Long range plan - Plowshare excavation program (Book 1 - 1966/1967 excavation program binder)

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Long Range Plan - Plowshare 1966/1967 Excavation Program Binder) This is an informal report intended primarily for internal or limited external distribution. The opinions and conclusions stated are those of the author and may or may not be those of the Laboratory. Work performed undo: the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract W-7405-ENG-48.

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This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency Portions of this document may be illegible in electronic image products. Images are produced from the best available

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-LITE'EMOPvE: Lawrence Radiation Laboratory SUBJECT: LONG RANC03 PLAN - PLOWSHARE EXCAVATION PROGRAM The purpose of this report is to present a proposed five-year progran ttf r for the Plowshare Excavation Program, In preparing this study we shall proceed as follows: (a) Review the significant advances (since 1963) in nuclear cratering technology^ and (b) identify the key uncertainties then proceed to identify key experiments and any new measure- ■ e\~' merits that may be required to increase our predictive capability.4 and/or to resolve the major uncertainties. It is probably clear that if one proceeds in this fashion one may not necessarily arrive at the existing long range excavation program , 4 (e.g.} the definitions of experiments beyond Cabriolet and Buggy),‘"'n*r''£7x' In fact, one might expect to derive a significantly different - , long range plan. H. SIGNIFICANT ADVANCES IN CRATERING TECHNOLOGY SINCE 1963 Several significant advances in nuclear cratering technology have been achieved since 1962, despite the restrictions imposed by,the Nucie,.r Test Ban Treaty; they are summarised and illustrated herein.

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Cabriolet, a 2.5 kt cratering experiment in hard dry rhyolite, vas originally scheduled for firing in April 196?• The detonation vas held in readiness for firing through four days of veather delay during that month, prior to cancellation of authorization to fire by the White House. Operations were terminated with receipt of the cancellation news. However, this experiment is still considered strategic to the Plowshare Excavation Program in that the experimental data on cratering mechanisms and final crater geometry will provide an important verification for the pre-shot theoretical calculations of cratering and the final crater di mensions. An example of the calculation prepared spring 19&7 for the Cabriolet experiment is shown in Figure 1. This figure shows the predicted true crater geometry, the free surface configuration at l6j ms, and the throwout mass-distribution. The second objective of this experiment is to document, as fully as possible, the ground deposition of radioactivities and the airborne radioactivity for periods up to 2b to h8 hours and to compare this data with the LRL cratering fallout model prediction and the atmospheric diffusion prediction of airborne concentrations. During summer 1967 the decision was made to dig down and to remove the device emplaced for the planned Cabriolet experiment of last April. The reasons for this decision were that there vas some doubt as to the continuing reliability of the device system after some appreciable period of emplacement and that leaving the old device in place might well compromise the radiochemical determination of the yield of a new experiment when fired. When the Cabriolet experiment is authorized for execution it is planned to reuse the old emplacement hole with another modem excavation nuclear explosive. At such time, a test of the capability of theoretically predicting cratering mechanisms and crater size (pre-shot) and the documentation of radioactivity from a modem excavation explosive can both be achieved.

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Fig. T Throwout calculation at 135 msec for 2.5-kt nuclear explosive in layered trachyte. {Cavity pressure e 48 bars.)

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The Inter-oceanic Canal Commission as veil as URL have in the past recommended cratering experiments to he done in veak saturated material that in many ways would be comparable to materials encountered on the proposed sea-level canal routes. Because of this interest, the Pre-Gondola I and II series were designed and executed in late 1966 and For one of the Pre-Gondola I detonations, LRL performed post-shot theo retical calculations on crater formation losing as input parameters the pre-shot geophysical measurements of density and compressions! wave velocity in the shot environment. Figure 2 shows the predicted true. crater boundary, the mound configuration at 36 milliseconds and the predicted mass deposition on the earth’s surface. The theoretical results indicate a crater radius between 20 and 25 meters which should be compared with an observed crater radius of 24.5 meters. The combined experience from these experiments and theoretical studies associated with them is considered to be a valuable contribution to cratering mechanics in weak saturated material. C* BIBAR scanning of debris clouds Information concerning the location, dimensions, internal structure, and rates of movement of the cloud resulting from the sub surface detonation of a nuclear explosive is of prime importance in assessing the radiological safety aspects of the detonation. One of the difficulties with visual and photographic tracking is that once the cloud becomes'very diffuse, it becomes undetectable. LRL has sponsored the use of the Stanford Research Institute laserradar (lidar) on the Pre-Gondola I series of experiments conducted by the Corps of Engineers, which consisted of four-20 chemical cratering In these experiments, the narrow beam (~„5 milliradi'an divergence): laser gun vas placed on the ground and a series of extremely short pulses (15 nanoseconds in length) were aimed at the detonation-produced clouds.

