Jacobs_Fermi_MI-65_ExhaustStackDesignReport_30pct_2021.11.15.pdf

Prepared for:

Prepared by:

tel:

e-mail:

15 November 2021

Fermi

MI-65 Exhaust Stack Design Report – 30 Percent Design

Fermi National Accelerator Laboratory

Jacobs

Keith Kibbee, P.E.

503.872.4573

Keith.Kibbee@jacobs.com

Tom Hoven, P.E.

469.941.8902

Thomas.Hoven@jacobs.com

Andrew Dunavent

619.272.7223

Andrew.Dunavent@jacobs.com

Steve Brodsky, P.E.

303.887.3262

Steven.Brodsky@jacobs.com

Jason Bittick

503.929.9907

Jason.Bittick@jacobs.com

Kenny Kong

503.830.5534

Kennith.Kong@jacobs.com

Tomasz Michalik

Tomasz.Michalik@jacobs.com

Scott Nance, P.E.

720.286.5633

Scott.Nance@jacobs.com

Charles Wang, Ph.D.

469.999.8905

Charles.Wang2@jacobs.com

Jason Wallace, P.E.

817.735.7136

Jason.Wallace@jacobs.com

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 2

Table of Contents

Executive Summary 3

Introduction 4

Review Existing Documentation and Laser Scanning 5

As-Built Model 5

Site Review 6

Exhaust Treatment Process Analysis 7

Duct Flow Mixing Study 8

Site Model CFD 9-11

Instrumentation and Control 12

Structural Roof Review 13-14

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 3

Based on the analysis conducted for this 30 percent design, the following items summarize salient observations and recommendations for design basis.

• Controls for the fans and evaporators are stand-alone and are not connected to a central control system. Controls for fans and evaporators will be interfaced with the existing PLC system, primarily for monitoring the system and minimal control (exhaust fan start and stop functionality only).

• Record drawings do not match field conditions. Notably, the fan installation on the roof and the evaporator arrangement in the cage. Scans of the existing conditions will be used to locate equipment.

• Existing roof deck is considered contaminated and will require special disposal.

• A structural review of the MI-65 building roof should be considered to be a part of the 60 percent design, as details regarding exhaust fan characteristics (e.g., weight) are very preliminary in the

30 percent design.

• Based on preliminary exhaust fan analysis, the MI-65 building roof appears to be generally suitable for currently anticipated incremental equipment weight and footprint.

• Psychrometric analysis suggests that the evaporator exhaust will need to be mixed with dilution air in order to avoid condensation of the resultant exhaust plume. This dilution air stream may also need some amount of heating capability to prevent potential freezing of the moisture in the exhaust.

• The CFD site dispersion model geometry has been updated to include the Target System

Integration Building (TSIB) building. The stack design in this analysis will be based upon the sub-model and results will be included in the 60 percent design.

Additional recommendations for design basis will be provided in the 60 percent and Construction

Document Design phases.

Executive Summary

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 4

Introduction

Research done at the MI-65 building generates tritium, which is then turned to vapor using evaporators and exhausted as water vapor. The vapor is discharged through exhaust fans and stacks on the building roof. Tritium exhaust has been monitored and found to collect on the MI-65 rooftop, nearby buildings, and nearby grounds. The objective of this report is to convey initial design intent of a replacement exhaust system that currently collects and disposes of tritium generated at Fermi

National Accelerator Laboratory (Fermi or Lab) by way of evaporation.

Fermi’s ES&H at the lab has determined that the dispersion pattern from the existing exhaust system is not discharging the exhaust sufficiently and that concentrations of tritium are accumulating beyond the allowable limit. A previous study of the wind patterns and dispersion using CFD was performed by

Jacobs to analyze the concentrations around the building under various wind, humidity, stack velocities, and stack heights. The baseline CFD model showed results that were in agreement with what Fermi has observed in the field, thus it is assumed the CFD model gives sufficient guidance to proceed further with additional design work.

The approach used for this 30 percent design is review existing facility documentation, conduct a preliminary review of the roof to assess additional loads, perform CFD modeling, and provide recommendations for the design basis. Each of these tasks are described in this report.

