Document: NUREG-0800
Document ID: 49aefb86-1adb-4b3c-826f-480e32947595
Document Type: srp
Title: Radiological Consequence Analyses Using Alternative Source Terms
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0037/ML003734190.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.0.1
CFR Part: 
CFR Title: 

Content:
has no impact on the EQ doses. The licensee can reference the rebaselining study to disposition the airborne activity EQ doses. (2) As part of a larger AST implementation, a licensee proposed removing analysis credit for in-containment fan cooler charcoal filter units. Offsite doses have been shown to be acceptable, but the in-containment source term and dose rates have increased. The new containment airborne 15.0.1-11 Rev. 0 -- July 2000 source concentrations are greater than those previously assumed in several of the plant EQ calculations. What are the analysis requirements? Answer: Those EQ calculations affected by the increased airborne source concentrations should be reanalyzed using the selected AST. This particular reanalysis requirement is driven not by the source term but by the plant modification. In addition, there are several potential non- radiological impacts, for example, the impact on the containment pressure-temperature transient, the impact on the fan of the reduced flow restriction, and so on, that may need to be considered. (3) A licensee proposes to change the response time of a containment purge system isolation damper from 2.5 seconds to 5.0 seconds on the basis of timing characteristic of an AST. The licensee states that increases in offsite dose are insignificant since the containment will be isolated before to the onset of gap release. Are dose calculations necessary? Answer: This is a selective implementation as only the timing characteristic is being proposed. The remaining characteristics of the AST are not being implemented. Thus, the previous analyses are not affected. Reanalyses would not normally be necessary. However, there may be other impacts that need to be considered, for example, can the damper close against the increased pressure that might exist at 5 seconds? Can the ductwork downstream of this damper withstand the increased pressure? If the damper could not close, dose calculations against the TEDE criteria would be