ML20129H996
| ML20129H996 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/17/1985 |
| From: | Standerfer F GENERAL PUBLIC UTILITIES CORP. |
| To: | Travers W Office of Nuclear Reactor Regulation |
| References | |
| 0284A, 284A, 4410-85-L-0146, 4410-85-L-146, NUDOCS 8507220122 | |
| Download: ML20129H996 (5) | |
Text
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Route 441 South Middletown, Pennsylvania 17057 0191 717 944-7621 TELEX 84-2386 Writer's Direct Dial Number:
(717) 948-8461 4410-85-L-0146 Document ID 0284A July 17,1985 Il R
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$g,5 TMI Program Office Attn: Dr. W. D. Travers Deputy Program Director US Nuclear Regulatory Commission U
q c/o Three Mile Island Nuclear Station to Middletown, PA 17057
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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. 34 Attached for your review and approval is Recovery Operations Plan Change No. 34. 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 for review of this document.
Sincerely, E
B507220122 850717
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PDR ADOCK 05000320 P
PDR F. R. Standerfer Vice President / Director, TMI-2 FRS/RDW/eml y
Attachments
Enclosure:
GPU Nuclear Check No. 00016892 cc: Program Director - TMI Program Office, Dr. B. J. Snyder GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
Three Mils Island Nuclear Station, Unit 2 (TMI-2)
Operating License No. DPR-73 Docket No. 50-320 Recovery Operations Plan Change Request (ROPCR) No. 34 The licensee requests the addition of the attached pages 4.3-4a and 4.3-5a to 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.of a criticality event during the handling and transfer of the TMI-2 defueling canisters. Based on previous safety evaluations submitted to the NRC, GPU Nuclear believes that a criticality event cannot occur during the handling and transfer of the TMI-2 defueling canisters; thus; these monitors are only being installed to meet the requirements of 10 CFR 70.24.
Description of Monitors The proposed monitors will consist of a neutron dose equivalent detector and a rate meter, modified for a louder 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 each of the following locations:
Monitor Location Fuel Transfer Canal 347' elevation of the Reactor Building at Criticality Monitor the shallow end of the Fuel Transfer Canal Fuel Pool "A" Criticality 349' elevation of the Fuel Handling Building Monitor at the north edge of Fuel Pool "A" Fuel Handling Building Truck 315' elevation of the Fuel Handling Building Bay Criticality Monitor near the environmental barrier in the truck bay 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". These documents require that 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 citrm setpoint of 1 Rem /hr was determined as follows:
239 u assembly yielded a Per ANSI /ANS 8.3-1979 a metdlic, unreflected P
neutron to gamma absorbed dose ratio of 12 to 1.
This was selected as a worst case conservative event for this analysis due to the different attenuations of gamma and neutron flux in shields expected for defueling operations.
An unshielded absorbed dose ratio of 12 to 1 after attentuation by a six inch lead shield, e.g., the Transfer Cask, yields a ratio of 81000 to 1 neutron to gamma. Since it is desirable for one monitor to cover a large area (such as the entire Fuel Pool) the alarm setpoints were based on the absorbed dose rate at 20 meters rather than at 2 meters. In this case the monitors must detect.2 Rad at 20 meters within one minute (equivalent to a rate of 12 Rad /hr). Using the ratios previously defined, this equates to a setpoint of 120 Rem /hr neutron and 1.5 x 10-4 Rem /hr gamma. Clearly only the neutron dose rate is detectable. Therefore, an alarm setpoint of 1 Rem /hr neutron is well above any expected neutron background but two orders of magnitude lower than required.
Additionally, per ANSI /ANS 8.3-1979, a similar analysis was performed using a moderated neutron-to-gamma dose ratio of 0.3 to 1. This ratio equates to a setpoint of 120 Rem /hr neutron and 6.0 x 10-3 Rem /hr gamma. Thus, based on this analysis, an alarm setpoint of 1 Rem /hr neutron is still two orders of magnitude lower than that required by regulation.
The locations of the criticality monitors, based on the above analysis, ensure adequate detection capability of the TMI-2 fuel material contained in the defueling canisters.
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 if a criticality event would occur during the handling and transfer of the TMI-2 core via the defueling canisters. Therefore, this proposed change does not present an undue risk to the health and safety of the public.
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- TABLE 4.3 (Cont'd)
RADIATION MONITORING'INSTRUMENTAION SURVEILLANCE REQUIREMENTS CHANNEL CHANNEL CHANNEL FUNCTIONAL CHANNELS FUNCTIONAL UNIT CHECK CALIBRATION TEST OPERABLE APPLICABILITY ACTION 5.
FUEL TRANSFER CANAL l
l a.
Criticality Monitor-S R
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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
-a.
Criticality Monitor S
R M
1 Ndte11 Note 12 (See following pages for Notes)
THREE MILE ISLAND - UNIT 2 4.3-4a R0PCR NO. 34
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TABLE 4.3-3 -(Cont'd) a-RADIATION MONITORING INSTRUMENTAION SURVEILLANCE REQUIREMENTS-
'NOTESi '(Cont'd)'
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During either of the following operations:
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a.
Handling of' canisters containing core material.
b.
-Handling of any heavy load over canisters containing' core material.
12)' Hith less-than one channel operable, terminate the'following ope' rations:
a.
Handling of can)tters containing core material.
1 b.
Handling of any heavy load over canisters containing' core material.
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THREE MILE ISLAND - UNIT 2 4.3-Sa R0PCR NO. 34 l
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