ML20141M092
| ML20141M092 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 03/19/1992 |
| From: | Tuckman M DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20141M094 | List: |
| References | |
| TAC-M81291, TAC-M81292, NUDOCS 9204010024 | |
| Download: ML20141M092 (7) | |
Text
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. Duhr lhurr Company MS Dwtn Cataa tu Nuclear Generation Department
\\ke President 600 Conwrd k nd 603)MiJ205 0ffire turt= SC29?M (M3)R313tM TU i
DilKE POWER March 19, 1992 U.
S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.
C.
20555
Subject:
Catawba Nuclear Station Docket Nos. 50-413 and 50-414 Reply to Request for Additional Information TAC NOS. M81291, M81292 Attached is a responso to the subject request for additional information.
In your letter dated February 11, 1992, four concerns were identified as needing additional information or clarification to complote your review. The four concerns involved (1) addressing inleakage into the control room air handling units, (2) redefining the pressurizing filter train flow rate, (3) clarifying the minimum flow required to pressurize the control room, and (4) submitting these changes on the latest approved Technical Specification revisions.
Each of these concerns is addressed below and shown, as appropriate, on the attached Technical Specificatic1 sheets.
The first conectn involves being able to quantify and justify the potential in7eakage into a control roor air handling unit.
During a site inspact.on in January, 1992, a small leak was found in a flexible connection on 2CR-AHUal. This flerible connection will be repaired to insure there is no inleakage prior to. implementation of the TS change.
Surveillance and maintenance procedures have been implemented to insure inleakage into a control room air handling unit is minimal.
Additionally, the dose analysis has been revised to include 30 cfm of unfiltered inleakage.
The original dose analysis included only' 10 cfm.
The extre 20 cfm provides additional margin of safety in the dose anal'/ sis.
It should be emphasized that, even with this increased inleakage assumption, the dose analysis is still well below GDC-19 limi;a -(See Attachment 1).
The second area of concern involved the prosaurizing filter train flow rate. The original submittal-requested that this flow rate be 5,000 cfm i 20% under all conditions.
Per discussions with your staff, we are amending this flow rate to 5,200 cfm 10% under standard test conditions.- The Technical Specification bases have been updated to reflect this flow rate is a test parameter and not a range that determines operability.
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9204010024 920319 PDR ADOCK 05000413
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Nuclear Regulatory Commission March 19, 1992 Page 2 The third area of concern involves changing Technical Specification surveillance requirement 4.7.6.e.3 to specify the minimum flow that will pressurize the control-room.
The surveillance requirement will be changed to reflect that the minimum pressurization flow is 2,000 cfm.
.This is shown on the attached marked-up Technical Specification she #.s.
The fourth concern raised in your letter involves submitting the requested changes on the latest revision
.of Technical Specifications.
This has been done and the appropriate sections i
are attached (Attachment 2).
It should be noted that the original proposal.was submitted on the latest Technical Specification sections.. However, since it was first submitted another revision l
of the Technical Specifications was issued.
The work associated with this Technical Specification amendment is scheduled to be completed prior to the upcoming outage. Therefore, we are requesting that review and approval of ' this Technical Specification amendment be completed prior to June 1, 1992.
If you have any further questions or require clarification of this material please call Mary Hazeltine at 803-831-3080.
Very truly yours,
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1 M..S.
Tuckman
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Nuclear Regulatory Commission March 19, 1992 j
Page 3 j
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Ebneter 1
Regional Administrator, Region II Heyward Shealy, Chief Bureau of Radiological Health SC R.
E. Martin, ONRR W. T. Orders Senior Resident Inspector American Nuclear Insurers M & M Nuclear Consultants INPO Records Center
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Arritcanesir.i 1%s JJ 2 It is proposed that the ESF design of the Control Room Ventilation (VC) System be modified from a recirculation pressurized system with a dual intake design to a once-through pressurized system with a dual intake design.
In a once-through pressurized system only three parameters are necessary to calculate the-Iodine Protection Factor (IPF) for the VC system assuming that the system maintains the control room pressure boundary at 1/8 inch positive pressure.
These three parameters are:
(1)
Pressurization flow rate to the control room, (2)
Iodine removal filter efficiency, and (3)
Unfiltered air infiltration rate.
For the first parameter, the minimum pressurization flow rate needed to maintain the control room pressure boundary at a positive pressure of greater than or equal to 1/8 inch w.g.
relative to adjacent areas will be specified in Catawba Technical Specification 3/4.7.6 " Control Room Area Ventilation System" as 2000 cfm to the control room.
For the second parameter, test criteria are given in the Surveillance Requirements of Tech Spec 3/4.7.6 to assure that the carbon and HEPA filters can romove 99 percent of the iodine from the influent.
The third parameter is conservatively assumed to be 30 cfm. (Note: Per Standard Review Plan (SRP) 6.4,
" Control Room Habitability System," only 10 cfm of unfiltered air is assumed in the dose analysis for pressurization systems).
Figure 4 from the Murphy-Campe paper (see enclosure) gives the IPF equation for a recirculation pressurized system as follows:
F
+
gF2
+
F3 IPF
=
EQUATION 1 (1
y) F
+
F i
3 where:
rate of filtered outside air intake j
F
=
3 rate of f:ltered air recirculation F
=
2 rate of unfiltered outside air infiltration F
=
3 y
filter efficiency /100
=
1 In the proposed VC System modification the rate of_ filtered air l
recirculation (F ) would equal 0 cfm, and EQUATION 1 simplifies to:
2 F
+
F3 l
IPF
=
EQUATION 2 l
(1 g) F
+
F 3
1 I
kTT A C if ME NT )
PA.Sc 2 of 1 4
l Substituting the above values into EQUATION'2 yields a calculated IPF of 40.6 as shown below:
2000
+
30 2030 IPF
=
=
=
40.6 0.99) 2000
+
30 50 (1
This IPF value changes the calculated contaol room operator thyroid dose from 8.45 Rom (Reference Revision 7 to_ Duke Power Company's Control Room Operator Dose calculation, provided to Jack Hayes) to 14.9 Rem.
Based on the GDC-19 equivalent thyroid dose limit of 30 Rom, the revised CNS control room operator thyroid dose is still at an acceptable level.
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