Draft 

ADVISORY BOARD ON 

RADIATION AND WORKER HEALTH 

National Institute for Occupational Safety and Health 

SC&A ASSESSMENT OF SELECTED NIOSH RESPONSES TO 

SC&A NUMEC SITE PROFILE FINDINGS 

Contract No. 211-2014-58081

Revision 0 

Prepared by 

John Mauro, PhD, CHP 

Ron Buchanan, PhD 

Joyce Lipsztein, PhD 

Steve Ostrow, PhD 

Joseph Zlotnicki, PhD, CHP 

S. Cohen & Associates 

1608 Spring Hill Road, Suite 400 

Vienna, Virginia 22182 

Saliant, Inc. 

5579 Catholic Church Road 

Jefferson, Maryland 21755 

August 2015 

Disclaimer 

This document is made available in accordance with the unanimous desire of the Advisory Board on 

Radiation and Worker Health (ABRWH) to maintain all possible openness in its deliberations. However, 

the ABRWH and its contractor, SC&A, caution the reader that at the time of its release, this report is predecisional and has not been reviewed by the Board for factual accuracy or applicability within the 

requirements of 42 CFR 82. This implies that once reviewed by the ABRWH, the Board’s position may 

differ from the report’s conclusions. Thus, the reader should be cautioned that this report is for 

information only and that premature interpretations regarding its conclusions are unwarranted.
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

2 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

S. COHEN & ASSOCIATES: Technical Support for the Advisory Board on Radiation & 

Worker Health Review of NIOSH Dose Reconstruction Program

DOCUMENT TITLE:

SC&A Assessment of Selected NIOSH Responses to 

SC&A NUMEC Site Profile Findings

DOCUMENT NUMBER/DESCRIPTION: NUMEC – Response to NIOSH Comments

REVISION NO.: 0 – (Draft)

SUPERSEDES: N/A

EFFECTIVE DATE: August 14, 2015

TASK MANAGER: John Mauro, PhD, CHP

PROJECT MANAGER: John Stiver, MS, CHP

DOCUMENT REVIEWER(S): John Stiver

Record of Revisions 

 

 

Revision 

Number

Effective 

Date Description of Revision

0 (Draft) 08/14/2015 Initial issue
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

3 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

TABLE OF CONTENTS

Abbreviations and Acronyms ..........................................................................................................4

1.0 Introduction..........................................................................................................................5

1.1 Finding 6. Issues related to the plutonium-grade mix assumed to be handled 

at NUMEC ...............................................................................................................5

1.2 Finding 7. Minimum Detectable Activities for in-vivo Monitoring of 

Am-241 and Pu-239.................................................................................................7

1.3 Finding 11. Concerns Regarding the Use of Helgeson Chest Count Data .............8

1.4 Finding 12. Issues Related to Neutron Dosimetry..................................................9

1.5 Finding 14. The Need for Adjustment Factors for NTA Film under 

Circumstances Where the Neutron Energy Distribution Includes Neutron 

Energies Well Below 1 MeV.................................................................................10

1.6 Finding 15. The Need for Adjustment Factors for Shallow and Deep 

Exposures for Open and Closed Window Dosimeters that Measure High 

and Low Energy Photon and Beta Exposures........................................................12

References......................................................................................................................................13
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

4 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

ABBREVIATIONS AND ACRONYMS

AWE Atomic Weapons Employer

Bq Becquerel

Ci/g curies per gram

cm centimeters

DOE (U.S.) Department of Energy

DR dose reconstruction

FFTF Fast Flux Test Facility

g gram

Ge germanium

ICRP International Commission on Radiological Protection

keV kilo-electron volt

LANL Los Alamos National Laboratory

MDA minimum detectable activity

MeV mega-electron volt

μg microgram

mg milligram

NaI sodium iodide

n/p neutron-to-photon ratio

nCi nanocurie

NIOSH National Institute for Occupational Health and Safety

NTA Nuclear Track Film Type A

NUMEC Nuclear Materials and Equipment Corporation

ORAUT Oak Ridge Associated Universities Team

ORIGEN2 Oak Ridge Isotope Generation and Depletion Code

rem Roentgen equivalent man

s second

SC&A S. Cohen and Associates (SC&A, Inc.)

