ML20039F132
| ML20039F132 | |
| Person / Time | |
|---|---|
| Site: | 07000025 |
| Issue date: | 12/31/1981 |
| From: | NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| References | |
| NUREG-0867, NUREG-867, NUDOCS 8201120030 | |
| Download: ML20039F132 (50) | |
Text
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1 The Effects of Natural Phenomena i
on the Atomics International Nuclear Materials Development u
Facility at Santa Susana, California A
Docket No. 70-25 y
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5{[JAN 5193g,s j 29%y
%q,,52 U.S. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards k
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i NOTICE Availability of Reference Materials Cited in NRC Publications Most documents cited in NRC publications will be available from one of the following sources:
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The NRC Pub!ic Document Room,1717 H Street., N.W.
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The Effects of Natural Phenomena on the Atomics International Nuclear Materials Development Facility at Santa Susana, California Docket No. 70-25 Trzr zzr ate u ished e en$be 1981 Division of Fuel Cycle and Material Safety Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, D.C. 20555
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l Previous Reports in the Series This is the fif th in a series of documents to be published concerning the effects of natural phenomena on existing plutoni-um fabrication facilities. The first in the series, NUREG-0547, covered the Babcock and Wilcox Company operations at Leechburg, Pennsylvania; the second, NUREG-0621, covered the Westinghouse Electric Corporation operations at Checwick, Pennsylvania; the third, NUREG-0722, covered the Exxon Nuclear Company operations at Richland, Washington; and the fourth, NUREG-0866, covered the General Electric Company operations at Pleasanton, California.
SUMMARY
DESCRIPTION OF THE PROPOSED ACTION Part 70 of Title 10 of the Code of Federal Regulations (10 CFR 70) defines and enumerates the Nuclear Regulatory Commission (NRC) policy and procedures for the issuance of licenses for possession and use of special nuclear material (SNM).
Implicit in Sections 70.22 and 70.23 of 10 CFR 70 is a requirement that existing plutonium fabrication plants be examined with the objective of improv-ing, to the extent practicable, their abilities to withstand adverse natural phenomena without loss of-capability to protect the public.* In accordance with these regulations, the Division of Fuel Cycle and Material Safety (the staff) of the NRC initiated an analysis of the effects of natural phenomena at the Atomics. International -(AI) Nuclear Materials Development Facility (NMDF).
Following completion of the analysis, the staff has prepared a condensation of the effects of natural phenomena on the facility. The condensation, published herein, is based on information contained in or derived from the following reports, or in literature referenced in the following reports:
T.T. Fuj ita.
" Review of Severe Weather Meteorology at Rockwell International, Chatsworth, California." The University of Chicago, _
report submitted to Argonne National Laboratory under Contract No. 31-109-38-3731, 30 June 1977.
" Seismic Risk Analysis for the Atomics International Nuclear Mate-rials Development Facility, Santa Susana, California." TERA Corpora-tion, Berkley, CA, report submitted to Lawrence Livermore Laboratory, 29 December 1978.
" Assistance in Hydrologic Aspects - Analysis of the Effects of Natu-ral Phenomena on Existing Plutonium Fabrication Facilities - Atomics International."
Transmitted by memorandum from L.G. Hulman of USNRC/DSE to R.W. Starostecki of USNRC/FC,19 January 1978.
" Description of the Site Environment Around the Atomics International Nuclear Development Field Laboratory, Chatsworth, California."
Transmitted by letter from I.C. Rouse of USNRC/FC to Dr. M.E. Remley of Rockwell International, Atomics International Division, 7 May 1980.
J. Mishima and L.C. Schwendiman, Battelle - Pacific Northwest Labo-ratory, and J.E. Ayer, USNRC.
" Identification of Features Within Plutonium Fabrication Facilities Whose Failure May Have a Signifi-cant Effect on the Source Term."
16 January 1980.
- " Statements of Consideration," 10 CFR 70; and 36 FR 17573, 2 September 1971.
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K.C. Mehta, J.R. Mcdonald, and F. Alikhanlou.
" Response of Struc-tures to Wind llazard at the Atomics International Nuclear Materials Development Facility, Santa Susana, California." Texas Tech Univer-sity, Institute for Disaster Research, Lubbock, TX, August'1980.
" Structural Condition Documentation and Structural Capacity Evalua-tion of the Atomics International Nuclear Materials Development Facility at Santa Susana, California, for Earthquake and Flood, Task II - St ructu ra l Capaci ty - Evaluation." ' Engineering Decision Analysis Company, Inc., prepared for Lawrence Livermore Laboratory, April 1979.
i D.W. Pepper.
" Calculation of Particulate Dispersion in a Design-Basis Tornadic Storm from the Atomics International Nuclear Materials Development Facility, Santa Susana, California."
E.1. du Pont de Nemours and Co., Savannah River Laboratory, Aiken, SC, prepared for the U.S.
Dept. of Energy under Contract DE-AC09-76SR00001, DP-1566, July 1980.
J. Mishima and J.E. Ayer.
" Estimated Airborne Release of Plutonium f rom Atomic International's Nuclear Material Development Facility in the Santa Susana Site, California, as a Result of Postulated Damage from Severe Wind and Earthquake llazard." Battelle - Pacific North-west Laboratory, PNL-3935, August 1981.
J.D. Jaraison and E.C. Watson.
" Environmental Consequences of Pos-tulated Plutonium Releases from Atomics International NMDF, Santa Susana, California, as a Result of Severe Natural Phenomena."
Battelle - Pacific Northwest Laboratory, PNL-3950, August 1981.
J.W. Johnson.
" Risk Analysis of Postulated Plutonium Releases from the Atomics International Plant, Santa Susana, California, as a Result of Tornado Winds and Earthquakes."
U.S. Nuclear Regulatory Commission, 20 October 1981.
This summary is derived from the condensation and the above-listed reports.
Tile PROBABLE EFFECTS OF NATURAL PilENOMENA ON THE ATOMICS INTERNATIONAL NUCLEAR I
MATERIALS DEVELOPMENT FACILITY In this summary of the probable effects of damage to the Al NMDF by torna-does and earthquake, the consequence of damage is expressed as dose to several human receptors.
Although dose from the more important pathways was consid-ered, almost all the dose contribution comes from plutonium inhalation during cloud passage and resuspension of deposited material.
The highest dose to organs of interest accrues to lungs and bone.
Therefore, the dose is expressed in terms of the 50 year committed dose to lungs and bone from inhalation.
The most-likely 50 year committed dose to the nearest resident from the tornado of greatest consequence considered is 0.44 rem to lungs and 0.80 rem to bone. This consequence is caused by a tornado with a wind speed of 67 m/s and probability of occurrence of 4 x 10 7 per iv
year. The most-likely value of 50-year committed dose to the popula-tion within - 80 km (50 mi) of the plant from the same event is 330 000 person-rem to lungs and 600 000 person-rem to bone.
When this tornado occurs, the most-likely doses occur roughly 90% of the time, and there is also a probability that higher doses will occur.
The highest calculated 50-year doses to the population within 80 km are 4.9 million person-rem to lungs and 9.0 million person-rem to bone.
These highest doses occur roughly 0.25% of the time. These dose and occurrence-rate estimates have a factor of roughly 10 uncer-tainty either way (with about 90% confidence).
Hence, the quoted numbers should not be interpreted as being precise--not even to one significant figure--but should be regarded as indicating values only of about an order of magnitude.
The most-likely 50-year committed dose to the nearest resident from damage caused by the most-severe earthquake considered is 3.0 rem to lungs and 5.6 rem to bone. That earthquake has an annual occurrence rate of about 1.3 x 10 3 and also causes a most-likely 50-year com-mitted dose to the population within 80 km (50 mi) of the plant of 200 000 person-rem to lungs and 380 000 person-rem to bone. These most-likely doses occur roughly 90% of the time. The highest 80-km calculated doses are 2.6 million person-rem to lungs and 4.7 million person-rem to bone, which occur roughly 0.25% of the time. These numbers, like those given above for severe winds, have only an order-of-magnitude precision and, hence, should be interpreted as being quite imprecise.
To put the consequence from wind and earthquake hazard in perspective:
if a worker is exposed for 50 years to the maximum permissible concentration of 239pu under present limits, at the end of that time he would have the maximum-permissible body burden and would have received a dose commitment. to bone of 750 rem.
This compares with a 50-year dose commitment of 0.80 rem to bone, to the nearest resident, from wind hazard that is most likely to occur in the case of the tornado of greatest consequence evaluated, and 5.6 rem to bone of that same resident in the case of the most-severe earthquake evaluated.
In the case of population dose from these events, the moct-likely 50-year committed dose to bone of the population within 80 km (50 mi) of the plant is 600 000 person-rem from the tornado and 380 000 person-rem from the earthquake. The 50-year collective dose equivalent to the total body from natural-background radiation, to the same population, is estimated at 28 million person-rem. Thus, the most-likely population dose to bone from the tornado or earthquake hazard is about 2% of the total-body dose from natural-background radiation. Of course, there are unlikely events that result in significantly greater doses, as described earlier.
The unlikely events causing the greatest doses have probabilities that are reduced by a factor of roughly 400 compared with the most-likely event.
The doses that result from facility damage due to severe weather and earthquake, when multiplied by the occurrence rate for the initiating event, yield the yearly risk.
(Risk, as defined here, is the statistical average consequence.
It should be recognized that many other definitions can be used of which incorporate public aversion to high-consequence for " risk," some accidents.)
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The greatest. risk from the severe weather considered is attributed to the tornado with a 67-m/s wind speed.
The most-likely radiological risk to the population within 80 km (50 mi) of the AI NMDF from this event is estimated to be 120 person-mrem /yr to the lungs and 220 person-mrem /yr to bone. This com-pares with an absolute risk of about 570 million person-mrem /yr from natural-background radiation to the total body of the same population. Similarly, the i
most-likely cadiological risk to the resident nearest the NMDF from the 67-m/s tornado is about 2x 10 4 mrem /yr to the lungs and 3 x 10 4 mrem /yr to bone.
From natural-background radiation the nearest resident receives an annual dose rate of 80 mrem /yr to the total body. The above comparisons are conservative in that they all neglect that the consequence component of risk from natural phenomena is the 50-year dose commitment, whereas from natural-background radi-ation it is the annual dose.
The most-likely' radiological risk from earthquake to the population within 80 km (50 mi) of the NMDF is about 230 person-rem /yr to the lungs and 440 person-rem /yr to bone.
The nearest resident would risk 3.5 mrem /yr to the lungs and 6.6 mrem /yr to bone from the same event. As discussed above, the consequence term of risk is the 50-year dose commitment.
The staff also analyzed the site from the standpoint of hazard due to flooding.
This analysis showed that neither the probable-maximum flood nor the probable-maximum precipitation poses a threat to the processed plutonium.
further consideration was given to deriving dose or risks asso-Therefore, no ciated with a flooding event.
RESULTS OF THE EFFECTS OF NATURAL PHENOMENA ON TIIE ATOMICS INTERNATIONAL NUCLEAR MATERIALS DEVELOPMENT FACILITY One of the aims of the analysis is to examine the plant with the objec-tive of improving, to the extent practicable, its ability to withstand adverse natural phenomena without loss of capability to protect the public. A judgment derived f rom structural analysis was that extensive structural modification to the plant would be necessary to prevent collapse as a result of the postulated earthquake.