The CFD modeling described in this 30 percent design milestone will inform:

• Equipment selection (Page 7)

• Annual estimated hours of safe operation (Page 7)

• The approximate ambient weather condition defining the boundaries of safe operating conditions (Page 7)

• The necessary volume of storage for non-safe operation periods (Pages 7-8)

MI-8

MI-65

N

TSIB

Plan View – TSIB, MI-8, MI-65

BLDG A

BLDG B

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 5

Review Existing Facility Documentation and Laser Scanning

Jacobs reviewed previous drawings and documentation provided by Fermi to determine existing conditions and design requirements. In addition, Jacobs performed laser scanning with the Trimble

X7 laser scanner. The objective was to capture the interior and exterior of the MI-65 building to obtain an accurate as-built model of the building. This information is necessary to inform subsequent analysis.

Key features of laser scanning include the following:

• Scanner accuracy is 0.03 millimeters at 20 meters.

• Each scan took 4 minutes for a total of 25 scans.

• Multiple scans were conducted to create overlapping information and limit blank spots due to objects blocking line of sight.

• The laser scanning process discovered no issues on-site and the process went very smoothly.

• Trimble Business Center software was used to register the laser scan and create the final point cloud.

As-Built Model

Jacobs created an as-built model by utilizing specialized software (ClearEdge 3D Edgewise) that automates the extraction process from a point cloud. ClearEdge 3D Edgewise is used to reduce the time to create a model by approximately 40%. The output model was then imported into Revit for finalization. The model will be utilized by all the disciplines to refence their evaluations and help build the design model.

• It took 8 hours to create the model and import into Revit.

• Total extractions include 13 architectural objects, 700 pipe objects, and 97 structural objects.

Perspective view of scanning data results

Perspective view of as-built Revit model

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 6

Site Review

A site visit was conducted to review existing systems including mechanical, electrical, I&C, and structural. Based on drawings received, and current site conditions, multiple discrepancies between the record documents and the actual conditions were observed including:

• Exhaust stack layout

• Fan curbs

• Evaporator configuration and caged area

It was additionally observed that the evaporators and exhaust fans are stand-alone systems that are manually operated and are not connected into a central control system.

Additionally, in conversations with the radiation officer on site, it is assumed that the roof material is contaminated. This will require additional procedures to adequately address this during construction.

Site visit photo of existing tritium exhaust stacks looking Southwest

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 7

Exhaust Treatment Process Analysis

Initial calculations suggest that the temperature and moisture content of the air discharged from the evaporator will exceed the limits for acceptable operation for much of the year if it is discharged directly to atmosphere. The dewpoint of the evaporator exhaust is approximately

106 degF – significantly higher than the range of ambient temperatures occurring at the site (shown in colors on the psychrometric chart below).

Mitigating the potential for condensation of this plume is accomplished by reducing temperature and moisture content of the exhaust stream to a level similar to the outdoor conditions prior to discharge. To achieve that condition and provide acceptable exhaust stack dilution performance, Jacobs proposes that the evaporator discharge be combined with a constant volume of ambient air prior to exiting the stack. The air would be pre-heated during certain times of the year to avoid moisture content in the air stream from freezing.

While the exact dilution air flow rate and temperature are to be determined, charts and diagrams on this page show a possible sizing range.

The chart below plots percentage of a typical year that year that discharge dewpoint temperature is acceptable to avoid condensation of the plume versus flow rate of dilution airflow.

0-5 0 5

Dewpoint Temp

(degF)

Dry Bulb Temperature (degF)

106 degF DB

100% RH

Frequency of occurrence of ambient outdoor conditions occurring for a typical year, plotted on the psychrometric chart.

Dewpoint of the evaporator exhaust must be depressed to avoid condensation of the plume. This effect is realized by mixing the exhaust stream with ambient air prior to discharge.

Percentage of typical year within limits

Dilution Airflow Rate (ft3/min)

95%

5,000 10,000 15,000 20,000 25,000

Pre-heat applied to dilution air to avoid freezing

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 8

Duct Flow Mixing Study

Jacobs proposes that the evaporator exhaust discharge be combined with a constant volume of ambient air prior to exiting the stack to avoid the potential for the moisture in the plume to re-condense in mid-air as it travels downwind. As this mixing action would occur in ductwork located between the proposed exhaust fans and the evaporator outlet, the potential condensation would be contained inside the duct. The proposed design affords greater amounts of moisture uptake than allowed by the current design due to the dilution air volume.

Success of this solution depends on effective mixing between these two flow streams. So, the objective of this computational fluid dynamics (CFD) study is to check mixing effectiveness between the evaporator air stream and the dilution air stream and, if necessary, explore ways to improve that mixing effectiveness. The initial study shown at the right assumes a dilution airflow rate of 10,000 cfm which theoretically should mitigate potential condensation for ~67% of the hours in a typical year (based on TMY3 data for a nearby weather station).

