ML080880009
| ML080880009 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 03/27/2008 |
| From: | Markley M NRC/NRR/ADRO/DORL/LPLIV |
| To: | Edwards M, Lippy D, Matthews T Omaha Public Power District |
| Markley, M T, NRR/DORL/LP4, 301-415-5723 | |
| References | |
| TAC MD6204, TAC MD7043 | |
| Download: ML080880009 (5) | |
Text
From:
Michael Markley To:
DONNA L LIPPY; MICHAEL EDWARDS; THOMAS C MATTHEWS Date:
3/27/2008 11:33:57 AM
Subject:
Requests for Additional Information Tom, Donna, and Mike, Attached are the RAIs for today's telecon. The attached files provide a clarification resulting from feedback from OPPD and revise the issuance to reflect today's date. I will forward the ADAMS accession number(s) as soon as it is available.
Michael Markley Sr. Project Manager Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Phone (301) 415-5723 Facsimile (301) 415-2102 Office: O-8D3 Mail Stop: O-8B1 e-mail: MTM@nrc.gov CC:
Glenna Lappert FORT CALHOUN STATION REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUESTS RE:
MODIFICATION OF CONTAINMENT SPRAY ACTUATION LOGIC (MD6204)
AND DAMPERS IN CONTAINMENT AIR COOLING (MD7043)
- 1.
Please describe the capacity of the high efficiency particulate air (HEPA) filter system in terms of particle accumulation vs. pressure drop and the particle accumulation/pressure drop predicted to occur as a result of the design basis loss-of-coolant accident (LOCA).
- 2.
(a)
Please discuss the ability of the HEPA filter to withstand the moist containment environment during a LOCA without falling apart or sagging to the point where its efficiency is less than that assumed in calculations (e.g., the strength and particulate removal capability).
(b)
Please discuss if the filters are changed-out only on a differential pressure or if there is an age limit. If there is no age limit please discuss what assurance is provided that the filters will not become brittle and fail at the onset of a LOCA (for example due to the initial pressure pulse).
(c)
If there is an age limit for the HEPA filters please discuss why this is not addressed in the technical specification (TS) surveillance requirements.
- 3.
Please discuss the basis for the 50% filter efficiency assumed in the dose calculations.
- 4.
Are the containment air-cooling and filter system (CACFS) and the associated air filters safety-related?
- 5.
Technical Specification 3.6(3)(a) indicates that the emergency mode dampers will be verified to be in their accident position and the fusible link damper operation will be checked for operability. If the emergency mode dampers are being fixed in the accident configuration please discuss how the fusible link affects the damper position.
- 6.
USAR Section 6.4, Engineering Safeguards Containment Air Cooling and Filtering System (CACFS), states that the unit housing was designed to withstand 2 pounds per square inch (psi) pressure differential (dp). Pressure relief valves or ports have been installed to limit the pressure differential across the housing to 1.5 psi. The relief valves or ports are required to close to prevent bypassing of the HEPA filters. The staff understands that as part of this license amendment the CACFS is to be the primary success path to mitigate the consequence of a LOCA.
Please discuss relative to 10CFR50.36(d)(2)(ii)(C) and 10CFR50.36(d)(3) why there are no Technical Specifications or Surveillance on these relief valves/ports to ensure the relief valves/ports open to reduce the maximum pressure drop and close to prevent bypass leakage.
- 7.
Please discuss the increase of the post-LOCA (dp) across the HEPA filter if the TS dp limit is reached immediately prior to the LOCA.
- 8.
