Methods for the noncorrosive removal of volatile fission products and UO2 dust from carbon steel and stainless steel have been developed. Procedures for applying these methods to the decontamination of the EGCR charge and service machines are described.

This manual represents the recommendations of the Instrumentation and Controls Division committee on Electrical and Electronic Symbols and Drawing that have been issued to date, and supersedes the previously issued ORNL Electrical Symbols List and CF-58-12-141, Electrical and Electronic Drawing Standards for Wiring and Device Coding and Applications.

A portable shield has been designed, developed, fabricated and shop tested to provide the HRT with a facility for direct dry maintenance operations. It provides temporary replacement for any one of the lower roof plugs and should permit many operations to be performed without flooding the reactor cell with water.

A literature study has been made of rates for the reaction of oxygen with high-purity artificial graphite. Values from a number of sources have been expressed on a common basis which provides approximate correction for the retarding effects of oxygen diffusion in the graphite pores. The corrected rates can be correlated by the equation k = 7.24 x 10^9 exp (-22 100/T), where k has units of weight fraction oxidized per hour and T as in °K. Effects of oxygen concentration, solid and gas-phase contaminants, and radiation on the observed rates are discussed. Methods for estimating rates and spatial distribution of heat release during graphite oxidation are presented. These should be of value in analyzing the hazard of a graphite fire following a coolant system rupture in a gas-cooled, graphite-moderated reactor.

The effect of adding small quantities of fuel or poison to the HRT has been estimated using perturbation theory. The results have been reduced to a single relation and a set of graphs which make the estimation of added reactivity relatively simple. The perturbation theory results are compared with multigroup results and reasonable agreement is demonstrated; however, there is some question concerning the prompt neutron lifetime.

EXPIRE is a calculation which predicts the reactivity-lifetime, instantaneous and integrated effective multiplication constants and instantaneous and integrated effective multiplication constants and instantaneous conversion ratio for heterogeneous reactors. The concentration of all the isotopes of interest from Th232 to Am243 are calculated as a function of time using the average reactor power density and a uniform flux distribution. The equations have been programmed for the IBM-704 computer and the average running time is approximately two minutes per reactor lifetime.

The attached paper is a translation of a rough draft of the paper, "Operating Experience of the APS-1", presented by M. Minashin in Russian at the IAEA Conference on Small and Medium Power Reactors, Vienna, Austria, September 5-9, 1960.

This report is a working document of the UB AEC Nuclear Cross Sections Advisory Group and is issued about twice a year for the purpose of stimulating important cross section measurements. The requests listed in this report have originated from various Atomic Energy Commission contractors, the Advisory Committee on Reactor Physics, and the Nuclear Cross Sections Advisory Group. The distribution is limited to members of the US Nuclear Cross Sections Advisory Group (NCSAG), the US Advisory Committee on Reactor Physics (ACRP), the Tripartite Nuclear Cross Sections Committee (TNCC), the European-American Nuclear Data Committee (EANDC), to US AEC off-site contractors, and to the requestors and measurers of the cross sections listed in this report. The contents of this document are not to be republished in part or in full without special permission of the chairman of the NCSAG, The unpublished data which appear in this report must not be quoted in publications without permission of the experimenter.

A short-term study was made to investigate the removal of radioiodine vapor from air-steam mixtures as could occur immediately following a nuclear incident in a pressurized water reactor. Activated charcoal traps, designed to simulate a small section of a commercial charcoal canister, were tested at gas velocities of 23.9 to 74.9 ft/min over the temperature range of 75 to 118°C. The iodine removal efficiency was found to range from 99.80 to 99.4% with an average of 99.9%. One test performed at a temperature of 105°C and with gas velocity of 290 ft/min indicated that the iodine removal efficiency was reduced to 99.54%. Activated charcoal exhibits a high efficiency for iodine vapor removal under these test conditions and appears suitable for application in the decontamination of air-steam mixtures.

Simon (1960) has given a general steady state theory of plasma accumulation (without energy losses) in an OGRA device. Such a device is fed by injection of energetic molecular ions which dissociate to produce trapped protons. Initial trapping is achieved by dissociation in the background gas. Such a device is usually characterized by a critical input current of critical plasma density (a function of input current) above which plasma density builds up to a value limited by Coulomb-scattering losses. For a regime of operation of current interest at Oak Ridge National Laboratory (600-kev hydrogen molecular ion injection and dissociation, highly efficient ion-pumping action of the trapped plasma), extremely simple approximate formulas have been derived which describe with a fair degree of accuracy the critical current of density for plasma build-up.

Equipoise-2, a two-dimensional, two-group neutron-diffusion code in R-Z geometry, has been programmed for the IBM-7090 computer. This code was designed to permit the running of large numbers of cases without requiring excessive machine time. Typical running times are of the order of one to three minutes per case for a 1000-point problems. The maximum number of mesh points that can be used is 1444.

