ML20206E114
| ML20206E114 | |
| Person / Time | |
|---|---|
| Site: | Paducah Gaseous Diffusion Plant |
| Issue date: | 04/27/1999 |
| From: | Toelle S UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | Paperiello C NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| GDP-99-0072, GDP-99-72, NUDOCS 9905050026 | |
| Download: ML20206E114 (9) | |
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USEC A Glo6al Entgy' Company April 27,1999 GDP 99-0072 Dr. Carl J. Paperiello Director, Office of Nuclear Material Safety and Safeguards Attention: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Paducah Gaseous Diffusion Plant (PGDP)
Docket No. 70-7001 Response to Request for Additional Information on Building C-331 and C-335 Seismic Upgrades (TAC No. L32107) i
Dear Dr. Paperiello:
The purpose of this letter is to respond to the NRC's April 7,1999 letter requesting additional information concerning USEC's application to amend Certificate of Compliance GDP-1. This amendment would extend the completion date for the Building C-331 and C-335 seismic upgrades to June 30,2000. Responses are provided in the enclosure.
If you have any questions or coraents on these re:;ponses, please contact me at (301) 564-3250.
There are no new comminnents contained in tMs submittal.
Sincerely, n
S. A.
I N Steven A.Toelle Nuclear Regulatory Assurance and Policy Manager
Enclosure:
United States Enrichment Corporation, Paducah Gaseous Diffusion Plant, Docket No. 70-7001, Response to April 7,'1999 NRC Request for Additional Information Concerning C-331 and C-335 Seismic Upgrades (TAC No. L32107)
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Mr. Robert C. Pierson (NRC)
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NRC Region III Office NRC Resident Inspector-PGDP NRC Resident Inspector-PORTS ii 4 01.J O Mr. Randall M. DeVault (DOE)
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, Bethesda, MD 20817-1818 Telephone 301-564-3200 Fax 301-564-3201 http://www.usec.com Offices in Livermore, CA Paducah, KY Portsmouth, OH Washington. DC
Enclosure GDP 99-0072 Page 1 of 8 United States Enrichment Corporation Paducah Gaseous Diffusion Plant Docket No. 70-7001 Response to April 7,1999 NRC Request for AdditionalInformation Concerning Building C-331 and C-335 Seismic Upgrades (TAC No. L32107)
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Enclosure GDP 99-0072 Page 2 of 8
. Q1 (NRC 4/7/99 Letter)
Provide the worst case uranium /HF consequences for the four evaluation cases outlined in Table 1 of the Compliance Plan Issue 36: (1) building collapse-no retention in cascade, (2) building collapse-i
, conservative estimate of retention in cascade, (3) partial building failure with no aerosol deposition, 1
and (4) partial building failure with aerosol deposition. The worst case would involve the directional sector with the highest onsite population, the wind associated with that direction, and the worst case meteorological conditions.
The' above information should be provided as a minimum. Additional consequence or risk
. information, as deemed appropriate, may be provided to further address uranium effects on onsite personnel.
Response to Question 1 Consequences
- Worst case consequences,' as defined in Question 1, for the four evaluation cases outlined in Table 1 of Compliance Plan Issue 36 are summarized for both uranium and HF in Table 1. This table
- shows the number of onsite personnel that receive a dose within a particular " bin" or " range." Bins
- that contain no workers are not listed in the summary table. For onsite personnel, D7 meteorological
- conditions produce the highest consequences for the collapse scenario, but F3 conditions produce the highest consequences for the partial failure scenario. Similarly, a wind direction from 082*
produces the highest consequences for the partial failure scenario, but wind from 035' produces the highest consequences for the collapse scenario.
Table. 2 shows comparable results for the same building response and source term combinations, but assuming the most likely meteorological conditions (D4) and wind direction (SSW) for PGDP. The results 'of all cases assume a factor of two credit for sheltering (reduction of unsheltered consequence data)-
The calculated consequences are based on several highly conservative assumptions:
PGDP was assumed to be operating at a 2200 MW power load.
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If any part of a target building fell within a 22.5' downwind sector of the release from either
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i C-331 or C-335, then the entire target building was assumed to be located at the centerline of the plume.
' Standard compass wind sectors were not assumed for the worst case conditions; instead,
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- wind directions (from 035* and from 082) were assumed that would maximize the number
~ f onsite workers affected by the plume.
o Toxicological doses were calculated based on an active " light exercise" breathing rate. This l.
1 Enclosure GDP 99-0072 Page 3 of 8 produced 20% higher doses than workers engaged in " normal activities" would obtain.
The release was assumed to occur on a weekday during daytime business hours when the onsite population is maximized.