SRDB Site Research Database

TBD technical basis document

TLD thermoluminescent dosimeter

WB whole body

ZPPR Zero Power Plutonium Reactor

ZPR Zero Power Reactor
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

5 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

1.0 INTRODUCTION

The Atomic Weapons Employer (AWE) Work Group held a meeting on August 3, 2015, to 

discuss, in part,

1

the National Institute for Occupational Health and Safety (NIOSH) responses to 

SC&A findings in SC&A 2013 pertaining to the Nuclear Materials and Equipment Corporation 

(NUMEC) site profile (ORAUT 2012c). The NIOSH responses are provided in NIOSH 2015, 

referred to as the May 14, 2015, NIOSH report. A total of 21 SC&A findings were discussed

and 11 were closed, but 10 remain “in progress.” Of those 10, the Work Group requested that 

SC&A provide additional information on NIOSH responses to Findings 6, 7, 11, 12, 14, and 16. 

The following is provided in response to the direction provided by the Work Group.

1.1 FINDING 6. ISSUES RELATED TO THE PLUTONIUM-GRADE MIX 

ASSUMED TO BE HANDLED AT NUMEC

SC&A expressed concern that, because information is lacking about the actual composition of 

plutonium handled at a given location and at a given time at NUMEC, the site profile 

recommends assuming Hanford Site (Hanford) reference fuel-grade plutonium (ORAUT 2012b), 

using the mixture identified in Table 5-3 of the NUMEC site profile (ORAUT 2012c). Hanford, 

and presumably NUMEC, handled other mixtures of plutonium over the years, including pure 

Pu-238 and Pu-239, as well as recycled plutonium from other Department of Energy (DOE)

sites, the United Kingdom, commercial reactors, and Zero Power Plutonium Reactor (ZPPR) fuel 

mixtures; these materials often had higher Pu-240, Pu-241, and Am-241 contents. The May 14, 

2015, NIOSH report (NIOSH 2015) provides a set of tables listing the specific activity (Ci/g of 

plutonium) of various isotopes of Pu, and also Am-241 for a range of grades2and ages of fuel,

and states that the site profile will be revised to include these tables. SC&A’s review of this 

NIOSH response, as provided below, includes a review of the revised tables to confirm that the 

assigned specific activities are scientifically sound and claimant favorable. 

SC&A spot checked NIOSH’s set of tables by consulting DOE 2003, which models the Fast Flux 

Test Facility (FFTF) explicitly as Template 3. This data source was prepared by DOE to support 

Yucca Mountain safety analysis studies by characterizing source terms, using ORIGEN2, the 

Oak Ridge Isotope Generation and Depletion Code (Croff 1980), to calculate isotopic inventories 

for a wide range of spent nuclear fuel held by DOE at its various facilities. Table 1 of the DOE 

report lists the masses of various isotopes, including those of Pu, in a single FFTF fuel assembly. 

Dividing the Pu-240 mass of 1,162.5 g by the total Pu mass of 9,679.3 g indeed yields 12% 

Pu-240 content, confirming the mix of isotopes provided in NIOSH’s response for fuel-grade Pu.

NIOSH’s response to SC&A’s Finding 6 continues by presenting newly found information 

regarding fuel fabrication contracts held by NUMEC in the 1960s to supply fuel with Pu-240 

contents of 8.1% to 8.5%. The report states:

 

1 The Work Group also discussed SC&A comments pertaining to the W.R. Grace site profile. Findings 

pertaining to the latter are not provided in this report.