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The return signals are filtered through a bandpass filter which reduces the background and sky illumination noise. A photomultiplier tube converts the small fraction of light received into electrical energy, which is displayed on a fast-rise oscilloscope. From the characteristics of the return signal many physical properties of the cloud can be determined. On the Pre-Gondola I experiments it was possible to detect and delineate the clouds 20 to 30 minutes after they were invisible to cameras and to the eye. It vas also possible to determine rate of growth, relative density, internal structure, and cloud volumes. Figure 3 illustrates the ability of the laser to determine the cross-sectional shape of a sub-visible cloud at various times. Figure k illustrates relative density contours of a cloud determined from analysis of return signals. Experiments of a. similar nature will be conducted by SRI and sponsored by LRL on the next nuclear rocket run at Jackass Flats, Hevada. The reactor effluent will be lased ctiici comparisons an d correlation made with radiochemical sampling. Project Cabriolet will also have a lidar exper iment as part of the technical program. Cloud volume, rate of drift, internal structure, and relative density will be correlated with the radiochemical sampling performed by aircraft. For the Pre-Gondola II event, KCG sponsored the airborne lidar observation of the cloud produced by this HE cratering shot. This exper iment add-on produced results on the cloud volume and the internal cloud structure (relative concentration of airborne material) to ranges that significantly exceeded those obtained previously by a ground based lidar. The value and feasibility of making this type of measurement from an airborne platform was positively demonstrated. In the absence of nuclear excavation experiments, LRL scientists have considered other radioactive sources and resulting clouds to use In studies of airborne radioactivity to long range. The purpose of such investigations is to verify the LRL atmospheric diffusion (numerical) model for predicting airborne cloud mass concentrations as a function of

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time. A large effluent cloud produced by the operation 'of a reactor engine at the Nuclear Rocket Development Station has been studied in detail. Initial cloud size and time dependent meteorological parameters along the path of the cloud were used as input to a cloud diffusion calculation with a computer code developed in support of Plowshare. Comparison of calculations with data indicate agreement, within a factor of 2, for air concentration of radioactivity out to two days, surface air concentration, dry deposition, vertical concentration profile shape, and cloud size. During the two days of data collection, the radioactive concentration at the cloud center decreased some seven orders of magnitude. Marvel is a physics experiment concerning the behavior of the region near the device as related to the method of explosive emplacement. It is to be fired at a location associated with an underground tunnel which contains a network of instrumentation to measure pressure, temperature, radioactivity and other quantities of interest at various points in the vicinity of the shot point. (See Figure 5, GLC-66lO~9i49.) Information obtained from this experiment will be useful in evaluating emplacement methods for Plowshare applications and as reference data for checking theoretical models of the effects that underground nuclear detonations 'have as related to different emplacement configurations. Several technical working groups in the area of. radioactivity, ground motion, cratering characteristics, and acoustic wave effects function in an advisory capacity to the Manager of the Nevada Operations Office of the Atomic Energy Commission, in regard to field programs and the feasibility studies associated with these studies. Some of the direct contributions to these studies by the LRL representatives are In addition to the "review of the data from tlje.study- • associated field programs, the LRL representatives have prepared a study of the identification and ranking of the

