ML20072M097
| ML20072M097 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 07/31/1994 |
| From: | OMAHA PUBLIC POWER DISTRICT |
| To: | |
| Shared Package | |
| ML20072M087 | List: |
| References | |
| NUDOCS 9409010200 | |
| Download: ML20072M097 (32) | |
Text
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f Evaluation of Cargill Corn Milling and Processing Facility Impact on Fort Calhoun Toxic Gas Monitoring Program 1
July, 1994 Omaha Public Power District i
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9409010200 940919 PDR ADOCK 05000285 p_
=
TABLE OF CONTENTS LIST OF TABLES.............................................iii
1.0 INTRODUCTION
1 1
2.0 BACKGROUND
1 1
1 3.0 APPLICABLE REGULATORY GUIDANCE................... 3 4.0 ANALYSIS METHODOLOGY.............................
5 5.0 HIGHWAY ANALYSIS RESULTS.........................
10 6.0 RAILROAD ANALYSIS RESULTS........................
12 7.0 CARGILL FACILITIES RESUL1S.......................
24 i
8.0 CONCLUSION
S......................................
28
9.0 REFERENCES
29 1
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i LIST OF TABLES Number Title Paae 5.1 Control Room Concentrations of Hazardous 12 Chemicals from Highway Accidents 6.1 Estimated Shipments to be Made on Cargill Railspur 15 6.2 Control Room Concentrations of Hazardous Chemicals from Rail Accidents 16 FCS Meteorological Site Data 17 6.3 4
7.1 Cargill Storage Tank Capacities Airborne Toxic Materials 26 7.2 Control Room Concentrations of Hazardous Chemicals from Cargill Tank Failure Accidents 27 7.3 Offsite Tank Failure Cumulative Frequency of Control Room Habitability Loss 27 8,1 Cumulative Toxic Hazard frequency Off-site Sources 28 iii
1.0 INTRODUCTI0t{
l This submittal documents an analysis which evaluates the impact of the newly constructed Cargill Corn Milling and Processing Facility (Cargill) operations on the Fort Calhoun Station (FCS) per regulatory requirements for toxic gas monitoring system (TGMS). The Cargill facility will transport, handle and store hazardous materials and thus the impact of a hazardous spill / release accident must be evaluated for control room habitability of the j
FCS. The applicable regulatory requirements and the basis for the current TGMS i
were reviewed. The analysis results indicate that the regulatory requirements as defined in NUREG-0737, Item III.D.3.4, Standard Review Plan Section 2.2.3 and Regulatory Guide 1.78 can be met for FCS without the need for a new TGMS which specifically monitors for materials used at the Cargill facility.
2.0 BACKGROUNQ The Cargill facility is scheduled to begin commercial operation in February, 1995. This facility will use several materials which have been classified as toxic per the EPA's Extremely Hazardous Materials List.
Those chemicals are: Sulfur Dioxide, Ammonia, Carbon Dioxide, Hydrochloric Acid, Sulfuric Acid, Gasoline and Ethanol. Regulatory requirements stipulate that hazardous materials which are either stored or transported within five miles of the FCS control room must be considered for impact on control room habitability in the event of an accidental release. The Cargill facility is located 1.3 miles due north of FCS, and therefore any spills of a toxic material which occur at the Cargill facility must be considered. Cargill will also ship toxic materials on a railspur which is located on the FCS site. The impact of a rail car spill must be considered. Cargill intends to ship toxic materials on U.
S.
Highway 75 which is approximately 0.7 miles from the control room intake.
2.1 Existing Toxic Gas Monitoring System The existing FCS Toxic Gas Monitoring System is described in USAR Sections 9.10 and 14.23. The Technical Specification Requirements for the existing system appear in Sections 2.22 and 3.1. The TGMS currently samples the control room Heating Ventilation Air Conditioning (HVAC) fresh air intake for six toxic gases (Ammonia, Hydrazine, Hydrochloric Acid, Hydrofluoric Acid, Sulfuric Acid, and Chlorine gas). The existing system will activate when monitored gas concentrations reach predetermined setpoints. TGMS actuation includes annunciation with the following sequence of events: the fresh air dampers shut automatically, and the control room ventilation shuts down j
simultaneously to stop infiltration of toxic gases through the closed dampers.
1 These automatic actions provide the control room operators time to don breathing apparatus (ref. 9),
1
de The FCS TGMS was installed to meet NUREG-0737, Item III.D.3.4 requirements for control room habitability following a postulated on-site or off-site chemical release (ref.1). The original evaluation (ref. 2) showed that:
- 1. The following existing off-site chemicals shipped by rail or stored at nearby facilities were identified as potential hazards to the control room personnel.
Ammonia 1
Hydrochloric Acid
- 2. The following existing on-site chemicals were identified as potential hazards to the control room personnel, flydrofluoric Acid Sulfuric Acid Hydrazine Chlorine Thus, on-site and off-site chemical releases were the basis for_ the TGMS at FCS.
1 With the installation of the current TGMS it was determined that - the j
requirements of NUREG-0737 had been met, and that the operators would be l
protected against the worst postulated toxic chemical release accident (ref.
2).
2.2 Impact of Cargill Facility on Existing Toxic Gas Monitoring System.
The existing system as described in Section 2.1 would'be able to detect a Hydrochloric Acid, Ammonia or an aqueous Sulfuric Acid leak if one occurs at the Cargill Facility and the wind conditions were from the north. The existing -
system would not be able to detect the remaining toxic chemicals which are-
- planned _to be either stored or shipped at the Cargill Facility (Ethanol, Sulfur Dioxide, Carbon _ Dioxide, and Gasoline). Therefore, an analysis'was conducted to determine what the-impact of a toxic chemical release at Cargill would be on control room habitability. No credit for toxic gas. monitoring was taken in the analysis which was performed and is sumarized herein. The following section discusses the regulatory requirements applicable to this analysis.