2

The grade of the plutonium is expressed in terms of weight percent of Pu-240 of the plutonium separated 

from the fuel. For example, weapons-grade plutonium is composed of 6% Pu-240 by weight, which is a relatively 

low percentage and is required to fabricate a weapon. Larger percentages of Pu-240, such as 12%, are acceptable 

for fuel-grade plutonium. 
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

6 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

Based on this information, Table 5-3 [of the NUMEC site profile, ORAUT 2012c] 

has been3revised to include the following four plutonium types: Hanford 6% 

weapons grade, DOE 8.5% material, Hanford 12% fuel grade, and 27% 

commercial fuel.

As further stated: “The Hanford and commercial specific activity data are from Table 5-3 

through Table 5-4 of the Internal Dosimetry section of the Hanford TBD” (ORAUT 2012c). 

SC&A verified this in the Hanford Occupational Internal Dose TBD (ORAUT 2012b), which 

also included the information in a table.

After more discussion of fuel composition, NIOSH’s response concludes by stating:

Table 7-4 [of the NUMEC site profile, ORAUT 2012c] will be updated to include 

the commercial reactor-grade fuel mix fractional activity data. Guidance will be 

added regarding selection of the appropriate inventory component for evaluation 

of internal doses based on available information.

While NIOSH’s response provides useful additional information on Pu content of different types 

of fuels and adds a new characteristic mixture of isotopes for consideration when doing dose 

reconstruction (DR), it does not demonstrate (as perhaps through dose calculations that could be 

examined) that the 12% Pu-240 mix is limiting with respect to personnel exposures and should 

be used in the absence of specific data about a worker’s activities at the NUMEC site. However, 

SC&A notes that the NIOSH response does commit to providing guidance on which inventory to 

choose in a future revision of the Technical Basis Document (TBD). Hence, in light of NIOSH’s 

commitment to include a more complete set of tables characterizing the Pu mix, our original 

concern regarding the use of the 12% mixture as the default is now moot, and SC&A concurs 

with this aspect of NIOSH’s response to Finding 6, with the following qualification. 

SC&A’s original review of the NUMEC site profile (SC&A 2013) raised the following concern:

Our review of this section of the Apollo and Parks Township site profile reveals 

that, overall, the site profile data for the plutonium mixtures are quite accurate. 

However, it is not appropriate to assume that all the plutonium can be 

generalized or averaged as NIOSH has done by using a 10-year decay time as a 

midpoint. This is especially troublesome considering the fact that Hanford 

handled other percentage mixtures of plutonium over the years, including pure 

Pu-238 and Pu-239, as well as recycled plutonium from other DOE sites, the 

United Kingdom, commercial reactors, and ZPPR fuel mixtures; these materials 

often had higher Pu-240, Pu-241, and Am-241 contents.

NIOSH 2015 does not appear to address all the possible sources and mixtures of plutonium that 

might have been present at NUMEC over the years. While it presents new information regarding 

Japanese and ZPR-III (located at Argonne National Laboratory-West on the Idaho National 

Laboratory site) fuels produced in the 1960s, it does not discuss possible United Kingdom fuel or 

 

3 We understand this statement to mean that the site profile will be revised to include these tables.
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

7 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

other fuels. We request that NIOSH address these specific categories of fuel, as was done for the 

other categories of fuel.

We understand that, if information is available on the grade and age of plutonium to which a 

claimant might have been exposed, then the DR will be based on that grade and age of 

plutonium. The NIOSH response, however, is silent on the approach that will be employed to 

reconstruct plutonium/Am-241 internal doses when no information is available regarding the 

grade and age of the plutonium to which the claimant might have been exposed. We assume that 

it might be possible to narrow down the ages and grades of plutonium that might apply to a given 

DR, but there may still be considerable uncertainty regarding which ages and grades might be of 

concern. Under these circumstances, will NIOSH run all combinations of grades and ages of 

plutonium that might apply and use the limiting scenario to envelope the actual dose? If so, will 

NIOSH develop a workbook that can be used under these circumstances?

