ML20199E693

Forwards RAI Re 970808 Request for Change to TS Tables to Revise Sensor Errors & Reduce Setpoint Tolerances for MSSVs

ML20199E693
Person / Time
Site:	Callaway
Issue date:	11/13/1997
From:	Westreich B NRC (Affiliation Not Assigned)
To:	Randolph G UNION ELECTRIC CO.
References
TAC-M99419, NUDOCS 9711210287
Download: ML20199E693 (4)

Text

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! $rL Garry L. Randolph- .

' :Vice President and Chief Nuclear Officer '

i S" . Union Electric-Company: ,

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Post Office-Box 620 Fulton, Missouri 65251

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SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION-(RAI) REGARDING MAIN STEAM SAFE 1Y VALVE SETPOINT TOLERANCE CHANGE (TAC:NO. M99419) >

Dear _Mr. Randolph:

By ictter dated' August 8. 1997. Union Electric _(UE) submitted an application -

for amendment-to Facility Operating License No. NFP-30 for the Callaway Plant that would change technical specification tables to-revise sensor errors and =

reduce the setpoint tolerances for the main steam line safety valves.

_The staff has reviewed the submittal and determined that further information= 1 is needed to complete our review. The requested information is included as an ,'

enclosure to this letter. In order to maintain the staff's review.. provide

. your response within 30 days of the date of this letter. If you have any~ ,

questions, please contact me at_(301).415-3456.

Sincerely.

Original Signed By Barry C. Westreich Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket No. 50-483 DISTRIBUT ON:

Docket /Fi e- EPeyton

Enclosure:

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.e Mr. Garry L. _ Randolph. -2 November 13, 1997

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Professional-Nuclear Mr. Otto L. Maynard Consulting.-Inc. President and Chief Executive Officer  !

19041 Raines Drive Wolf Creek Nuclear Operating Corporation Derwood. Maryland -20855 P.O. Box 411 ,

Burlington Kansas 66839 '

Gerald Charnoff. Esq.

. Mr. Dan I. Bolef. President Thomas A. Baxter.-Esq&

Shaw. Pittman. Potts Trowbridge Kay Drey. Representative 2300 N. Street. N.W. Board of Directors Coalition Washington, D.C. 20037 for-the Environment -

6267 Delmar Boulevard

Mr. H. D. Bono University City. Missouri 63130 Supervising Engineer.

Quality Assurance Regulatory Support Mr. Lee Fritz-Union Electric Company Presiding Cor.nissioner Post Office Box 620 Callaway Cou'ity Court House Fulton, Missouri 65251 10 East Fifth Street Fulton Missouri 65151 U.S. Nuclear Regulatory Commission Resident Inspector Office Mr. Alan C. Passwater. Manager 8201 NRC Road Licensing and Fuels Steedman Missouri 65077-1302 Union Electric Company Post Office Box 66149 Mr. J. V. Laux. Manager St. Louis, Missouri 63166-6149 Quality Assurance Union Electric Company Post Office Box 620 Fulton, Missouri 65251 Manager - Electric Department Missouri Public Service Comission 301 W. High-Post Office Box 360 Jefferson City. Missouri 65102 Regional Administrator Region IV U.S. Nuclear Regulatory Comission Harris Tower & Pavilion 611 Ryan Plaza Drive. Suite 400 Arlington. Texas 76011-8064 Mr. Ronald A. Kucera. Deputy Director Department of Natural Resources P.O. Box 176 Jefferson City. Missouri 65102

,E UNION ELECTRIC COMPANY-CALLAWAY PLANT

-DOCKET N0. 50-483 RE0 VEST FOR ADDITIONAL'INFORMATION REGARDING MSSV TOLERANCE CHANGE

'1 . ITS Page 3.7-4 does not include the note that specifies that the as left' lift setting tolerance should be 1% of the nominal setpoint. ITS -

-BASES Page B 3.7-4. Surveillance Requirement SR 3.7.1.1 does not include a discussion on the as left tolerance of 1%. Address these comments.

2. On page 2 of the Significant Hazards Evaluation it was stated. " ..where the 1236 psia secondary setpoint reflects the Westinghouse transient methodology of modeling all main steam line safety valves as lifting at the same setpoint." It is the staff's understanding that 1236 corresponds to the lowest setpoint (1185 psig) plus tolerance (psia

+3%).

This is non-conservative from an overpressure Jerspective since the setpoints for the remaining valves are set hig1er than 1185 psig.

Justify this assumption.

3. On page 2 of the Significant Hazards Evaluation it wus. stated.

... changes were made to the model to account for the presence of a pressurizer loop seal and to expressly model five MSSVs per steam generator " Describe the changes that were made end the effect of these char.ges on the results of the analyses.

4. On page 3 of the Significant Hazards Evaluation it was stated that Westinghouse reviewed the RCP locked rotor / shaft break accident and found that the MSSV tolerance change to +3/-1% has no impact on the transient. The letter dated August 8. 1997, stated that an earlier submittal dated September 12, 1994, was denied because the high pressure criterion for the locked rotor event was extended to above 110% of the design pressure. This implies that the RCP locked rotor transient was affected by the tolerance change in the September 1994 analysis.

Describe the differences between the September 12, 1994, submittal and the current submittal (August 8, 1997) that changed the impact of the increase in tolerance on the locked rotor transient.

5. AFW flow calculation assumptions for steam generator pressure should include accumulation for safety valve 11ft in addition to tolerance.

The licensee assumed 1236 psia which does not include accumulation.

Account'for accumulation. (Page 4 of the Significant Hazards Evaluation)

6. For the SBLOCA evaluation, were the MSSVs assumed to all lift at the same setpoint>of 1236 psia? Justify your answer in the same manner as for Question 2 above. (Page 5 of the Significant Hazards Evaluation)

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7. Explain the statement. " Voltage and frequency relays associated with the reactor coolant pump provide no additional safety function for this event." (Page A 2 of the submittal)

8. What was assumed for initial pressurizer level in the analysis? How was level uncertainty accounted for in this assumption?

9. You stated that Callaway specific calculations have shown that a nominal reactor coolant temperature results in conservative peak RCS pressure calculations. Explain this statement and discuss the calculations that were performed. Was the assumption of nominal temperature found to be more conservative than nominal plus/minus uncertainty?

10. The staff could not find the figures referenced in the results section on Page A-5. Provide these figures in the order referenced.

11. Provide the actual values of the peak primary and secondary pressures and the minimum DNBR achieved in the analyses and the limit for each.

12. On Page A-8 of Table 2 -

a. confirm that the information under Item 1 is for minimum reactivity feedback case,

b. justify the use of one second delay between high pressurizer pressure reactor trip setpoint reached and the point at which the rods begin to drop under Item 2.

c. provide a listing for the peak secondary pressures for each of the two items.

13. WCAP-7769. Rev. I states. "The required safety valve relief capacity is determined for a complete loss of steam flow to the turbine with credit taken for steam generator safety valve operation. For the sizing main feedwater flow is maintained and no credit for reactor trip is taken."

In Appendix B. Section 3.0 " Sizing of Pressurizer Safety Valves."

Subsection 3 1 of the submittal. it was stated that feedwater flow is isolated at the start of the transient. Discuss these two statements and the effects of the different assumptions on the sizing analysis.

Justify your assumption of feedwater isolation in light of the information in the WCAP.

14. List and justify the initial cor.ditions (pressure, temperature, level, etc.) assumed for the sizing calculations.

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