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At least 19 records

Visual Impact Assessment of the Energetic Materials Complex Construction Project on Manhattan Project–Era Historic Properties, the TA-06-0037 Concrete Bowl, and the TA-22-0001 Quonset Hut

Concern for potential visual effects to historic Manhattan Project–era properties emerged early in the planning and consultation phase for the upcoming Energetic Materials Complex (EMC) construction project. In initial discussions with project managers and design team members, resource managers became aware of the need to consider potential impacts to the viewsheds of two nearby properties that are eligible for inclusion in the Manhattan Project National Historical Park (MAPR). Resource managers recognized that viewshed characteristics important to the integrity of the Concrete Bowl (Technical Area [TA-]06-0037) and the Quonset Hut (TA-22-0001) conceivably faced the prospect of lasting and irreversible visual impacts. A strategy to gather necessary data soon emerged. The approach presented to the New Mexico State Historic Preservation Officer (SHPO) on April 7, 2021, combined gathering baseline information from field visits with a geographic information system (GIS)-supported viewshed analysis. Accordingly, results from the viewshed analysis would help resource managers determine if a more comprehensive visual impact assessment (VIA) would be needed. If necessitated by the outcome of the GIS viewshed analysis, initial consultation with the SHPO specified the production of a VIA that would explore any potential visual adverse impacts to the Concrete Bowl and the Quonset Hut. Cultural resources and GIS specialists with the Laboratory performed a viewshed analysis shortly after consultation with the SHPO. The analysis indicated a high likelihood that at least one of the two Manhattan Project–era properties would experience at least a minimal level of visual impact and that a VIA would be needed. The resulting analysis provides a description of the undertaking, an account of the properties affected along with an evaluation of historical significance, an examination of potential visual impacts, and a determination of effect to the identified historic properties.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Neutronics Calculation Advances at Los Alamos: Manhattan Project to Monte Carlo

The history and advances of neutronics calculations at Los Alamos during the Manhattan Project through the present are reviewed. Substantial improvements to neutron diffusion methods and the invention of both the Monte Carlo neutron transport methods in 1947 and deterministic discrete ordinates Sn in 1953 were all made at Los Alamos just after the Manhattan Project. We briefly summarize early simpler and more approximate neutronics methods and then describe the need to better predict neutronics behavior through consideration of theoretical equations, models and algorithms, experimental measurements, and available computing capabilities and their limitations. This paper briefly covers key advances in deterministic methods during the Manhattan Project. These capabilities, coupled with increasing postwar defense needs and the invention of electronic computing with the Electronic Numeric Integrator and Computer, known as ENIAC, and the Mathematical Analyzer Numerical Integrator and Automatic Computer Model, known as MANIAC, led to the creation of Monte Carlo and deterministic discrete ordinates neutronics transport methods. We note the important role that the scientific comradery between the Los Alamos scientists played in the process. This paper briefly covers the early methods, algorithms, computers, and electronic and women pioneers that enabled Monte Carlo to spread to all areas of science. We focus heavily on these early developments and the subsequent creation of the MCNP® code, advances in its associated nuclear data, and its applications to problems of national defense at Los Alamos.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Manhattan Project 1940s research on the prompt fission neutron spectrum

We describe how the prompt fission neutron spectrum (PFNS) was determined for the Manhattan Project at Los Alamos. Early work before World War II at American and British universities is described, together with theoretical work by Feather at Cambridge and Bethe at Los Alamos. As the Manhattan Project was being planned in 1942, two experiments on natural uranium were commissioned that proved to be influential: 1) An integral experiment at Chicago by Christy and Manley that accurately determined the average PFNS spectrum energy, 2.2 ± 0.2 MeV; 2) Bloch and Staub’s Stanford cyclotron measurement of the PFNS spectrum, which obtained an average energy of 1.70 ± 0.34 MeV. These two papers, previously unavailable outside of Los Alamos, are reproduced in the Supplementary Appendix. From these data, at the beginning of the project in 1943 Serber estimated an average 235 U PFNS energy of 2 MeV, and indeed this agrees with today’s best estimate. The challenges facing the scientists involved both the availability of only very small samples of enriched uranium and plutonium targets, and fast neutron detection technologies. During the project, 235 U and 239 Pu PFNS were measured by Nicodemus and Staub. These also proved to be quite accurate and gave an average spectrum energy of 2 MeV for 235 U. [This is not reproduced in the Appendix because it was published after the war in Physical Review 89, 1288 (1953)]. New methods were developed to enable more accurate measurements, and this paper describes how the PFNS was determined surprisingly well by 1945. We end by describing the post-war measurements in the 50s, including the PFNS data used by Ford and Wheeler in their simulations in 1951, the Bonner 1952 data, the seminal 1952 Watt paper with a new empirical parametrization of the PFNS, and the accurate PFNS measurement undertaken at Los Alamos by Cranberg et al. in 1956. We compare the measurements with our best understanding today as embodied in the Evaluated Nuclear Data File ENDF/B-VIII.0. Some images from historical documents in our Los Alamos National Security Research Center (NSRC) archives are shown.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗

Nuclear Science for the Manhattan Project and Comparison to Today’s ENDF Data

Nuclear physics advances in the United States and Britain from 1939 to 1945 are described. The Manhattan Project’s work led to an explosion in our knowledge of nuclear science. A conference in April 1943 at Los Alamos provided a simple formula used to compute critical masses and laid out the research program needed to determine the key nuclear constants. In short order, four university accelerators were disassembled and reassembled at Los Alamos, and methods were established to make measurements on extremely small samples owing to the initial lack of availability of enriched 235U and plutonium. I trace the program that measured fission cross sections, fission-emitted neutron multiplicities and their energy spectra, and transport cross sections, comparing the measurements with our best understanding today as embodied in the Evaluated Nuclear Data File ENDF/B-VIII.0. The large nuclear data uncertainties at the beginning of the project, which often exceeded 25% to 50%, were reduced by 1945 often to less than 5% to 10%. Uranium-235 and plutonium-239 fission cross-section assessments in the fast mega-electron-volt range were reduced following more accurate measurements, and the neutron multiplicity $\overline{v}$ increased. By a lucky coincidence of canceling errors, the initial critical mass estimates were close to the final estimated masses. Some images from historical documents from our Los Alamos archives are shown. Many of the original measurements from these early years have not previously been widely available. Through this work, these data have now been archived in the international experimental nuclear reaction data library (EXFOR) in a collaboration with the International Atomic Energy Agency and Brookhaven National Laboratory.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

The Los Alamos Computing Facility During the Manhattan Project

This paper describes the history of the computing facility at Los Alamos during the Manhattan Project, 1944 to 1946. While the hand computations are briefly discussed, the paper’s main focus is on the IBM Punch-Card Accounting Machines (PCAMs). During World War II, the Los Alamos facility was one of the most advanced PCAM facilities, both in the machines and in the problems being solved.

97 MATHEMATICS AND COMPUTING↗

Historic Buildings Report: Five-Year Preservation Planning for Manhattan Project National Historical Park Sites

This report offers a preservation maintenance plan for the next five years for buildings and structures included in or eligible for inclusion in the Manhattan Project National Historical Park at Los Alamos National Laboratory. There are twenty-three buildings, structures, and ruins of previously standing buildings covered within this report. Many of the preservation maintenance issues addressed here concern problems with health and live safety of staff and visitors alike, and also structural concerns that affect the long-term preservation of these important buildings.

42 ENGINEERING↗

The Manhattan Project Nuclear Science and Technology Developments at Los Alamos: A Special Issue of Nuclear Technology

The year 2020 marked the 75th anniversary of the Trinity experiment, the world’s first nuclear explosion, on July 16, 1945, near Alamogordo, New Mexico. Trinity was a vital proof step toward the culmination of the Manhattan Project and the end of World War II. The technical accomplishments made by scientists and engineers from the United States, United Kingdom, and Canada (some originating in Germany, Hungary, Italy, France, and other countries) were recognized by many events in 2020, including a visit to New Mexico’s Los Alamos National Laboratory by U.S. Department of Energy (DOE) National Nuclear Security Administration (NNSA) dignitaries; historical documentaries. The importance of Trinity as a foundational accomplishment for the broad nuclear science and engineering community is clear; indeed, New Mexico’s chapter of the American Nuclear Society (ANS) is referred to as the Trinity Section. The events surrounding Trinity have even entered into high culture with recent performances of John Adams’s opera Doctor Atomic in San Francisco, Amsterdam, Chicago, New York, and Santa Fe.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Beyond the Manhattan Project: Books and documentaries that showcase Lab history after World War II

They are at it again, on this occasion just in time for National Library Week. Last year, staff members from the National Security Research Center (NSRC, the Laboratory’s classified library) recommended their favorite books and movies about Los Alamos National Laboratory during the Manhattan Project. This time out, NSRC Director Riz Ali and Senior Historian Alan Carr, joined by Historian Nicholas Lewis, tackle a greater challenge, recommending their favorite books, publications and documentaries that cover the Laboratory’s history after World War II.