The relatively small risk to the public from the unlikely events previously discussed would indicate that the public is not seriously threatened by the presence of the Al NMDF.
Thus, it is the judgment of the staff that the benefits to be gained by substantial plant improvements to further mitigate against adverse natural phenomena are not cost effective.
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F CONTENTS Page
SUMMARY
iii LIST OF FIGURES.
viii LIST OF TABLES ix 1.
INTRODUCTION I
1.1 Preface I
1.2 Technical Analysis.
I 1.2.1 Severe-Weather Event 2
1.2.2 Earthquake.
2 1.2.3 Flood 2
1.3 Results 2
2.
SITE CHARACTERIZATION.
5 2.1 Severe-Weather Meteorology.
5 2.1.1 Straight-Line Winds 5
2.1.2 Tornado Frequencies 6
2.1.3 Summary and Conclusions 8
2.2 Seismic Analysis.
8 2.3 Hydrologic Analysis 9
2.4 Ecological Character.
10 2.4.1 Topography and Land Use 10 2.4.2 Regional Demography 11 2.4.3 Flora and Fauna 11 2.4.4 Climatology and Meteorology 12 3.
STRUCTURAL ANALYSIS.
13 3.1 Areas of Concern.
14 3.2 Structural-Condition Documentation.
16 3.3 Response of Structures to Natural Phenomena 16 3.3.1 Wind Hazard 16 3.3.2 Seismic Hazard.
19 4.
SEVERE-WEATHER DISPERSION.
21 4.1 Tornado Structure 21 4.2 Dispersion in a Tornadic Storm.
23 5.
RELEASES 25 l
6.
DOSE TO MAN.
26 6.1 Environmental Exposure Pathways for Plutonium 26 6.2 Radiation-Dose Models for an Atmospheric Release 26 f
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CONTEBCES Page 29 6.3 Radiation Doses 29 6.3.1 Earthquakes 6.3.2 Tornadoes 31 31 6.4 Discussion.
7.
RISK ANALYSIS.
32 35 REFERENCES FIGURES No.
1 Flow Diagram for Severe-Weather Aspects of Analysis 3
2 Flow Diagram for Seismic Aspects of Analysis 4
3 Atomics International Site and Vicinity.
5 4 Cumulative Number of Tornadoes as a Function of Distance from 6
the Atomics International Site 5 Probabilities of Straight-Line and Tornado Winds vs. Wind Speed 7
at Atomics International 6 Return Period vs. Peak Acceleration at Atomics International 9
10 7 Map of the Al Site and Surroundings Within 8 km........
8 Schematic Diagram of Tornado Model DBT-77.
22 9 Pressure Field Inside the Model Tornado 23 10 Maximum Ground-Level Centerline Air Concentration from 25 Initialization Point in Storm.
11 Significant Potential Exposure Pathways Through Which People May Be Exposed from an Accidental Release of Plutonium 28 12 Complementary Cumulative Distribution for Dose to Lungs of 33 Population Due to Damage from Tornadoes 13 Complementary Cumulative Distribution for Dose to Lungs at the Nearest Resideuce Due to-Damage f rom Tornadoes 33 14 Complementary Cumulative Distribution for Dose to Lungs of 34 Population Due to Damage from Earthquake 15 Complementary Cumulative Distribution for Dose to Lungs at the Nearest Residence Due to Damage from Earthquake
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l TABLES No.
Page 1 Population Distribution Within 80 km of the AI Site in 1980.
11 2 Annual Average Relative Concentrations 14 3 Five Percentile Short-Term Relative Concentrations 15 4 Fifty Percentile Short-Term Relative Concentrations.
15 5 Source-Term Estimates for the AI NMDF Due to Wind and Earthquake Hazard..
27 6 Isotopic Composition of the Plutonium Mixture.
29 7 Fifty-Year Best-Estimate Committed Dose Equivalents from Inhalation Following Severe-Wind and Earthquake Events 30 8 Best-Estimate Maximum Plutonium Deposition at Significant Locations 30 9 Phenomena Probability and Associated Uncertainties 32 10 Risk to Nearest Resident and Nearby Population from Postulated Damage Due to Natural Phenomena 35 ix
THE EFFECTS OF NATURAL PHENOMENA ON THE ATOMICS INTERNATIONAL NUCLEAR MATERIALS DEVELOPMENT FACILITY i
AT SANTA SUSANA, CALIFORNIA 1
1.
INTRODUCTION i
1.1 PREFACE 1 The regulations that establish procedures and criteria for the issuance of licenses to possess and use (and, thereby, fabricate) special nuclear mate-rials (SNM) are contained in Title 10 Part 70 of the Code of Federal Regula-tions, commoaly denoted as 10 CFR 70.
In part, 10 CFR 70 describes the content of license applications and supporting documents and requirements for approval of applications and issuance of licenses. Due to a change in the regulations.
i that became effective on 2 September 1971, applications for licenses to possess and use SNM in a plutonium fuel fabrication plant are required to contain a description and safety assessment of the design bases of the principal struc-ture, systems, and components of the plant, including provisions for protection against natural phenomena. Therefore, facilities for which the license appli-cation was filed after 2 September 1971 must be designed to provide protection against natural phenomena. This was not a requirement for facilities of this type that were licensed earlier.
4 Specific address to the problem of existing facilities and protection against the effects of natural phenomena was contained in the required pre-amble to the rulemaking that became effective on 2 September 1971. The State-ments of Consideration stated that existing licensed plutonium fabrication plants would be examined with the objective of improving, to the extent prac-ticable, their abilities to withstand adverse natural phenomena without loss of capability to protect the public. The U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Material Safety and Safeguards has started the exami-nation of existing licensed plutonium fabrication plants.
This summary de-scribes the analyses that support the examination and conclusions reached rel-ative to the Atomics International (AI) Nuclear Materials Development Facility (NMDF) at Santa Susana, California.
1.2 TECHNICAL ANALYSIS
Experts in the fields of seismology / geology, surface hydrology, normal-and severe-weather phenomena, structural analysis, source-term cha acteriza-tion, meteorological dispersion, demography, ecology, and radiological impact have been engaged.in the analyses.
These experts, assembled in teams, have
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reviewed the facility and provided a realistic assessment of the range of
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credible consequences of natural phenomena and the likelihood thereof.
l 1.2.1 Severe-Weather Event l
The site has been described with respect to credible severe weather.
Tornado frequency of occurrence by Fujita scale on a historic, statistical basis constitutes the basic input to the review process.
Severe-weather characterization includes recurrent high-velocity nontor-nadic winds that can have more serious consequences than tornadoes in the event of breach of confinement. Severe-weather characteristics are translated into transient and steady-state forces for application to structural analysis that determines the response of structure and confinement to storm-induced forces.
Source terms and estimates of rate of release and quantity of material avail-able for dispersion are estimated for each postulated breach of confinement.
Analysis of dispersion, airborne concentration, and deposition by and from severe weather is coupled with demographic and land / water-use data to permit assessment of radiological impact of releases. Figure 1 is a graphic depiction of the input / output information flow from reviewer to reviewer in the analyti-cal chain associated with the determination of the consequences of the severe-weather event.
1.2.2 Earthquake i
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For the seismic event, ground motion at the plant foundation is provided j
as input for the structural and component analysis. Response of the structure and confinement to seismic forces has been determined. For the event of breach
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of confinement, a description of the expected damage was provided to an expert j
on aspiration and levitation of heavy-metal compounds who estimated the rate of release and quantity of material available for dispersion. A meteorologist estimated deposition and airborne concentrations, which--when coupled with demographic and land-and water-use data-permitted an assessment of the radio-logical impact on man and his environment. Figure 2 is a schematic diagram of the flow of information that took place during the review of the consequences of seismic events.
1 1.2.3 Flood The plant site has been characterized with respect to flooding potential.
l The NMDF is not subj ect to flooding from a probable-maximum flood on a small stream adjacent to the site.
Overland flow from a local probable-maximum pre-cipitation would not exceed 150 mm (6 in) at the building. The results of the flooding analysis precluded further analytical work from the standpoint of hydrologic risk.
l 1.3 RESULTS l
The completed work provides a description and safety assessment of the design of the principal structures, systems, and components of the plant with l
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3 For Each Recurrence Interval Estimate Wind Speed Characterization of High in Upper Cloud Layers Cherector-Velocity, Non Tornedic ~
Vs. Height & Energy iration Winds & Their Return Dissipation RetesW/in intervals i
Storm Cell T
l Recurrence Interval Vs.
l Max. Wind Speed, Radius of Max. Wind & Max. AP/At For Tornadic Winds Structurb m Analysis t
Bldg. Response; Roof, Well, Freme, Glove Box,
& MechanicalSystem Damage W/ Estimate of Error Bonds f
i Source Term i
i r Quentity, Rats & Characteristics of Releases From Structures: Wet
& Dry Deposition Velocities; Meteorology Height (Location) of Releases Wind Rose, Site & Environs Tornadic Climatology, Wind Stability, Dispersion Short Term Meteorology Dets.
Avg. Annual X/Q & Conc.of f
Airborne Material Ground Level Centerline Concentration Vs. Downwind Distance & Tinu, Concentration Demography Width Profiles Vs. Distance &
Trajectory of Pollutant Cloud t
i Site Description, Ecology
[ Dose Local & Distant Demography, I
Calculation
& Land Use Patterns t
Done to Max. individual / Population Via Direct Exposure, Estimated Potential Environmental Contam-instion, Estimeted Potential Dese to Max. individuel/ Population Via ladirect Exposure Vs. Event Recurrentlaterval Figure 1.
Flow Diagram for Severe-Weather Aspects of Analysis of the Effects of Abnormal Natural Phenomena on Operating Plutonium Fabrication Facilities.
4 eismic C ac r-g,,,,;,,
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Recurrence Interval Vs.
Y "g" Value to Bedrock & Plant Maintain Uniformity Foundation, Time History of of Treatment of Seismic, Acceleration, & Site Hydrologic, & Severs Ground Period weather Event r
Structural Analysis Bldg. Response Major Cracking, Collapse: Glove Box
& Mechanical System Damage W/ Estimate of Uncertainties Source Term Quantity, Rate & Characteristics Demography of Releases From Structures, Wet Meteorology
& Dry Deposition Velocities,
& Point of Release f
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Wind Rose, Site & Enviruns Loca Dis n Demog phy Dose Climatology, Wind Stability
& Land Use Patterns Calculation j' Short Term & Annual Avg. Meteorology
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Data, Avg. Annual X/Q,& Conc.of Airborne Material Dose to Max. Individual / Population Via Direct Exposure, Estimated Potential Environmental Contamination, Estimated Potential Dose to Max.
Individual / Population Via Indirect Exposure Vs. Event Recurrence Interval Figure 2.
Flow Diagram for Seismic Aspects of Analysis of the Effects of Abnormal Natural Phenomena on Operating Plutonium Fabrication Facilities.
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respect to its ability to withstand the effects of natural phenomena. The results include an assessment of the consequences to the public and the envi-ronment of exposure of the plant to potentially damaging natural phenomena.
This analysis is a part of both the safety assessment and the environmental review that normally precedes a licensing action.
This is consistent with both Part 51 and Sections 10 CFR 70.22 and 10 CFR 70.23 of the regulations that establish procedures and criteria for the issuance of licenses to possess and use SNM.