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3.0 APPLICABLE REGULATORY GUIDANCE The basis for the existing FCS TGMS is-NUREG-0737, Item III.D.3, " Control Room Habitability Requirements." As noted in Section 2.0, the TGMS was installed for off-site and on-site release requirements. For this analysis only the off-site releases are applicable (Cargill facility).
Given that the scope of analysis involves off-site chemical releases, the below identified Standard Review Plan (SRP) sections and Regulatory Guide (RG) were determined to be appropriate. These are as follows:
SRP 2.2.1-2.2.2
" Identification of Potential Hazards in Site Vicinity" SRP 2.2.3
" Evaluation of Potential Accidents" SRP 6.4
" Habitability Systems" RG 1.78
" Assumptions for Evaluating the Habitability of a Nuclear Power. Plant Control Room During a Postulated Hazardous Chemical Release" The guidance provided in these documents is summarized below in the context of the proposed changes.
q SRP 2.2.1 and 2.2.2. " Identification of Potential Hazards in Site Vicinity" j
i This document provides guidance to identify potential external hazards.
-It is pointed out that hazards which are identified as a result of transportation or storage events require further review under SRP 2.2.3. The hazard applicable to this proposed change is the transportation and storage of
' toxic chemicals off-site (ref. 4).
I SRP 2.2.3 " Evaluation of Potential Accident" Given a potential hazard identified under SRPL Sections _2.2.1 and 2.2 2, SRP Section 2.2.3 is used to determine which events must be considered further-as design basis events. The SRP Section 2.2.3 acceptance criteria states (ref.
'4):
"Accordingly,- the expected rate of occurrence of. potential exposures in.
excess of the'10CFR Part 100 guidelines-of approximately 104 per year is acceptable if, when combined with reasonable qualitative arguments, the realistic probability can be shown to be lower."
3
l SRP Section 2.2.3 goes on to say that if accidents involving the release of chemicals do not meet the above acceptance criteria, an evaluation of t!'e effects of these analyses on control room habitability should be made using SRP 6.4, " Habitability Systems."
I A probabilistic and design basis accident analysis was performed for the original licensing submittal regarding NUREG-0737 requirements. The original analysis employed site specific meteorology for off-site accidents, along with previously recorded transportation frequencies and estimates of the probability of occurrence for a given off-site accident. This approach was taken to eliminate those accidents for which the probability of exceeding airborne toxicity limits is less than 1E-07 events per year.
SRP 6.4 " Habitability Systems" The toxic gas portion of SRP 6.4 references Regulatory Guide 1.78 as the method to be used to determine whether the quantity or location of toxic material is such that additional analysis is necessary. The referenced methods to be used in any additional analyses are consistent with Regulatory Guide 1.78.
Reaulatory Guide 1.78 "Assumotions for Evaluatina the Habitability of a Nuclear Power Plant Control Room Durina a Postulated Hazardous Chemical Relftasst" The purpose of Regulatory Guide 1.78 is to identify chemica"1s which could render the control room uninhabitable. Screening criteria are provided in terms of proximity (within a five mile radius) and frequency (10 per year for truck and 30 per year for rail) of shipments. A list of some hazardous chemicals and their toxicity limits was also provided (ref. 5).
For those chemicals which could not be eliminated by the proximity / frequency / weight screening criteria, Regulatory Guide 1.78 provides methodology for calculation of control room toxic concentration versus time after an accidental release. The acceptance criterion for Regulatory Guide 1.78 is that the time from detection to the time when the toxicity limit is reached must be greater than two minutes to allow operators to don self-contained breathing apparatus.
The deterministic analysis (ref. 6) performed showed that this criterion was satisfied with the exception of six chemicals (Ammonia, Chlorine, Hydrochloric Acid, Carbon Dioxide, Gasoline and Sulfuric Acid). The two-minute criterion was used in the evaluation of releases from Cargill operations.
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4.0 ANALYSIS METHODOLOGY This report addresses potential chemical releases from Cargill operational accidents. All transportation routes were considered for Cargill releases. A survey of Cargill chemicals was conducted by OPPD for storage of potentially hazardous' chemicals. OPPD personnel have met with Cargill representatives on
- several occasions to discuss storage and material processing operations. The inventory listed in this analysis (Table 7.1 and ref. 6) is a result of those meetings with Cargill representatives.
The general approach applied for Cargill release considerations consisted of the following steps. Note that steps 1 and 2 involve deterministic analyses, and Steps 3 and 4 involve probabilistic analyses. The probabilistic analyses are only performed for those chemicals that exceeded the deterministic screening criteria of Steps 1 and 2.
Steo 1 - Hazardous Chemical Identification For the purposes of this analysis, a chemical is identified as hazardous if it meets all of the following criteria:
a.Transportationand/orstorageofachemicaloccurswithinafive-mile radius of the plant.
- b. Shipment frequency is greater than 10 per year for truck and 30 per year for rail,
- c. Chemical appears on either the Regulatory Guide 1.78 list of potentially hazardous chemicals or'the Environmental Protection Agency's (EPA's) list of Extremely Hazardous Substances -(ref. 7).
Sten 2 - Control Room Concentrations t
For each chemical identified as being hazardous in step 1, a calculation
= of control room concentration versus time is performed. The accident _is assumed to occur at the transportation and/or storage location closest to the control room intake. No credit. was taken for operation of the TGMS. _The calculations (ref. 6) were performed using the T0XIC 5.2 computer code, following the-guidance of Regulatory. Guide 1.78. The 'T0XIC 5.2 code ~ accounts for such parameters as chemical volatility, atmospheric dispersion and' control room intake / exhaust flow. The T0XIC 5.2 code is a dispersion modelling code utilizing the Pasquill-Gifford equations. This code is' used to predict the
. movement of toxic clouds from accident sites and calculates buildup of toxic concentration within the control room.
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i
.j Steo 2 - Control Room Concentration 1 (Continued)
In accordance with Regulatory Guide 1.78 chemicals are judged not to require an automatic detection system if either:
- a. control room concentrations never reach toxic limits, or
- b. there is at least two minutes between the time that the toxic gas is detectable by smell by the operating crew and the time that the toxic limit is reached.