An experiment was performed at the ORR in order to find a good fission chamber location. Two locations on the pool side of the reactor tank were explored with a one inch diameter fission chamber. The thermal neutron flux attention was found to vary nearly exponentially with distance, and no shadowing effect could be seen during a reactor startup. The fission products high gamma flux could be discriminated without difficulties. Both positions seem to be adequate to locate a reactor control fission channel.

A stimulation study of the deign as of June 1960 of the gas-cooled ORR Loop No. 1 was made using the ORNL analog computer. The proposed method of temperature control is evaluated, and the dynamic behavior of the loop for accidents and component failures is presented in graphical form.

These specifications for the fuel assemblies for Core I of the Experimental Gas-Cooled Reactor (EGCR) have been developed for use in procuring the first core loading. A fuel assembly for EGCR consists of a cluster of seven cylindrical fuel elements spaced and supported within a graphite sleeve. Each fuel element consists of a stainless steel tube containing a column of hollow UO2 pellets and having a spacer brazed at the midsection to control the spacing between fuel elements in a cluster. A master specification for the fuel assembly, a supplementary specification for each of the components, and a specification on record keeping during manufacture are included.

On 3/14/60 the Applied Physics Corporation was awarded a subcontract for the design and development of a high-temperature high-pressure spectrophotometer system based on the Cary Model 14pm Spectrophotometer insofar as possible, and consistent with our specifications, No. CTD-2, December 16, 1959.

An analog simulation is made of the HRP in-pile slurry loop in the LITR. The radiolytic gas pressure in the pressurizer is determined. This pressure is a result of the generation of radiolytic gas in the loop core. A graphical result is obtained showing the effect of catalyst activity and pressurizer flow rate on the pressure rise from radiolytic gas. The thermal behavior of the system is studied, and the response to various controller settings is predicted. Controller settings very near optimum for the actual process were recommended from the analog study,

The development of nuclear reactors and other nuclear particle sources has given the analyst a new analysis method which can be successfully applied to the determination of microgram and submicrogram quantities of many elements. Known as "radioactivation analysis", this method is one in which an "activation" by some type of nuclear reaction is used to produce a radioactive isotope of the element to be determined. Since this radioisotope decays with its own characteristic radiations and half-life, it is possible to make radioactivation analysis a very specific analysis. Chemical separations of the radioisotope are employed whenever necessary and its radioactivity measured by some type of radiation counter.

A helium coolant purification system was designed for the proposed 800 MWT Pebble Bed Reactor. The purification system will operate on a coolant side stream with a flow rate 1% of the total coolant flow and there are provisions for radioactive and non-radioactive contamination removal.

An estimate was made of the beam hole currents to be expected from both the radial and tangential beam holes in the present HFIR design. The angular fluxes required for these calculation were determined by an 18-group, S8 transport calculation (SNG reactor code). Both type beam holes produced thermal neutron currents of 7.5 x 10^10 neutrons/cm^2 sec. at a power level of 100 Mw. The nonthermal component of the beam current was 7.0 x 10^10 and 4.5 x 10^10 neutrons/cm^2 -sec for the radial and tangential holes, respectively.

The hardness of several materials that have been considered for use as valve scats and bearings in thorium oxide slurry systems were measured and are reported for comparison with thorium oxide.

A generalization of Wigner's simple model for the distribution of nuclear level spacings is studied. It is based on a stochastic process which reproduces the correct joing probability distribution of N enerfy levels for small spacings. The case N=3, which includes the effect of the correlation between adjacent spacings, is discussed in detail. The resulting distribution and the correlation coefficient are compared with experimental data. No definite conclusion can be drawn except to say that the effect of the correlations on the spacing distributions on the spacing distribution is very small.

Five irradiated and five unirradiated wafers were analyzed. Each wafer was analyzed for samarium by emission spectrography. The unirradiated wafers were analyzed for uranium by coulometric and potentiometric methods and for uranium isotopes by mass spectrometry. The irradiated wafers were analyzed for uranium and plutonium by coulometric methods, for plutonium isotopes by the 256-channel alpha pulse analyzer, and for the isotopes of uranium and of plutonium by mass spectrometry. The methods of preparing wafers for analysis are discussed; the data are tabulated.

In the Communications of the ACM of April, 1960, p. 240, there appeared two Algol algorithms for the computation of In, the modified Bessel function of the first kind. One of these algorithms uses a convergent series and the other an asymptotic series. Their author, Dorothea S. Clarke, did not give any information with regard to which algorithm is more appropriate in a given situation (a given situation meaning the computation of In (x) for a definite pair of numbers n and x). Such information is necessary, however, if the algorithms are to be useful, particularly since the asymptotic series is in many cases not valid.

The ORNL analog computer was used to examine one aspect of a safety system for the EGCR. The thermal behavior of the fuel as a result of increases in reactivity at various power levels and gas flows was examined. Safety actions initiated by wither a flux-minus-flow signal or a reactor outlet gas temperature signal were included in simulation.