Criticality Alarm Systems (CAS) and Criticality Detection Systems (CDS)

DOE-STD-1135-99

Another essential element of the safety authorization basis is effective configuration

control of facility modifications and items that impact nuclear safety. An entire

chapter in the SAR is dedicated to "Prevention of Inadvertent Criticality"(see DOE-

STD-3009-94).

There are many training classes for preparation of safety analysis reports, technical

safety requirements and hazard classification. See Appendix A for training resources.

The individual should be able to:

a. Identify and discuss essential elements of deterministic and probabilistic risk

assessment techniques.

b. Identify and discuss the methods used to determine and analyze failure modes.

c. Discuss the methods used to identify and categorize the hazards associated with

DOE nuclear systems.

d. Define the following terms with respect to probabilistic risk assessments:

Probability, Reliability, Availability, Unavailability, Risk, Safety, Accident

sequence, Dominant contributors, and Minimal cut set.

e. Define the following terms and differentiate between the associated processes:

Event tree and Fault tree.

f. Describe the content of the sections of a safety analysis report (SAR) per the local

DOE site office expectations.

g. Explain a hazard analysis technique and how Technical Safety Requirements

(TSRs) are derived.

h. Identify criticality safety controls that are required by the facility safety

authorization basis documents.

i. Explain Threshold values and the Graded Approach used in hazard classification.

j. Explain how natural phenomenon events are evaluated in NCS.

7.0 Criticality Alarm Systems (CAS) and Criticality Detection Systems (CDS)

Each Contractor typically has a documented process for evaluating CAS or CDS

placement and coverage. There are several industry documents which provide

guidance related to criticality accident alarm and detection systems. ANSI/ANS 8.3

is the most commonly used and most complete resource for this competency.

The individual should be able to:

a. Perform an evaluation of placement and determine coverage area for a CAS or

CDS at their facility.

b. Define the following terms: Criticality accident, Minimum accident of concern, and

Process area.

c. Discuss the general principles associated with the use of criticality alarm/detection

systems including: Installation, Coverage, Detection, Alarms, Dependability,

Surveillance, and Maintenance.

d. Discuss the requirements for testing the criticality alarm/detection system.