The toxicity limits used in these calculations are based. on the "Imediately Dangerous to Life and Health" (IDLH) concentrations published by the National Institute of Occupational Safety and Health (NIOSH) (ref. 8). The chemical toxicity limits are those proposed by NIOSH since these limits are based upon acute short-term toxic releases, The NIOSH toxicity limits were established based upon serious irreversible health effects or death as a result of a single exposure for a relatively short period of time. This approach is consistent with methods described in Regulatory Guide 1.78.- For conservatism the toxicity limit for Carbon Dioxide stated in Regulatory Guide 1.78 was used in this analysis.
The IDLH values, by definition were developed for a maximum 30 minute exposure at the maximum IDLH concentration. The Regulatory Guide 1.78 toxic limits assume only a two minute exposure to a concentration that begins low (at detection) and increases to the limit at the end of the two minutes. There
-have been previous utility submittals (e.g., Vermont Yankee, Safety Evaluation Report for Vermont Yankee's Technical Specification Amendment, Docket No.
50-271, supporting Amendment No.132 to Facility Operating License No. DPR-28, dated October 24,1991) which stipulate usage of.IDLH toxic limits. Subsequent work in toxicity limits since inception of Regulatory Guide 1.78 has provided justification for use of the IDLH values. NRC workshops conducted with toxicity experts revealed that for chlorine, Ammonia, and Sulfur Dioxide, use of the IDLH values versus Regulatory Guide 1.78 values was warranted. The use of IDLH values is conservative compared to Regulatory Guide 1.78. Therefore, based on 'these arguments, for all chemicals of interest to this evaluation.
except for Carbon Dioxide, the IDLH toxic limits were used.
Due to the lack of readily retrievable information for the chemical properties of Gasoline, the conservative chemical properties of Pentane were used for an initial screening.
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Steo 3 - Probability of Control Room Uninhabitability Section 2.2.3 of the SRP and 5.2.4 of NUREG-1407 state that if the original design basis does not meet R.G.1.78 requirements, the licensee may choose an alternate approach of demonstrating that the probability of occurrence of the original design basis event is sufficiently low (i.e, less than 1E-06/yr) and the conditional core damage probability is judged to be less than 1E-01. The acceptance criterion for the toxic material being analyzed is a demonstration that the core damage frequency due to Cargill offsite toxic releases is less than 1E-06/yr. NUREG-1407 further states, if the original design basis hazard combined with the conditional core damage probability is not less than 1E-06/yr, additional analysis may be needed. For this analysis, the core damage frequency is equal to the probability of loss of control room habitability (from Cargill off-site sources) times the conditional core damage probability. For chemicals which require probabilistic analysis the annual probability of control room uninhabitability is calculated using the following information (ref. 10):
Potential Caraill Offsite Releases For Rail. and Truck Shioments:
n=s i=2 j=7 xPreixIPscen I(Pstab xD rack xP mp)
F=
I Nship x
t i
n=1 i=1 j=1 where:
F=
frequency of loss of control room (event frequency / year)
Nship= shipment frequency for each shipment route and toxic chemical per j
year (shipments / year)
Pre 1= probability of a spill per mile traveled (spills / shipment-mile)
Pscen* probability of a release scenario (e.g., maximum concentration or maximum duration-concentration)
Pstab" probability of a specific atmospheric stability class (A-G) l D rack = critical length of transportation route where a spill could t
result in loss of control room habitability for a given scenm to (miles)
P mp= probability of plant impact; the normalized probability that the i
wind is directed from the hazardous length of track to the control
- room, l
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1
Sigp 3 - Probability of Control Room Uninhabitability (Continued)
Caraill Storaae Facilities:
n=2 j=7 F = Prail x IPscen x Z(PstabxPwindxP mp) i n=1 j=1 where:
F=
frequency of control room uninhabitability (event frequency /yr)
Prat 1= vessel failure rate (failures /yr)
Pscen= probability of release scenario (e.g., maximum concentration or maximum duration-concentration)
P np= probability of plant impact (0 or 1) i Pstab= probability of specific atmospheric stability class (A-G)
Pwind= probability of winds blowing from a specific wind sector to the Fort Calhoun site, only winds from the north sector are applicable.
Sten 4 - Conditional Core Damaae Freaue02 NUREG-1407 further states that if the original de ign basis hazard combined with the conditional core damage probability is not less than 1E-6/yr, additional analysis may be needed. For this analysis, the core damage frequency is equal to the probability of loss of control room habitability i
(from Cargill offsite sources) times the conditional core damage probability (ref. 10).
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4 Step 4 - Conditional Core Damaae Frequency (Continued)
For Rail. and Truck Shioments:
n=s 12 j=7 xPre1xIPscen I(PstabxD rackxP mp)
{P = 0.001 X F}
P = 0.001 x I N: hip x
t i
n=1 i=1 j=1 where:
P=
frequency of core melt (event frequency / year)
.001=
frequency of core melt given a loss of control room habitability. The frequency of core melt has been previously shown to be on the order of less than 0.0001 per the IPEEE model developed by OPPD for NRC submittal in response to Generic Letter 88-20.
Nship= shipment frequency for each shipment route and toxic chemical per year (shipments / year)
Frep= probability of a spill per mile traveled (spills / shipment-mile)
Pscen= probability of a release scenario (e.g., maximum concentration or maximum duration-concentration)
Pstab= probability of a specific atmospheric stability class (A-G)
D rack = critical length of transportation route where a spill could result t
in loss of control room habitability for a given scenario (miles)
P mp" probability of plant impact; the normalized probability that the i
wind is directed from the hazardous length of track to the control room.
