Review of NIOSH Strategy for 

Reconstructing Doses to Workers at 

Test Area North (TAN) 

John Mauro and Amy Meldrum

S. Cohen and Associates

Contractor to:

Advisory Board on Radiation and Worker Health/ABRWH

Center For Disease Control and Prevention

November 10, 2015
Scope of Programs, Campaigns, Research and 

Activities at Test Area North (TAN)

• Aircraft Nuclear Propulsion Program (ANP) (1952–1961)

• Initial Engine Test (IET)

• Heat Transfer Reactor Experiments (HTREs)

(Above 3 to be expanded upon later)

• Technical Support Facility (TSF)

 TAN 607 Hot Shop

 LOFT (TAN 650)

 Storage Pool

 Storage Pads (TAN 790 and 791)

 Radwaste Liquid Disposal System

 Storage Building

 Radiography Facility (TAN 607)

• Water Reactor Research Test Facility (WRRTF)

 Low Power Test Facility (LPTF)

 Shield Test Pool Facility (STPF)

• Specific Manufacturing Capability (SMC)

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Focus and Scope of TAN Review

• An evaluation of the completeness of the external 

dosimetry data at the various TAN facilities

• Applicability of ORAUT-OTIB-0054 and Tables 5-22 

and 5-23 of internal dosimetry TBD to the 

performance of internal DR for facilities at TAN 

that handled and stored spent and irradiated fuel

• The unique circumstances associated with 

exposures to airborne effluents from the ANP, 

which are not addressed in OTIB-0054

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REVIEW OF EXTERNAL DOSIMETRY 

DATA

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Review of TAN External Dosimetry Data

• Methods – Performed a search of SRDB 

records using search terms including: 

dosimetry, dosimeter, external, personnel, 

badge, exposure, and film. The following were 

found and used to assess external data 

completeness:

 37 documents

 12,177 pages of records

 181,183 beta/gamma readouts

 6,665 neutron readouts

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External Dosimetry – TAN as a Whole

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Each point on this graph represents a date for which a beta/gamma or 

neutron dosimeter change-out was observed within the SRDB documents 

for a worker corresponding to any area of TAN. There is a small temporal 

gap in 1961 in the beta/gamma dosimeters, and several gaps in the 

neutron dosimeters.
External Dosimetry – Sub-Areas of TAN

•

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Dosimeters Marked ‘ANP’

• Dosimeters Marked ‘STPF’
External Dosimetry – Sub-Areas of TAN

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• Dosimeters Marked ‘IET or STEP’ (Both seen with code 68)

• Dosimeters Marked ‘TSF’
External Dosimetry – Sub-Areas of TAN

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• LPTF

 Only documents that were labeled ‘excerpts’ 

were found for LPTF, contained few dozen 

beta/gamma dosimeters, and few neutron 

dosimeters.

• ‘TAN’ Only

 Hundreds to thousands of beta/gamma 

dosimeters from 9/1962 to 12/1964 only had TAN 

marked within the dosimetry record. No neutron 

dosimeters were marked as being ‘TAN’ only.
Observations for TAN

• External dosimetry for TAN as a whole appears to be fairly 

complete from mid-1955 through part of 1970, with a small gap 

from June through December 1961

• It is not possible to group the data by subdivisions of TAN; i.e., 

the data lack adequate granularity

 Important because activities and research throughout TAN 

were extremely diverse. It will be difficult to build external 

dosimetry co-worker models for each subdivision of TAN.

• Neutron dosimetry data appears spotty. The possible reasons 

for this require further investigation

 May need additional data capture

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Observations for TAN

• We do not believe we can consistently assign 

external monitoring data to the different work 

areas, operations, and campaigns within TAN, 

at least given the data reviewed.

• NIOSH might not be able to build co-worker 

models for many of the subdivisions of TAN, if 

co-worker models are necessary. This could 

be an important SEC issue.

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USE OF OTIB-0054 TO 

RECONSTRUCT INTERNAL DOSES 

TO TAN WORKERS

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Applicability

• TAN opened in 1952 for 

ANP, with support facilities 

and programs including TSF, 

IET, WRRTF. These facilities 

handled irradiated and 

spent fuel.

• Irradiated fuel and 

components from 

reactors/research facilities 

were often stored at TAN 

hot cells, hot shop, and 

storage pool. All of these 

facilities had potential for 

internal exposures

• Irradiated and spent fuels 

included:

 ANP Fuel

 System for Nuclear Auxiliary 

Power (SNAP) and associated 

transients (SNAPTRAN)

 Special Power Excursion Reactor 

Test (SPERT)

 Loss of Fluid Test (LOFT) Facility

 Fuel from Heat Transfer Reactor 

Experiment (HTRE)

 Disassembly of SL-1

 Storage of TMI fuel and debris

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Methods*

• ORIGEN simulations to determine if:

 The ratio of inventories of reference FPs to other FPs, 

as used in OTIB-0054 (reflect ‘conventional’ reactors) 

are reasonable, if not bounding, as compared to these 

ratios for TAN irradiated fuel

 The ratio of reference FPs to TRUs as in Tables 5-22 

and 5-23 of the TBD (reflect ‘conventional’ reactors) 

are reasonable, if not bounding, as compared to these 

ratios for TAN irradiated fuel

• Evaluated for the purpose of internal DR based on 

gross beta/gamma urinalyses

*Use of ORIGEN simulation and/or Tables 5-22, 5-23 are not considered 

useful/appropriate for internal exposure assessment for workers handling 

spent/irradiated fuel associated with ANP.

