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## Lesson 9

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Outline of Typical CSEOutline of Typical CSEOutline of Typical CSEOutline of Typical CSE

Lesson 9

- Description of projects
- Accident presentations
- Overview of NCSE

Cover sheet

- Strict format: see example

Outline of Typical CSE

- Introduction
- Description of process
- Computational methodology
- Discussion of contingencies
- Normal & accident analysis
- Postings & controls
- Summary & conclusions
- Appendices

Introduction

- Why the work is being done
- Revision history
- Necessary administrative boilerplate

Outline of Typical CSE

- Introduction
- Description of process
- Computational methodology
- Discussion of contingencies
- Normal & accident analysis
- Postings & controls
- Summary & conclusions
- Appendices

Description of process

- Necessary description of the process
- Overview of the procedural steps
- Important interactions with preceding and following processes (and any others)
- Necessary description of the hardware
- Gloveboxes, canisters, storage racks, etc. (Include pictures)
- Relative positions, etc.
- Special materials
- Different variations allowed in geometry and process (important to criticality)
- Compare to the Contingency Table to make sure that all of the relevant MAGICMERV normal parameters are mentioned

Outline of Typical CSE

- Introduction
- Description of process
- Computational methodology
- Discussion of contingencies
- Normal & accident analysis
- Postings & controls
- Summary & conclusions
- Appendices

Computational Methodology

- Non-KENO
- Indication that relying on ANS-8.1 limits and/or hand calculational techniques
- KENO
- Indication that relying on criticality calculations+
- Basis of criticality control (k-safe)
- Boilerplate on the codes used
- Description of the computer used
- Point to the verification document
- Summarize validation and point to the Validation appendix

- Introduction
- Description of process
- Computational methodology
- Discussion of contingencies
- Normal & accident analysis
- Postings & controls
- Summary & conclusions
- Appendices

Discussion of contingencies

- Parametric review: Checklist of parameters important to criticality in THIS analysis
- mass, absorbers, geometry, interaction, concentration, moderation, enrichment, reflection, volume
- Contingency analysis
- Definition of normal case vs. parameters
- Definition of credible accidents vs. parameters
- Contingency table including controls

- Introduction
- Description of process
- Computational methodology
- Discussion of contingencies
- Normal & accident analysis
- Postings & controls
- Summary & conclusions
- Appendices

Normal & accident analysis

- Materials discussion, including assumptions (point to appendix)
- Normal Model development
- Normal & accident
- Simplified through the use of parametric studies
- Contingency case models as variation on normal model

Normal & accident analysis (2)

- JUST DO IT: Calculate the normal case and each of the contingencies you have identified
- Table of results that stands alone
- Like Tables in Section 6.4 of ExampleCSE
- Enough column to differentiate cases (repeat columns from contingency table, if desired)
- Keff+/-sigma column AND Keff+2sigma column
- Mark the limiting case with BOLD or larger font (or both)
- Discuss results in text

Analysis phase

- Table of results that stands alone
- Like Tables in Section 6.4 of ExampleCSE
- Enough column to differentiate cases (repeat columns from contingency table, if desired)
- Keff+/-sigma column AND Keff+2sigma column
- Mark the limiting case with BOLD or larger font (or both)

- Introduction
- Description of process
- Computational methodology
- Discussion of contingencies
- Normal & accident analysis
- Postings & controls
- Summary & conclusions
- Appendices

Postings & controls

- Description of:
- Engineered safety features
- Administrative controls
- Operator aids
- Procedural changes
- Postings
- Most important and most often referred to
- Very controlled format
- Posting
- Basis

WHAT you control

- Limits are set so that criticality cannot occur when operators comply with the limits
- Examples
- Mass limit is 350 g 235U (i.e., maximum mass)
- Mass limit is 200 g 239Pu (i.e., maximum mass)
- Concentration limit is 1 g 235U/liter (i.e., maximum concentration)
- Moderation limit is H/U = 4 (i.e., maximum moderation)
- Volume limit is 4 liters (i.e., maximum volume)
- Container limit is 4 containers (i.e., maximum number of containers)
- Spacing limit is 2 feet (i.e., minimum spacing)
- Stacking limit is 4 high (i.e., maximum number of items in a stack)