The analysis and results provide a basis for determining the modifications, to the extent practicable, necessary to improve the existing plant's ability to withstand adverse natural phenomena.
2.
SITE CHARACTERIZATION 2.1 SEVERE-WEATHER METEOROLOGY 2 The AI NMDF is located in the southern portion of the State of California in the Simi Hills of southeastern Ventura County. The site consists of about 120 ha (290 acres) on Burro Flats at about 550 m (1800 f t) MSL, as shown in Figure 3.
The geographical coordinates are 34* 15' N Lat. and 118* 43' W Long.
Both straight-line winds and tornadoes are considered in arriving at wind-hazard probabilities for the site.
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Figure 3.
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Atomics International Site e==
o*'-
- and Vicinity.
(Contour e
ewwubo lines are given in feet M
-% N MSL.)
(1000 ft = 300 m; 7
S 10 mi = 16 km.)
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2.1.1 Straight-Line Winds For straight-line winds, the probabilities were determined by combining the observation years for the period 1950-1975 at three stations: Burbank,
6 Los Angeles City, and Los Angeles Airport (normalized to the city). For the 68 observation-years the annual extreme wind speed of the fastest-mile wind j
was 21.5 m/s (48 aph), occurring at the Los Angeles City (Civic Center) station in 1959.
Seasonal variation of the occurrences of maximum wind speeds shows that these occurrcaces are centered during cold months when Santa Ana wind con-ditions occur in southern California. The fastest-mile wind speed of the year has not been recorded in the months of May through September. The fastest-mile wind speed of 11 m/s (24 mph), or a corresponding peak gust of 13.5 m/s (30 mph), occurred in every year in the period of record. Wind speeds of peak gusts are higher than those of the fastest-mile winds because the duration of the peak gust is considerably shorter than that of the fastest-mile wind. The peak gust is defined as 25% greater than the fastest-mile wind speed.
In about half the years of the 68. observation-year record, fastest-mile wind speeds greater than 15.5 m/s (35 mph) and corresponding peak gusts of 20 m/s (44 mph) were posted.
2.1.2 Tornado Frequencies During the 26 years,1950-1975, 23 tornadoes were reported to have taken place within 230 km (144 mi) of the AI NMDF site. The average frequency was 0.9 tornado per year regardless of tornado site or intensity. Because of the proximity of the site to the Pacific Ocean, increasing ' distance from the facil-ity encompasses proportionately larger water surface.
In recognition of this, the numbers of tornadoes vs. distance from the AI NMDF have been prorated to show the tornado frequency as if the entire area within any range of the site had no water areas. Figure 4, which is based on data from the National Severe Storms Forecast Center (NSSFC), shows the distribution of tornadoes vs.
distance from the AI NMDF for both actual and prorated cases.
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Figure 4.
so Cumulative Number of Tornadoes N, = 0.29 R as a Function of Distance from
[*
the Atomics International (water oreo prorated)
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Site.
(Based on 23 tornadoes
,o on the NSSFC tape -- 1950-75.)
q (100 mi = 160 km.)
v N = 0.19 R A
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- RANGE IN MILES
7 With a mean damage path of 19 of the tornadoes on the NSSFC tape with 2
2 known path characteristics of 0.024 km (o,oi mi ) per tornado, the estimated 2
2 total damage area for the 23 reported tornadoes is 0.6 km (0.23 mi ).
The probability of any point within a radius of 230 km (144 mi) experiencing any tornado damage is 2.21 x 10 7 per year.
Reported tornadoes since 1950 were used to compute tornado-hazard probability. The recommended probabilities are shown in Figure 5.
The figure shows tornado-hazard probabilities as a function of wind speed.
0 50 10 0 ISO 200 250 mph
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STRAIGHT-LINE WINDS 48 STATES PEAK GUST from 5
(SELS LOG 1955-72) gg' Figure 5.
Probabilities of Straight-k Line and Tornado Winds vs.
ggi Wind Speed at Atomics
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International.
(The probability of straight-line gusts is higher than ig.
that of tornadoes at wind I
speeds less than 90 mph.
B Above 90 mph, the proba-bility of tornado winds 10-*
exceeds that of straight-I I
line winds.)
(100 mph
= 45 m/s.)
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TORNA DOES
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The Damage Area' Per Path Length (DAPPLE) method was used to compute the
. tornado-hazard probabilities within given distances of the AI NMDF site.
Practically no surveys for DAPPLE are available for California tornadoes, so DAPPLE values.obtained from 174 Midwestern tornadoes in the "superoutbreak" of 3-4 April 1974 were used to represent the California tornadoes. The use of
8 these values overestimates usually larger than California tornadoes.the damage areas because Midwestern tornadoes are
{
However, the degree of overestima-tion may be offset by the effects of low reporting efficiency that results from factors such as the weakness of California tornadoes and relative lack of public awareness.
A 160-km (100-mi) radius was selected for assessment of the tornado risk applicable to the AI NMDF site.
2.1.3 Summary and Conclusions Results of the foregoing computations of wind-speed probabilities are summarized in Figure 5, which includes three curves applicable to the AI NKDF:
(1) Probability of fastest-mile wind speed, (2)
Probability of peak gust (assumed to be 1.25 times the fastest-mile wind speed), and (3)
Tornado probability within the 160-km (100-mi) range.
The figure reveals that the speeds of straight-line winds are higher than those of tornado winds when the probability is greater than about 10 6 year.
Tornadoes become per important when the probability decreases below 10 8 2.2 SEISMIC ANALYSISa A detailed seismic-risk analysis of the AI NMDF site at Santa Susana, California, has been completed.
To ensure credible results, sophisticated but well-accepted techniques were employed in the analysis.
The calculational method that was used has been previously applied to safety evaluations of major p roj ects.
The historical seismic record was establishe1 after a review of available literature, consultation with operators of local seismic arrays, and examina-tion of appropriate seismic-data bases including those of the U.S. Geological Survey, the California Institute of Technology, and the National Earthquake Information Service.
Input to the probabilistic seismic-risk assessment is comprised of earth-quake occurrence frequency relations, attenuation functions, and specification of local source regions. Earthquakes in the source region containing the site dominate the risk at the site; thus, particular attention was directed to the validity of the statistics associated with this region.
Paramount to the seismic analysis is the specification of attenuation, or decay of peak accel-eration, with distance from the earthquake.
was developed that considered data Therefore, an attenuation relation to estimate the far-field attenuation, data at aboutin the range of 20 to 100 km (12 to 60 mi) 10 km (6 mi) to fix near-field trends, and data within 10 km to establish very-near-field accelerations.
These input data were used to calculate, for circular sectors within each source region at the site, the expected annual number of earthquakes producing accelerations greater than a specified value for each source region.
The expected numbers are summed for each region and the resulting risk calculated.
}
Uncertainties in the input were explicitly considered in this analysis.
l For example, allowance was made for uncertainty in predicting the maximum-
9 possible earthquake in each source zone, the magnitude of the data dispersion I
about the mean acceleration-attenuation relationship, and the recurrence rela-tion for the source region containing the site.
The results of the risk analysis, which include a Bayesian estimate of the uncertainties, are expressed as return period vs. acceleration in Figure 6.
The best-estimate curve indicates that the AI facility will experience 0.3 g every 55 years and 0.6 g every 750 years. The bounding curves roughly repre-sent one-standard-deviation confidence limits about the best estimate, reflec-ting uncertainty in certain portions of the input.
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Return Period vs. Peak Accelera-
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2.3 HYDROLOGIC ANALYSIS The AI NMDF site has been reviewed with respect to potential flooding up to and including the probable-maximum flood (PMF). The NMDF is not subject to flooding from a PMF on the adjacent small stream. Overland flow from a local probable-maximum precipitation (PMP) would not exceed 150 mm (6 in) at the building unless unusual drainage features exist adjacent to the building.
Thus, the low likelihood of occurrence of either the PMF or the PMP, combined with the absence of threat to in-process plutonium, dictate against further consideration of radiological risk due to flooding of the NMDF site.
10 2.4 ECOLOGICAL CHARACTERS 2,4.1 Topography and Land Use The NMDF is located at 556.0 m (1824 ft) MSL in the Simi Hills of south-eastern Ventura County, about 8 to 10 km (5 to 6 mi) west of Canoga Park and about 47 km (29 mi) northwest of downtown Los Angeles.
The site comprises about 120 ha (290 acres) of varying topography in a relatively iso. lated moun-tain setting. The neared communities are in the Simi Valley about 5 km (3 mi) north of the site.
Immediately adjacent to the site is the Rocketdyne Santa Susana Field Test Laboratory. A map of the Al facilities and surroundings is shown in Figure 7.
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p 7N k"~' N Map of the AI Site and b5 Surroundings Within 8 km y
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The Simi Hills have never supported intensive farming or development be-cause the terrain is too rugged and rocky.
Consequently, about 73% of the area within an 8-km (5-mi) radius of the NMDF is undeveloped.
Where farming is carried out, sweet corn and hay appear to be the primary crops; however, truck farms exist in the Simi Valley 5 km (3 mi) north, and in the Thousand Oaks area 15 km (9 mi) southwest, of the site. Dense residential development begins in the San Fernando Valley about 6 km (3.5 mi) east of the NMDF where, homes are rapidly replacing the farms previously located there.
Reservoirs existing near the site are used primarily for irrigation, flood control, and recreation.
Chatsworth Re:iervoir, about 6.5 km (4 mi) east of the site, is currently dry, and it is expected to remain so until a decision is made and implemented to replace the present earthen dam with a required
11 l
reinforced-concrete structure. Supplemental city-water supplies are drawn from the Van Norman and Encino Reservoirs, both 13 km (8 mi) from the NMDF, to the east-northeast and southeast, respectively.
2.4.2 Regional Demography The 1980 projected population distribution within 80 km (50 mi) of the NMDF is shown in Table 1.
About 110 000 persons are estimated to live within an 8-km (5-mi) radius of the NMM; the nearest resident lives 2.1 km (1.3 mi) from the site.
Table 1.
Population Distribution Within 80-km of the AI Site in 1980 Distance (km)
Sector 0-1.6 1.6-3.2 3.2-4.8 4.8-6.4 6.4-8 8-16 16-32 32-48 48-64 64-80 N
0 4
690 3 642 8 694 210 1 150 535 781 304 NKE O
O 86 4 002 1 153 131 2 161 870 825 822 EE O
O 115 4 318 3 310 7 045 11 572 21 662 5 220 41 587 ENE O
O 0
676 820 4 277 47 051 4 338 4 000 18 925 E
O O
O 892 5 613 22 408 341 737 188 251 147 971 89 996 ESE O
O 0
72 9 644 65 555 272 816 811 904 1 075 509 834 921 SE O
O 58 303 7 774 32 012 50 693 585 C58 1 042 501 811 545 SSE O
20 14 0
360 2 384 10 165 0
38 612 12 422 E
O 0
0 29 130 1 465 1 912 0
0 0
SSW 0
0 0
0 2 995 3 604 2 928 0
0 0
SW 0
0 0
0 892 6 871 3 194 0
0 0
WSW 0
0 0
0 0
35 903 19 615 37 196 0
0 W
0 0
0 0
0 5 809 33 993 158 872 26 144 0
WNW 0
0 0
2 692 4 644 1 778 11 548 22 460 24 688 13 578 NW 0
43 4 894 9 961 9 356 1 740 5 731 5 856 793 117 NNW 0
0 4 606 12 666 3 527 13 7 116 54 69 1 018 Annular totals 0
67 10 463 39 253 53 932 191 205 824 182 1 837 156 2 367 113 1 825 235 Grand total 7 153 606 2.4.3 Flora and Fauna 2.4.3.1 Terrestrial The natural vegetation of the Simi Hills is chaparral, a plant community of very dense vegetation of broad-leaved evergreen shrubs, dominated by either chamise, or manzanita, and California lilac; numerous other shrub species are subdominant.