Risk Analysis Results of risk calculations are summarized in Table 3. Table 3 presents injury frequency data for four renal injury categories based on the same combinations of conditions as the consequence calculations presented in Tables 1 and 2. The calculated risk in each of four renal injury categories considers the probability of the event (conservatively assumed to be a 70 year retum period) and the l
probability of the wind direction from C-331 or C-335 to the target building, given the damage state, source term, and meteorological conditions. However, no credit was taken for the fact that at least 70% of the time the plant population is well below (less than half of) the assumed peak population.
The risk calculations incorporated probability data of wind blowing from a source building (C-331 or C-335) to a target building. The calculations did not, however, consider the probability of the specified meteorological conditions; therefore, no credit was taken for probabilities of the selected meteorological conditions. Consequences for a G stability class would likely be less than or equal to those for F stability. By adding the probability of G stability conditions in with the probability l
for F stability conditions, the five meteorological conditions examined (F1, F3, D3, D4, D7)
E represent a significant portion (about 44%) of the total annual meteorological conditions at PGDP.
All the factors discussed suggest that the actual risk associated with the worst estimate source term i
for the building collapse scenario would probably be much less than the risk shown in Table 3. The l:
calculated annual rate of potentially lethal injury (0.8731) for the 1653 onsite workers (excluding risk to workers in C-331 and C-335) equates to 61 potential lethal injuries per year per 100,000 people. To place this result in perspective, the societal risk for a lethal accident at home is about 14 l-per 100,000 per year, while the occupational death rate for police officers is about 22 per 100,000 l
per year. Considering all the conservatism discussed above, the likely risk for the worst accident
- (buildings collapse) with the worst estimate' source term is projected to fall somewhere between these categories (home accident and occupational hazard of police work).
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Enclosure GDP 99-0072 Page 7 of 8 Q2 (NRC 4/7/99 Letter)
For the estimated consequences to onsite personnel, either provide justification for your determinations where no additional interim compensatory measures are necessary or propose
. additional interim" compensatory measures.
Response
The consequences for the four cases specified in Question 1 along with the four additional cases are summarized in the response to question 1 above. The first case specified in Question 1 is a worst case bounding analysis and is extremely conservative. As indicated in the Compliance Plan Issue 36 JCO, this' case assumes a complete collapse of the buildings and that all of the UF in C-331 and C-335 is released instantaneously as a puff release with no credit given for the structural integrity of the converters or deposition within the buildings. Additionally, meteorological conditions were chosen to maximize the exposure to on-site personnel. Based on the construction progress expected
- by June 30,1999, the evaluation basis earthquake is not expected to cause a ger eral collapse in any section. Local collapse may be experienced in some sections. Because of the extreme conservatism of this analysis and the state of construction, it is not considered to be a realistic representation of the consequences resulting from the collapse of C-331 and C-335.
The second case specified in Question 1 represents a conservative, but more realistic analysis of the consequences resulting from the collapse of C-331 and C-335. Case 2 assumes that some of the UF 6 remains in the converters 'and allows for aerosol deposition. This is considered the most credible
" worst ' case" scenario upon which to judge the need for additional compensatory actions. In this
. case, the maximum on-site uranium toxicity consequence is low renal injury (50 to <100 mg U
' intake).. All of the remaining cases result in uranium intake <30 mg.
I i
i Interim compensatory actions currently being implemented include restricting operations in C-331 and C-335.to subatmospheric pressure and limiting access to these buildings to only essential personnel.- No further actions have been identified to protect the general public or the personnel in these facilities. Any additional compensatory actions would be for the protection of other on-site
< personnel. Each occupied facility at PGDP has a local emergency plan which includes earthquake response. In general, personnel are instructed to evacuate away from the plume if there is time to do so. Otherwise, instruction is given to shelter-in-place. This involves going (or remaining) inside,
, i closing all windows and doors, shutting off all sources of outside ventilation, and remaining there until the shelter-in-place order is lifted, j
Based on' the discussion above, no ' additional interim compensatory actions are practical or
. necessary to protect on-site workers not located in C-331 and C-335.
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Enclosure GDP 99-0072 Page 8 of 8
- Q3 (NRC 4/7/99 Letter)
Discuss the use of the term " injuries" associated with onsite workers in the buildings in your to the January 27,1999 RAI Question 1. To the extent possible, discuss the effects of uranium intakes for onsite workers in the buildings.
Response
Injury to personnel in C-331 and C-335 as discussed in the USEC response to the January 27,1999 I
- RAI Question I was based on the methodology used in the Compliance Plan Issue 36 JCO. No attempt was made to identify the degree ofinjury in these buildings; however, injuries are likely to be serious to fatal in the event of building collapse.
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