While that theory assumes perfect mixing between the dilution air stream and the evaporator exhaust stream, preliminary results shown on this page suggest that mixing has low effectiveness for this initial configuration. Large difference between the evaporator and dilution air flow rates causes the two streams to stratify and stay separate. Next steps in this design effort will include testing mixing improvement concepts virtually, using iterative

CFD analysis.

1,000

2,000

3,000

4,000

32” SS

@ 1,800 fpm

24” Stack

@ 3,500 fpm

Revised Evaporator

Condition:

235 cfm

106 degF

0.0537 lbw/lbda

Pre-Heat OSA:

10,000 cfm

53.1 degF

0.0078 lbw/lbda

8” SS

@ 673 fpm

Speed

Speed [ft/min]

Temperature

Temperature

[degF]

Front Section View Front Section View

Revised Evaporator

Condition:

235 cfm

106 degF

0.0537 lbw/lbda

Pre-Heat OSA:

10,000 cfm

53.1 degF

0.0078 lbw/lbda

Section View

Temperature

Distribution at

Stack Outlet

53.1 degF 67.3 degF

Perspective View Looking from above the Duct

Stack Outlet

Red streamlines indicate the flow pattern of evaporator exhaust

32" Duct

8" Duct

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 9

Site Model CFD

Computational Fluid Dynamics (CFD) will be used to analyze the dispersion and droplet size during the transport of the exhaust in the ambient air. This analysis approach involves building a 3D model of the site and the exhaust stacks for use in running CFD equations to analyze the physics and airflow of the exhaust stream at various ambient conditions. During the exhaust dispersion and transport in the ambient air, the tritium particles will have their fate tracked both spatially as well as psychometrically, as their size may change based upon ambient conditions.

This modeling exercise utilizes a variety of input data for running the calculations which include the following main items:

• Site geometry

• Meteorological data and ambient conditions selected for analysis

• Exhaust stack design and release parameters

The stack design and release parameters for this analysis are being developed with the sub-model exercise previously mentioned. Details of the site geometry are included to the right.

A detailed list of the assumptions of this modeling exercise and meteorological scenarios to be included are outlined elsewhere in this report.

35’

Tritium Exhaust Stacks

Height

Above

Roof (ft)

Exhaust

Airflow

(cfm)

Velocity

(fpm)

Temp.

(degF)

HTO

Evaporation

(gal/hr)

Stack N 10.0 255 1,300 80.0 16

Stack E 7.0 235 1,200 80.0 16

Stack W 7.0 185 950 80.0 8

Perspective View Looking North – MI-65

98’

N

Stack N

Stack SE

Stack SW

N

TSIB

MI-8

MI-65

TBD Pending

Sub-model

Perspective View Looking North – TSIB, MI-8, MI-65

Proposed Stack Locations

Proposed

Stack

Locations

MI-8

MI-65

N

TSIB

35’

46’

’ BLDG A

(rooftop 20’)

BLDG B

(rooftop 30’)

49’

18’

300’

13.3˚

Plan View – TSIB, MI-8, MI-65

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 10

Site Model CFD - Model Setup & Key Assumptions

1. Model geometry is based on the July 2020 CFD study previously performed. Geometry associated with TSIB has been added based upon “Fermi TSIB_60% Drawings.pdf”.

2. Air density (0.0711 lb/ft3) and climate conditions are based on W. Chicago/D.U. Page, Illinois.

3. Tritium is exhausted in tritiated water vapor form. This study focuses on the pathway of these water droplets and the degree of evaporation or condensation that they experience along that pathway until reaching the building rooftop or the ground. Assumptions associated with this type of simulation are as follows:

a) Water vapor properties are assumed for the droplets.

b) Vapor pressure of the droplets vary continuously with temperature based on the

Wagner equation.

c) The size of water droplets discharged from the exhaust stacks are different based on the exhaust pre-conditioning system. The sub-model is utilized to reveal the droplet size through pre-conditioning system and leaving stacks.

d) The tendency for droplets to evaporate or condense is driven by the enthalpy difference between the stack vapor and the ambient air.

e) Aerodynamic drag is considered in the analysis with the droplets assumed to be spherical.

f) The water droplets are allowed to accumulate on building rooftops and the ground.

However, the droplets do not accumulate on the MI-65 exterior walls; the droplets are free to continue their path along the MI-65 walls until they evaporate or they reach the ground.

g) Accumulation and evaporation results are presented as a percentage of a particle count rate of vapor droplets exhausted at the stacks.