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For Caraill Storage Facilities:
n=2 j=7 P = 0.001 x Pran x IPscen x I(Pstab xPwind xP mp)
{P= 0.001 X F}
i n=1 j=1 where:
P=
frequency of core melt (event frequency /yr)
.001 = frequency of core melt given a loss of control room habitability Pran= vessel failure rate (failures /yr)
Pscen= probability of release scenario (e.g., maximum concentration or maximum duration-concentration)
P mp= probability of plant impact (0 or 1) i Pstab= probability of specific atmospheric stability class (A-G)
Pwind= probability of winds blowing from a specific wind sector to the Fort C'lhoun site, only winds from the north are applicable.
Step 4 calculates the frequency of conditional core damage resulting from Cargill chemical releases. In order to cause such a release, the control room uninhabitability must lead to a plant trip as stated in the equations above with operating crew and equipment failure. This in turn would have to lead to a failure of a critical safety function such as core cooling or decay heat removal.
The SRP Section 2.2.3 guideline of IE-7/ year actually refers to the frequency of a 10CFR100 fission product release involving significant core damage.
5.0 HIGHWAY ANALYSIS RESULTS The highway analysis involved a survey of chemicals which are shipped to or from Cargill within a five mile radius of FCS. The highway analysis is evaluated consistent with Steps 1 and 2 from Section 4.0.
5.1 Hazardous Chemical Identification There are four highways within five miles from the power plant (V. S. 30, U. S. 75, State 91 and State 133). The Cargill Corporation was contacted for future truck / highway shipments since their corn milling and processing plant, located 1.3 miles north of FCS, will be going inte picduction in early 1995 and significant quantities of Ethanol and Carbon Dioxide will be shipped from their facility.
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The Cargill chemicals identified during the survey were compared to Regulatory Guide 1.78 and EPA's list of Extremely Hazardous Substances. The chemicals which will be shipped within the frequency of the screening requirements above and within five miles of FCS and are considered toxic were as follows:
Ethanol Carbon Dioxide Hydrochloric Acid Sulfuric Acid Gasoline 5.2 Control Room Concentrations Loss of control room habitability occurs when the control room concentration of a identified hazardous chemical exceeds its " toxic limits" in less than two minutes after detection. The toxic limits for all chemicals with exception to Carbon Dioxide were the NIOSH "Immediately Dangerous to Life and Health (IDLH) concentrations.
To calculate control room concentrations as a result of a truck release, the computer program T0XIC 5.2 was used. Control room habitability is maintained if control room concentrations remain less than the IDLH value, or if there is at least two minutes between the time the toxic gas is detected by smell by the operators and the time that the IDLH value is reached. The limit of two minutes is stipulated in Regulatory Guide 1.78.
The results indicated that none of the hazardous chemicals proposed to be shipped to or from Cargill over the highways within five miles of the power plant would exceed the Regulatory Guide 1.78 acceptance criterion in the event of a toxic chemical release. Table 5.1 provides a list of proposed highway shipments along with the IDLH value.
As shown, in the table, the maximum control room concentration for each chemical is less than its corresponding IDLH value. Therefore, the " toxic limit", is not reached, and control room habitability is maintained in the event of a postulated highway accident (Ethanol, Carbon Dioxide, Hydrochloric Acid, Gasoline, and Sulfuric Acid).
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Table 5.1 Control Room Concentrations of Hazardous Chemicals from Hiahway Accidents Chemical Quantity Maximum Control IDLH Room Concentration (nom)
(nom)
Hydrochloric Acid 5,000 gal.
15 100 (4 trucks per week)
Carbon Dioxide 20 tons 1,633 10,000 (24 trucks per day)
Ethanol
- 9,600 gal.
109.0 1,000 (20trucksperday)
Sulfuric Acid 4,000 gal, na na (1 truck per month)
Gasoline 8,300 gal.
232 300 (7 trucks per week)
- an actual release of 29,000 gallons (standard railcar capacity) was assumed since the frequency of shipments is significant na - designates "not applicable" since Sulfuric Acid is a non-volatile chemical and was determined not to be a hazard to the control room.
6.0 RAILROAD ANALYSIS RESULTS The railroad analysis involves steps 1 through 4 from Section 4.0,
" Analysis Methodology." The sections below show that, of the Cargill hazardous chemicals identified, only Sulfur Dioxide exceeds the Regulatory Guide 1.78 criteria. Therefore, probabilistic analyses (Sections 6.3 and 6.4) were performed for Sulfur Dioxide. Table 6.1 provides a list of all shipments proposed to be moved on the railspur.
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6.1 Hazardous Chemical Identification Reestablishment of a railspur is currently underway by Chicago and Northwestern Railway 0.4 miles west of the control room intake. This railspur will be rerouted through the Cargill corn milling and processing plant which is currently under construction. Representatives of Cargill provided a list of all chemicals which could be transported on the railspur.
As indicated in Section 5.1, the chemicals listed were compared to Regulatory Guide 1.78 and EPA's list of Extremely Hazardous Substances.
Chemicals which appeared on either list were considered for further evaluation. The chemicals which were considered toxic and may be shipped frequently, as identified in Table 6.1, are as follows:
Gasoline Ethanoi Carbon Dioxide Sulfur Dioxide 6.2 Control Room Concentrations As in Section 5.2, the computer code T0XIC 5.2 was used to calculate the control room concentrations. For chemical s that act as asphyxiants (e.g.
Carbon Dioxide), control room habitability was assumed to be lost if the concentration exceeded the Regulatory Guide 1.78 toxic limit. For Carbon Dioxide it was assumed that the gas would not be detected prior to reaching asphyxiation level, thus the two-minute threshold criterion is not used.
The T0XIC 5.2 analysis results are listed in Table 6.2. The IDLH value, volume shipped, and maximum control room concentration are listed. From the deterministic analyses performed it was determined that in the event of a Sulfur Dioxide spill from a catastrophic rail car failure the IDLH values would be exceeded. Therefore, further analysis was required for Sulfur Dioxide to determine the probability of control room uninhabitability.