In the past much of the Simi Hills crest was semibarren, whereas the crest and the remaining upland areas were covered by chaparral dominated by chamise chaparral or coastal sagebrush. Open geasslands occurred primarily on the lower southeast slopes, and oak woodland appeared only in the canyons near ephemeral streams.
12 Currently, most of the Simi Hills area is dominated by an oak woodland with undergrowth of grass or sage species. Canyon vegetation is dominated by shrub willow, California bay, and broom; no oaks are evident.
The chamise chaparral has evidently been replaced by oak woodland, suggesting that success at fire-suppretsion activities has allowed the fire-tolerant chaparral vegeta-tion to be replaced by the less fire-tolerant oaks and sages.
Animals of rural cismontane coastal areas would likely be present at the Simi Hills site as well as would animals characteristic of the coastal sage, chaparral, and oak woodland.
These include mule deer, gray fox, and bobcat; several kinds of rodents; quail and scrub jays; smaller birds of the tit and wren variety; and various reptiles including lizards and rattlesnakes.
2.4.3.2 Aquatic Because there is no natural surface water at the NMDF site, there are no resident populations of aquatic biota.
Bell Canyon, although containing flowing water during periods of heavy rainfall (December through March), is merely a dry natural channel during most of the year. Therefore, it does not sustain a permanent population of aquatic biota.
There is no information available on aquatic biota that may be present in Bell Canyon during periods of flow.
2.4.4 Climatology and Meteorology 2.4.4,1 Climatology The climate of the Los Angeles Basin is Mediterranean, with hot, dry summers and mild winters with light to moderate precipitation.
The local climate is controlled by the position and strength of the semipermanent high-pressure center in the northeastern Pacific Ocean and its subsidence inversion, the local topography, and the distance from the ocean.
In summer, the Pacific high-pressure center controls airflow over the basin and prevents rain-producing weather systems from entering the area.
Summer weather is typically a succession of clear, cool nights and hot, sunny days with light to moderate winds and no rain.
Sea breezes frequently affect the NMDF site and moderate afternoon temperatures.
In winter, the high pressure center weakens and moves to che south and west; thus, fronts and wave cyclones originating over the Pacific Ocean can enter the area and produce periods of clouds, rain, northerly to northwesterly winds, and occasional strong winds. Most rainfall la the area result of this frontal activity, but year-to-year variations of rainfall is a are large.
No long-term temperature or precipitation data are collected at or near the site.
The long-term climatological data for Burbank, California, about considered representative of 25 km (15 mi) east-southeast of the site, are onstte conditions. The Burbank Airport elevation is 213.0 m (699 ft) MSL, and the NMDF elevation is 556.0 m (1824 ft) MSL. The normal annuus temperature at l
the airport is 17.6 C (63.6 F); monthly normals vary from 11
'*C (53.6 F) in January to 23.4 C (74.1 F) in August. Normal annual precipitation is 369 mm (14.53 in); mcnthly precipitation ranges from a t race (1ers than 0.25 mm or 0.01 in) in July to 82 mm (3.22 in) in February.
l
13 The NMDF is usually above the base of the subsidence inversion associated with the Pacific high pressure ridge (whereas the Burbank Airport is not),
resulting in lof ting-type dispersion conditions.
The vertical stability of the inversion layer prevents the mixing of materials released above it downward into the basin.
In summer, local wind patterns generally are determined by the effects of local topography and diurnal heating and cooling. Up-valley, up-slope winds along the south slope of the Simi liills result in light southeast winds in the morning at the site. Modified maritime air often covers the site as a result of sea-breeze currents in the af ternoon. During the night, radiation cooling leads to light down-canyon, down-slope winds.
Santa Ana winds are frequent (about 21% of all hours) at the site and are caused by centers of high pressure to the north and northeast of the site.
Winds at the site during Santa Ana conditions are typically from the northeast and usually are quite strong.
In 1976, all but 2 of the 191 hours0.00221 days <br />0.0531 hours <br />3.158069e-4 weeks <br />7.26755e-5 months <br /> with wind speeds greater than 8.7 m/s (17 kt) at the site occurred during Santa Ana con-ditions. A gust of 31.9 m/s (62 kt) was recorded at the site during Santa Ana conditions.
2.4.4.2 Dispersion Meteorology The average annual relative-concentration (x/Q) and relative-deposition (D/Q) values for the AI NMDF were calculated using one year (1976) of wind-speed and -direction data collected at the AI facility on Simi Ridge, synthe-sized stability-classification procedures, and the XDQDOQ model developed by the NRC.
Table 2 provides X/Q values at selected distances for 16 directions from the plant for continuous ground-level releases.
The model includes an allowance for plume meander during light winds and stable atmospheric conditions.
The accident-case (short-term, up to 2-h) relative concentrations have been computed, using the onsite meteorological data and the NRC accident dis-persion model, and are given in Tables 3 and 4.
The model is direction depen-dent and calculates the X/Q values out to a distance of 5 km (3 mi) immediately following the natural destructive event.
The calculation computes the X/Q values that are exceeded 5% and 50% of the time as a function of distance and direction. This model also includes allowance for plume meander during light-wind and stable atmospheric conditions.
3.
STRUCTURAL ANALYSIS The analysis of the response of structures that house plutonium-handling operations at the AI NMDF site was done in several steps. The features with-in the facility, the failure of which may have a significant effect on the quantity of material released, were identified for analysts who were involved in assessing the structural responses of the plant and its equipment. The present structural condition was documented to provide the engineering basis for subsequent structural evaluations.
Finally, the structural response of the building and its components was expressed in terms of threshold values of
14 3
Table 2.
Annual Average Relative Concentrations (s/m )
Based on Continuous Ground-Level Release and One Year of Onsite Meteorological Data, AI NMDF, Chatsworth, California Distance (ka)
Sector 0.8 1.6 3.2 6.4 16 40 80 N
5.9-6tl 1.8-6 6.3-7 2.4-7 7.0-7 2.2-8 9.4-9 NNE 4.0-6 1.2-6 4.2-7 1.6-7 4.6-8 1.5-8 6.2-9 KE 2.5-6 7.5-7 2.5-7 9.2-8 2.7-8 8.5-9 3.6-9 ENE 2.0-6 6.0-7 2.0-7 7.5-8 2.2-8 6.9-9 3.0-9 E
1.5-6 4.6-7 1.6-7 5.8-8 1.7-8 5.4-9 2.3-9 ESE 1.5-5 4.5-6 1.6-6 5.9-7 1.7-7 5.4-8 2.3-8 SE 2.8-5 8.7-6 3.0-6 1.1-6 3.3-7 1.0-7 4.5-8 SSE 1.6-5 5.1-6 1.8-6 6.7-7 2.0-7 6.2-8 2.6-8 5
5.1-6 1.6-6 5.6-7 2.1-7 6.2-8 1.9-8 6.3-9 SSW 3.3-6 1.0-6 3.5-7 1.3-7 3.8-8 1.2-8 5.2-9 SW 1.7-6 5.1-7 1.7-7 5.8-8 1.6-8 5.2-8 2.3-9 WSW 3.9-6 1.2-6 4.2-7 1.6-7 4.6-8 1.4-8 6.2-9 W
6.1-6 1.9-6 6.8-7 2.6-7 7.6-8 2.4-8 1.0-8 WNV 3.8-5 1.2-5 4.1-6 1.5-6 4.6-7 1.4-7 6.1-8 NW 6.9-5 2.2-5 7.5-6 2.8-6 8.4-7 2.6-7 1.1-7 NNV 3.7-5 1.2-5 4.0-6 1.5-6 4.5-7 1.4-7 6.0-8 18 Scientific notation:
5.9-6 = 5.9 x 10 8 wind-speed and ground-shaking levels necessary to produce postulated damage.
The following sections summarize the above steps.
6 3.1 AREAS OF CONCERN The consequence of concern in this study is the generation and release of an aerosol composed of particles of about 5-pm aerodynamic equivalent diameter (AED).*
In the Al plant finely divided Pu02 Powders are starting materials.
Powders are of more concern because, under comparable conditions, less work is required to aerosolize a highly subdivided material than is required for bulk solids and liquids. The areas of principal concern are glove boxes where large quantities of Pu-bearing powder are free in the glovebox atmosphere at some point in the process (i.e. during pouring, weighing, sieving, etc.).
The specific features that warrant individual attention at each location where dispersible plutonium compounds are held in significant quantities were identified, as were other features that may contribute to plutonium release through interaction or secondary effects.
- A particle exhibiting the aerodynamic behavior of a unit-density sphere of the stated size.
I 1
I
15 Table 3.
Five Percentile Short-Term (2-h) 3 Relative Concentrations (s/m ) for the Al NMDF, Chatsworth, Californiatl Distance (km)
Sector 0.15 0.5 1
2 5
1 2
N 1.4-2t 1.7-3 5.9-4 3.3-4 1.6-4 NE 6.8-3 8.4-4 3.0-4 4.0-5 6.0-5 E
2.9-3 4.5-4 1.0-4 6.6-5 2.4-5 SE 2.8-2 3.5-3 1.2-3 7.5-4 4.8-4 S
1.3-2 1.6-3 5.5-4 3.0-4 1.4-4 SW 3.7-3 4.9-4 1.7-4 8.0-5 3.4-5 W
1.4-2 1.7-3 6.2-4 3.4-4 1.7-4 NW 3.8-2 4.6-3 1.6-3 1.0-3 7.2-4 t1 Based on one year (1976) of ensite meteorological data and the short-term dispersion model described in !!egulatory Guide 1.145, U.S. Nuclear Regulatory Commission.
12 Scientific notation:
1.4-2 = 1.4 x 10 2, Table 4.
Fif ty Percentile Short-Term (2-h) 3 Relative Concentrations (s/m ) for the AI NMDF, Chatsworth, Californiatl Distance (km)
Sectoc 0.15 0.5 1
2 5
2 N
1.9-3t 2.2-4 1.2-5 2.2-5 3.5-6 NE 7.0-4 6.9-5 2.0-5 5.5-6 1.0-6 E
1.5-3 1.7-4 5.6-5 1.2-5 3.5-6 SE 8.0-4 1.0-4 3.5-5 1.1-5 2.0-6 S
9.0-5 8.2-5 2.4-5 7.2-6 2.0-6 SW 2.0-4 2.1-5 5.9-6 1.7-6 3.7-7 W
5.3-3 6.4-4 2.0-4 1.4-4 5.6-5 NW 3.5-3 4.0-4 1.3-4 6.5-5 2.7-5 t1 Based on one year (1976) of onsite meteorological data and the short-term dispersion model described in Regulatory Guide 1.145, U.S. Nuclear Regulatory Commission.
