ML20134B882
| ML20134B882 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco, 07200011 |
| Issue date: | 12/02/1993 |
| From: | Shetler J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| DAGM-NUC-93-217, NUDOCS 9701310127 | |
| Download: ML20134B882 (8) | |
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l SACRAMENTO MUNICIPAL UTIUTY DISTRICT O 6201 S Street, P.o. Box 15830, Sacramento CA 95852-1830,(916) 452 3211 f
AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA i
DAGM/NUC 93-217 December 2,1993 Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, DC 20555 Docket No. 72-11 Rancho Seco Independent Spent Fuel Storage Installation RESPONSE TO REQUEST FOR ADDITIONAL INFORM ATION REGARDING REVISION 1 TO Tile R ANCIlO SECO INDEPENDENTSPENT FUEL STOR AGE INSTALLATION ENVIRONMENTAL REPORT Attention: Michael G. Raddatz As requested in your letter dated October 25,1993, we are previding our response to your request for additional information so that you can complete your review of Revision I to the Rancho Seco Independent Spent Fuel Storage Installation (ISFSI) Environmental Report.
Members of your staff with questions requiring additional information or clarification may contact Bob Jones at (916)452-3211, extension 4676.
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Sincerely, A
J mes R. Shetler Deputy Assistant General Manager Operations 310017 I
cc:
B. Faulkenberry, NRC, Walnut Creek S. Weiss, NRC, Rockville Document Control Desk, Washington 9701310127 931202 PDR ADOCK 05000312 Y
PDR RANCHO SECo NUCLEAR GENERATING STATION O 1444o Twin Cities Road, Herald, CA 95638-9799;(209) 333-2935 k_
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ADDITIONAL INFORM ATION IN SUPPORT OF THE RANCHO SECO ISFSI ENVIRONMENTAL REPORT Question 1:
a)
What lission gasin ventory didyou use in the site boundary accident dose calculation?
b)
Also, the X/Q value usedin the ER is di/Tewnt than the dentult value in the safety analysis wport (SAR). Whem didyou get this number?
Resnonses:
a)
Pacific Nuclear Calculation 2069.0505 " Rancho Seco NUHOMS Fission Gas Release Dose Assessment" demonstrates compliance with the regulatory exposure limits for a canister leakage accident at the Rancho Seco ISFSI. The fission gas inventory considered for the site boundary calculation included a number offission gas nuclides whose inventories were determined using ORIGEN2.
l Of those nuclides, "Kr was considered to be the only significant contributor to offsite l
accident case exposures (17,345 Cut %s of"Kr were assumed to be released by one leaking canister). This is due to its relatively large abundance in the decayed fuel, and the nature of the postulated accident. Theleakage scenario is characterized by relatively low temperatures and no dispersion of fuel matter (as in a plant LOCA). Details regarding the determination of the fission gas inventory in a design basis fuel assembly, and the accident dose calculation, are discussed in calculation 2069.0505 (see Volume IV of the ISFSI Safety Analysis Report (SAR).
b)
The default X/Q value used in Revision 0 to the ISFSI SAR was based on the originally proposed ISFSI location, approximately 100 feet south of the Interim Onsite Storage Building (IOSB). The X/Q value used in Revision 1 to the Environmental Report is a conservative value based on the currently proposed ISFSI location, approximately 600 feet west of the IOSB.
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e ADDITIONAL INFORM ATION IN SUPPORT OF THE RANCHO SECO ISFSI ENVIRONMENTAL REPORT Assuming a wind speed of 0.6 m/s, ground level release, Pasquill F wind stability, and a 350 meter fence distance, the X/Q factor was calculated using the following relation (1):
3.=
I 22 exp o
O nUO 0 (2
y g I
n(0.6)(18)(6.1)(1)
=
= 4.83E-3 Question 2:
i To verify the olTsite dose, we need to know what was usedfor the souwe term, what was the decayperiod, and what is the height ofthe benn.?
Resnonse:
Pacific Nuclear Calculation 2069.0500 " Radiological Source Term Calculation for Rancho Seco Fuel" determined the design basis storage and transportation radiological source terms for a Rancho Seco design basis fuel assembly. Calculations were made using the ORIGEN2-PC computer code.
As discussed in calculation 2069.0500 (see Volume IV of the ISFSI SAR), the Rancho Seco design basis fuel total gamma source term is 4.78 x 10" photons /sec/ assembly, and the neutron source term is 1.63 x 10' neutrons /sec/ assembly for a 5.5 year decay period.
The berm height was assumed to be zero.
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t ADDITIONAL INFORM ATION IN SUPPORT OF THE RANCHO SECO ISFSI ENVIRONME.NTAL REPORT 1
Question 3:
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The orientation ol'the pad to the closest ISFSI boundary is at an angle to the site l
boundary. Didyou use the closest point, with shielding at the boundary from those closest casks to those behindit?
Resnonse:
1 Shielding calculations were based on the distance from the closest site boundary to the edge of the closest horizontal storage n odule. The site dose calculations take no credit for either the two casks or the 2x11 array of storage modules providing any shielding.
Ouestion 4:
J Also Table 5-1 of the ER seems to contain a typo. The souwe strength says per assembly, when the NUHOMS SAR saysit is per DSC(e.g., 24 assemblies).
