The document describes two safety circuit designs for a laboratory that will conduct flooding experiments. The first circuit uses a truth table and Karnaugh map to determine that both the pump and valve must be activated for water to flow. The second circuit uses a multiplexer, where the inputs are experiment status and a card, and the select line is the pump and valve status. Both circuits will undergo reliability analysis to select the final design for the Component Flooding Evaluation Laboratory.

1. COMPONENT FLOODING EVALUATION
LABORATORY SAFETY CIRCUIT
INTRODUCTION
• March 11, 2011, tsunami at the Fukushima Daiichi Nuclear Power Plant ( NPP )
has highlighted the importance of flooding as a potential hazard
• Traditionally, NPP flooding analysis involves identification of the frequency of
expected flooding depths and then assuming that components below the flooding
depths fail during the flooding event. [lwrs.inl.gov]
CFEL KEY FEATURES
• The heart of CFEL is the testing bay where flooding experiments will be
performed ( Figure 1)
• Researchers will configure experiments in bay and then bay will be rapidly
flooded.
SAFETY CIRCUIT DESIGN
• CFEL safety circuit ensures that no water flow occurs during configuration of the experiment within the
testing bay
• Safety circuit was particularly designed to provide the safety requirement during the experimental setup in the
testing bay
• Safety circuit design begins with construction of a four Variable T-T. Inputs to the Truth Table (T-T) are
Experimenter (A), Card (B), Pump (C) and Valve (D). (Figure 2)
• The second safety circuit uses
a Multiplexer (MUX ) (Figure
5).
• The input of the two data lines
are zero and an AND
combination of Experimenter
and the Card given by 𝐈 𝟎
• The select line is the OR
combination of the Pump and
the Valve given by S.
• The output is given by Z as
shown in Equation (2)
CONCLUSION AND FUTURE WORK
• Following safety circuit operational confirmation, each circuit will be subjected to
reliability analysis to determine the Mean Time To Failure (MTTF).
• Based on the reliability analysis results one circuit will be selected for CFEL and
further analysis will be performed to determine if parallel safety circuits are
wanted.
Sneha Suresh, Dr. Chad Pope (Advisor)
Nuclear Engineering, Idaho State University
• For water to flow, the system pump must be activated and the flow control valve
must be open. Thus, a safety strategy coupling pump and valve status and
personnel access was developed.
The T-T is construction
• For an n- variable T-T, the number of input
combinations required are 2 𝑛
• There are 4 variables and 2n = 16 input
combinations ( Table 1)
• These combinations are then written in BCD
(Binary Coded Decimal) or the 8-4-2-1
format from 0 (0000) to 15 (1111).
• The Karnaugh map (K-map) is arranged in a
4 × 4 grid (Figure 3)
• Values from the T-T are transferred onto 2-
dimensional grid with the cells arranged in
gray code
• Boolean expression for the logic given in
Equation (1)
• Logic diagram for Boolean expression
shown in Figure 4
Fig. 1. Testing bay
Fig. 2. The key features of CFEL
Table. 1. Truth Table
Fig. 3. K-map
Fig. 4. First Safety Circuit Logic Diagram
Fig. 5. Second Safety Circuit using a 2:1 MUX
(1)
(2)