# Static and Dynamic Criticality: Are They Different?

## Abstract

Let us start by stating that this paper does not contain anything new. It only contains material that has been known for decades, but which is periodically forgotten. As such this paper is intended merely to refresh people's memories. We will also mention that this paper is an example of the occasional discrepancy between textbook methodologies and real world applications, in the sense that the conclusions reached here contradict what it says in most textbooks, i.e., most textbooks incorrectly interpret the methods presented here, particularly with respect to the use of importance sampling to maintain population control. This paper is not intended as a general tutorial on criticality calculations. It is intended only to clarify the accuracy of various methods for solving criticality problems, such as a true time dependent dynamic calculation, versus an alpha or K static calculation. In particular, we address the long standing controversy between users of the TART code [1] with the dynamic method, and users of the MCNP code [2] with the alpha static method. In this paper we will prove which methods are accurate and inaccurate.

- Authors:

- Publication Date:

- Research Org.:
- Lawrence Livermore National Lab., Livermore, CA (US)

- Sponsoring Org.:
- US Department of Energy (US)

- OSTI Identifier:
- 15009756

- Report Number(s):
- UCRL-TR-201506

TRN: US0406611

- DOE Contract Number:
- W-7405-ENG-48

- Resource Type:
- Technical Report

- Resource Relation:
- Other Information: PBD: 12 Dec 2003

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 22 GENERAL STUDIES OF NUCLEAR REACTORS; 38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; ACCURACY; CRITICALITY; SAMPLING

### Citation Formats

```
Cullen, D E, Clouse, C J, Procassini, R, and Little, R C.
```*Static and Dynamic Criticality: Are They Different?*. United States: N. p., 2003.
Web. doi:10.2172/15009756.

```
Cullen, D E, Clouse, C J, Procassini, R, & Little, R C.
```*Static and Dynamic Criticality: Are They Different?*. United States. doi:10.2172/15009756.

```
Cullen, D E, Clouse, C J, Procassini, R, and Little, R C. Fri .
"Static and Dynamic Criticality: Are They Different?". United States. doi:10.2172/15009756. https://www.osti.gov/servlets/purl/15009756.
```

```
@article{osti_15009756,
```

title = {Static and Dynamic Criticality: Are They Different?},

author = {Cullen, D E and Clouse, C J and Procassini, R and Little, R C},

abstractNote = {Let us start by stating that this paper does not contain anything new. It only contains material that has been known for decades, but which is periodically forgotten. As such this paper is intended merely to refresh people's memories. We will also mention that this paper is an example of the occasional discrepancy between textbook methodologies and real world applications, in the sense that the conclusions reached here contradict what it says in most textbooks, i.e., most textbooks incorrectly interpret the methods presented here, particularly with respect to the use of importance sampling to maintain population control. This paper is not intended as a general tutorial on criticality calculations. It is intended only to clarify the accuracy of various methods for solving criticality problems, such as a true time dependent dynamic calculation, versus an alpha or K static calculation. In particular, we address the long standing controversy between users of the TART code [1] with the dynamic method, and users of the MCNP code [2] with the alpha static method. In this paper we will prove which methods are accurate and inaccurate.},

doi = {10.2172/15009756},

journal = {},

number = ,

volume = ,

place = {United States},

year = {2003},

month = {12}

}