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Observations/Conclusions

• Based on this modeling exercise for conventional 

reactor fuel, OTIB-0054 approach is generally 

claimant favorable when the fuel is not highly 

enriched, maintains integrity following burn-up, 

and is at a high power level (e.g., 200 MW)

 However, this does not follow SC&A’s observations 

regarding indicator radionuclides and assumptions 

used, based on actual measurements (slide 17).

• Underscores the importance of limiting our 

observations to general trends and consistent 

behavior

 For example, dose estimates based on a 200-day burn 

model will generally overestimate dose from 

actinides, when the actual reactor was operated for 

significantly less time

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Observations/Conclusions (continued)

• For spent nuclear fuel associated with ANP, use of 

OTIB-0054 is inappropriate for the following 

reasons:

 Highly enriched (i.e., 93.4%) fuel used in IETs contains 

limited amounts of U-238, which will result in limited 

production of Pu-239/240 and other actinides

 Wafer-thin ribbons of UO2 and absence of cladding 

ensured high release fraction by recoil and/or 

diffusion of many FPs. Most notably are volatile 

radionuclides (iodine, cesium, etc.)

 Release and depletion of FPs from fuel elements must 

further be assumed by the fact that for some IETs, 

intentional fuel failure (and unintentional fuel failure) 

resulted from temperatures exceeding 3,200°F

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Observations/Conclusions (continued)

• SC&A’s Evaluation of the NIOSH SEC ER Proposed 

Use of FAP Bioassay Indicator Radionuclides (in 

Conjunction with OTIB-54 and TBD-5) for 

assessment of FAP and Actinide intakes at INL 

(October 2015) observes that:

 Actinide intakes assigned using NIOSH’s 

recommendations in TBD-5, Table 5-22 and based on 

Sr-90 intake values, or Table 5-23 based on Cs-137, are 

sometimes significantly less than those derived from 

measured values.

• Contradicts modeling results

 Further INL document research is needed to evaluate 

NIOSH’s recommended ratio values, especially for 

actinides and Cs-137/Sr-90. Records with quantitative 

radionuclide analyses are especially important.

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INTERNAL EXPOSURES FROM 

AIRBORNE EMISSIONS AT ANP

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Aircraft Nuclear Propulsion Program

• After WWII, concern over surprise attack by 

the Soviet Union generated interest in 

development of nuclear-powered surveillance 

aircraft that could remain airborne for long 

periods of time

• Nuclear reactor for aircraft propulsion would 

require deviations from conventional reactor 

design, including fuel designs

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Heat Transfer Reactor Experiments 

(HTREs)

• To test viability of a reactor for aircraft 

propulsion, 3 different reactors were built 

(HTRE 1, 2, and 3)

• All 3 were direct cycle, air-cooled

 Air from turbojet engine compressed and forced 

past wafer-thin concentric ribbons of nuclear fuel 

enriched to 93.4%

 Air heated to 1,250 °F by fuel temps of up to 

3,000°F powered turbine engine

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Initial Engine Tests (IETs)

• Testing program for 3 HTRE assemblies 

designated as Initial Engine Tests (IETs), IET#1 

through IET #26

• IETs #1, #2, #5, #7, and #9 did not require 

nuclear power, and had no potential for 

release of radioactivity or human exposure

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Environmental Radioactive 

Release Quantities with 21 IETs

• In a 1991 two-volume INEL-HDE Task Group 

Report (Idaho National Engineering Historical 

Dose Evaluation), DOE estimated total release 

of 755,440 Ci comprised of 51 radionuclides

• Highest releases were from IET #3, #4, and 

#10, with combined estimated release of 

~682,000 Ci (90% of total)

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Objective

• Under contract to the CDC, SC&A was tasked to critically 

review previous IET release estimates reported by the 

INEL-HDE Task Group in behalf of IET #3, IET #4, and IET 

#10. 

• SC&A’s review (issued in 2003) identified errors in the 

INEL-HDE Task Group model that underestimates 

environmental releases several fold. 

 For example, the INEL-HDE Task Group estimated the 

release of 270,000 for IET #10, which is 7.65-fold lower than 

the revised SC&A estimate of 2,020,000 Ci.

• Key members of the INEL-HDE Task Group attended 

both meetings and agreed with SC&A’s revised 

estimates for IETs #3, #4, and #10.

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Methods

• Review of DOE and CDC reports on the 

emissions associated with the various IETs that 

comprised the ANP

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Observations

• Independent analyses of airborne emissions 

associated with the major IETs, as performed by 

SC&A under contract to CDC, revealed that the 

DOE significantly underestimated the airborne 

emissions for the IETs with the largest airborne 

emission

• Outdoor exposures associated with releases from 

the ANP need to consider the results of CDC’s 

investigations into these source terms

• Challenges associated with reconstructing 

outdoor onsite exposures associated with these 

releases

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Comments and Questions?

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