ML20141G553
| ML20141G553 | |
| Person / Time | |
|---|---|
| Site: | Westinghouse |
| Issue date: | 06/30/1997 |
| From: | Goodwin W WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | Gaskin C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML19317C479 | List: |
| References | |
| CON-NRC-97-027, CON-NRC-97-27 TAC-L30974, NUDOCS 9707090288 | |
| Download: ML20141G553 (5) | |
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O 10'l tse,y Westinghouse Commercial Nuclear Drawer R Electric Corporation Fuel Division fyn"[Ag2so i
June 30,1997 U.S. Nuclear Regulatory Commission ATTN:
Mr. Charles Gaskin Licensing Section 1, Licensing Branch FCS&S Division, NMSS 11555 Rockville Pike Mail Stop T8D14 Rockville, MD 20852-2738 Dear Mr. Gaskin.
SUBJECT:
RESPONSE TO SNM-Il07 LICENSE CONDITION REQUESTING
SUMMARY
CSE AND FAULT TREE INFORMATION CSE summary and fault tree information is provided in this correspondence as attachments covering the remaining items scheduled for submittal June 1997 as follows:
Final Assembly - Summary of CSE Also, submittal will be made by separate cover to modify the table in Section 6.2.3 of SNM-1107 1
to change the criticality safety basis for Final Assembly, Fuel Rod Storage and Fuel Assembly Storage.
j If you have any questions, please contact me at (803) 776-2610.
Sincerely, WESTINGHOUSE ELECTRIC CORPORATION 9707090288 970630 PDR ADOCK 07001151 ff-C PDR WJacSJ j W. L. Goodwin, Manager Regulatory Affairs Docket 70-1151 License M-1 7g g
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SUMMARY
OF CRITICALITY SAFETY EVALUATION (CSE) FOR FINAL ASSEMBLY STORAGE OF FUEL RODS -
SUMMARY
Fuel rods are stored in aluminum channels in the Frazier racks adjacent to the Final Assembly area of the plant. After fuel rods pass final inspection, they are loaded into these channels to
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await being placed into a skeleton, forming a completed fuel assembly.in Final Assembly.
The criticality safety basis of rod storage in Frazier racks was=' established years ago using maximum permissible values (MPV's) from our previous SNM license. These bases pre-date the -
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current fault tree / initiating event methodology.
Since that time,. calculations have been
' performed that confirm the conservatism in these bases, and lead to the conclusion that criticality is not credible for rod channels stored in these racks.
Double contingency protection is provided by preventing an adverse geometry / configuration -
. (<12" vertical spacing between channels in the storage racks, or > 4 b" rod depth in channels),
i and preventing moderator from being available. This is accomplished by passive engineered controls and some administrative controls.
'Although not required because it was determined that criticality was not credible, a fault tree was prepared and is included for information, and to illustrate the strength of the criticality controls.
I In performing this CSE, it was determined that moderation is also an appropriate Criticality Safety Basis for fuel rod storage. The license will be modified to reflect this.
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TRANSPORTATION CARTS -
SUMMARY
Fuel rods are transferred in individual aluminum channels from the rod storage area (Frazier racks) to Final Assembly. The carts used to transport the channels are loaded by fork lift, and pushed by hand into Final Assembly. The carts are designed to maintain a minimum 12" spacing side-to-side between adjacent channels by passive engineered control. End-to-end spacing is maintained by administrative control. Only one channel is allowed per transfer cart.
l The criticality safety basis of channel transport was established years ago using maximum permissible values (MPV's - safe slab height 4.5" max.) from our previous SNM license. These bases pre-date the current fault tree / initiating event methodology. Since that time, calculations have been performed that confirm the conservatism in these bases, and lead to the conclusion that criticality is not credible for transportation of rod channels on carts.
Double contingency protection is provided by preventing adverse geometry / configuration, and preventing moderator from being available. This is accomplished by passive engineered controls and some administrative controls. Potential ways of achieving adverse configuration (or a J
condition that goes beyond bounding assumptions) include more than one channel on a cart, rod a
depth in channel exceeding 4 b", >4" elevation difference between channels, or > 24" horizontal overlapping of ends of channels.
Although not required because it was determined that criticality was not credible, a fault tree was prepared and is included for information, and to illustrate the strength of the criticality controls.
In performing this CSE, it was determined that moderation is also an appropriate Criticality Safety Basis for transferring channels of fuel rods on carts. The license will be modified to reflect this.
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l FUEL ASSEMBLY FABRICATION, INSPECTION, & WASHING / RINSING -
SUMMARY
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After fabrication and inspection, the fuel assemblies are lowered into a series of 3 tanks (wash, l
first rinse, and final rinse) to improve their cosmetic appearance before shipping, and to remove debris that may contribute to fuel failure at the reactor site. After final rinse, cleaning, and QC I
inspection, the assemblies are enclosed in a protective bag for storage and/or shipping.
l The most reactive condition of the fuel in Final Assembly is during washing and rinsing l
operations. Therefore these conditions were selected for bounding analyses and evaluation for i
the entire Final Assembly area. It was concluded that:
l It is possible to exceed the license limit of K-eff s 0.95 for normal operations and expected process upsets if certain fuel assembly designs are rinsed without neutron absorber, but Criticality K-eff 21.0 is not credible for the wash / rinse tanks.
e Double contingency protection for assemblies outside the wasurinse tankv is provided by l
preventing adverse geometry / configuration (<l2" minimum spacing ) and preventing moderator I
from becoming available. This is accomplished by passive engineered controls and some administrative controls. It was concluded that criticality is not credible in Final Assembly for assemblies outside the wash / rinse tanks.
Double contingency protection for assemblies in the wasWrinse tanks is provided by preventing two different postulated geometry / configuration conditions, either one of which could cause K-l eff 21.0: fuel rod lattice expands significantly, or minimum 12" horizontal spacing between l
assemblies violated. Three contingencies or events were identified that prevent the fuel rod
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lattice from being expanded significantly; four were identified that prevent minimum spacing I
from being violated.
This is accomplished by passive engineered controls and some administrative controls. It was concluded that criticality is not credible in Final Assembly for assemblies in the wash / rinse tanks.
Although not required because it was determined that criticality was not credible, fault trees were prepared for Final Assembly, and are included for information, and to illustrate the strength of i
the criticality controls.
In performing this CSE, it was detern med that moderation is also an appropriate Criticality l
Safety Basis for fabrication and inspection of fuel assemblies in Final Assembly that are outside l
the wash / rinse tanks. Also, it was determined that neutron absorber was not needed to assure K-eff s 1.0 for fabrication, inspection, and washing / rinsing. The license will be modified to reflect this.
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FUEL ASSEMBLY STORAGE -
SUMMARY
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After washing, rinsing, and final QC inspection, the assemblies are wrapped in waterproof bags, which are installed on the assembly such that any water in the assembly drains out internally l
l through the bottom nozzle. The assemblies are normally then stored in fixed racks that provide just over 15" minimum separation between assemblies.
I Double contingency protection is provided by preventing an adverse geometry / configuration
(<12" horizontal spacing between fuel assemblies in the storage racks), and preventing moderator from being available.
This is accomplished by passive engineered controls and some l
administrative controls.
i Although not required because it was determined that criticality was not credible, fault trees were prepared for Final Assembly, and are included for information, and to illustrate the strength of the criticality controls. See Figure 5.3-2 enclosed.
In performing this CSE, it was determined that moderation is also an appropriate Criticality Safety Basis for fuel assembly storage, and that neutron absorber was not needed to assure K-eff i
s 1.0. The license will be modified to reflect this.
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