The other hazardous chemicals including Gasoline, Ethanol, and Carbon Dioxide met the requirements of Regulatory Guide 1.78 and no further analysis was required.
6.3 Probability of Control Room Uninhabitability i
A hazard model was developed to calculate the annual probability (F) of control room uninhabitability as described in section 4.0. The probability of j
loss of control room habitability, given a release, varies as a function of distance from the control room fresh air intake, wind direction, speed,-and atmospheric stability.
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i
For Rail car accidents the frequency of loss of control room is established as:
I n*s i=2 ja7 xPre1xEPscen E(PstabxD rackxP mp)
F=
I Nship x
t i
n=1 i=1 j=1 where:
F=
frequency of loss of control room (event frequency / year)
Nship= shipment frequency for each shipment route and toxic chemical per year (shipments / year). From surveys provided by Chicago and Northwestern Railway, and information provided by Cargill, Table 6.1 for rail shipments has been established. The appropriatenumberofcars/yearwasusedintheprobability analysis for each specific hazardous material which could not meet deterministic requirements. As an example for Sulfur Dioxide, 26 cars are anticipated to be shipped per year on the rail spur, and thus for this calculation, Nship= 26 Pre 1= Probability of a spill per mile traveled (spills / shipment-mile).
From studies of accident data in the Handbook of Chemical Hazards Analysis Procedures, USEPA, 1989, it was shown that the mainline accident rate is approximately 6E-7/ car-mile with 70% of releases from railcars involving a partial loss of cargo through 2" holes and 30% involving a total loss of cargo. Spur accident rates were halved since switching on these lines is performed at a much slower velocity. The accident rate was assumed to be 3E-7/ car-mile for the rail spur.
Pre 1=
3E-07 car-mile Pscen= probability of a release scenario (maximum concentration or maximum duration-concentration) as stated above 70% of releases are partial losses (maximum duration releases) and 30% of the releases are complete losses (maximum concentration). Both cituations were analyzed to determine the greatest impact.
The.refore, depending upon a maximum duration or maximum concentration release, P cen= 0.70 o* 0.30 3
D rack = critical length of transportation route where a spill could result t
in loss of control room habitability for a given scenario (miles).
These values are calculated from a spreadsheet program for a particular shipment of a hazardous material. For example for Sulfur Dioxide the critical track length was found to be; D rack = 2,115 feet.
t 14
4 Pstab= probability of a specific atmospheric stability class (A-G).
The probability of a specific atmospheric stability class is dependent upon site specific data provided in Table 6.3. The following information is provided for classes A-G; Stability Class Probability of Wind Stability A
0.027 B
0.055 C
0.069 0
0.407 E
0.299 F
0.115 G
0.028 P mp= probability of plant impact; the normalized probability that the i
wind is directed from the hazardous length of track to the control room. The probability of plant impact was calculated. This probability is a function of probability of location in a specific wind sector, probability of a specific atmospheric class, and length of track in a particular sector. For Sulfur Dioxide rail shipments 0.4 miles from the plant it was found that the probability of plant impact was; P mp=
0.063 (for atmospheric class G) i All other chemicals which are used at the Fort Calhoun Station were screened against toxicity 6nd volume of material. The probability for loss of control room habitability for the Sulfur Dioxide rail case was found to be; F=5.50E-08/ year Table 6.1 Estimated Shinments To be Made on Caraill Railsour Hazardous Chemical Quantity Number of Shipments j
oer Year Gasoline 28,000 gal.
104 Ethanol 29,000 gal.
2,372.5 Carbon Dioxide 60 tons 2,920 Sulfur Dioxide 90 tons 26 15
l Table 6.2
[gntrol Room Concentrations of Hazardous Chemicals from Rail Accidents Chemical Quantity Maximum Control IDLH Room Concentration (pom)
(opm)
Gasoline 28,000 gal.
382
- 300 Ethanol 29,000 gal.
20/.2 1,000 Carbon Dioxide 60 ton 5,576.3 10,000 Sulfur Dioxide 90 ton 101.3 100
- Due to the lack of readily retrievable information for the chemical properties of Gasoline, the conservative chemical properties of Pentane were used for an initial screening and yielded a value (382 ppm) in excess of the IDLH for Gasoline (300 ppm). The volatile property of Pentane maximizes the source term of the spill. In actuality, Gasoline would not yielo as significant a source term. Based on engineering judgement, gasoline is not classified as a hazard since nominal Gasoline properties, for the 10XIC code input parameters, indicate that 2.4 minutes would be available between the time Gasoline is sensed in the control room and when the control room becomes uninhabitable.
Therefore, no further analysis was deemed necessary since Gasoline meets the detenninistic screening requirements of Section 4.0, Step 2.