HOW you control

- Your NCSE will include the following sections:

7.1 Engineered safety features

7.2 Procedural requirements

7.3 Postings

- Remember our preference
- Passive control: railroad bridge over highway
- Active control: lights and gate at railroad crossing
- Administrative: stop sign at railroad crossing

Control Selection

- Passive engineered control examples
- Mass: container design (i.e., limit container size)
- Absorption: solid poisons (Raschig rings, boron-Al plates
- Geometry: container design (slab tanks, pencil tanks, bottle diameter)
- Interaction: spacers (storage racks, bird cages, carts)
- Moderation: sealed containers or systems (covers on storage racks to exclude sprinkler water)
- Reflection: spacers (storage racks, bird cages)
- Volume: container design

Writing Controls

- Clear
- Concise
- Unambiguous
- Doable
- Simple and easy to perform
- Directly controllable by operator
- Language that an operator will understand
- Relates to upset/change that needs to be prevented

Procedures- General

- Procedures provide instructions to perform tasks:
- Administrative
- Technical
- Maintenance
- Emergency
- Ranked according to safety significance
- Procedures for fissionable material operations are reviewed by NCS Engineers
- Should be scheduled
- Comments should be documented
- Comment resolution/procedure approval is documented
- Good “conduct of operations” requires verbatim compliance with procedures (so make sure it is possible!)

Postings

- Immediate information that the operator would NOT be expected to remember from training
- Very controlled format in Sect. 7
- Control
- Basis: Tied directly to Section 5 (Do not add or subtract)
- Similarly controlled format in the posting itself:
- Important words CAPITALIZED and possibly in a stand-out color
- Few articles (a, an, the)
- No convoluted IF/THEN syntax (KISS)

Postings

- As we discussed before, Section 7 contains the postings and basis for each
- In addition, Appendix C contains PowerPoint slide examples of the Postings themselves

- Introduction
- Description of process
- Computational methodology
- Discussion of contingencies
- Normal & accident analysis
- Postings & controls
- Summary & conclusions
- Appendices

Summary & conclusions

- Summary
- Conclusions

Appendices

- A. Materials and compositions
- B. Input and output listings
- C. Postings
- D. Comment review sheets
- E. Validation check sheets (Deleted - no longer required)
- F. Validation report
- G. Parametric studies

Appendix C: Postings (Example)

- Nuclear Criticality Safety Limits and Controls
- NO MORE than 4300 kg Plutonium per 8-liter container.
- •NO MORE than ONE operator may carry ONE 8-liter container at a time to the drum loading area.

App. H: Parametric Studies

- Stand alone pre-analysis studies in order to refine the normal case (What is normal?)
- Ideal: Perturbations on limiting case
- At minimum:
- PS#1 = Worst case of concrete
- PS#2 = 12” of water is infinite
- PS#3 = 6% water for sprinkler is conservative
- Follow format of AppendixH.doc in public area

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Parametric studies

- Arise out of modeling questions
- Most reactive material makeup
- Most reactive reflection
- Most reactive placement of fissile (primary)
- Most reactive arrangement of other material (including other fissile elements)
- Acceptability of modeling simplification (e.g., leaving out walls, ceilings, etc.)
- Sometimes order matters—you want to clear up the most “independent” modeling questions first to use in the others

35

Parametric study example

- You are analyzing storage of four 10 liter canisters in a 90x90x90 cm glovebox against a wall (Pu-239/water mixture)
- Assume the “normal” case still has the following ambiguities:
- H/D range of .8 to 1.2
- Placement of canisters in glovebox
- Type of concrete (among 4 SCALE choices)
- Optimum H/X ratio
- What parametric studies would you run?
- In what order?

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