4. Airflow around the building reaches steady state conditions (i.e. pressures and velocity etc., do not change with time).

5. On-site topography and finished floor elevation differences are negligible, including any elevation changes on MI-65 building rooftop.

6. All building rooftops and surfaces are at ambient temperature.

7. The approaching wind velocity profile is modeled using a variation of wind speed versus height as provided by ASHRAE. Terrain surrounding the site is assumed to be villages, countryside with trees, hedges.

8. For this analysis, three ambient conditions will be considered, which are tabulated on the right, including cold dry (-2 F degree, 30%RH), moderate humid (54 F degree, 71%RH) and warm humid (73 F degree, 90%RH). Droplet accumulation will then be calculated for two prevailing wind directions (South and North) coincident with these three seasonal conditions, each at two different wind speeds, which are calm condition (less than 2 mph) and 11 mph.

Dry Bulb Relative Barometric

Temp Humidity Enthalpy PressureWeather

Condition degF %RH BTU/lbda in.Hg.

-2 30 -0.3 29.65

54 71 20.0 29.26

73 90 35.2 29.21

Cold Dry

Warm Humid

Moderate Humid

Warm Humid

Moderate Humid

Cold Dry

70%

60%

50%

40%

30%

20%

10%

80%

90%

100%

Dry Bulb Temperature (degF)

Moist Air Enthalpy (BTU/lb)

Relative Humidity

Psychrometric Chart with (TMY3) hourly ambient data

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 11

Site Model CFD - Site Weather Conditions: Wind

Droplet accumulation will be calculated for two prevailing wind directions coincident with the three seasonal conditions described on the previous page, each at two different wind speeds. The conditions that will be simulated in this study are tabulated at the right.

Annual wind statistics shown below suggest the following:

• Winds out of the South are prevailing, occurring approximately 19% of a typical year. This direction would send exhaust effluent over the MI-65 rooftop towards its North yard and MI-8.

• West and Southwest winds occur approximately 30% of a typical year sending exhaust to the Northeast, in the yard between MI-8 and Bldg A.

• Winds out of the North and Northeast direction occur approximately

20% of the year sending exhaust towards the South and Southwest sections of the site.

Annual Wind Rose.

W. Chicago/D.U. Page, Illinois

Annual Wind Statistics, Typical Meteorological Year (TMY3) data

W. Chicago/D.U. Page, Illinois

2.5 - 7.5

7.5 - 12.5

12.5 - 17.5

17.5 - 22.5

22.5 - 27.5

> = 27.5

Wind Speed

Bin (mph)

Cases Wind Speed (mph) Wind Direction Dry Bulb (degF) Relative (%RH) Enthalpy (BTU/lbda) Barometric (in.Hg)

< 2.0

North

-2.0 30.0 -0.3 29.65

2 54.0 71.0 20.0 29.26

3 73.0 90.0 35.2 29.21

South

-2.0 30.0 -0.3 29.65

5 54.0 71.0 20.0 29.26

6 73.0 90.0 35.2 29.21

11.0

North

-2.0 30.0 -0.3 29.65

8 54.0 71.0 20.0 29.26

9 73.0 90.0 35.2 29.21

South

-2.0 30.0 -0.3 29.65

11 54.0 71.0 20.0 29.26

12 73.0 90.0 35.2 29.21

MI-8

MI-65

N

TSIB

Plan View – TSIB, MI-8, MI-65

BLDG A

BLDG B

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 12

Instrumentation and Controls

Instrumentation and control (I&C) analysis and design is called out as being a part of the Project’s 60 percent design deliverable. In advance of that phase, Jacobs has completed certain preliminary I&C analysis which are summarized below. Such information should therefore be considered to be preliminary and is provided to encourage Fermi’s review and comments.

Exhaust fan I&C is characterized as follows:

• Fan switch box shall be stand alone and include three disconnects (one for each exhaust fan).

• Determination of whether flow sensors shall be included in each duct or one common duct to monitor flow/no flow conditions (needs to be finalized by FNAL).

• I&C design does not need to account for explosive conditions.

• It is assumed that corrosive conditions will not be accounted for in I&C design.

• Remote control station for exhaust fans will be included.

• I&C will include run and stop pilot lights and alarm condition pilot lights.

• I&C will include verification for flow pilot light.

• Exhaust fans will be inline tube type with belt drives.