99 GENERAL AND MISCELLANEOUS↗

Plutonium in Manhattan Project workers: Using autopsy data to evaluate organ content and dose estimates based on urine bioassay with implications for radiation epidemiology

Purpose Radiation dose estimates in epidemiology typically rely on intake predictions based on urine bioassay measurements. The purpose of this article is to compare the conventional dosimetric estimates for radiation epidemiology with the estimates based on additional post-mortem tissue radiochemical analysis results. Methods The comparison was performed on a unique group of 11 former Manhattan Project nuclear workers, who worked with plutonium in the 1940s, and voluntarily donated their bodies to the United States Transuranium and Uranium Registries. Results Post-mortem organ activities were predicted using different sets of urine data and compared to measured activities. Use of urinalysis data collected during the exposure periods overestimated the systemic (liver+skeleton) deposition of 239 Pu by 155±134%, while the average bias from using post-exposure urinalyses was –4±50%. Committed effective doses estimated using early urine data differed from the best estimate by, on average, 196±193%; inclusion of follow-up urine measurements in analyses decreased the mean bias to 0.6±36.3%. Cumulative absorbed doses for the liver, red marrow, bone surface, and brain were calculated for the actual commitment period. Conclusion On average, post-exposure urine bioassay results were in good agreement with post-mortem tissue analyses and were more reliable than results of urine bioassays collected during the exposure.

60 APPLIED LIFE SCIENCES↗

This St. Patrick’s Day, take a look at “lucky” Lab artifacts from the Manhattan Project

What luck! Tucked inside J. Robert Oppenheimer’s book Bhagavad-Gita is a four-leaf clover. The famed physicist and first Lab director regularly quoted the Hindu scripture, most notably upon witnessing the Trinity test, which was the successful detonation of the first-ever Los Alamos created atomic bomb. Oppenheimer was said to have recalled the line, “Now I am become Death, the destroyer of worlds.” (The quote, though, has been widely misinterpreted.) The clover is taped to what appears to be a calling card from his spouse Kitty and was found inside his copy of the Bhagavad Gita, which was donated to the Lab’s Bradbury Science Museum by private donors Ben and Sara Beck Svetitsky in early 2020. Kitty Oppenheimer was educated as a botanist and biologist, and accompanied her husband to Los Alamos, along with their two children. The family was here in 1943 through the end of World War II in 1945. The book, with the card found inside, makes up one of two of J. Robert Oppenheimer’s personal effects within the Lab’s collections.

99 GENERAL AND MISCELLANEOUS↗

Installation of Ramps and Utility Cabinet at TA-18-1 Slotin Building (Historic Building Report No. 395)

The information below is presented in response to requests for additional information that resulted from a phone conference on November 12, 2020 between Harvey Kaplan of the New Mexico State Historic Preservation Office, DOE NNSA Los Alamos Field Office Manhattan Project National Historical Park Representative, Vicki Loucks, LANL Program Manager for Manhattan Project National Historical Park, Cheryl Abeyta, and LANL Historic Buildings Program Staff, Jeremy Brunette and J.T. Stark. The DOE NNSA Field Office (Field Office) initiated the call to propose additional work be performed to a previously reviewed project, “Restoration of TA-18-0001 (Slotin Building)” (LA-UR-19-26609) (HPD Log # 111110). Of the six actions discussed on the call, which included (1) exterior paint color, (2) entrance ramps, (3) non-period metal siding removal, (4) interior floor finish, (5) reopening secondary entrance door, and (6) addition of utility cabinet with period doors, additional information for two of the actions was requested for further review. The two actions, the construction of entrance ramps and installation of a utility cabinet are addressed in detail.

42 ENGINEERING↗