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i Table 6.3 (ref. 6)
Fort Calhoun Station MeteorqJoaical Site Data Stability Stability Frequency of Wind Direction Frequency of Class Class Average Stability Wind Direction Windspeed (m/
Class (%)
Within Stabil-sec) ity Class (%)
A 3.5 2.7 NNE 5.4 A
3.5 2.7 NE 3.4 A
3.5 2.7 ENE 2.4 A
3.5 2.7 E
1.6 A
3.5 2.7 ESE 2.1 A
3.5 2.7 SE 3.0 A
3.5 2.7 SSE 6.6 A
3.5 2.7 S
7.3 A
3.5 2.7 SSW 5.6 A
3.5 2.7 SW 3.2 A
3.5 2.7 WSW 2.4 A
3.5 2.7 W
5.3 A
3.5 2.7 WNW 8.4 A
3.5 2.7 NW 15.4 A
3.5 2.7 NNW 17.9 A
3.5 2.7 N
10.0 B
3.6 5.5 NNE 3.9 8
3.6 5.5 NE 3.7 8
3.6 5.5 ENE 2.6 B
3.6 5.5 E
2.6 i
B 3.6 5.5 ESE 3.9 B
3.6 5.5 SE 5.3 8
3.6 5.5 SSE 9.7 B
3.6 5.5 S
11.5 l
l 17
Table 6.3 (cont'd)
Fort Calhoun Station Meteorological Site Data Stability Stability Frequency of Wind Direction Frequency of Class Class Average Stability Wind Direction Windspeed(m/
Class (%)
Within Stabil-sec) ity Class (%)
B 3.6 5.5 SSW 6.7 8
3.6 5.5 SW 4.6 8
3.6 5.5 WSW 3.0 B
3.6 5.5 W
3.1 B
3.6 5.5 WNW 5.4 6
3.6 5.5 NW 10.5 B
3.6 5.5 NNW 13.9 B
3.6 5.5 N
9.6 C
3.6 6.9 NNE 3.9 C
3.6 6.9 NE 2.6 C
3.6 6.9 ENE 2.7 C
3.6 6.9 E
3.1 C
3.6 6.9 ESE 4.5 C
3.6 6.9 SE 7.0 C
3.6 6.9 SSE 10.6 C
3.6 6.9 S
10.7 C
3.6 6.9 SSW 6.9 C
3.6 6.9 SW 4.2 C
3.6 6.9 WSW 2.4 C
3.6 6.9 W
3.3 C
3.6 6.9 WNW 4.7 C
3.6 6.9 NW 11.6 C
3.6 6.9 NNW 13.4 C
3.6 6.9 N
8.5 18
Table 6.3 (cont'd)
Fort Calhoun Station Meteorolo9 cal Site Data 1
Stability Stability Frequency of Wind Direction Frequency of Class Class Average Stability Wind Direction Windspeed (m/
Class (%)
Within Stabil-sec) ity Class (%)
D 3.6 40.7 NNE 3.9 D
3.6 40.7 NE 2.9 D
3.6 40.7 ENE 3.0 0
3.6 40.7 E
4.0 0
3.6 40.7 ESE 5.1 0
3.6 40.7 SE 8.7 0
3.6 40.7 SSE 12.0 D
3.6 40.7 S
10.1 D
3.6 40.7 SSW 5.5 D
3.6 40.7 SW 2.7 0
3.6 40.7 WSW 2.2 0
3.6 40.7 W
2.6 D
3.6 40.7 WNW 4.9 0
3.6 40.7 NW 11.6 0
3.6 40.7 NNW 13.7 D
3.6 40.7 N
7.1 E
2.7 29.9 NNE 1.8 E
2.7 29.9 NE 1.6 E
2.7 29.9 ENE 1.7 E
2.7 29.9 E
2.9 I
E 2.7 29.9 ESE 6.2 E
2.7 29.9 SE 13.1 E
2.7 29.9 SSE 12.0 E
2.7 29.9 S
10.8 E
2.7 29.9 SSW 6.2
)
i l
l 19
Table 6.3 (cont'd)
Fort Calhoun Station Meteorological Site Data Stability Stability Frequency of Wind Direction Frequency of Class Class Average Stability Wind Direction Windspeed(m/
Class (%)
Within Stabil-sec) ity Class E
2.7 29.9 SW 3.6 E
2.7 29.9 WSW 3.3 E
2.7 29.9 W
5.7 E
2.7 29.9 WNW 10.1 E
2.7 29.9 NW 11.2 E
2.7 29.9 NNW 6.6 E
2.7 29.9 N
3.4 F
1.8 11.5 NNE 1.3 F
1.8 11,5 NE 1.5 F
1.8 11.5 ENE 1.5 F
1.8 11.5 E
2.6 F
1.8 11.5 ESE 8.2 F
1.8 11.5 SE 12.2 F
1.8 11.5 SSE 7.7 F
1.8 11.5 S
10.1 F
1.8 11.5 SSW 8.9 F
1.8 11.5 SW 6.1 F
1.8 11.5 WSW 6.0 F
1.8 11.5 W
9.0 F
1.8 11.5 WNW 13.0 F
1.8 11.5 NW 7.4 F
1.8 11.5 NNW 2.4 F
1.8 11.5 N
2.3 I
l 20 J
1 i
Table 6.3 (cont'd)
Fort Calhoun Station Meteorological Site Data Stability Stability Frequency of Wind Direction Frequency of Class Class Average Stability Wind Direction Windspeed (m/
Class (%)
Within Stabil-sec) ity Class (%)
l G
1.7 2.8 NNE 2.4 G
1.7 2.8 NE 2.8 G
1.7 2.8 ENE 2.4 G
1.7 2.8 E
4.6 G
1.7 2.8 ESE 12.2
~b 1.7 2.8 SE 11.0 G
1.7 2.8 SSE 8.6 G
1.7 2.8 S
8.0 G
1.7 2.8 SSW 9.5 G
1.7 2.8 SW 7.4 G
1.7 2.8 WSW 5.2 G
1.7 2.8 W
7.2 G
1.7 2.8 WNW 6.3 G
1.7 2.8 NW 4.7 1
G 1.7 2.8 NNW 3.2 i
G 1.7 2.8 N
4.1 6.4 Frequency of Conditional Core Damage as a Function of Railspur Shipments j
l Sections 6.1 and 6.2 show that rail shipments of Sulfur Dioxide are the only events which do not satisfy the deterministic criteria of Regulatory Guide 1.78. SRP Section 2.2.3 requires that such an accident be considered as a design basis event only if the frequency exceeds 1E-06/ year. To calculate the probability of conditional core damage as a result of shipping Sulfur Dioxide by rail the frequency of loss of controi room must be analyzed.
21 1
j 6.4.1 Initiating Event The initiating event considered in this section is a Sulfur Dioxide shipment accident on the railspur. As calculated in Section 6.3, the frequency of this initiating event is 5.5E-08/ year. This initiating event does not lead directly to core damage. For core damage to occur, a severe plant transient i
and trip must occur, and there must be failure of a critical safety function.