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most significant radionuclides produced "by nuclear deto nations in regard to their impact on man. Their report has "been made available to all concerned "with the feasi bility studies of the nuclear sea-level canal. At this date_, the effect of any concentrating mechanisms in the ecological system remains to be factored into the study, and the results evaluated. This committee has met on a fairly frequent basis during the calendar yean, reviewing the proposed field programs and the work of subcontractors to the Nevada Operations Office of the AEG. In this regard, the structures survey progrem, the identification of instrument locations for recording strong motion for future earthquakes, and the assessment of damage from past earthquakes in Central and South America have all been subject to review. At this date, there are eleven strong motion self recording stations in the pertinent Central and South American countries for the purposes of recording any motion from future earthquakes. The committee has been active in identifying the technical needs of the ground motion prediction and structures response areas are related to strategic future modifications of the program.. Representatives on this committee have played an important role in the designing of the geophysical measurements program on the canal route in Panama, in regard to the measurements of density, 3-P velocity logs, water content and photo logs ' in the holes drilled. This- interaction of LRL representatives is stragetic in the acquisition of the proper input data to theoretical cratering calculations, Further, 1RL scientists have identified an acute need for theoretical cratering cal culations associated with high yield cratering events - a fact which' we will discuss more fully in this paper-

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III. CENTRAL AND KEY ISSUES IN EXCAVATION TECHNOLOGY: Listed Delov are the key issues for the further development of nuclear cratering technology, as they are known at this date. 1. The development of predictive capability for cratering mechanisms and final crater dimensions for yields of 1 MT and up. 2. The seismic ground motion prediction capability for yields greater than or equal to 1 1*0?, including the question of disturbance of adjacent slopes of previously excavated craters by the disturbance associated with the Joining row charge. 3. The long terra slope stability problem when the slopes or portions thereof are saturated. h. The experimental confirmation of the "scrub” concept for the control and reduction of released radioactivities in the debris clouds. 5. A demonstration experiment in the area of ground water contamination bearing on the water quality in the flooded craters or channels. 6. Studies of cloud phenomenology and the development of the physical, understanding concerning the differences in cloud phenomenology resulting from a detonation in a wet vs. dry environment. 7. A definitive study of air blast effects from row charges.

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8. A venting model which takes into account the differences in cavity conditions during a vent. 9. Studies or experiments in the area of directed blasting techniques for the production of land olidfe dams.v>\ 10. Additional debris entrapment experiments will be needed as key physics questions are identified and appropriate experiments are designed to answer these questions. IV. PLAHHED AM) COMUTTEI) EXPERIMENTS At this date, the Cabriolet experiment is included in this category. The objectives of this experiment are: 1. The verification of the LRL capability to calculate (pre shot) cratering mechanisms and final crater dimensions and mass deposition above and around the crater; 2. To document the radioactivity released and its distribution from a modem excavation explosive; 3. To explore means of controlling or minimizing the radioactivity released by means of scrubbing with the injection of calcium chloride into the radioactive cloud. Buggy is defined as a row charge excavation experiment in hard dry rock; the five 1.2 kt nuclear explosives are to he emplaced at a depth of approximately 150 feet. The objectives of this experiment are essentially the same as those for Cabriolet with the addition that it will he the first nuclear row charge event, and then is intended to demonstrate that channels maybe excavated with nuclear explosives. Of the key issue identified for the further development of nuclear cratering technology, the most crucial is the attainment of a predictive capability for cratering events at yields of 1 MT or higher. This capa bility is required to estimate the yield required to produce the' excavation

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through the isthmian divide for IOCS studies. Should these calculations indicate that yields higher than those currently assumed are required for the excavation, this vould have a profound effect on the feasibility of the current nuclear excavation plans for a sea level canal. Its impact on the seismic damage assessment for the canal is clear. It is presently assumed that about 4 cm per second motion in Panama City represents an upper limit of the ground motion that the city might be able to sustain. If higher yields than those mentioned in current plans are required, this limit could well be exceeded. Construction of the canal, using the present detonation schedule might prove to be impractical unless nev methods such as nibbling, or water vapor boosting were explored. It is of paramount importance to ascertain the yields levels required for the divide cut at an early date. Almost as important as cratering dynamics calculations is the devel opment …