Additionally, SC&A suggests that NIOSH include Hanford Table 5-5, “Activity Composition of 

Hanford Reference Commercial Power Fuel-Grade Plutonium Mixture” (in addition to 

Tables 5-3 and 5-4), in the site profile for convenience to the dose reconstructor. 

1.2 FINDING 7. MINIMUM DETECTABLE ACTIVITIES FOR IN-VIVO 

MONITORING OF AM-241 AND PU-239

SC&A expressed concern that the minimum detectable activities (MDAs) of in-vivo monitoring 

of Am-241 and Pu-239 selected for use in DRs for NUMEC personnel may not be entirely 

consistent with the MDAs used at other sites performing similar activities, and may not always 

be claimant favorable. In response to this concern, NIOSH states that “the values listed for 

americium-241 are consistent with contemporary MDA values for other sites, such as Hanford.” 

SC&A reviewed NIOSH’s response, and we remain concerned with the reliability of in-vivo

monitoring MDAs. 

We believe that the lung counting values are not reliable for Am-241, and that 1968 is the only 

year that has a maximum reported MDA value of 0.38 nCi, which can be used to assign a 

plausible maximum intake rate of Am-241. For all the other years, either there are no reported 

MDAs (1970–1971), or the maximum reported MDAs are much lower than the 0.33 nCi Hanford

MDA, as cited by NIOSH in its response to Finding 7. An MDA of 0.33 nCi is reported by 

Hanford (ORAUT 2012b) for 1967, when a large NaI detector was used and counting time was 

30 min. In addition, the MDAs reported for Los Alamos National Laboratory (LANL) (ORAUT

2013) for 1970–1984 are 0.3-0.32 nCi. The MDAs for Am-241 at Rocky Flats (ORAUT 2014) 

were about one order of magnitude higher than the NUMEC values until 1976, when high purity 

Ge detectors were introduced, and the MDAs were comparable to those listed in the NUMEC 

site profile (ORAUT 2012c). In addition, the International Commission on Radiological 

Protection (ICRP) Publication 54 (ICRP 1989) reports an MDA of 20 Bq (0.54 nCi) for Am-241 

lung counting. SC&A believes that these low reported values of MDAs for Am-241 in-vivo lung 

monitoring need to be further explored.
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

8 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

With respect to the MDAs for Pu-239, we remain concerned that the values adopted in the 

NUMEC site profile might not be credible. NIOSH should clarify if the MDAs for Pu-239 were 

obtained by measuring Pu directly, as it implies in the TBD:

The evaluation of Pu-239 activity was based on the assumption that only Pu-239 

was present and all 17-keV X-rays were from Pu-239. The difficulty in measuring 

the low-energy X-rays results in MDA values that represent significant lung 

burdens.

At Hanford (ORAUT 2012b) and at Rocky Flats ORAUT 2014), Pu-239 was not detected 

directly. At LANL (ORAUT 2013), the MDAs for Pu-239 were much higher than the ones 

reported for NUMEC, and they were calculated for 2.3 cm to 2.5 cm chest thickness, using 

phoswich detectors. The MDA varied from 21 nCi (60 min counting time) to 48 nCi (2,000 s 

counting time) in 1970–1974, depending on the literature reference cited in the LANL 

Occupational Internal Dose TBD (ORAUT 2013). For 1980–1984, the MDAs varied from 

48 nCi to 60 nCi, depending on the literature reference cited in ORAUT 2013. There are no 

Pu-239 results for 1985–1998 (ORAUT 2013).

The values of the MDAs for Pu-239 chest counts at NUMEC for 40 min counting time (NIOSH 

2015), are as follows: 

Chest wall thickness MDA Pu-239 (nCi)

1 cm 3–4

2 cm 9–10

3 cm 17–20

We are concerned with these values, because we do not believe it is feasible to achieve these 

MDAs using a NaI detector to measure the 17 keV Pu-239 photon. Additional discussion of this 

matter is warranted. In addition, SC&A does not agree with NIOSH’s proposal (NIOSH 2015) 

of using MDA values of 35 nCi for Pu-239 and 0.40 nCi for Am-241, when the bioassay records 

do not provide the MDA. NIOSH did not provide justification for the use of such MDAs.

