Environmental consequences of proposed changes in reactor operations

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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 responsi bility 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. Refer ence herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recom mendation, 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 thereof.

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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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RICHLAND, WASHINGTON HANFORD ATOMIC PRODUCTS OPERATION Hanford Operations Office EHVTROKMETJTAL CONSEQUENCES OF PROPOSED CHANGES IN REACTOR OPERATIONS In reply to the reference letter, the attached, document'(1TW-5^953) presents the influence of proposed increases in reactor power levels on the radioactive con There are two radioisotopes (phospnorus-32 and arsenic-76) which are major con tributors to radiation exposure received from consuming Columbia River water or fish. The generation of'these isotopes in reactor effluent has been and is under study by the Hanfdr&^Laboratorxes with the objective of identifying the sources of these isotope?. Achieving this objective would provide a possible means of eliminating or Reducing the concentration of these isotopes in reactor effluent. This is a complex^matter, however, and a quick resolution is not Under the worst of the normal conditions under consideration, the radioactive content in the river would probably cause excessive contamination of the river as a drinking water source and cause restriction of sport fishing in certain areas. Both of these effects would have substantial potential impact on com munity relations. Any plan to routinely exceed the Hanford control limit for environmental, exposure must be viewed with extreme pessimism. Very truly yours. WE Johns on: ARK :bh A PRIME CONTRACTOR FOR THE U.S. ATOMIC ENERGY COMMISSION

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ENVIRONMENTAL CONSEQUENCES OF PROPOSED CHANGES IN REACTOR OPERATIONS At the request of the Advisory Committee on Reactor Safeguards, a brief study was made on the effects of radioactive materials, both under conditions of normal operation, and conditions of accidental fuel melting, in the reactor cooling water. The following report indicates predictions based on the best available information. A range of conditions was considered to provide information on changes less than the maximum proposed. The increased concentrations in Columbia River water during a normal river flov year would not cause annual exposures to the population from drinking water in excess of the NCRP non-controlled exposure limit. (1) During a minimum river flow year, the annual exposure would not exceed the NCRP limit,- but would exceed the The maximum proposed increase in power level would therefore probably yield exposures in the environs that approach permissible levels more closely than desirable. Predicted maximum concentrations of p32 would be such that the continuous consumption of 0.1 to 0-3 pounds of whitefish per week would result in the permissible nonoccupational body burden.^3>^) During certain seasons of the year, fishing may have to be curtailed, or reactor operations controlled. Fishing restrictions would probably result in unfavorable public reaction. The small increases predicted for chemical toxicity and water temperatures in the Columbia River were considered to be of little significance, even though some minor damage to aquatic life could occur during unfavorable thermal river conditions.v3>5,6) Release of fission products to the effluent as a result of a major melt-down was considered improbable, since the water would be expelled before the jackets melt. Calculations on a single tube partial release indicate that the resulting conditions, although troublesome, should not present a major hazard to individuals in the environs. Ill. NORMAL OPERATIONS A. Proposed Operating Conditions The proposed increases in reactor production may be accomplished by a combination of three changes in reactor operation; namely, increase in water flow rates, bulk outlet temperatures, and operating efficiency. The introduction of I and E slugs will probably permit increases of ten percent in water flow rates and five percent in operating efficiency. The incidence of'slug rupture is expected to be negligible with use of the I and E slug; this will permit the proposed increase in operating efficiency. Proposed increases In bulk outlet temperatures to 95°C and 98°C will supply the remainder of the expected increase in power level and reactor production.

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1. Method of Extrapolation Estimates of the concentration of radioactive materials in the river were based on November, 1957 power levels, bulk outlet temperatures, river flow rates, and fractions of MPCqj as applied to both normal and minimum river flow rates. The term MPCqj, as used in this report, refers to the continuous, occupational maximum permissible con centration for exposure of the gastrointestinal tract from ingestion of water. The MPCgi was calculated from radio-isotopic concentrations in Columbia River water at Pasco by using the method for a mixture of isotopes, as outlined in National Bureau Standards Handbook 52. November, 1957 conditions were chosen as a base which included the effects of operating changes during 1957, and had the highest average and maylmnm bulk outlet temperatures. The river flow rates for a normal and minimum flow year are illustrated in Figure 1. River flow rates change the environmental effects of reactor waste discharge considerably; in fact, the effect of minimum river flow rates are almost as great, as a 20 to 30 percent increase in reactor production. In the calculations, it was assumed that increases in production, from more coolant and higher onerating efficiency would cause a linear increase in. concentrations cf of radioactive isotopes in reactor cooling water. The production increases resulting from higher bulk outlet temperatures were assumed to produce an exponential (e^^^) increase in concentrations of the isotopes, There is only limited evidence to support the K values, but these values have been used successfully in previous predictions. 2. Drinking Water Effects Eight operating cases were considered in relation to the fraction of MPCqj in river water at Pasco. These are tabulated in Table I and shown in Figure 2. Table I and Figure 2 show that under normal river flow conditions (Cases B through G), the annual average percent of MPCqj should remain below the HAPO control limit.^7J ptie HAPO con trol limit is one-twentieth of the maximum permissible concentration for occupational exposure. Monthly maximum exposure would exceed the HAPO control limit in Case G. Case G is based on the improbable assumption that all reactors would have a bulk out let temperature of 98°C during all operating time. Comparisons of Cases B and G with A and H, respectively, demonstrates that river flow rate fluctuations can have a very significant effect on predicted GI tract exposures. Annual average exposure under Case H (minimum river flow) would slightly exceed the HAPO control limit, while the monthly maximum would be one and one-half times this limit. The annual average and monthly maximum percentages predicted for Case H would approach one-half and exposure limit, the nationally accepted limit for exposure of the general public, is "For individuals outside of controlled areas, the maximum permissible When Case F was adjusted for a minimum river flow condition, the annual average exposure was found to be just below the HAPO control limit. The monthly maximum was just over this limit. Monthly maximum exposures in Cases C and D, when adjusted for minimum river flow conditions, also remained below the HAPO control limit.

