ORP-69528-VA

Revision 0

Semi-Annual DNFSB Briefing on 242-A

Evaporator Safety Bases 

Prepared for the U.S. Department of Energy

Assistant Secretary for Environmental Management 

P.O. Box 450 

Richland, Washington 99352 
ORP-69528-VA

Revision 0

Semi-Annual DNFSB Briefing on 242-A Evaporator Safety Bases 

K. Subramanian

Washington River Protection Solutions

P. Schroder

Department of Energy - Office of River Protection

Date Published

September 2023 

To be Presented at

DNFSB Briefing 242-A 

DOE-ORP

Richland, WA 

09/19/2023 

Prepared for the U.S. Department of Energy

Assistant Secretary for Environmental Management 

P.O. Box 450 

Richland, Washington 99352 

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in and to any copyright covering this paper. 

Release Approval Date 
ORP-69528-VA

Revision 0

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Printed in the United States of America 
Semi-Annual DNFSB Briefing on 242-A 

Evaporator Safety Bases

Paul Schroder, DOE-ORP, DOE-AMTF

Karthik Subramanian, WRPS, Chief Engineer

September 19, 2023
2

Agenda

• Safety share

• Kick-off (DOE-ORP)

• Background

• Process & Hazards

• Interim Controls

• Planned Improvement Controls

• Questions
3

Safety Share
4

Background

• 2021 – 2022: Series of Q/A sessions with DNFSB staff

• 7/19/2022: DNFSB letter regarding concerns

• 4/17/2023: DOE Letter to DNFSB with interim controls and planned 

improvements

• 6/27/2023: DNFSB letter requesting semi-annual briefings covering

o Design, procurement, and installation of the planned improvements

o Any emergent technical issues and funding constraints

o Compensatory measures or interim controls to be used
5

Safety Basis Strategy

• The safety posture at 242-A is continuously improving

• Current safety basis revisions include:

o Improvements to safety instrumented systems (SISs)

o Safety significant seismic switches 

o Further interim controls developed for hazards of concern

• Planned improvements will implement full engineered controls for fire and seismic 

events
6

242-A Evaporator Process/Hazards

• All interim controls will be 

implemented prior to next 

Evaporator campaign

• S1: Overflow of waste leading to 

flammable gas deflagration in Tk-C- 100 or piping

• S2: Flammable gas deflagration in C- A-1

• S3: Seismically induced flammable 

gas deflagration

• S1/S2: Mitigation through dump of 

material from C-A-1 back to the feed 

tank utilizing safety instrumented 

systems (SISs)

• S3: Specific Administrative control 

(SAC) actuated manually via SS 

control room switches or seismically 

qualified SS external switch

Reboiler E-A-1

VACUUM

CONDENSERS

E-C-1 E-C-2 E-C-3 

Steam

CONDENSATE 

TANK

TK-C-100

Vapor-Liquid

Separator

C-A-1

Feed Tank

AW-102 Receiver Tank

Slurry

Pump

LERF

Basin

S1

S2
7

Interim Control Strategy: Seismic & Fire

• Use of two Specific Administrative Controls (SACs) for fire and seismic response 

incorporated into the DSA/TSR prior to next operation of the 242-A evaporator

• SAC for Response to Seismic Events (upgraded from key element)

o Two safety significant shutdown hand switches are located in easily accessible 

locations in the control room

o Actuated manually using a seismically qualified safety significant seismic shutdown 

hand switch located on the southeast exterior concrete wall

• Combustible material SAC for Fires

o Implemented in the 242-A Evaporator condenser room keeping the combustible 

loading below the temperatures at which the SS equipment can be affected

o More stringent implementation of combustible material SAC, including procedural 

restrictions on maintenance activities, and removal of combustible materials

• Defense-in-depth programmatic element for fire detection to respond at 

conservative temperature/temperature change to protect the solenoid 

functionality 
8

Planned Improvements

• Execution plan has been established and acceleration opportunities are being identified

o Committed to establishing engineered controls as planned improvements

o No budget/funding constraints are currently anticipated

o Known supply chain challenges with procurement of I&C, communications components

o Preliminary Schedule has been developed to incorporate the planned improvements

• Initial technical concepts of deployment have been developed for fire response and seismic 

response built upon the current system upgrades

• Fire response 

o Incorporate depressurization of the air supply lines to the dump valve actuators

o Two technologies available are fusible plugs that melt at certain temperatures and a ®FireChek

valve that shuts off the upstream pressure and vents the downstream pressure

• Seismic response

o Seismic detection system and automated actuation of the 242-A Evaporator vessel dump system

o Taking lessons learned from other Hanford facilities in procuring and testing seismic shutdown 

switches

o Failure Modes and Effects Analyses (FMEAs) as part establishing design requirements have been 

initiated
9

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

FY24 FY25 FY26 FY27

Conceptual Design

Detailed Design Procurement

Component Testing & 

Qualification

Pre-Fabrication & 

Construction Testing

SBA Implementation

Conceptual 

Design Detailed

Design

Component 

Procurement 

Testing & 

Qualification

Pre-Fabrication & 

Construction Testing

SBA Implementation

Influence of Evaporator Campaigns (EC

• ~5-7 evaporator campaigns between FY24-FY27

• ECs limits facility resource availability

• Each EC is a approximately 6 weeks outage time

• No facility modifications/testing during ECs

• Realistic schedule 

• Aggressive schedule 

Known Risks and Challenges

• Supply chain challenges in equipment and resources (e.g. nuclear safety)

• New DSA/requirements and operational execution

SBA Development SBA Review/Approval

SBA Development SBA Review/Approval

Process Hazards Analysis, Control 

Decision, Component Selection

Preliminary Planned Improvement Schedule

Process Hazards Analysis, Control 

Decision, Component Selection
10

Questions
11

BACKUP
12

BACKUP: Seismic
13

Backup: Fire
14

®FireChek Style 
15

Fusible Plug Style

Fusible plus to be chosen based upon materials of 

construction and temperature ranges for use