On March 22, 1975, a fire was experienced at the Browns Ferry Nuclear Plant near Decatur, Alabama. The Special Review Group was established by the Executive Director for Operations of the Nuclear Regulatory Commission (NRC) soon after the fire to identify the lessons learned from this event and to make recommendations for the future in the light of these lessons. Unless further developments indicate a need to reconvene the Review Group, its task is considered complete with the publication of this report.

On March 22, 1975, a fire at the Browns Ferry Nuclear Plant caused a shutdown of Units 1 and 2. The facility subsequent to the shutdown was found to have incurred substantial damage to power, control, and instrumentation wiring. All three units are presently in the shutdown condition with the fuel removed from the vessels for Units 1 and 2; the Unit 3 reactor is still under construction with operation for that unit scheduled for early 1976.

This report describes a novel approach developed at the Oak Ridge National Laboratory
(ORNL) for the estimation of the uncertainty in the prediction of the neutron multiplication factor
for spent nuclear fuel. This technique focuses on burnup credit, where credit is taken in criticality
safety analysis for the reduced reactivity of fuel irradiated in and discharged from a reactor.
Validation methods for burnup credit have attempted to separate the uncertainty associated with

This report evaluates the radiological impacts during postulated accidents associated with the
transportation of spent nuclear fuel to the proposed Yucca Mountain repository, using the
RADTRAN 5.5 computer code developed by Sandia National Laboratories. RADTRAN 5.5 can
be applied to estimate the risks associated both with incident-free transportation of radioactive
materials as well as with accidents that may be assumed to occur during transportation. Incidentfree
transportation risks for transport of spent nuclear fuel to Yucca Mountain were evaluated in

The objective of this calculation is to provide the uncertainty term for fission product and minor actinides which contributes to the determination of the critical limit for burnup credit calculations. The scope of this calculation covers PWR and BWR spent nuclear fuel. This activity supports the Criticality Department's validation of burnup credit. The intended use of these results is in future Criticality Department calculations and analyses.