2 f
Scientific notation:
1.9-3 = 1.9 x 10 3
16 7
3.2 STRUCTURAL-CONDITION DOCUMENTATION The purpose of this effort was to document the present condition of the AI NMDF to provide the engineering basis for subsequent structural evaluations.
The documents related to the original design and construction of the building structure and critical equipment components were surveyed, including the following:
(1) Construction drawings and specifications, (2) Design computations, (3) Codes and standards in c#fect at the time of design, (4) Soils reports and other
- levant soils data, and (5) Test data and/or material specifications on materials used in construction.
It was necessary for structural engineers to conduct an extensive site inspection to field check the construction plans and to obtain details on con-nections and other information that were not shown on the plans.
The areas that were structurally evaluated were those identified as areas of concern.
However, the areas adjacent to those listed were investigated to identify their effects on the critical areas.
The results of the construction-data review, facility inspection, and structural-data organization were documented in a form that was used in sub-sequent evaluations.
The following information was given in the report and shown on schematic plans:
(1) Line drawings showing plans and sections; (2) Connection details between building elements; (3) Member properties; (4) Masses (based on a detailed weight takedown);
(5) Construction details; (6) Equipment locations, support details, and connecting pipes, ductwork, etc.;
(7) Any recommendations for materials testing and/or additional probing inspections; and (8) Summary of soils data.
3.3 RESPONSE OF STRUCTURES TO NATURAL PHENOMENA 3.3.1 Wind Hazards Damage scenarios for selected probabilities of occurrence of wind speed were established from the threshold values of wind speed for various calculated failure modes.
Four damage scenarios for selected wind-speed values are pre-sented to establish a trend of increasing damage with diminishing probability of occurrence. The specific wind-speed values chosen provide a gradation from minimum damage to extensive damage to the areas of concern in the AI NMDF.
The wind-speed range associated with each damage scenario is based on the vari-ability in the damage pattern. These wind-speed ranges may be used to provide error bands on potential damage to the facility.
17 3.3.1.1 Damage Scenario for a Nominal Wind Speed of 49 m/s (110 mph)
Probability of Occurrence Probability of 3 x 10 6 per year.
Wind-Speed Range Range of 47 to 51 m/s (105 to 115 mph) based on failure of doors.
Glovebox Room One of the two doors in the east or west exterior wall could fail due to atomspheric pressure change.
Subsequent to failure, wind could circulate through the room, but the damage to glove ooxes and filters would be minimal.
The enclosures around the doors will protect the inside from windborne debris.
Exhaust-Filter Room and Air Lock No damage.
Vault No damage.
3.3.1.2 Damage Scenario for a Nominal Wind Speed of 58 m/s (130 mph)
Probability of Occurrence l
Probability of 8 x 10 7 per year.
l Wind-Speed Range Range of 54 to 63 m/s (120 to 141 mph) based on failure of doors.
Glovebox Room No additional damage.
Exhaust-Filter Room and Air Lock Exterior doors could fail due to wind forces. Wind circulating through the building could cause interior partitions in the exhaust-filter room to collapse.
Debris from the collapsed wall could strike the exhaust-filter enclosures.
18 i
Vault No damage.
3.3.1.3 Damage Scenario for a Nominal Wind Speed of 67 m/s (150 mph)
Probability of Occurrence Probability of 4 x 10 7 per year.
Wind-Speed Range Range of 58 to 77 m/s (130 to 173 mph) based on roof failure.
Glovebox Room Interior partitions at the north or south end of the glovebox room could collapse due to wind circulating through the building. One or two glove boxes near the partition could be crushed by the collapsing wall. The roof and the exterior walls remain intact.
Exhaust-Filter Room and Air Lock The secondary wide-flange beams fail due to lateral-torsional buckling.
As the beams twist, the dead load is transferred to bending about their weak axes.
A mechanism develops that could cause the beams to collapse, possibly striking the filter enclosures.
Twisting of the beams will likely create a tear in the roof deck at veld points. A small portion of the roof deck may tear and collapse with the beams.
Vault No damage.
3.3.1.4 Damage Scenario for a Nominal Wind Speed of 76 m/s (170 mph)
Probability of Occurrence Probability of I x 10 7 per year.
Wind-Speed Range Range of 67 to 86 m/s (150 to 193 mph) based on roof failure.
19 Glovebox Room Main girders of the roof undergo lateral-torsional buckling with subse-quent development of a mechanism that could cause collapse of the roof.
In addition to the roof, the concrete wall panels will also collapse. All glove boxes are likely to be crushed under the weight of the roof and wall panels.
Collapse of the roof could cause tears in the roof deck, providing openings through which source material could be transported by the winds.
Exhaust-Filter Room and Air Lock Collapse of the roof in a manner similar to that in the glovebox room could crush the filter enclosures. Any material available for transport could be carried through openings in the roof deck.
Vault No damage.
3.3.2 Seismic Hazard 9 The purpose of this analysis is to evaluate the structural capacity of those building structures and critical equipment components that could poten-tially release hazardous chemicals into the environment from the NMDF as a result of damage or failure during an earthquake.
The effort focused primarily on the building structure as representing the final confinement barrier for release of hazardous chemicals. The desig-nated process equipment, such as glove boxes and exhaust ducting, was also evaluated for structural capacity.
The loss of primary confinement due to direct glovebox failure or from indirect glovebox damage caused by interaction with adjacent equipment and connections is identified as the ultimate mode of release resulting from extreme earthquake hazard. The structural capacity of the building and associated equipment systems as related to the ultimate mode of release are addressed in this summary, but operational and functional as-pects of the facility are not addressed.
The NMDF is a one-story windowless tilt-up concrete building with a light-weight concrete-fill steel roof deck with roof-beam support, and a concrete floor slab on grede.
The building is rectangular in plan with a length-to-width ratio of 3.25:1.
Deviatiops from structural symmetry include the vault, mezzanine, and difference in wall thickness of the north wall. The vault is located on the exterior side of the west wall and is a cast-in place concrete box.
The small mezzanine (partial second floor) area is located adjacent to the west wall.
The lateral-force-resisting system is a shear-wall box system tied to-gether by a relatively flexible steel roof diaphragm. The diaphragm consists of light-weight concrete fill on steel decking welded to the main roof beams
20 and is connected to the shear walls by welds to the peripheral steel chord members that are anchored to the walls at the roof line. The structure may be considered to resist seismic forces as two independent systems: one for each major building direction, north-south and east-west.
Due to the diaphragm flexibility and large length-to-width ratio, torsional coupling of the two systems will be negligible. For both systems, the roof and the tributary wall inertia is transferred to the active panel shear walls by the diaphragm acting as a deep beam with chord flanges. The vault is weakly coupled to the east-west system through flexure of the above-vault wall panel. The in-plane wall seismic shear forces are transferred to grade through the individual spread footings and through the building floor slab. The slab is positively connected to the wall panels near the wall base for this purpose.
The evaluation of the structure, in terms of ground-acceleration capacity, utilized simple finite-element dynamic models to assess the component stress levels associated with a given level of ground acceleration. The controlling collapse capacities (0.60 to 0.87 g) were all associated with loss of diaphragm support for the west and east walls. Once the diaphragm resistance is lost, the roof-girier/ column pin-jointed frames with attached wall panels will pro-gressively collapse after only a few cycles of motion.
The median seismic capacity of the east-west force-resisting system is 0.60 g.
Based on the sta-tistical uncertainty bound analysis, the estimated 11-0 standard-deviation upper-and lower-bound seismic capacities are 0.88 g and 0.4 g, respectively.
The interior partitions and secondary architectural systems in the criti-cal areas do not sustain major damage prior to diaphragm failure and, there-fore, are not themselves critical in terms of release of hazardous material.
The equipment items exhibit a higher structural capacity tha-does the structural system, and are generally affected only by total facility collapse or by the large relative displacements between the floor and the roof that occur just prior to collapse.
The following three scenarios present a description of the behavior of the structure resulting from increasing ground acceleration.
The scenarios are based on the median predicted capacities of the NMDF structural systems.
The return period associated with the scenario for each level of ground accel-eration is taken from "best-estimate" data relating peak ground acceleration to return per.iod.
3.3.2.1 Ground accrieration of 0.20 to 0.35 g The return period for 0.35 g is 100 years, for a probability per year of 1 x 10 2 At a ground acceleration less than 0.20 g, there is no significant effect of the occurrence of an earthquake.
Above 0.20 g, minor structural damage in the form of concrete cracking in the vicinity of panel inserts and minor yielding of diaphragm connections is initiated.
3.3.2.2 Ground Acceleration of 0.35 to 0.55 g The return period for 0.55 g is 550 years, for a probability per year of about 2 x 10 3 Progressive concrete-cracking damage and yielding of steel
21 connections continues at accelerations greater than 0.35 g.
At an acceleration of 0.41 g, -Pier No. 2 of the south wall forms a yield hinge at the pier-spandrel junction, and the concrete panel inserts connected to the exterior mezzanine columns fail in shear preventing further composite panel / column be-havior in resisting the mezzanine-floor inertia. Further resistance is pro-vided by the columns acting alone.
The portion of the panel wall above the vault forms a yield hinge at an acceleration level of 0.47 g, but the vault-box structure is not affected.
For ground acceleration in excess of 0.50 g, the diaphragm is highly overstressed with significant yielding of both perimeter and interior connections.
i 3.3.2.3 Ground Acceleration of 0.55 g and Greater The return period for 0.60 g is 750 years, for a probability per year of 1.3 x 10 3 At accelerations greater than 0.55 g the diaphragm is severely damaged. At an acceleration of 0.60 g, the diaphragm chord along the west and east walls will fail in tension at the splice plates. The internal diaphragm seam welds will fail at 0<62 g; therefore, complete loss of diaphragm strength must be associated with 0.60 g.
After a few cycles at this level of accelera-tion, the pin-jointed roof girder / column connection will allow wall collapse to occur in the glovebox-room area.
The progression of collapse at greater levels of acceleration is uncertain, but the crushing of critical glove boxes j
by falling roof girders must be assumed to occur at 0.60 g.
Thus, this estab-lishes the ground-acceleration level associated with loss of confinement. The hinging of the above-vault wall panel will allow partial roof collapse in this area of the glovebox room, but the vault will remain intact at levels in excess of 2.0 g.
4.
SEVERE-WEATHER DISPERSION 4.1 TORNADO STRUCTURE 10 A model has been developed to represent the windspeed and pressure dis-tribution in and around a tornado vortex. The model tornado DBT-77 was devel-oped to provide more realistic estimations of tornadic features than has been available in earlier models.
Input data is derived from vast experience with actual tornado-damage estimates, and represents the state-of-the-art in tor-nado modeling.
The model incorporates an axially symmetric vortex with a cylindrical core.
The inner core rotates like solid discs stacked in a cylinder, whereas the cuter core has air currents spiraling upward. A shallow layer, directly above the earth's surface, provides inflow air to the vortex. A schematic dia-gram of DBT-77 is shown in Figure 8.
The depth of the inflow layer is related to the radius of the outer core; large tornadoes have larger inner cores and deeper inflow layers than do small tornadoes.
The horizontal wind speed of a tornado is the vector sum of tangential, radial, and translational velocities.
