ML20199J240
| ML20199J240 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 01/27/1998 |
| From: | Wharton L NRC (Affiliation Not Assigned) |
| To: | Gambhir S OMAHA PUBLIC POWER DISTRICT |
| References | |
| TAC-M98933, NUDOCS 9802050266 | |
| Download: ML20199J240 (4) | |
Text
_ _ _ _____________ - - _
January 27, 1998 Mr. Si K. Gambhir Division Managet Production Engineering Omaha Public Powe District Fort Calhoun Statica FC 2-4 Adm.
Post Office Box 39f' Hwy.75 North oi crf Calhoun t
Fort Calhoun, Nebrawa 68023-0399
SUBJECT:
FORT CALHOUN STATION, UNIT NO.1 REQUEST FOR ADDITIONAL I
INFORMATION ON MAIN STEAM SAFETY VALVES (MSSVs)(TAC NO. M98933) i
Dear Mr. Gambhlt:
By letter dated March 2d,1996, Omeha Public Power Distric' submitted for NRC review, technical specificatb7 changes for the Fort Calhoun Station, Unit No.1. The app!! cation addresses incorporating additional restrictions on the operation of the MSSVs.
The staff has reviewed your response and determined that further information is necessary to complete its review of your submittal. We have enclosed the request for additionallnformation.
Please provide written responses to the er' closed questioris within 30 days of receipt of this letter.
Sincerely, Original Signed By l
L. Raynard Wharton, Project Manager Project Directorate IV 2
, Division of Reactor Projects - lil/lV g
Office of Nuclear Reactor Regulation Docket No. 50 285 DISTRIBUTION:
Docket File RWessman
Enclosure:
Request for AdditionalInformation PUBLIC MShuabi PDIV 2 Reading WJohnson, Region IV cc w/ encl: See next page EGA1 OGC WBateman ACRS RWharton EPeyton DOCUMENT NAME: FC98933 RAI OFC A?SIV 2/PM PDIV 2/LA NAME arton -
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DATE 1/21/98 1/0 7/98' OFFICIAL RECORD COPY hkh
[1, o-9002050266 900127 PDR ADOCK 05000205 P
PDR gow
Mr. S. K. Gam'nir January 27, 1998 cc w/ encl:
Winston & Strewn A"TN: Perry D. Robinson, Esq.
1400 L Street, N.W.
Washington, DC 20005-3502 Mr. Jack Jensen, Chairman Washington County Board of Supervisors Blair, Nebraska 68008 Mr. Wayne Walker, Resident inspector U.S. Nuclear Regulatory Commission Post Office Box 309 Fort Calhoun, Nebraska 68023 Regional Administrator, Region IV U.S. Nuclear Regulatory Comniission 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 -
Ms,- Cheryl Rodgers, LLRW Program Manager Environmental Protection Section Nebraska Department of Health 30*i Centennial Mall, South P.O. Box 95007 --
Lincoln, Nebraska. 68509-5007 Mr. James W. Chase, Manager Fort Calhoun Station -
Post Office Snx 399 Fort Calhoun, Nebrasb 68023 -
Mr. James W. Tills
' Managei - Nuclear Licensing Omaha Public Fower District Fort Calhoun Station FC 2 4 Adm.
Post Office Box 399 -
, Hwy. 75 - North of Fort Calhoun
- Fort Calhoun, Nebraska 68023-0399 -
l
REQUEST FOR ADDITIONAL INFORMATION OMAHA PUBLIC POWER DISTRICT
]
FORT CALHOUN STATION. UNIT NQJ DOCKET NO. 50-285 1.
Justify the increase in total relief capacity of the ten main steam safety valves from 6.54E6 lb/hr to 6.606E6 lb/hr and discuss the effect of the pressure drop on the capacity.
)
2.
List and justify your assumptions and initici conditions for each analysis. Identify and justify all changes from the current analyses of record. Also provide a sequence of events for each analysis, in addition address any effects of the pressure drop to the safety valves on the DNB analyses, discuss which valve was assumed to failin the analyses (size and setpoint) and your assumption for initial pressurizer level.
3.
OPPD stated, "The CESEC-Ill model does not allow modeling of individual valves, rather
]
d models sets of valves, one on each steam generator." OPPD also stated,"The CESEC-Ill model allows input of valve accumulation and blowdown for individual valves to address the lift setpoint of the valve...." Explain in more detail how CESEC-Ill models the valves. Also include a discussion on the fo'hwing statements in your submittal:
" and the pressure losses in the main steam line to the SG were added to obtain the maximum secondary system pressure within the steam generator" "The modeled CESEC-Ill MSSV valve areas of 0.4497 ft8 were modified to account for piping pressure losses between the SG and MSSVs."
"The modeled original valve design's accumulation was modified from the value of 3% to account for piping pressure losses between the SG and the MSSVs and the differential pressure developed as a result of flow through the valves."
"The modeled valve actuation setpoints were modified to account for the pipe run differential pressure that would exist prior to the valve's opening."
4.
OPPD stated, "the applicable transient for... maximum secondary pressure is loss of feedwater." Table 1 shows Case 1 under Loss of Load as the most limiting transient for secondary pressure. Explain this statement.
5.
OPPD stated,"In order to generate acceptable results for the peak secondary pressure case, it was necessary to credit the Low Steam Generator Level Trip (LSGLT) for the Loss of Feedwater case. This is consistent with ABB-CE methodology." Provide a reference for this methodology and its approval.
{
1 i
2 6.
. Justify basing the pressure limits of 1100 psia and 2750 psia on absoluto design pressures of 1000 psia and 2500 psia instead of gauge pressures of 985 psig and 2485
_ sig.
p 7.
In the FSAR loss of load section, only peak primary pressure ana!yses are discussed, explain why the peak secondary pressure analyses era not included in the discussion.
. Why isn't the Case 3 primary pressure reponed given that its higher? Also, peak secondary pressure corresponding to the analysis for the peak primary pressure is provided. Explain why the peak secondary pressure obtained from the Limiting Secondary Pressure Case (Case 1 in Table 1 of the submittal) is not included.
8.
Explain in more detail the difference between using 'he power dependent insertion limits curv3s and the ARO curves and the effect of these differences on the analyses.
l
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