6.4.2 Frequency of Core Damage
)
The core damage frequency from this initiating event is estimated as follows-P = F x Pcore l
F=
5.50E-08/ year Pcore= 0.001 (in actuality a value of 7.4E-05 was calculated, as described below), however, to be conservative a value of 0.001 aas used in this analysis. Use of 0.001 accounts for any uncertainties 1
or biases which were not explicitly identified.
- Thus, P=5.5E-011/ year The value for Peore was developed from OPPD's Individual Plant Examination (IPE) for FCS. The IPE (ref. 9) was developed to evaluate the frequency of core damage events at FCS. The IPE developed a model that estimates the probability of core damage following an initiating event that challenges continued plant operation or is a design basis accident. Several initiating event types were evaluated in the IPE. The following event types were included in the IPE which would require consideration for applicability to the toxic gas release event:
- 1) Transients
- 2) LOCAs (Loss of Coolant Accident)
- 3) SGTR (Steam Generator Tube Rupture)
- 5) LOOP /SB0 (Loss of Offsite Power / Station Blackout)
- 6) Special Initiators (i.e., support system failures)
From a review of the event types and the automatic response without operator intervention for most events it was determined that only transient j
initiators required further evaluation, with respect to applicability to a toxic gas release. The calculation of the conditional core damage probability for an unmitigated plant trip is based upon incapacitation of the FCS operators in the event of a toxic hazard. It was assumed that the transient, concurrent with toxic release, would occur four hours into tne operators 1
eight-hour shift.
22
The quantification of the conditional core damage probability was based on the dominant cutsets from the FCS IPE. The cutsets represented in this calculation include all cutsets involving operator actions which could be impacted by a toxic gas condition. The calculation involved the following steps: 1) identify all cutsets involving manual reactor trip and 2) set a human error rate for human actions in the first four hours.
The FCS has a number of automated functions which preclude the need for operator actions following a manual reactor trip.
Motor-driven main feedwater and condensate pumps continue to operate to remove decay heat following a plant trip.
Feedwater regulating valves automatically ramp down to control steam generator level following a plant trip.
Steam generator water level control, which prevents steam generator overfill.
Two 100% capacity auxiliary feedwater pumps automatically start in the event main feedwater is unavailable.
Adequate inventory exists in the condenser hotwell and emergency feedwater storage tank to assure makeup water to the steam generators for more than four hours.
The key plant feature which could challenge plant shutdown capability by disabling main feedwater is the automatic fast transfer of the offsite power supply from the main generator to an offsite source following a turbine generator trip. Failures in the fast transfer logic and unavailability of the preferred offsite source could require operator action to align AC power.
The resulting core damage probability was calculated to be 7.4E-05. The dominant contributors to this probability were cutsets involving unavailability of the offsite power supply with subsequent independent failures causing failure of the Auxiliary Feedwater System. Given the unce>tainties involved in this analysis, this result was conservatively rounded to 1E-03.
Utilizing the conservative conditional core damage probability of 1E-03 with the frequency for loss of control room habitability yields a conditional core damage frequency of 2.74E-10/ year. This result shows that the estimated conditional core damage frequency due to a rail accident causing a loss of of f-site power is well below the SRP Section 2.2.3 and NUREG-1407 guidelines of IE-06. Thus, this event does not require consideration as a design basis event, and the Regulatory Guide 1.78 provisions for an automatic detection system are not required.
23
i L0 CARGILL FACILITIES RESULTS On-site visits and phone calls to Cargill were performed to determine the amount of toxic materials which are stored at their site (Table 7.1).
7.1 HAZARDOUS CHEMICAL IDENTIFICATION The chemicals which must be considered for further consideration are Ethanol, Gasoline, Carbon Dioxide, Hydrochloric Acid, Sulfur Dioxide, and Ammonia.
L2 CONTROL ROOM CONCENTRATI0H As performed in Section 5.2, the computer code T0XIC 5.2 was used to calculate the control room concentrations.
For chemicals that act as asphyxiants (e.g. Carbon Dioxide), control room habitability was lost if the concentration exceeded the Regulatory Guide 1.78 toxic limit. For Carbon Dioxide it was assumed that the gas would not be detected prior to reaching asphyxiation level, thus the two-minute warning criterion is not used.
The results are listed in Table 7.2.
The IDLH value, volume stored, maximum control room concentration are listed. From the analyses performed it was determined that in the event of a Sulfur Dioxide or Ammonia tank catastrophic spill that the IDLH values would be exceeded. It was also determined that if a maximum duration leak occured in a Carbon Dioxide tank that the IDLH values would be exceeded. The requirements of Regulatory Guide 1.78 were met for Gasoline, Ethanol, and Hydrochloric Acid releases. Sulfuric Acid was screened out based on its non-volatile characteristics (98% conc.).
Therefore, further analysis was required for Sulfur Dioxide, Ammonia and Carbon Dioxide to determine the probability of control room uninhabitability.
7.3 PROBABILITY OF CONTROL ROOM UNINHABITABILITY A hazard model was developed to calculate the annual probability (F) of control room uninhabitability as described in Section 4.0. The probability of loss of control room habitability given a release, varies as a function of distance from the control room fresh air intake, wind direction, speed, and atmospheric stability.
For Cargill tank accidents the frequency of loss of control room was provided in Section 4.0. The assigned probabilities to these events is as follows:
24
l Caraill Storage Facilities:
n2 J7 F = Prati x IPscen x E(PstabxPwindxP mp) i n1 j1 where:
F=
frequency of control room uninhabitability (event frequency /yr)
Prat 1 = vessel failure rate (failures /yr)
Prai) = 1E-4/yr. (ref. 10)
P con = probability of release scenario (e.g., maximum concentration or 3
maximum duration-concentration) (ref. 10)
Pscen = 90% of releases involving a partial loss of cargo (maximum-concentration), 10% of releases involve a release through a 2" orifice (maximum-duration)
P mp = probability of plant impact (0 or 1) i Pstab " Probability of specific atmospheric stability class (A-G) which is the same as reported in Section 6.3.
