ML20147C765
| ML20147C765 | |
| Person / Time | |
|---|---|
| Site: | 07001308 |
| Issue date: | 11/15/1978 |
| From: | Stevenson R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Rouse L NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| NUDOCS 7812180397 | |
| Download: ML20147C765 (3) | |
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4 g UNITED STATES t NUCLEAR REGULATORY COMMisslON E 'O E WASHINGTON, D. C. 20555 5? rj
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Docket No. 70-1308 SNM-1265 MEMORANDUM FOR: Leland C. Rouse, Acting Chief Fuel Reprocessing and Recycle Branch i
THRU: W. T. Crow, Section Leader Uranium Fuel Fabrication Section Fuel Processing and Fabrication Branch FROM: Robert L. Stevenson Fuel Processing and Fabrication Branch
SUBJECT:
' NUCLEAR CRITICALITY SAFETY REVIEW 0F AMENDMENT APPLICATION FOR STORAGE OF LACROSSE FUEL BUNDLES AT GENERAL ELECTRIC (GE) MORRIS OPERATION, CONTROL N0. 78309A The subject GE application, dated September 22, 1978, was supplemented by additional information dated October 26 and November 9,1978, which provided responses to the two nuclear criticality safety questions in our memorandum of October 18, 1978. These questions concerned the proposed k-infinity limit to be used with the 10 x 10 type BWR fuel, and the proof of subcriticality for the situation where fuel accidentally extends partly out of the storage basket after dropping or tipping in the cask unloading pit. Review of the GE responses, including independent computer calculations by NRC, indicates that the fuel arrangement will be subcritical under normal and accident conditions and hence approval of the license amendment is recommended. The basis for this conclusion is discussed below.
B_a_ck ground The criticality safety basis for the storage of irradiated " light water reactor"(LWR) fuel at the Morris Operation was reviewed in our memoranda of July 23 and October 20, 1975. The earlier review, including independent computer calculations by the reviewer, shcwed that the multiplication factor for the 3.4% enriched BWR fuel, without burnup allowance, was acceptably low under normal (k-effective below 0.8) and accident conditions (k-effective below 0.9). The Lacrosse fuel is stainless steel clad of 3.92% enrichment before burnup, and about 10% wider than the BWR fuel previously analyzed.
78121803]
r A y Leland C. Rouse .
s higher .
On the basis of the approximately 0.5%/ absolute enrichment and larger size, relative to that in earlier analyses and the counteracting effect of the stainless steel cladding compared to zircaloy cladding in the earlier analyses, one expects a higher multiplication factor for both the normal and accident cases than the values calculated in 1975. However, the increase would not be expected to be sufficient to raise the factor to 0.95 for either the normal or accident cases.
Discussion GE provided calculations asing a validated calculational method, for the k-infinity of the Lacrosse fuel of 1.35, and a multiplication factor for normal storage in the stainless steel baskets of 0.855, assuming no burnup and the wall thickness of the pipes of the baskets at the minimum tolerance ,
value.
The validity of the GE safety conclusion for the " normal" storage condition is conservatively confirmed by reference to Lantz's correlation for fuel storage ("A Graphic Method for Comparing k. in Fuel Storage Pools," in Trans. ANS, Vol. 27,1977, p. 409).
For the unlikely accident in which a loaded fuel basket is dropped or tipped diagonally across the cask unloading pit to permit nine assen611es to extend about 42 inches out of the basket, GE reported a k-effective of 0.923 1 0.007 under conservatively assumed conditions of assembly spacing.
The GE calculations were independently confirmed by C. R. Marotta of the Transportation Branch using the NRC calculational method with the 123-group cross-section set, which indicated k-effective for the accident case to be 0.935 0.005.
The GE lattice k-infinity value was confirmed by reference to the value in WCAP-2999 and to the value developed during the independent NRC accident -
case calculation reported above.
It is agreed that the 1.38 k-infinity limit proposed by GE, which is above .
the 1.352 GE calculated for the most reactive Lacrosse fuel bundle, will not cause the storage array multiplication factor to exceed 0.90. Also, the arrangenent of fuel in the basket drop accident would be predicted to remain subcritical.
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.p-L. C. Rouse -
3-l Conclusion The calculations reported by GE and independently confirmed by NRC establish that the Lacrosse fuel bundles should be well subcritical under normal and accident conditions. Approval of the amendment '
authorizing Lacrosse fuel storage is recommended, rbtk h /f Nvorvwrv Robert L. Stevenson Fuel Processing and Fabrication Branch Division of Fuel Cycle and -
Material Safety m
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