This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: NEEP 411: HW#5 Severe Accident Calculations: Structural Calculations Due: Friday, October 28 th , 2011 1. In class, we formulated a crude expression for the temperature of the pressure vessel lower head as a function of time, where time is measured after a large mass of relocated corium settles on the lower head: Here is the temperature difference between the vessel and containment air, is the initial temperature difference, = is the time constant and T = . The numbers we obtained for these values are: = 270 K, T = 1300 K and = 1.1 hr. Suppose that the lower head is subjected to a membrane stress of 100 MPa while experiencing this temperature history. The creep strain rate can be described in power law form as: where A is a temperaturedependent coefficient, n = 4 at this level of stress, the creep strain rate has units of [hr1 ] and the stress has units of [MPa]. For the SA533B steel used for nuclear pressure vessels, an approximate expression for A(T) is: In the expression for A ( T ), T must be in [K]. The value of A o is 1.667 10 12...
View Full
Document
 Fall '09

Click to edit the document details