Pwind = pobability of winds blowing from a specific wind sector to the Fort Calhoun site, Table 6.3 provides the meteorological probability of winds blowing from a specific sector for the Fort Calhoun Station site. Since Cargill is located to the north only those wind classes were utilized.
The frequency of control room loss of habitability can be found in Table 7.3 for each hazardous chemical release. The total frequency from release of Cargill hazardous chemicals was determined to be 4.61E-07/ year.
7.4 Frequency of Conditional Core Damace_As a Function of Offsite Releases Sections 7.1 and 7.2 show that offsite releases of Ammonia, Carbon Dioxide and Sulfur Dioxide are the only events which do not satisfy the deterministic criteria of Regulatory Guide 1.78. SRP Section 2.2.3 requires that such an j
accident be considered as a design basis event only if the frequency exceeds 1E-06/ year. To calculate the probability of conditional core damage as a result of offsite storage of Ammonia, Sulfur Dioxide and Carbon Dioxide the frequency of loss of control room must be analyzed.
25 7
m
7.4.1 Initiatina Event The initiating event considered in this section is an Ammonia, Sulfur Dioxide or Carbon Dioxide tank failure. As calculated in Section 7.3, the frequency of this initiating event is 4.61E-07/ year. This ' initiating event does not lead directly to core damage. For core damage to occur, a severe plant transient and trip must occur, and there must be failure of a critical safety function.
7.4.2 Freauency of Core Damaae The core damage frequency from this initiating event is estimated as follows:
P = F x Pcore F=
4.61E-07/ year Peore= 0.001 (in actuality a value of 7.4E-05 was calculated per Section 6.4.2), however, to be conservative a value of 0.001 was used in this analysis.
Thus, P = 4.61E-10/ year This result shows that the estimated conditional core damage frequency due to a storage tank accident is well below the SRP Section 2.2.3 and NUREG-1407 guidelines. Thus, this event does not require consideration as a design basis event, and the Regulatory Guide 1.78 provisions for an automatic detection system are not required.
Table 7.1 Caraill Storace Tank Capacities Airborne Toxic Materials Facility Dist.from Plant Chemical Amount of Toxic Material Site (miles)/oirection Cargill 1.3/0 Ethanol 1.4 million gallon tank Carbon Dioxide (3)600 ton tanks Sulfuric Acid 7000 gallon tank Gasoline 60,000 gallon tank Ammonia 20,000lbs. tank Hydrochloric Acid (aq.)
25,000 gallon tank Sulfur Dioxide 28,000 gallon tank 26
~_
~
Table 7 2 Control Room Concentrations of Hazardous Chemicals from Caroill Tank Failure Accidentt Chemical Quantity Maximum Control IDLH Room Concentration (com)
(com)
Ammonia 20,000lb.
exceeded IDLH 300 Sulfur Dioxide 28,000 gal.
exceeded IDLH 100 Hydrochloric Acid 25,000 gal.
12.82 100 Carbon Dioxide 600 tons exceeded IDLH 10,000 Gasoline 60,000 gal.
211.7 300 Ethanol 1.4 million gal 216.4 1,000 Iable 7.3 Off-site Tank Failure Cumulative Freauency of Control Room Habitability Loss Hazardous Chemical Frecuencv/velt Ammonia 1.15E-08 Carbon Dioxide 3.09E-07 Sulfur Dioxide 1.4E-07 Cumulative Frequency 4.61E-07/ year 27
\\
8.0 CONCLUSION
S The analysis considered in this report evaluates control room habitability in order to address NUREG-0737, Item Ill.D.3.4, requirements for Cargill toxic chemical releases.
The evaluation includes both deterministic and probabilistic analyses, and takes no credit for the existing TGMS. The deterministic analyses show that the Regulatory Guide 1.78 guidelines are met for all chemicals except Ammonia, Sulfur Dioxide and Carbon Dioxide. The combined probabilistic analyses summarized in Table 8.1 show that the probability of conditional core damage due to a Cargill chemical release is well below the SRP Section 2.2.3 guideline for consideration as a design basis event.
Together these analyses show that the Cargill releases are not considered a design basis event, and therefore no other provisions are necessary to address a Cargill release.
Table 8.1 Cumulative Toxic Hazard Freauency Offsite Sources Source Chemical Frequency of Control Estimated Core Room Habitability loss Damage Frequency (year-1)
(year-1)
Railspur Sulfur Dioxide 5.50E-8 5.50E-11 Cargill Sulfur Dioxide 1.40E-7 1.40E-10 Cargill Carbon Dioxide 3.09E-7 3.09E-10 Cargill Ammonia 1.15E-8 1.15E-11 Summing the Estimated Core Damage Frequency Yields Total Fort Calhoun Toxic Hazard Frecuency 5.16E-10/ year i
1 28 j
9.0 REFERENCES
i 1.
NUREG-0737, "TMI Action Plan," Item III.D 2.
Fort Calhoun Station Updated Safety Analysis Report 1
3.
Fort Calhoun Station Technical Specifications 4.
NUREG-0800, Standard Review Plan, Sections 2.2.1, 2.2.2, 2.2.3 S.
Regulatory Guide 1.78, " Assumptions for Evaluating the Habitability of a Nuclear Power Plant Control Room During a Postulated Hazardous Chemical Release," June, 1974 6.
OPPD Engineering Analysis, EA-FC-94-012, Rev.1, " Toxic Hazards Analysis" 7.
" Technical Guidance for Hazard Analysis, Emergency Planning for Extremely Hazardous Substances," U.S. Environmental Protection Agency, Federal Emergency Management Agency, U. S. Department i
of Transportation, December, 1987 8.
" Pocket Guide to Chemical Hazards," National Institute of Occupational Safety and Health, September,1985 9.
NUREG/CR-5669(PNL-7522), " Evaluation of Exposure Limits to Toxic Gases for Nuclear Reactor Control Room Operators", July 1991 10.
Omaha Public Power District, Fort Calhoun Station, Individual Plant Examination Submittal, December 1993 29
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