ML17292B662
| ML17292B662 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 05/11/1999 |
| From: | Jack Cushing NRC (Affiliation Not Assigned) |
| To: | Parrish J WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| References | |
| TAC-M96928, NUDOCS 9905180161 | |
| Download: ML17292B662 (6) | |
Text
Mr. J. V. Parrish Chief Exejcutive Officer Washington Public Power Supply System P.O. Box 968 (Mail Drop 1023)
Richland, WA 99352-0968
SUBJECT:
SUPPLEMENTAL REQUEST FOR ADDITIONALINFORMATION(RAI) FOR THE WASHINGTON PUBLIC POWER SUPPLY SYSTEM NUCLEAR PROJECT NO. 2 (WNP-2) (TAC NO. M96928)
Dear Mr. Parrish:
The NRC staff has reviewed your amendment request pertaining to secondary containment and i
standby gas treatment drawdown time dated October 15, 1996, and supplemented by letters dated December 4, 1997, and April 12, 1999. As a result of the review, the staff has determined that additional information is needed to complete the review. The information needed is detailed in the enclosure.
The enclosed request was discussed with Mr. Arbuckle of your staff on May 6, 1999. A mutually agreeable target date of June 1, 1999, was established for responding to the RAI.
Ifcircumstances result in the need to revise the target date, please call me at your earliest opportunity at (301) 415-1424.
Docket No. 50-397
Enclosure:
Supplemental Request for, Additional Information cc w/encl: See next page Sincerely, Jack Gushing, Project Manager, Section 2 Project Directorate IV8 Decommissioning Division of Licensing Project Management Office of Nuclear Reactor Regulation MM (~Z~~-"': @-":>"
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON> D.C. 2055&4001 May 11, 1999 Mr. J. V. Parrish Chief Executive Officer Washington Public Power Supply System P.O. Box 968 (Mail Drop 1023)
Richland, WA 99352-0968
SUBJECT:
SUPPLEMENTAL REQUEST FOR ADDITIONALINFORMATION(RAI) FOR THE WASHINGTON PUBLIC POWER SUPPLY SYSTEM NUCLEAR PROJECT NO. 2 (WNP-2) (TAC NO. M96928)
Dear Mr. Parrish:
The NRC staff has reviewed your amendment request pertaining to secondary containment and standby gas treatment drawdown time dated October 15, 1996, and supplemented by letters dated December 4, 1997, and April 12, 1999. As a'result of the review, the staff has determined that additional information is needed to complete the review. The information needed is detailed in the enclosure.
The enclosed request was discussed with Mr. Arbuckie of your staff on May 6, 1999. A mutually agreeable target date of June 1, 1999, was established for responding to the RAI.
Ifcircumstances result in the need to revise the target date, please call me at your earliest opportunity at (301) 415-1424.
Sincerely, Docket No. 50-397
Enclosure:
Supplemental Request for Additional Information cc w/encl: See next page ack Gushing, Project Manager, Section 2 Project Directorate IV8 Decommissioning Division of Licensing Project Management Office of Nuclear Reactor Regulation
Nuclear Project No. 2 CC:
Mr. Greg O. Smith (Mail Drop 927M)
Vice President, Generation Washington Public Power Supply System P. O. Box 968 Richland, Washington 99352-0968 Mr. Albert E. Mouncer (Mail Drop 1396)
Chief Counsel Washington Public Power Supply System P.O. Box 968 Richland, Washington 99352-0968 Ms. Deborah J. Ross, Chairman Energy Facility Site Evaluation Council P. O. Box 43172 Olympia, Washington 98504-3172 Mr. D. W. Coleman (Mail Drop PE20)
Regulatory Affairs Manager Washington Public Power Supply System P.O. Box 968 Richland, Washington 99352-0968 r
Mr. Paul Inserra (Mail Drop PE20)
Manager, Licensing Washington Public Power Supply System P.O. Box 968 Richland, Washington,99352 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavilion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Chairman Benton County Board of Commissioners P.O. Box 69 Prosser, Washington 99350-0190 Senior Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 69 Richland, Washington 99352-0968 Mr. Rodney L. Webring (Mail Drop PE08)
Vice President, Operations Support/PIO Washington Public Power Supply System P. O. Box 968 Richlarid, Washington 99352 Perry D. Robinson, Esq.