Response
As discussed in the answer to Question 2 above, the Rancho Seco design basis fuel total gamma source term is 4.78 x 10" photons /sec/ assembly, and the neutron source term is 1.63 x 10' neutrons /sec/ assembly for a 5.5 year decay period. These were the source terms used in the Rancho Seco site-specific ISFSI dose calculations.
Table 5-1 of the ER does contain a typo since the total gamma source and total neutron source per DSC, as contained in Table 3.1-la of the SAR for the standardized NUHOMS storage system, refers to the design basis fuel used for the standardized S AR radiological analyses.
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l ADDITIONAL INFORM ATION IN SUPPORT OF THE RANCHO SECO ISFSI ENVIRONMENTAL REPORT j
Question 5:
l In order to verify occupational doses we need to kno w the dose mte at each step ofthe l
Operation.
l a)
Ho w manypeople am wquired for each step? For ho w long?
l b)
Didyou use the numbers from the NUHOMS SAR for these?
Resnonse:
a)
Table 7-3 of the Rancho Seco ISFSI SAR, Revision 1, shows the occupancy, ambient dose rate, and duration factors used for each step of the occupational dose calculation. It is attached to these responses for the reviewer'sconvenience.
l b)
The ambient dose rates around a loaded NUHOMS-MP187 eask were not taken from the NUHOMS SAR, they were calculated specifically for this license application. Other general area exposure rates, numbers of personnel, and l
operation durations were estimated based on actual data from Oconee l
NUHOMS 24P system fuelloads.
References l
1.
USNRC Regulatory Guide 1.109," Calculations of Annual Doses to Man from Routine l
Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR i
Part 50, Appendix 1," Revision 1, October 1977.
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"^o" 7-' 4 SMUD REVISION 1 N
Rado SomISFSI sys7EM Table 7-3 Estimated OccuDational ExDosure for One HSM Load Effective l
Number Time in Total l
of Radiation Personnel l
Operation Personnel Field (hours)
Dose (mrom) l LOCATION: Auxiliary Building and Fuel Pool Ready the DSC and 2
0.0 0.0 Cask for Service"'
l Place the DSC into 3
1.0 6.0 the Transfer Cask l
Fill the Annulus and 2
2.0 8.0 Install the Seal l
Fill the DSC Cavity 1
0.5 1.0 with Water Place the Cask in 5
1.0 10.0 j
the Fuel Pool verify and Load the 3
8.0 48.0 l
Assemblies in the Dsc l
Place the cask /DSC 5
2.0 20.0 in the Decon Area
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LOCATION: Cask Decon Area Cask Decontamination 7
1.0 51.8 Drain Watar Above 3
0.25 23.3 i
DSC Shield Plug l
Decon the DSC Top N/A N/A N/A O
l Shield Plug l
Remove Water from 2
0.5 26.0 the DSC Cavity Set-up Welding Machine 2
1.5 103.0 Wald the Top Shield 3
6.0 129.0 0
Plug and Perform NDE' 0
Drain the DSC Cavity' 2
0.5 26.0 i
teMeep e
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SMUD e^oe 7-' S REVISION 1 ISS Ranso Seco ISFS1 sys7at Table 7-3 Estimated Occucational ExDosure for One HSM Load (continued)
Effective Number Time in Total of Radiation Personnel Operation Personnel Field (hours)
Dose (mrom) l l
Vacuum Dry and 2
0.5 26.0 l
Helium Backfill 50 Helium Leak Test 2
1.0 4.0 the Shield Plug Seal Weld Vent 2
1.5 150.0 and Siphon Ports Fit-Up the DSC 2
1.0 105.0 Top Co'_r Plate Wald the Top Cover 5
14.0 199.8 and Perform NDE05 Drain the Annulus 2
0.25 35.9 l
Install the Cask Lid 2
1.0 59.6 LOCATION: Auxiliary Building Bay Ready the Skid and 2
0.0 0.0 Trailer for Service"'
Place the Cask 2
0.5 12.1 l
Onto the Skid Install the Ram 2
1.0 29.8 Trunnion Support and l
Cask Shialding Secure the cask 2
1.0 31.4 to the Skid I
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FPOM PS OPPC
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P.
9 SMUD
"^o" 7 ' S Rancho Seco ISFSI REVISION 1 N3
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$YSTEM 1
Table 7-3 Estimated occuoational Excesure for one HSM Load (concluded)
Effective Humber Time in Total of Radiation Personnel operation Personnel Field (hours)
Dose (mrom)
LOCATIoWe ISFS! Site Ready the itsM and 2
Q,0 0.Q Ram for servt;;c*
Transpo rt the Cask 6
1.0 0.0 to the IsrsIm Position the Cask 3
1.0 0.0 Close to the HSM*
Remove the Cask Lid 3
1,Q 59.7 Align and Dock the 2
0.25 85.3 Cask with the llSM d
Lift the Ram Into 2
0.5 14.9 Position and Align With the Cask Transfer the DSC to 3
05 0.0 the H3H*
Lift the Ram onto 2
Q.25 100.8 Trailer and Un-Dock the Cask Install the HSH 2
0.5 34.2 Access Door TOTAL 1400.6 NOTESt (1)
This operation is performed away from any eignificant radiation fleid (2)
Not applicable.
The DSC inner and outer top covers are installed above the top shield plug, which does not, therefore, require decontamination.
(3)
Monitoring operation personnel may leave the radiation work area.
(4)
Workers are assumed to remain at a distance from the Cask sufficient to
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expose them to a negligible dose.
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