ML20058P468
| ML20058P468 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/09/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20058P467 | List: |
| References | |
| NUDOCS 9008170077 | |
| Download: ML20058P468 (2) | |
Text
..
i.
. [j' h " %),,
UNITED STATES y
g NUCLEAR REGULATORY COMMISSION i
r,,
l WASHINGTON. D. C. 20655
\\...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO FACILITY OPERATING LICENSE NO. OPR-73 GPU NUCLEAR CORPORATION i
THREE MILE ISLAND NUCLEAR STATION, UNIT NO. 2 l
DOCKET NO. 50-Oc0 i
l INTRODUCTION l
At the time GPU Nuclear Corporation (GPUN/the licensee) submitted its March i i
l 1990 chan'ge request they were approaching the end of defueling at TMI-2 and the transition from Mode 1 to Mode 2.
Mode 1 was the defueling mode, Mode 2 would be reached when defueling was complete, the possibility of criticality was precluded, and all fuel canisters were removed from the reactor building.
Mode j
3 would be reached when all the fuel bearing canisters were shipped off site.
The licensee requested the change recognizing that criticality monitors would not be needed in certain areas once the fuel canisters were removed and the mode change had occurred.
These areas included the end fitting storage area, the fuel transfer canal, the spent fuel pool, and the Fuel Handling Building (FHB) truck bay.
l The NRC staff and consultants from Battelle Memorial Institute's Pacific
)
Northwest Laboratory reviewed the licensee's mode change documents and performed independent inspections of the reactor building, and the FHB.
In a letter i
dated April 26, 1990 the staff found that all fuel bearing canisters had been I
shipped off site and that the possibility of criticality was precluded.
The facility was permitted to transition from Mode 1 to Mode 2 on-April 26, 1990 and from Mode 2 to Mode 3 on April 27, 1990.
EVALUATION The fuel bearing canisters have been removed from the treas served by the subject criticality monitors.
The areas have son residual contamination which antains fuel.
None contains greater than 450 grams of special nuclear material; the quantity, which if unshielded, would require criticality monitoring in accordance with 10 CFR 70.24(a).
The NRC staff approved a safe fuel mass limit (the quantity of fuel'which can safely be contained in a single mass in any geometry without the possibility of an inadvertent criticality) of 140 Kg for areas outside the reactor vessel.
None of the areas served by the subject criticality monitors contains as much as half of the safe fuel mass-limit.
9008170077 900809 PDR ADOCK 05000320 P
o 2-The change would also delete the requirement to maintain operable monitors when fuel canisters are maintained under water shielding. Although the point is moot since all the fuel canisters have been shipped off site, the NRC staff concurs that there is no need to maintain operable monitors for this situation.
The purpose of the monitors is to warn and protect workers from radiation due to an inadvertent criticality.
The water would act as a shield to stop ike radiation, simultaneously protecting the workers and leaving the monitors below their alarm threshold.
CONCLUSION
'The areas served by the end fitting storLge area monitors, the fuel transfer canal mcaittrc. the spent fuel pool mcnitors and the FHB truck bay monitors no longer contain enough fuel to cause a criticality.
There is no longer any reason to require operable criticality monitors in these areas. When fuel canisters are stored under water there is no technical reason to require criticality monitors.
The proposed change does not reduce any safety margins or result in any environmental impact.
)
DATED:
2 Principal Contributor: Lee H. Thonus l
I
.