1.3 FINDING 11. CONCERNS REGARDING THE USE OF HELGESON CHEST 

COUNT DATA

In response to SC&A’s concern regarding the use of Helgeson chest count data, NIOSH 2015 

asserts that the use of the Helgeson chest count data is appropriate because of the dates that they 

were used, the organization that used it (University of Pittsburgh), the fact that it was used 

primarily for Pu-239 measurements, and, when used for uranium, the results would be biased 

high (i.e., claimant favorable). In addition, NIOSH states that there have been no issues 

identified related to using Helgeson chest counts for fission products, plutonium, or americium. 

As such, NIOSH’s position is that there is no need to make revisions to the site profile with 

respect to Helgeson chest counting at this time. 
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

9 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

The NUMEC site profile (ORAUT 2012c) explains that:

In 1968 and 1971, Helgeson performed WB [whole body] counts on individuals 

for fission products, 235U, 241Am, with 239Pu estimated from the 241Am results 

based on expected activity ratios for 239Pu/241Am.

Table 5-9, as revised by NIOSH 2015, reports Am-241 MDAs for 1968 (minimum 0.13–

0.38 nCi) and 1969 (0.16 nCi, based on the data from one individual). For 1968–1971, there is 

only one reported MDA value for Pu-239, 10 nCi, based on the result from one individual, 

without a reported MDA for Am-241. There are no reported values for Am-241 MDAs for 

1970–1971. As explained in Finding 7 of this document, SC&A believes that the reported 

MDAs are too low to be credible.

SC&A reviewed the 1989 Pantex document (Blake 1989) in reference to the issues with the 

Helgeson in-vivo results for uranium; these results indicated that the recorded uranium body 

burdens were biased high. The documents concerning the NUMEC Helgeson in-vivo counts 

performed in 1968, 1971, and 1975 do not address issues with the Helgeson data (Caldwell 

1968a and Caldwell 1968b). However, SC&A is concerned with how the MDA value of 63 μg

for U-235 used in Table 5-8 of the NUMEC TBD was derived, because NIOSH states on page 52 

of the NUMEC TBD (ORAUT 2012c):

The MDA for 235U was about 63 μg, as indicated from the cursory review of 

worker dosimetry records in 1971 and later years, which is a reasonable default 

MDA value. [Emphasis added.]

The U-235 MDA value for the Helgeson system was given as 0.08 mg on PDF pp. 8 of Caldwell 

1968a. It would be pertinent for NIOSH to provide additional information substantiating the use 

the MDA value of 63 μg U-235, and if possible, several examples of DR reports that use 

Helgeson count data for SC&A to review. Helgeson used a thin NaI crystal (NIOSH 2012b). 

This MDA is lower than the one reported at Y-12, when using a single 9-inch NaI detector in 

1959 (ORAUT 2012a). When enriched uranium is measured, U-235 is easier to detect than Am241. The in-vivo lung monitoring results based on U-235 should not be used for depleted or 

non-enriched uranium. 

1.4 FINDING 12. ISSUES RELATED TO NEUTRON DOSIMETRY

In this finding, SC&A raised a number of issues regarding the different types of neutron 

dosimeters used at NUMEC and the circumstances under which the dosimeters were used. We 

noticed that Table 6-2 of the site profile (ORAUT 2012c) only lists neutron track-A (NTA) film

and thermoluminescent dosimeters (TLDs) for routine dosimetry, and does not include indium 

foils, which are addressed in Section 6.3.2 of the site profile. In response to this inquiry, NIOSH 

explained that indium foil is used for criticality assessments, and there is no need to include them 

in Table 6-2. SC&A accepts this explanation. 

