ML20206M293
| ML20206M293 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/18/1986 |
| From: | Standerfer F GENERAL PUBLIC UTILITIES CORP. |
| To: | Travers D, Travers W Office of Nuclear Reactor Regulation |
| References | |
| 0061P, 4410-86-L-0129, 4410-86-L-129, 61P, NUDOCS 8608210091 | |
| Download: ML20206M293 (6) | |
Text
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GPU Nuclear Corporation Nuclear
- eme:r8o o
s Middletown, Pennsylvania 17057-0191 717 944 7621 TELEX 84-2386 Writer's Direct Dial Number:
(717) 948-8461 4410-86-L-0129 Document ID 0061P August 18, 1986 TMI-2 Cleanup Project Directorate Attn:
Dr. W. D. Travers Director US Nuclear Regulatory Commission c/o Three Mile Island Nuclear Station Middletown, PA 17057
Dear Dr. Travers:
Three Mile Island Nuclear Station, Unit 2 (TMI-2)
Operating License No. DPR-73 Docket No. 50-320 Recovery Operations Plan Change Request No. 39 Attached for your review and approval is Recovery Operations Plan Change No. 39.
This change request proposes the addition of criticality monitors to Table 4.3-3 of.the Recovery Operations Plan. The proposed criticality monitors are being installed in order to comply with the requirements of 10 CFR 70.24.
Per the requirements of 10 CFR 170, an application fee of $150.00 is enclosed.
Sincerely, F. R. Standerfe Vice President / Director, TMI-2
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FRS/RBS/eml Attachments s
Enclosed: GPU Nuclear Corp. Check No. 00025260 I
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e GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
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Three Mile Island Nuclear Station, Unit 2 (TMI-2)
Operating License No. DPR-73 Docket No. 50-320 Recovery Operations Plan Change Request-(ROPCR) No. 39 The licensee requests the attached pages 4.3-4a and 4.3-5a replace the existing pages 4.3-4a and 4.3.5a of the Recovery Operations Plan. This change request proposes the addition of criticality monitors to Table 4.3-3.
Reason for Change The proposed criticality monitors are being installed in order to comply with the requirements of 10 CFR 70.24, " Criticality Accident Requirements." These monitors will alert personnel to the occurrence of a criticality event during the handling, transfer, and storage of the proposed TMI-2 end fitting storage containers. Based on evaluations submitted to the NRC, GPU Nuclear believes that a criticality event cannot occur during the handling and transfer of the TMI-2 end fitting storage containers; thus, these monitors are being installed only to meet the requirements 10 CFR 70.24.
Description of Monitors The proposed monitors will consist of a gamma detector and a rate meter, modified to emit an increased amplitude alarm. The alarm setpoint of these monitors will be set at 1 Rem /hr based on the requirements of 10 CFR 70.24.
The attached proposed surveillance requirements are based on those listed in Table 3.3-6 of the Babcock and Wilcox Standard Technical Specifications.
Location of Monitors GPU Nuclear is installing two (2) criticality monitors, as required by 10 CFR 70.24, in the vicinity of the end fitting storage containers.
The containers will be located near the head storage stand on elevation 347' of the Reactor Building.
Justification for Alarm Setpoint and Location The locations and alarm setpoint of the criticality monitors were based on the requirements of 10 CFR 70.24 and ANSI /ANS-8.3-1979, " Criticality Accident Alarm System"; i.e., the monitoring system must be capable of detecting a criticality that produces an absorbed dose of 20 Rads at an unshielded distance of 2 meters within one minute.
The alarm setpoint of 1 Rem /hr was determined as follows:
The monitoring system must be capable of detecting a combined neutron and gamma dose of 20 Rads in one (1) minute at an unshielded distance of 2 meters from the reacting material (10 CFR 70.24). Using the guidance in ANSI /ANS 8.3-1979 (Reg. Guide 8.12) the most conservative case for this situation is a postulated criticality that will result in a neutron to gamma dose rate ratio of 12 to 1.
Thus, the expected gamma dose rate is derived from:
u and Yu are the nu + Yu = 20 Rad / minute where n unshielded neutron and gamma dose rates, respective:.y.
