Document: NUREG-0800
Document ID: ff35052f-d051-4098-a352-1e382f87365a
Document Type: srp
Title: NUREG-0800
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340655.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6
CFR Part: 
CFR Title: 

Content:
assumptions used in the thermal analysis, if thermal analysis is used to establish the qualification of instrumentation and components for use in superheated steam environments. The CONTEMPT-4 code is being developed to provide improved capability to analyze the long-term response of an ice condenser containment to a loss-of-coolant accident. When the CONTEMPT-4 code is available, the CSB will perform confirmatory analyses using this code. 3. The TMD code is used to evaluate the transient pressure responses (internal) of the ice condenser containment subcompartments. The code is described in the proprietary report WCAP-8077 (Ref. 22). The TMD code utilizes an ice condenser heat transfer coefficient obtained from the 1974 full-scale section tests of the ice condenser. The TMD code also utilizes a compressibility factor "Y" to account for compressible flow effects. As stated in the D. C. Cook Safety Evaluation Report, the CSB has reviewed the assumptions and equations used in the TMD code and with the exception of the critical flow model used to predict subcompartment vent mass flow rates, has concluded that the TMD code conservatively calculates transient pressure response. The TMD code calculates the critical flow of a two-component, two-phase fluid (air, steam, and water) assuming a thermal equilibrium condition. However, a correction factor is then applied to the calculated critical flow. The CSB has not accepted the use of this corrected critical flow, referred to as "augmented flow," and has required that the short-term transient responses of subcompartments be determined using the TMD code without applying a correction factor to the critical flow; i.e., without the "augmented flow" correlation. Before accepting the containment transient responses calculated by the TMD code, the CSB reviews the modeling of the containment subcompart- ments, the size and area of assumed vents between nodes, volumes of nodes, the flow loss coefficients for each vent modeled, and