However, SC&A’s Finding 12 also raises questions regarding the methods used to derive fast 

neutron dose. Specifically, Table 6-2 of the site profile lists multiple technologies, including 
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

10 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

NTA, CR-39, Albedo TLD, and (implied) thermal neutron photographic film. We believe that a 

little more explanation is needed regarding how the data acquired from these devices will be 

used to reconstruct neutron doses. For example, Table 6-2 describes the method for deriving the 

fast neutron dose that involved subtraction of the thermal dose, but it is not clear if this was 

determined from a cadmium-filtered film badge or not. The Landauer “Z1” dosimeter contains a 

neutron sensitive CR-39 component, but this is not mentioned in the table or text. Both the text 

and table are unclear and inconsistent regarding the use of CR-39. Table 6.2 indicates that Z1 

badges are used (for beta/gamma), but nowhere does it say that they contain a CR-39 neutron 

component. The text in section 6.3.2 mentions the use of NTA and then states that after 1968,

neutron monitoring was performed with TLDs. Table 6-2 does say that other types of neutron 

dosimeters (not mentioned in the body of the text) did contain CR-39 components. NIOSH 

needs to revisit this section and ensure that both the table and text agree with each other and with 

the dosimetry practices of the period.

1.5 FINDING 14. THE NEED FOR ADJUSTMENT FACTORS FOR NTA FILM 

UNDER CIRCUMSTANCES WHERE THE NEUTRON ENERGY 

DISTRIBUTION INCLUDES NEUTRON ENERGIES WELL BELOW 1 MEV

SC&A reviewed the references in NIOSH’s response (Author unknown 1977, Corridoni 1982, 

and Caldwell 1968c) and found the following:

1. n/p = 0.34: The n/p geometric mean value of 0.34 in the first table of NIOSH’s 

response was derived from averaging the TLD data in the three columns in Table 1 of 

the first reference (Author unknown 1977). These data consisted of recorded neutron 

and gamma doses for 17 operators and associated workers for 3 different months in 

1977.

2. n/p = 0.23: An n/p value of 0.23 to 0.42, with an average of 0.33, was stated in the 

second paragraph of NIOSH’s response, with reference to Corridoni 1982. SC&A 

found that this reference states, on page 4, an n/p value of 0.23 for 1981 compared to an 

n/p value of 0.35 for 1980. However, SC&A could not locate the n/p upper value of 

0.42, or an average n/p value of 0.33, in this reference. Could NIOSH clarify how the 

n/p values of 0.42 and 0.33 were obtained?

3. n/p = 1.00: The second table in NIOSH’s response lists a geometric mean n/p value of 

1.00 for glovebox workers. Although not stated, SC&A assumes that this value came 

from the first reference ((Author unknown 1977); where Table 2, page 27, of that 

reference lists the TLD dose results for 13 temporary area monitors’ results (neutron and 

gamma dosimeters on water-bottle phantoms) near process gloveboxes for four different 

periods in 1975. SC&A calculated an overall average n/p value of 0.62 using the stated 

average n/p value at the bottom of the page for each of the four periods. How did 

NIOSH derive the n/p value of 1.00; was 0.62 rounded up to 1.00?

4. n/p = 2.33: The third paragraph in NIOSH’s response states an n/p value of 2.33 for 

one worker involved with manufacturing neutron sources in 1968 (Caldwell 1968). 

SC&A found that this n/p value was derived from the first quarter exposure results for 
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

11 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

1968 for a worker that has a 1.309 rem photon TLD dosimeter reading and a total 

neutron dose of 3.054 rem calculated from a combination of time-in logs and area 

neutron surveys; i.e., n/p = 3.054/1.309 = 2.33.