Tangential velocity is treated as a function of both height and radius, whereas radial velocity varies with the crossing angle of inflow air relative to the vortex streamlines. The crossing angle is assumed to be constant at a given height, with airflow outside the
22 R. V-
- R. -
Figure 8.
i Schematic Diagram of Tornado l
Model DBT-77.
(In this simpli-umuuuu
.-=-IN N ER CORE-*~
fled model, the core is divided vrYoYTV.v.
/y,
%s l
/
into inner and outer portions.
] H,=lR..
f.
k(g :rNrtow -.
Vertical motions are concen-l
. JLAYER.
trated in the outer core and the inner core is assumed to wwwwwwwwwwwv1wwwwswwwwswwv rotate like a stack of solid discs in a cylinder.)
4 l
- T' Wu_TER... of t
following logarithmic spirals toward the vortex center. Vertical veloc-core It ity is a function of divergence in the air column and varies with height.
reaches a maximum at the top of the inflow layer. Vertical accelerations in the inflow layer vary with radius and core size. For a given tangential ve-locity, small vortices induce greater vertical accelerations than do large ones.
Furthermore, the height at which the maximum vertical acceleration exists decreases with core radius.
As a result, it is postulated that small vortices are capable of picking up objects near the ground.
The " damage height" of a tornado is the height throughout which maximum damage caused by a given vortex r.ill occur.
Due to variations in inflow-layer depths of torna-does with different core sizes, tall objects are most affected by large-core tornadoes, whereas objects near the ground receive the full impact of small-core tornadoes.
Extremely large pressure gradients must exist inside the tornado vortex to generate the large vertical velocities computed with the model. Because buoyancy alone is incapable of inducing such accelerations, nonhydrostatic-pressure gradients must be present. Nonhydrostatic pressure is assumed to be function only of height and radial velocity. What causes nonhydrostatic-a pressure gradients is poorly understood.
In this model, the inertia of the inflow air is assumed to act as a radial compressor to induce nonhydrostatic pressures in the outer core. Thus, air moves against the horizontal pressure gradients, from low pressure to high pressure, while losing kinetic energy.
Total pressure is the pressure generated by the swirling motions of the vortex added to the nonhydrostatic pressure. The total pressure field is represented in Figure 9.
Meteorological parameters such as pressure, windspeed, and temperature vary with time as a tornado passes over a fixed point.
In particular, pres-sure tendencies vary significantly with the ratio of core size to transla-tional velocity.
A fast-moving small-core tornado induces extremely large pressure changes.
23 F
OUTER CORE i
- 1NNER C O RE -*.
[...,}
l sprudf j p red VERTICAL VELOCITY I s-Figure 9.
2Pye Pressure Field Inside the l
Ad*5' Model Tornado.
(Pressure
?.
jumps and vertical-veloc-i N,, !
- $i a
ity changes characterize soer PRESSURE II = 0.15 8 -y-p v.,
the boundaries of the outer core.
Similar ob-i servations have been j
10 ecru se noted in data inferred
' " * '" 'i from real tornadoes.)
I i
I i
TANGENTIAL VELOCITY, j
i
_ __ __ q __ _ _;,_ __ _ _ _
i.
j i
I I
The total mass of air transported upward by a tornado is proportional to the maximum tangential velocity and to the square of the core radius.
A
" mini-tornado" (max V = 25 m/s or 56 mph and R = 10 m or 33 f t) may transport about 3 Mg/s (about 3 ton /s) of air, whereas a " maxi-tornado" (max V = 100 m/s or 220 mph and R = 150 m or 500 ft) may transport about 2l00 Mg/s (about 2320 ton /s) of air.
The model DBT-77 was developed to provide a mathematical representation of the motions associated with a tornado.
The equations appear to simulate actual tornado features well. The model is used as input to predict the ulti-mate fate of particles entrained by a tornado.
4.2 DISPERSION IN A TORNADIC STORM 11 A three-dimensional numerical model is used to calculate the dispersion of small particulates in a tornadic storm.
The model is designed to allow various meteoroloo,ical parameters to be updated es more precise information becomes available.
The three-dimensional transient equation of concentration transport is solved by a quasi-Lagrangian method of second moments in an Eulerian mesh centered over the assumed trajectory of the storm.
The horizontal-wind field varies with height over a one-hour period after the AI NMDF is breached.
The updrafts and downdrafts associated with the
{
24 tornadic storm are calculated from initial empirical estimates,10 and then advected with the storm. The horizontal rotational-wind field within the storm cell is also advected with the vertical-velocity field.
As the storm cell spreads horizontally, the wind field within the storm cell spreads accordingly.
Because of the lack of precise information regarding turbulence within severe storms, the turbulence-diffusion coefficients are obtained from empir-ical estimates.
These estimates are based on sparse data measured within storms and on theoretical equations appearing in the literature.
Scavenging is calculated as a sink term to the governing equation. Wash-out scavenging below the cloud base acts on large particles; rainout scaveng-ing acts on small particles within the cloud. However, limited knowledge of scavenging in severe storms necessitates the use of a single general expression based on rainfall rates, droplet size, and 100% collision efficiency.
The effect of topography surrounding the AI site is introduced through specifi-cation of roughness heights used in determining turbulent diffusion below the cloud. The effect of topography on advection is not considered.
The pollutant is assumed to be dispersed throughout the thunderstorm cell.
A skewed log-normal distribution is used to initialize the concentration field.
About 35% of the material is dispersed within the upper regions of the cloud, 15% within the middle section of the storm, and 50% within the lower layers and cloud base of the storm.
Once the concentration field is established, scavenging and downdraf t velocities begin to bring the concentration to the ground.
The updraft and downdraft vertical-velocity distributions and wet deposi-tion account for most of the material being deposited at the surface one hour after initial uptake of the material.
Scavenging accounts for about 50% of the particle removal from the cloud within 15 minutes. A constant rainfall rate of 20 mm/h (0.8 in/h) is used throughout the calculation. The deposition of concentration at the surface consists primarily of plutonium particles sus-pended within waterdrops.
As additional information on rainfall rates and velocities in tornadic storms becomes available, deposition will likely become highly nonuniform.
Ground-level air concentration begins to reach the surface within five minutes.
Results show values of ground-level concentrations to begin occur-ring within 10 to 20 km (6 to 12 mi) of the AI NMDF. Peak centerline concen-trations occur within 12 km (7.5 mi) of the point of initial dispersion within the cloud.
Ground-level X/Q values are shown in Figure 10 for each of four translational velocities.
The concentration decreases significantly with are reached.
The lateral spread of distance after peak ground-level values ground-level concentration is governed principally by the size of the thunder-storm cell directly overhead.
Downdrafts and scavenging have more influence on bringing the concentration directly from the storm cell to the surface than does turbulent diffusion.
Concentration reaching the anvil portion of the cloud is advected at a faster velocity than concentration in the lower levels of the storm. About 5% of the concentration is advected out of the anvil into the stratosphere.
Results obtained with a modified Gaussian puff model were considered to be low and showed the inflexibility of the analytical solution to account for l
8
25 10 "
7 3
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i 10 "._l, l
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/5 Air Concentration from Initial-10-" f
'\\ (* '*N.
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y 10-" [
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m/s m/s
.c 1,
1 10-"
(
t o-"
10-'
i I
I 1
f O
10 20 30 40 50 60 Longitudinal Distance (X), km the transient-nature 'of trie vertical-wind field. Ground-level X/Q values were several orders of magnitude lers. in value than X/Q values obtained from the i
numerical method.
5.
RELEASES 12 The objective of this section is to provide " realistic" estimates of the quantity of plutonius nade/ airborne, as a result of the postulated damage sce-narios,jand released to the ambient atmosphere around the facility. Estimates of airborne releases are necessary for the calculation of dose, which is one i_ompon' ect c,f the ultimate risk analysis.
Inhalation is the only important pathway for-acute atmospheric releases of plutonium; therefore, emphasis is on the estimation of released plutonium particulate material of a size range that can be cairiid-downwind and inhaled.13 Particles of 10-pm AED or less are conservatively, assumed to be the respirable fraction.
Such an assumption over-states the potential effect by a factor of 1.5 to greater than an order of mag-nitude,' depending on the lung-deposition model chosen.14 i
The..'est2diated source terms are based on potential damage to enclosures and thd result [ing airborne release. The damage scenarios are derived from the structural analysis.
To provide a range of potential source terms to include the vast majority of normal processing conditions, "best-estimate" and " upper"
,' t.nd " lower" limits are provided. The range'of source terms was calculated by combining ranges'of damage with the airborne' release determined from ranges of inventory of dispersibl.e materials at risk.
I r
F
.f I
l_
s i
l l
26 The largest postulated airborne releases from the building are for the maximum wind hazard (76 m/s or 170 mph) and seismic hazard (ground acceleration greater than 0.55 g).
Both hazard scenarios postulate virtually complete de-struction of tne facility.
Wind hazard at higher velocities and earthquakes with higher ground accelerations should not result in significantly greater source terms.
Tne source terms are expressed as mass of airborne plutonium particles, AED of 10 pm or less, released with time. From 0.5% to 91%'of the source term is generated from two hours to fcur days af ter the event. The overall building source terms from the damage scenarios evaluated are shown in Table 5 in order of increasing severity of wind hazard and earthquake.
6.
DOSE TO MAN 13 This section presents estimates of the potential environmental conse-quences in terms of radiation dose to people resulting from postulated pluto-nium releases accidentally caused by severe weather or other natural phenomena.
The accident scenarios considered include earthquakes, tornadoes, and high winds.
6.1 ENVIRONMENTAL EXPOSURE PATHWAYS FOR PLUTONIUM Experience has shown that the more important pathways for exposure to plutonium and daughter products released to the atmosphere are inhalation, cloud submersion, ingestion, and direct ground irradiation.
Of these four pathways, almost all the dose contribution comes from inhalation. Therefore, the radiation doses from inhalation during initial cloud passage and from in-halation of resuspended environmental residual contamination are calculated.
For liquid releases, the important exposure pathways are aquatic-food inges-tion, water consumption, and shoreline exposure.
However, the results of flooding analysis showed that in-process plutonium is not jeopardized by either the probable-maximum flood or probable-maximum precipitation.
As a result, this release scenario was not considered further. The significant potentisl exposure pathways that have been considered are shown in Figure 11.
6.2 RADIATION-DOSE MODELS FOR AN ATMOSPHERIC RELEASE Fifty-year committed-dose-equivalent factors for acute inhalation were calculated using the computer code DACRIN.15 This code incorporates the ICRP Task Group Lung Model to calculate the dose commitment to lungs and other organs of interest.
The translocation of americium from the blood to organs of interest has been changed to the values suggested in ICRP-19.
In plutonium dosimetry, the organs of interest are the total body, kidneys, liver, bone, and lungs.
Doses only to the lungs and bone are included in this discussion, because these two organs receive the highest doses.
Plutonium particulates that deposit onto the ground surface from the plume can be resuspended to the atmosphere of natural processes, and subsequently inhaled by people.
Resuspension rates for material deposited on the ground are time dependent and tend to diminish after initial deposition. Local con-ditions can be expected to affect the rate strongly; rainfall, winds, and sur-face characteristics are predominant.
The exact relationships are not well
i 27-i i
Table 5.