• PLC tag numbers will be NUMI-EVAP-PLC.

• The PLC will utilize 24 volt service (120 volt service presents safety concerns).

• Variable frequency drive (VFD) control panel will be located in the motor cage.

• Fan VFD fault and flow fault will be included.

• Only one phase current at each motor will be monitored.

• Heater current draw and ductwork temperature will be monitored.

• Resistance temperature detector (RTD) will be three wire platinum, 100 Ohm (not thermocouple).

• Temperature transmitters will use thermal heads.

• Redundant power supply will be included (per critical infrastructure).

• The VFD control circuit will be 24 volt DC per request of the system owner.

Site visit photo of existing P&ID

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 13

Structural Roof Review

Codes and Standards

• International Building Code (IBC) 2018 Edition

• International Existing Building Code (IEBC) 2018 Edition

• ASCE 7-16 – Minimum Design Loads and Associated Criteria for Buildings and Other Structures

• AISC Manual of Steel Construction, 15th Edition

• AISC 360-16 Specification for Structural Steel Buildings

Design Loads

• Roof Live Load - 20psf

• Roof Dead Load – Design dead loads include the self-weight of the structural components and permanent fixtures

• Snow Load

• Ground Snow Load = 25psf

• Importance Factor – 1.0

• Exposure Factor – 1.0

• Thermal Factor – 1.0

• Flat Roof Snow Load = 20psf

• Wind Loads

• Risk Category – II

• Ultimate Design Wind Speed – Vult = 107mph, Vasd = 83mph

• Exposure – C

• Enclosure Classification – Enclosed

• Internal Pressure Coefficient, GCpi = +/- 0.18

• Seismic Loads

• Risk Category – II

• Seismic Importance Factor – 1.0

• Mapped Spectral Response Coefficient – Ss = 0.135g, S1 = 0.066g

• Site Class – D (Default)

• Spectral Response Coefficient – Sds = 0.144g, Sd1 = 0.106g

• Seismic Design Category – B

• Basic Force Resisting System – Steel Systems Not Specifically Detailed for Seismic Resistance

• Response Modification Factor, R = 3.0

Site visit photo of interior roof structure

FDZE7302 Fermi MI-65 Exhaust Stack Design – 30% Review Stage PRELIMINARY 15 November 2021 14

Structural Roof Review Cont.

Structural Scope

• Structural scope currently includes the verification of the existing roof members for support of the new exhaust fans.

• The complete structural review of the MI-65 building roof will be completed during the 60 percent design, as details regarding exhaust fan characteristics (e.g., weight/height) are still preliminary at the current design stage

• Details for repair/patching of existing holes in the roof as well as details for sub-framing beneath the new fans and associated openings

General Description of Existing Building Structure

• The existing building is a conventional steel framed structure with a footprint of approximately

5700sf. The roof structure consists of a 1½" metal deck supported by W12x26 beams and W30x124 girders. The typical bay spacing is 30 ft and the girders have a center-to-center span of 60ft. The girders are supported by stepped wide flange columns that also support an existing bridge crane.

The lateral system for the building consists of WT bridging at the roof level to act as a structural diaphragm and concentric braced frames along the perimeter walls. The foundation system was not identified on the provided structural drawings.

Design Approach

• In accordance with the IEBC, this would qualify as a level 2 alteration since this project involves the reconfiguration of the existing exhaust system and replacement of equipment on the roof. The

IEBC requires that any existing gravity load carrying element in which loading is increased by more than 5% shall be evaluated in accordance with the IBC for new structures. Only local verification of the existing roof members will be required, this task will be completed when final equipment has been selected. The affected roof members will be analyzed for support of the increased weight due to the new fans as well as wind load effects.

• The existing building currently supports 3 exhaust fans on the roof weighing 132 lbs each for a total of 396 lbs

• The proposed new fans are anticipated to have a max worst case weight of 2397 lbs each

• Design lateral loads for the building would only be marginally increased due to the increased size of the new fans. The IEBC indicates that analysis of the overall building lateral system is not required until loads are increased by more than 10%, therefore a comprehensive global analysis of the existing structure is not required.

• Based on the preliminary exhaust fan selection, it appears that the MI-65 building roof will be suitable for support of the new exhaust fans. It is likely that sub-framing beneath the footprint of the new fans and local reinforcing of members may be required. Additionally, in order to avoid concentrating the load onto a single existing roof member alternative locations for the fans may also be considered to better distribute the loading.

Site visit photo of interior roof structure