SC&A reviewed NIOSH’s proposed neutron dose assignment method for the period that NTA 

neutron film was used at NUMEC in the context of these reference data. Both of the NUMEC 

locations performed a variety of handling and fabrication operations with uranium and 

plutonium, from reactor fuels to (alpha, n) neutron sources, with some work in gloveboxes. This 

presents a challenge in reconstructing neutron doses, especially compared to an AWE facility 

that only performed routine fuel processing. While the n/p methodology that NIOSH is 

proposing for NUMEC has been used at other AWE and DOE sites, the dose data used to derive 

the n/p values suggested by NIOSH for NUMEC are not comprehensive or robust. A brief 

summary of this is as follows:

1. The n/p = 0.34 value to be applied to typical workers was derived from one 3-month 

study conducted in 1977 for 17 workers at one location (Table 1 of the first reference, 

Author unknown 1977). This would only provide a snapshot in time of the n/p value 

and would not necessarily be representative of all the typical workers’ locations and 

time periods that NTA film was used (1950s and 1960s) at the two NUMEC locations.

2. The n/p = 1.00 value to be applied to glovebox workers was derived from one 4-month 

study conducted in 1975 in areas near 13 gloveboxes (Table 2 of the first reference, 

Author unknown 1977). The discussion in that document on PDF pp. 21–22 indicates 

that these were rough field measurements that were only indicators, because there were 

numerous dosimetry issues. For example, the results did not necessarily represent the 

doses to the workers because they could not be placed where the workers were working, 

but had to be placed to the side or in adjacent areas; the gamma fields were not uniform 

and were subject to a large amount of uncertainty because of streaming and a variety of 

gamma radiation shielding installed on the difference gloveboxes. While informative, 

these data do not establish a sufficient basis upon which to derive n/p values for all 

glovebox workers and time periods that NTA film was used (1950s and 1960s) at the 

two NUMEC locations.

3. The n/p = 2.33 value to be applied to workers involved in manufacturing neutron 

sources was derived from one 3-month gamma TLD dosimeter reading and area neutron 

surveys using neutron survey instruments and a time log for one worker in 1968 

(Caldwell 1968). Details of the processing situation (gloveboxes, shielding, etc.) were 

not provided. This would only provide a snapshot in time of the n/p value and would 

not necessarily be representative of all the neutron source manufacturing exposures and 

time periods that NTA film was used (1950s and 1960s) at NUMEC.

SC&A concludes that, while informative, the data provided do not appear to be sufficiently 

robust to cover the various situations and time periods that NTA film was used at NUMEC to 

generate n/p values with acceptable accuracy for DR purposes. NIOSH may want to consider 

adopting a bounding n/p ratio that ensures that the neutron doses are not understated for 

circumstances where the available n/p data are limited.
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

12 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

1.6 FINDING 15. THE NEED FOR ADJUSTMENT FACTORS FOR SHALLOW 

AND DEEP EXPOSURES FOR OPEN AND CLOSED WINDOW DOSIMETERS 

THAT MEASURE HIGH AND LOW ENERGY PHOTON AND BETA 

EXPOSURES

SC&A expressed concern with NIOSH’s position that no adjustment factors are needed for the 

data acquired from dosimeters used to record external exposures to photon and beta emissions at 

NUMEC. SC&A’s review of the site profile identifies the very broad range of photon and beta 

exposures that workers might have experienced, and that, unless the dosimeters were calibrated 

for the specific energy distribution experienced by the workers, there would be a need for 

adjustment factors for at least some exposure scenarios.

NIOSH concurred that the site profile needs to be revised to account for possible over- and/or 

under-responses of dosimeters under some circumstances. The decision to modify the site 

profile approach for situations where low-energy photons and betas are present seems 

appropriate by assuming <30 keV photons for plutonium workers for open window results. 

However, NIOSH should endeavor to gather more information on the differing film badges and 

the protective coverings to enable a better assessment of situations where low-energy photons or 

betas were under-reported or missed entirely.
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

13 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

REFERENCES

Author unknown 1977. Summary of B&W and NRC Review Team Meeting, January 19, 1977. 