Source-Term Estimates for the AI NMDF Due to-Wind and Earthquake Hazard (ag) i.l Mass Release of Plutonium in Respirable '
Size Ranae ($ 10 pm AED)
Event Upper Bound Average Lower Bound Wind hazard
)
Nominal wind speed 49 m/s (110 mph), 3 x 10.s per year
(
probability of occurrence Instantaneous' tt tI t1 Additional mass released in next 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 3.0 t3 t8 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 9.0 fl 11 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />
't!
t t
t l
3 days t1 ta tt Nominal wind speed 58 m/s (130 mph), 8 x 10 7 per year probability of occurrence Instantaneous 10 5
3 Additional mass released in next 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 3
0.01 0.01
.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 9
0.03 0.03 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> 0.08 0.08 0.08 3 days 0.4 0.4 0.4 Nominal wind speed 67 m/s.(150 mph), 4 e 10 7 per year probability of occurrence Instantaneous 30 20 20 Additional mass released in next 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 3
0.4 0.4 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 9
1
'I I
16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> 1
3 days 20 Nominal wind speed 76 m/s (170 mph),1 x 10 7 per year probability of occurrence
~
Instantaneous 4000 4000 4000 Additional mass released in next 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 20 4
3 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 60 10 10 16 hour1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />s-200 30 30 3 days 700 200 200 Earthquake hazard Linear acceleration less than 0.55 g, greater than No significant daw ge resulting 2 x 10 8 per year probability of occurrence in airborne releape Linear acceleration exceeding 0.55 g; probability of occurrence of 0.60 g is 1.3 x 10 3 per. year Instantaneous 4000 4000 4000 Additional mass released in next 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 20 0.04 0.04.
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 60 0.1 0.1 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> 200 0.3 0.3 3 days 700.
2
'I l18 'Less than 0.1 pg of plutonium.
28 ATMOSPHERIC RELEASE l
LIQUID I
- RELEASE, j
l l
h DEPOSITION
),,f
/
TO WATER f!
TO GROUND
/
/
" ~ '
I INHALATION
/
Mh RESUSPENSION f
/
1R RIGATION N
& INHALATION t'
(21Q9t:9 DIRECT
(
4 ;}
$ g g Q POSURE CROP UPTAKE BY INGESTION AQUATIC FOODS SHOREUNE EXPOSURE
/ +1 !
\\ f
=
AQUATIC FOOD INGESTION y
DRINKING
(\\
(
I WATER h
-lNGESTION pI (([
PEOPLE 1
g
\\
[(
ls
/
t s
}
\\
)
E Figure 11.
Significant Potential Exposure Pathways Through Which People May Be Exposed from an Accidental Release of Plutonium.
enough understood to account for these effects. However, the airborne concen-tration from resuspended material can be estimated using a resuspension factor, which is defined as the resuspended air concentration divided by the surface deposition.
A simple time-dependent model, recommended by Anspaugh et al.,18 was used to predict the average airborne concentration of a resuspended con-taminant.
This model estimates values for the resuspension factor between 10 4 m1 at initial deposition and 10 8 m1 about 20 years later. About 99%
of the total 50-year exposure from resuspension occurs in the first five years.
Chronic 50 year committed-dose-equivalent factors for inhalation of resuspended material were calculated using DACRIN.15 1
29 6.3 RADIATION DOSES The plutonium postulated to be released to the atmosphere is in the form of plutonium oxides.
Lung retention, as described by the ICRP Task Group Ltng Model, depends on the chemical nature of the compound inhaled. Compounds of plutonium fall largely into Class Y (retained for years) or Class W (retained for weeks).
There is no evidence of plutonium existing in the environment as Class D material.
Actinides in the oxide form are currently classified as Class Y, which is assumed in this study. Only that plutonium released in the respirable particle size range was considered (median AED less than 10 pm).
The isotopic composition by percent weight used in the calculations is given in Table 6.
Table 6.
Isotopic Composition of the Plutonium Mixture Isotope Percent Weight 238Pu 1.1 239Pu 61.6 240Pu 20.9 2' aiu 12.6 242Pu 3.8 241Am 0.0 100 6.3.1 Earthquakes Committed radiation-dose equivalents to bone and lungs of the human body were calculated for an earthquake event causing a peak ground acceleration of 0.55 g.
Significant damage was not postulated for an earthquake producing less than 0.55 g.
For the zero-to-two-hour period, accident atmospheric-dispersion values for 5% and 50% conditions, calculated by NRC for the AI NMDF site, were used to estimate potential committed dose equivalents to the population and a maxi-mum individual.
Annual average atmospheric-dispersion and deposition values, given in Section 2.4.4, were used for all other time periods. For the 5% con-dition, the annual dispersion anc deposition values were multiplied by four.
Four combinations of release and dispersion were considered, referred to as Cases I through IV.
The calculated committed dose equivalents via inhalation listed in Table 7, as are descriptions of the four dispersion / deposition are cases.
The estimated maximum plutonium ground depositions at the site bound-ary, nearest residence, and farm are listed in Table 8.
30 Table 7.
Fifty-Year Best-Estimate Cossaitted Dose Equivalents from Inhalation Following Severe-Wind and Earthquake
. Events (Class Y material)
Population Dosett Dose at Nearest Residence (person-rea)
(rea)
Caset Case Case Case Case Case Case Case Event Organ I
II III IV I
.II III IV 49-m/s Lungs Ot3 0
4.1+3t*
3.9+4 0
0 2.9-3 1.2-2 tornado Bone 0
0 7.6+3 7.2+4 0
0 5.5-3 2.1-2 53-m/s Lungs 7.5+3 7.5+4 2.0+4 2.0+5 1.2-2 1.2-1 3.1-2 3.1-1 tornado Bone 1.4+4 1.4+5 3.6+4 3.6+5 2.2-2 2.2-1 5.6-2 5.6-1 67-m/s Lungs 3.3+5 3.3+6 4.9+5 4.9+6 4.4-1 4.4+0 6.5-1 6.5+0 tornado Bone 6.0+5-6.0+6 9.0+5 9.0+6 8.0-1
-8.0+0 1.2+0 1.2+1 76-m/s Lungs 1.4+5 1.4+6 1.6+5 1.5+6 1.0-1 1.0+0 2.7-1 1.1+0 tornado Bone 2.6+5 2.6+6 3.0+5 2.7+6 1.9-1 1.9+0 5.0-1 2.0+0 Earthquake Lungs 2.0+5 2.4+6 2.3+5 2.6+6 3.0+0 1.7+2 3.3+0 1.7+2
> 0.55 g Bone 3.8+5 4.5+6 4.3+5
-4.7+6 5.6+0 3.1+2 6.1+0 3.1+2 il Population within an 80-km radius of the plant.
t2 Case definitions (parenthetical values are approximate probabilities):
I - Most-likely release (0.95) and most-likely dispersion (0.95).
II - Most-likely release (0.95) and conservative dispersion (0.05).
III - Conservative release (0.05) and most-liiely dispersion (0.95).
IV - Conservative release (0.05) and conservative dispersion (0.05).
t The most-likely release from the 49-m/s tornado is zero.
8 3
t Scientific notation:
4.1+3 = 4.1 x 10.
4 Table 8.
Best-Estimate Maximum Plutonium Deposition at Significant Locationstl 2
Plutonium Deposition (pCi/m )
Event Site Boundaryt2 Residence Fara 8
0 0
49-m/s tornado Ot 58-m/s tornado 1.6-3t*
5.7-3 5.7-3 67-m/s tornado 6.7-2 2.1-1 2.1-1 76-m/s tornado 7.3-1 4.5-2 4.5-2 Earthquake > 0.55 g 3.0+1 5.2-1 2.3-1 ft Case I - Most-likely release and most-likely dispersion.
12 Located 410 m NW of the plant.
8 The most-likely release from the 49-m/s tornado is zero.
1 1
Scientific notation:
1.6-3 = 1.6 x 10 3 4
31 6.3.2 Tornadoes Average tornado atmospheric-dispersion and deposition values are dis-cussed in Section 4.2.
Values for four windspeeds of 49, 58, 67, and 76 m/s (110, 130, 150, and 170 mph, respectively) were calculated. These values were assumed to apply during the first two hours after the event.
During this time, the tornadoes were assumed to move in an easterly direction. Annual l
average atmospheric-dispersion and deposition values were used for all other time periods.
Committed radiation-dose equivalents are given in Table 7 for Class Y plutonium.
The estimated maximum plutonium ground-contamination levels at the significant locations are listed in Table 8.
6.4 DISCUSSION For the tornado, the majority of the radionuclide intake occurs after the first two hours.
At this time, historical site-specific meteorological con-ditions are considered to resume.
The calculated committed dose equivalents are based on the ICRP Publica-tion 2 Metabolic Model, the ICRP Task Group Lung Model, and standard-man parameter values. To the best of the staff's knowledge, there are no reported assessments of the accuracy of dose calculations using these models and para-meter values.
Dose results are usually presented with no indication of the error associated with their use.
Present insights into the degree of uncer-tainty involved are very limited and qualitative. Dose results presented in this section are probably accurate within a factor of ten.
The 50 year collective-dose equivalent to the total body from natural-background radiation within an 80-km (50-mi) radius of the AI NMDF is 29 mil-lion person-rem.
In the vicinity of Chatsworth, California, the natural-background dose rate is reported to be 80 mrem /yr to the total body. An indi-vidual receives a total-body dose of about 4 rem from natural-background radi-ation during a 50-year period.
The average annual dose to the total body of an individual from medical X-ray examinations is about 20 mrem, which corre-sponds to a 50 year collective-dose equivalent of 7.1 million person-rem. The dose contribution from exposure to fallout is negligible when compared with natural-background and medical X-ray exposure.
If a radiation worker were involved in an occupational accident and received a maximum permissible bone burden of 23sPu, his 50-year committed dose equivalent to bone would be greater than 1000 rem.
Existing guidelines on acceptable levels of soil contamination from plu-tonium can be found to range from 0.01 to 270 pCi/m. The EPA has proposed 2
2 a guideline of 0.2 pCi/m for plutonium in the general environment.17 This guideline is based on an annual dose of 1 mrad to lungs from inhalation and 3 mrad to bone from ingestion.
If other reported guidelines are normalized to these doses, and the same resuspension factor is used, they are all in reason-able agreement with 0.2 pCi/m,
2 The predicted levels of maximum-residual plutonium contamination on the ground following the earthquake and the 67-m/s (150-mph) and 76-m/s (170-mph) tornadoes'are above the EPA proposed guideline at some or all of the signifi-cant locations.
The estimated contamination levels that are most likely to
32 2
occur at these locations range from about 0.2 to'30 pCi/m.
The predicted ground-contamination levels for the other severe natural phenomena are.below the EPA proposed guideline. These data are summarized in Table 8.
7.
RISK ANALYSIS s 1
Occurrence rates (probability per year) and associated approximate con-fidence bounds for the wind and earthquake events that were considered in the risk analysis are given in Table 9.
The 50-year committed dose equivalents resulting from tornado and earth.
quake at the AI NMDF are given in Table 7.
Figures 12 through 15 are graphs of complementary distribution functions, with approximate 90% bounds, for tornadoes and earthquakes. The curves are adequate to show general behavior.
Other curves, including those obtained using isotonic regression analysis, have been provided by Johnson.is Table 10 indicates the risks resulting from the various tornado and earthquake events, in terms of dose rate, where " risk" is the probability of the event multiplied by the' dose rate associated with it.