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2. Drinking Water Effects - contd FROM DRINKING COLUMBIA RIVER WATER AT PASCO Bulk Fraction of Present * Columbia River-Pasco A No Change 1.0 1.0 1.0 1.0 Minimum 1.4 2.4 B No Change 1.0 1.0 1.0 1.0 Normal 1.0 1-7 C No Change 1.1 1.05 1.10 1.16 Normal 1.3 1-9 * November, 1957 values were used as the base. ** Average and maximum Bulk Outlet Temperatures were 80°C and 88°C in Case E seems to be most probable. It is based on a ten percent increase in reactor flow rate, a five percent increase in operating efficiency, and a ten degree increase in bulk outlet temperature for a total production increase of about twenty-nine per cent. The same results are obtained if the increase in bulk outlet temperature is applied to either the present average (80°C) or the present maximum (88°C). For this case, the annual average and the monthly maximum GI tract exposures were below the HAPO control limit for normal or minimum river flow years. From 35 to 45 percent of the exposure to the gastrointestinal tract is derived from the As76 concentration in river water . A significant reduction in the concentration of As76 in reactor coolant would be very beneficial in reducing the exposure to people in the immediate environs whose source of drinking water is the Columbia River. In all eight cases considered, the exposure rates to bone, gonads, and other organs would increase, but the gastrointestinal tract would remain the critical organ. (8)

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COLUMBIA RIVER FLOW Estimated '% of Occupational MPCGI in Columbia River Water at Pasco

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Aquatic organisms concentrate radioactive isotopes from river water. The principal radio-isotope observed in fish caught from the Columbia River near HAPO is P32. Whitefish flesh contains concentrations of which have resulted in recent recommendations for restrictions on certain reactor operations, especially during the fall months when river flow is low and fish metabolism is high. P32 concentrations in whitefish would increase by a factor of 3 under the most probable reactor operating conditions (Case E). Adjustment of present p32 concentrations by this factor of 3 indicates that the con tinuous consumption of 0.2 pounds per week of whitefish flesh would result in the nonoccupational maximum permissible body burden of p32. The maximum predicted p32 concen tration (Case H) would reduce the allowable consumption to 0.1 pounds per week. This range of values compared to the national average fish consumption (0.4-h pound per week) indicates that it may be necessary to restrict fishing near the project during the fall season. The restriction of fishing would probably result in unfavorable public reaction. The predicted effect on aquatic life of temperature increases in the Columbia River from increased bulk outlet temperatures do not appear to be significant.) The pre dicted maximum additional temperature increase is about C.3°C and should not be noticeable when considering normal temperature variations in Columbia River water. The passage of hot effluent waters over salmon spawning areas could lead to deleterious effects on salmon eggs. General warming of the Columbia River would accelerate bacterial diseases of adult salmon. Here again, the predicted contribution from the proposed changes of HAPO should be slight. Other conditions not associated with Hanford tend to obscure possible effects. Sodium dichromate is added to the reactor cooling water as a corrosion inhibitor. In December, 1957, concentrations of chromate ion in the Columbia River ranged from 0.005 to 0.015 ppm. The USFES recommends a maximum permissible chromate concen tration of 0.05 ppm in water used for human consumption. Aq.uatic Biology has recom mended an upper limit of 0.02 to 0.03 ppm of chromate io&.in the Columbia River, based on studies of chemical toxicity to juvenile fish.'-5' Predicted increases in the amounts of chromate ion discharged to the river would raise the river concen trations to a maximum of 0.018 ppm at minimum river flow- It Is predicted that no demonstrable damage to Columbia River trout or salmon would result from this possible increase in the chromate ion concentrations. IV. ACCIDENTAL RELEASES TO COLUMBIA RIVER A. Methods of Release In the event of a loss of cooling water to the entire reactor, predictions Indicate that the first step would be the .formation of steam with the expulsion of water from the reactor tubes and the water system. This should occur before melting takes place so that only an insignificant portion of the total fission product burden will accompany the water expelled. In the subsequent events, the fission products should be released either to the gas system of the reactor or through the tubes to headers on the back or front face of the reactor. Here they will escape from any break in the piping to the atmosphere of the reactor building, or, if no break has occurred in the rear face piping.

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they ’/rill escaoe through the vents in the doracor;ier.':o che staoh. In either case^ the the retention basins will provide a water seal at the end of the downconer, and even fission products dissolved in this water will remain in the basin, since the basin operates as an overflow device and depends upon a continuing source of water at the inlet to maintain flow. The major effects on the river from such an incident, then, would appear to be from possible fallout from the airborne materials. Previous studies have indicated that river problems here, although of sizeable magnitude in the worst postulated case, would be minor in comparison with the more direct effects of the fallout in other regions. The possibility of an incident involving only one or several tubes is of more concern, since, in this case, the water flow through the reactor is maintained, and fission products may have direct access to the river through the retention basin. A partial block, which would maintain a small flow through the tube, would probably release a higher fraction to the effluent than one which completely stopped the flow, thus permitting pressure to build up in the tube and eventually releasing the fission products to the gas system of the reactor. We have chosen to evaluate the case of a possible flow blockage in one tube with the resultant release of fission products in the form of a "glorified rupture". The time schedules for melting of aluminum and uranium upon loss of water to a single tube have been calculated by Ekern for tube powers to 1300 KW It may be noted that, in this case, the tube will melt in the center region within about eleven seconds even if the panellit trip works. This will provide a path for the fission products to the …