Winston & Strawn 1400 L Street, N.W.
Washington, DC 20005-3502 Mr. Bob Nichols Executive Policy Division Office of the Governor P.O. Box 43113 Olympia, Washington 98504-3113
SUPPLEMENTAL RE VEST FOR ADDITIONALINFORMATION WASHINGTON PUBLIC POWER SUPPLY SYSTEM NUCLEAR PROJECT NO. 2 NP-2 DOCKET NO. 50-397 1.
The WNP-2 drawdown analysis takes credit for 40 percent mixing of leakage from primary containment within secondary containment prior to processing by the standby gas treatment (SGT) system (Note (a) to Table 1 of Attachment 2 of the October 15, 1996 submittal).
a.
Describe the calculation that was done with GOTHIC to derive the 40 percent mixing fraction. Was the same model (noding, penetrations, flow paths, ventilation systems in operation) used for the mixing study as for the actual drawdown analysis' b.
Demonstrate, by describing the flow paths available for any leakage from the primary containment to secondary containment exhaust paths, that there willbe adequate mixing prior to release, that is, there willbe no flow directly to the exhaust path that can remain unmixed.
(Such flow is sometimes referred to as slug flowor stream flow.) In particular, address those penetrations which contribute the most to La.
2.
Describe how the service water temperature is included in the GOTHIC calculation.
a.
How does the assumed winter value of 77'F compare with previously measure service water temperatures' b.
What is the sensitivity of the drawdown time to the service water temperature?
3.
The drawdown calculations assume an initial secondary containment humidity of 0 percent because the drawdown time is "somewhat" longer than with humid (less dense) air.
However, NRC Information Notice 88-76 states that the effect of outside air temperature on reactor building delta-P increases as the humidity increases in the reactor building.
a.
Show that assuming 0 percent humidity bounds the effect of outside temperature.
4.
The GOTHIC analysis assumes a flow split of 60 percent/40 percent between the upper and lower elevations.
Why was this particular flowsplit selected' 5.
How is heat transfer from the primary to secondary containment modeled?
What temperature is assumed for the primary containment?
6.
Describe how wind and outside temperature conditions are modeled in the GOTHIC calculations.
7.
The GOTHIC analysis assumes that Pa is maintained for 30 days.
Discus's the conservatism of this assumption.
Provide a sensitivity analysis to demonstrate the conservatism of this assumption.
ENCLOSURE 8.
Page 5 of 14 of the October 15, 1996, submittal states that the proposed change would increase the drawdown time from 120 seconds to 20 minutes and establish acceptable drawdown as a function of secondary containment differential pressure and SGT flow rate.
A curve of acceptable region for secondary containment differential pressure and SGT flow rate is derived. The October 15, 1996 submittal states that the SGT flow rate must be greater than or equal to 5000 cfm within 2 minutes.
a.
What is the purpose of this criterion (5000 cfm in 2 minutes)?
How is it used?
9.
An equation of flow into the secondary containment as a function of the pressure drop is given in the October 15, 1996, submittal (Page 19 of 20, Attachment 3B). This curve provides regions of acceptable and unacceptable performance of the SGT.
It appears that this curve is derived completely from analysis and normalized so as to give 0.25 inch water gauge at 2240 cfm. The equation appears to be based on such difficult-to-quantifyitems as leakage through seams in the secondary superstructure and leakage through closed doors.
Wh'at confidence is there that this equation represents the behavior of the WNP-2 secondary containment and SGT system? What confidence is there that, as the condition of secondary containment leakage paths may change with time that this equation willcontinue to be valid?
- 10. Explain why the bypass leakage is being increased from 0.74 to 18 scfm.