!=
i Table 9.
Phenomena Probability and Associated Uncertainties l
I Wind Speed Peak Ground Probability Approximate 90% Bounds (m/s)
Acceleration per Year on the Probability 58 8.0-7t1 8.0-8 8.0-6 67 4.0-7 4.0-8 4.0-6 76 1.0-7 1.0-8 1.0-6
> 0.55 g 1.3-3 1.3-4 1.3-2 il Scientific notation:
8.0-7 = 8.0 x 10 7
33 10 Rout 00 #1M AnnLisl8 FOR AI. POP. Lusse Sn00TM0 CC0F 10-8 4
104
+.____y t
x ita.
Figure 12.
i
---t
--9 Complementary Cumulative g
1 Distribution for Dose to o
L n Lungs of Population Due b '" '
to Damage from Tornadoes.
i--t y
L cr 10-e i g*
g HI 104 I' ' on ges
- s o. -
- nos goe nos i
50 YR DOSE COMMITMENT IPERSON-REM)
TORun00 RIM ANAList$ FOR Al. MR. Lume.
sn00TMEO CCDF 10-'
ir.
I x ir.
L
_ L, Figure 13.
w I.
g y
Complementary Cumulative 1
1-,
Distribution for Dose to e ie.
i Lungs at the Nearest Res-o 0
T.
idence Due to Damage from 2
W I
Tornadoes.
E 8 0-'
E i
E I
W ir.
10-se
-HI L04 I O-8 1go 108 50 YR DOSE COMMITMENT (PERSON-REMI
34 (ARTMeuAnt Otm AnALTOIS FOR AI. PSF. LUNS.
On00fMEO CCOF ici
- 0-8 x tr'-
Figure 14.
g Complementary Cumulative g
Distribution for Dose to g
it-*.
"I Lungs of Population Due to Damage from: Earth-0 quake.
a 10-s,
a
{
11 104 11 kO' 10' l'O' 30' 50 YR DOSE COMMITMENT (PERSON-REM)
EARTMOUAnt RIM ANALT0!O FOR Al. MR. LUNO en00TMEO CC0F ici ld x
Figure 15.
a s ire.
Complementary Cumulative E
Distribution for Dose to Lungs at the Nearest Res-o idence Due to Damage from E,,
Earthquake, d
E E
E il 104 a
' De toi 108 tes t
SO YR DOSE COMMITMENT (PERSON-REM)
35 Table 10.
Risk to Nearest Resident and Nearby Population from Postulated Damage Due to Natural Phenomena Population Doset!
Dose at Nearest Residence (person-res/yr)
(res/yr)
Caset2 Case Case Case Case Case Case Case Event Organ I
II III IV I
II III IV 58-m/s Lungs 5.4-3t3 3,o.3 8.0-4 4.0-4 8.6-9 4.8-9 1.2-9 6.2-10 tornado Bone 1.0-2 5.6-3 1.4-3 7.2-4 1.6-8 8.3-0 2.2-9 1.1-9 67-m/s Lungs 1.2-1 6.6-2 9.8-3 4.9-3 1.6-7 a.M i.3-8 6.5-9 tornado Bone 2.2-1 1.2-1 1.8-2 9.0-3 2.9-7 1.fs-7 2.4-8 1.2-8 76-m/s Lungs 1.3-2 7.0-3 8.0-4 3.8-4 9.0-9 5.0-9 1.4-9 2.8-10 tornado Bone 2.3-2 1.3-2 1.5-3 6.8-4 1.7-8 9.5-9 2.5-9 5.0-10 i
Earthquake Lungs 2.3+2 1.6+2 1.5+1 8.5+0 3.5-3 1.1-2 2.1-4 5.5-4
> 0.55 g Bone 4.4+2 2.9+2 2.8+1 1.5+1 6.6-3 2.0-2 4.0-4 1.0-3 f3 Population within an 80-km radius of the plant.
2 t
See corresponding footnote, Table'7.
13 Scientific notation:
5.4-3 = 5.4 x 10 3 REFERENCES 1.
J.E. Ayer and W. Burkhardt. " Analysis of the Effects of Abnormal Natural Phenomena on Existing Plutonium Fabrication Plants." Proceedings of the ANS Topical Meeting on the Plutonium Fuel Cycle, Bal Harbour, FL, 2-4 May 1977.
2.
T.T. Fuj ita.
" Review of Severe Weather Meteorology at Rockwell Interna-tional, Chatsworth, California." The University of Chicago, report sub-mitted to Argonne National Laboratory under Contract No. 31-109-38-3731, 30 June 1977.
3.
" Seismic Risk Analysis for.the Atomics International Nuclear Materials Development Facility, Santa Susana, California."
TERA Corporation, Berkeley, CA, report submitted to Lawrence -Livermore Laboratory, 29 De-cember 1978.
4.
Derived from:
" Assistance in I!ydrologic Aspects
. Analysis of the Effects of Natural Phenomena on Existing Plutonium Fabrication Facilities -
Atomics International." Transmitted by memorandum from L.G. Hulman of USNRC/DSE to R.W. Starostecki of USNRC/FC, 19 January 1978.*
36 5.
" Description of the Site Environment around the Atomics International Nuclear Development Field Laboratory, Chatsworth, California." Trans-mitted by letter from L.C. Rouse of USNRC/FC to Dr. M.E. Remley of Rock-well International, Atomics International Division, 7 May 1980.*
6.
J. Mishima and L.C. Schwendiman, Battelle - Pacific Northwest Laboratory, and J.E. Ayer, USNRC.
" Identification of Features Within Plutonium Fabrication Facilities Whose Failure May Have a Significant Effect on the Source Term."
16 January 1980.*
7.
" Structural Condition Documentation and Structural Capacity Evaluation of the Atomics International Nuclear Materials Development Facility at Santa Susana, California, for Earthquake and Flood, Task 1 - Structural Con-dition."
Engineering Decision Analysis Company, Inc., prepared for Lawrence Live rmore Laboratory, March 1978 (and Addendum, July 1978).
8.
K.C. Mehta, J.R. Mcdonald, and F. Alikhanlou. " Response of Structures to Wind Hazard at the Atomics International Nuclear Materials Development Facility, Santa Susana, California." Texas Tech University, Institute for Disaster Research, Lubbock, TX, August 1980.
9.
" Structural Condition. Documentation and Structural Capacity Evaluation of the Atomics International Nuclear Materials Development Facility at Santa Susana, California, for Earthquake and Flood, Task II - Structural.Capac-ity Evaluation."
Engineering Decision Analysis Company, Inc., prepared for Lawrence Livermore Laboratory, April 1979.
10.
T.T. Fuj ita.
" Tornado Structure for Engineering' Applications with Design-Basis Tornado Model (DBT-77)."
The University of Chicago, report sub-mitted to Argonne National Laboratory under Contract No. 31-109-38-3731, August 1977.
11.
D.W. Pepper.
" Calculation of Particulate Dispersion in a Design-Basis Tornadic Storm from the Atomics International Nuclear Materials Develop-ment Facility, Santa Susana, California "
E.I. du Pont de Nemours and Co., Savannah River Laboratory, Aiken, SC, prepared for the U.S. Dept. of Energy under Contract DE-AC09-76SR00001, DP-1566, July 1980.
12.
J. Mishima and J.E. Ayer. " Estimated Airborne Release of Plutonium from Atomics International's Nuclear Material Development Facility in the Santa Susana Site, Cali fornia, as a Result of Postulated Damage from Severe Wind and Earthquake Hazard." Battelle - Pacific Northwest Labora-tory, PNL-3935, August 1981.
13.
J.D. Jamison and E.C. Watson. " Environmental Consequences of Postulated Plutonium Releases from Atomics International NMDF, Santa Susana, Cali-fornia, as a Result of Severe Natural Phenomena." Battelle - Pacific Northwest Laboratory, PNL-3950, August 1981.
14.
T.T. Mercer.
" Matching Sampler Penetration Curves to Definitions of Respi rable Fraction."
Health Physics 33(3):259-264, Fig. 2,
- p. 260, September 1977.
37 1
15.
J.R. Ilouston, D.L. Strenge, and E.C. Watson.
"DACRIN - A Computer Program for Calculating Organ Dose from Acute or Chronic inhalation." Battelle -
q Paci fic Northwest Laboratory, BNWL-B-389, December 1974, and BNWL-B-387, i
Supp., February 1975.
I 16.
L.R. Anspaugh, J.ll. Shinn, P.L. Phelps, and N.C. Kennedy. "Resuspension and Redistribution of Plutonium in Soils."
llealth Physics 29:571-582, i
October 1975.
l 17.
" Proposed Guidance on Dose Limits for Persons Exposed to Transuranium Elements in the General Environment."
U.S.
Environmental Protection d
Agency, EPA 520/4-77-016, September 1977.
f k
18.
J.W. Johnson.
" Risk Analysis of Postulated Plutonium Releases from the Atomics International Plant, Santa Susana, California, as a Result of Tornado Winds and Earthquakes."
U.S.
Nuclear Regulatory Commission, 20 October 1981.*
l l
s in the NRC Public Document Ro'm for inspection and copying for a fee.
- Available o
RC e oRu 335 U.S. NUCLE AR REGULATORY COMMISSION BIBLIOGRAPHIC DATA SHEET NUREG-0867
- 4. TITLE AND SUBTITLE (Add Volume No., sf apprewnare) 2 (Leave bfanaj The Effects of Natural Phenomena on the Atomics Inter-national Nuclear Materials Development Facility at Santa 3 RECIPIEN T'S ACCESSION NO.
~
Susana, California. Docket tin. 70_?;
- 7. AU THORiS)
- 5. D ATE REPORT COVPLE TED November
)[MS MONTH 9 PE RF ORMING ORGANIZATION N AVE AND M AILING ADDRESS (include 2 0 Codel DATE REPORT ISSUED
. Office of Nuclear Material Safety and Safeguards yONyn g u,n U.S. Nuclear Regulatory Cormiission December 1981 Washington, DC 20555 s (t m, uana;
?
8 (Le.we blanki
- 12. SPONSORING ORG ANIZATION NAME AND MAILING ADDRESS (/nclude 2,0 Codel Same as 9, above
- 11. CONTR ACT NO.
l
- 15. SUPPLEYE NTARY NOTES i4 ft,,,, y,y,j
- 16. ABSTR ACT (200 words or lessi An analysis of the Effects of Natural Phenomena on the Atomics International Nuclear Materials Development Facility at Santa Susana, California has been prepared by the Office of Nuclear Material Safety and Safeguards. The analysis is in support of the Special Nuclear Materials License held by the subject company.
It addresses the probable effects of damage to the General Electric Plant by severe weather and earthquake and expresses the consequences of damage as dose to several human receptors. The doses that result from facility damage are multiplied by the occurrence rate for the initiating event yielding the yearly risk.
- 17. KEY WORDS AND DOCUVENT AN ALYSIS 17a. DESCRIPTORS 17n. IDE N TI F IE RS/ OPE N-EN DE D TE R MS 18 AVAIL ABILITY ST ATEMENT
- 19. SECURITY QL4SS (Th,s reportl 21 NO OF PAGES Unc1assified Unlimited
- 20. SECURITY CL ASS /This pagel
- 22. P RICE Unclassified s
N RC F ORM 335 (7 77)
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