7- -
y Anda n /Yu = 12 u
Thus:
13 Yu = 20 Rad / minute So:
1.5 Rad / minute Yu = 20 Rad / min
=
13 And:
nu = 20 Rad / min - 1.5 Rad / min = 18.5 Rad / minute Based on the current plan to use 1.375 inches of lead shielding, the reduction in gamma dose rates will be about 20 after shielding. Also, this shielding configuration would result in a reduction of neutron dose rates of about 2.2.
Thus:
YL!
1.5 Rad / min where Ys and as are 0.08 Rad / minute the shielded gamma and 20
=
20
=
Ys =
neutron dose rates respectively.
And:
nu 18.5 Rad / min 3E3! =
2.2 8.4 Rad / minute ns =
=
So, the shielded neutron to gamma dose rate ratio will be:
3 s_
8.4 Rad / min 105 0.08 Rad / min ys =
=
In order to meet the criterion of 10 CFR 70.24:
20 Rad / minute Ys + ns =
Thus:
20 Rad / min 0.19 Rad / minute 106 Ys =
=
The dose rate at 2 meters from the top of each drum will be 0.19 Rad / min, or 11 Rad / hour. If the criticality monitors are located at the top of the "D" ring (in order to provide a "line-of-sight" and ease of installation and maintenance), the dose rate at that location would be:
(11 Rad /hr) (2 meters)2
= 3 Rad / hour (4 meters)4 Dy
=
r~
e y
Thus, it is feasible to use gamma detectors as criticality monitors in this location because the alarm can be set much higher than the current background of about 80 mrem / hour. The alarm set point of 1 Rem / hour was established in order to minimize spurious alarms due to transient changes in radiation levels.
Based on the above analysis, the locations of the criticality monitors ensure adequate detection capability for the TMI-2 fuel material contained in the end fitting storage containers.
Safety Evaluation Justifying Change The addition of the proposed criticality monitors does not reduce any margins of safety during defueling activities. These monitors would serve to alert personnel in the unlikely event that a criticality occurred during the handling, transfer and storage of the TMI-2 end fitting storage containers.
This proposed change does not present an undue risk to the health and safety of the public.
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-TABLE 4.3-3 (Cont'd) y 5g RADIATION MONITORING INSTRUMENTATION SURVEILLANCE REQUIREMENTS 5
E G
CHANEL g
CHANNEL CHANNEL FUNCTIONAL CHANNELS 5
FUNCTIONAL UNIT CHECK CALIBRATION TEST OPERABLE APPLICABILITY ACTION 5.
FUEL TRANSFER CANAL N
a.
Criticality Monitor S
R M
'l Note 11 Note 12 6.
FUEL POOL "A" a.
Criticality Monitor S
R M
1 Note 11 Note 12 7.
FUEL HANDLING BUILDING TRUCK BAY b
a.
Criticality Monitor S
R M
1 Note 11 Note 12 8.
WASTE HANDLING Am PACKAGING FACILITY a.
Exhaust Monitor D
SA W
l Note 1 Note 13 9.
REACTOR BUILDING a.
End Fitting Storage S
R M
1 Note 14 Note 15 Area Criticality Monitor (See following pages for Notes.)
TABLE 4.3-3 (Cont'd)
=
x RADIATION MONITORING INSTRUMENTATION SURVEILLANCE REQUIREMENTS 5
E NOTES:
- 11. During either of the following operations:
7 a.
Handling of canisters containing core material.
b.
Handling of any heavy load over canisters containing core materials.
c 2
Z
- 12. With less than one channel operable, terminate the following operations:
ro a.
Handling of canisters containing core material.
- b.
Handling of any heavy load over canisters containing core material.
13.
With the required monitor inoperable, secure the ventilation system and suspend all operations involving movement of radioactive materials or generation of airborne contamination until the inoperable monitor is restored to operable status.
14.
During periods when personnel are in the containment and end fittings are being transferred to or stored in their designated location outside the Reactor Vessel.
a
- 15. With less than one channel operable, terminate the following operations:
w h
a.
Handling of end fitting storage containers outside the Reactor Vessel.**
b.
Handling of any heavy load over the end fitting storage container area.
- This shall not prohibit placing a canister in transit in a safe storage location.
- This shall not prohibit placing a end fitting storage container in transit in a safe storage location.
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