USAR Section 6.3 states The function of the containment spray system is to limit the containment pressure rise and reduce the leakage of airborne radioactivity from the containment by providing a means for cooling the containment following a loss-of-coolant accident (LOCA). This system reduces the leakage of airborne radioactivity by effectively removing radioactive particulates from the containment atmosphere. The license amendment request states The proposed modification changes containment pressure control during a LOCA from containment spray (CS) to the containment air coolers and mitigates the control room and offsite doses by the use of containment high efficiency particulate air (HEPA) filters. Containment spray will no longer remove particulate from the containment atmosphere. The CACFS will be the only mechanism to remove airborne particulate. In 2001 FCS requested and received a license amendment to use the Alternate Source Term (AST) which revised the amounts of particulate released into the containment atmosphere during a LOCA. FCS decided not to take credit for the CACFS filters (license amendment No. 198).
Using the proposed new licensing basis (containment air-cooling and filter
system with no containment spray) and beginning with the CACFS filters at the TS differential pressure limit at the onset of a LOCA, please discuss how OPPD determined that the additional pressure drop from particulate deposition on the filters in the CACFS will not cause the fan performance to drop blow the minimum acceptable limit over the duration of the event.
Please discuss if the evaluation includes the pressure drop across the moisture separator, mist eliminator, and pre-filter (if installed) and if the fan will operate in stall or surge condition.
- 9.
Please describe where in the Fort Calhoun Station (FCS) plant where CACF filter dp may be read (a) during normal operation, and (b) post-LOCA?
- 10.
(a)
Please discuss how leakage around bypass dampers and relief ports accounted for in your analysis?
(b)
Please discuss how you verify that leakage around bypass dampers and relief ports does not exceed what is assumed in your analyses?
- 11.
In section 6.4.7.3 of Fort Calhoun USAR it is stated that the HEPA filter banks were initially in-place tested for leakage. However, on Page 11 of 32 of of the FSC implementation of GSI 191 Sump Modification - Dose Consequences, provided by LIC-07-0052 and prepared for Omaha Public Power District by Stone and Webster (ADAMS accession number ML072150295) it is stated that the existing containment recirculation fan coolers (CRFC) HEPA filter/filter housing configuration at FCS does not support the use of dioctyl-phthalate (DOP) testing for bypass leakage. Prior to license amendment 198 (4/4/2001) FCS was performing technical specification required halide bypass leakage tests on the CACFS charcoal adsorbers located immediately after the HEPA filters. (There is a similarity in techniques between the halide and the DOP test regarding the injection of the challenge chemical, the collection of the upstream concentration, and the collection of the downstream concentration).
Please reconcile the discrepancy between the statement that the HEPA filter banks were tested in place, the fact that prior to amendment 198 (4/4/01) FCS could successfully perform in-place halide tests on the charcoal adsorbers and the statement that the CRCF does not support the use of DOP for bypass testing of the HEPA filter banks.
- 12.
In accordance with your regulatory evaluation as provided by letter dated December 12, 2007 (LIC-07-0104), Fort Calhoun Station (FCS) is committed to the draft General Design Criteria. As such Draft Criterion 64 Testing of Air Cleanup Systems, states that capability shall be provided for in situ periodic testing and surveillance of the air cleanup systems to ensure (a) filter bypass
path has not developed and (b) filter and trapping materials have not deteriorated beyond acceptable limits.
Please discuss how FCS complies with Draft Criterion 64.
Mail Envelope Properties (47EBBE65.B9A : 7 : 34856)
Subject:
Requests for Additional Information Creation Date 3/27/2008 11:33:57 AM From:
Michael Markley Created By:
MTM@nrc.gov Recipients nrc.gov TWGWPO01.HQGWDO01 GKL1 CC (Glenna Lappert) oppd.com dllippy (DONNA L LIPPY) medwards (MICHAEL EDWARDS) tcmatthews (THOMAS C MATTHEWS)
Post Office Route TWGWPO01.HQGWDO01 nrc.gov oppd.com Files Size Date & Time MESSAGE 1157 3/27/2008 11:33:57 AM Second RAIs CS.doc 50688 3/27/2008 11:26:20 AM Update to RAIs on Dampers.doc 39936 3/27/2008 11:25:38 AM Options Expiration Date:
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