[SRDB Ref ID: 142792] 

Brake, R., 1989. Untitled letter to G. Runkle (U.S. Department of Energy), Los Alamos National

Laboratory, Los Alamos, New Mexico, November 9, 1989. SRDB Ref ID: 11091.

Caldwell, R.D., 1968a. Interpretation of Helgeson Body Counting Data, memorandum to Health 

and Safety Files, Nuclear Materials and Equipment Corporation, Apollo, Pennsylvania, April 24, 

1968. SRDB Ref ID: 19970.

Caldwell, R.D., 1968b. Letter to L. D. Low (U.S. Atomic Energy Commission), “Whole Body 

Counting,” Nuclear Materials and Equipment Corporation, Apollo, Pennsylvania, October 2, 

1968. SRDB Ref ID: 19850.

Caldwell, R.D., 1968c. Untitled letter to L. D. Low (U.S. Atomic Energy Commission), Nuclear 

Materials and Equipment Corporation, Pennsylvania, September 23. [SRDB Ref ID: 142650, 

pp. 90–92] 

Corridoni, R.D., 1982. Untitled memorandum to the B&W Safety Advisory Board, Babcock & 

Wilcox, March 23. [SRDB Ref ID: 142790] 

Croff, A.G., 1980. ORIGEN2—A Revised and Updated Version of the Oak Ridge Isotope 

Generation and Depletion Code, ORNL-5621, Oak Ridge National Laboratory, Oak Ridge, 

Tennessee. July 1980.

DOE 2003. Source Term Estimates for DOE Spent Nuclear Fuels, U.S. Department of Energy, 

DOE/SNF/REP-078, Rev. 0. March 2003.

ICRP 1989. Individual Monitoring for Intakes of Radionuclides by Workers. ICRP Publication 

54. Ann. ICRP 19 (1-3). International Commission on Radiological Protection, 1989.

NIOSH 2015. NIOSH Responses to SC&A Review of ORAUT-TKBS-0041, Rev. 02: Site Profile 

for Nuclear Materials and Equipment Corporation, Apollo and Parks Township, Pennsylvania, 

Rev. 0-A, May 14, 2015.

ORAUT 2012a. Y-12 National Security Complex – Occupational Internal Dose, ORAUTTKBS-0014-5, Rev. 03. Oak Ridge Associated Universities Team, Cincinnati, Ohio. March 12, 

2012.

ORAUT 2012b. Hanford – Occupational Internal Dose, ORAUT-TKBS-0006-5, Rev. 05, Oak 

Ridge Associated Universities Team, Cincinnati, Ohio. November 5, 2012.
Effective Date:

August 14, 2015

Revision No.

0 (Draft)

Document No./Description:

NUMEC – Response to NIOSH Comments

Page No.

14 of 14

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and 

Worker Health for factual accuracy or applicability within the requirements of 42 CFR 82.

ORAUT 2012c. Site Profile for Nuclear Materials and Equipment Corporation, Apollo and 

Parks Township, Pennsylvania, ORAUT-TKBS-0041, Rev. 02, Oak Ridge Associated 

Universities Team, Cincinnati, Ohio. November 26, 2012.

ORAUT 2013. Los Alamos National Laboratory – Occupational Internal Dose – ORAUTTKBS-0010-5, Rev. 02. Oak Ridge Associated Universities Team, Cincinnati, Ohio. April 18, 

2013.

ORAUT 2014. Rocky Flats Plant – Occupational Internal Dose, ORAUT-TKBS-0011-5, 

Rev. 03. Oak Ridge Associated Universities Team, Cincinnati, Ohio. September 30, 2014

SC&A 2013. Review of the NIOSH Site Profile for Nuclear Materials and Equipment 

Corporation Park Township and Apollo Sites, SCA-TR-SP2013-0038, Rev. 0. SC&A, Inc., 

Vienna, Virginia, and Saliant, Inc., Jefferson, Maryland. April 19, 2013.