ML20137H785

Forwards Followup Response to NRC Request for Addl Info Re Conformance to Reg Guide 1.97.Rev 3 to 840914 Reg Guide 1.97 Rept Also Encl

ML20137H785
Person / Time
Site:	Rancho Seco
Issue date:	01/13/1986
From:	Reinaldo Rodriguez SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Miraglia F Office of Nuclear Reactor Regulation
References
RTR-REGGD-01.097, RTR-REGGD-1.097 RJR-86-11, TAC-51126, NUDOCS 8601220029
Download: ML20137H785 (5)

Text

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SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT f

6201 S Street. P.O. Box 15830, Sacramento CA 95852-1830,(916) 452-3211 RJR 86-11 AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA January 13, 1986 DIRECTOR 0F NUCLEAR REACTOR REGULATION ATTENTION FRANK J MIRAGLIA JR DIRECTOR PWR-B DIVISION U S NUCLEAR REGULATORY COMMISSION WASHINGTON D C 20555 DOCKET 50-312 RANCHO SEC0 NUCLEAR GENERATING STATION UNIT N0 1 REGULATORY GUIDE 1.97 REQUEST FOR ADDITIONAL INFORMATION The District is enclosing in Attachment I its follow-up response to the NRC's request for additional information concerning conformance to Reg. Guide 1.97.

The NRC sent this request based on an interim report prepared by its contractor, INEL, who reviewed the District's various Reg. Guide 1.97 submi ttal s. The District submitted these reports on September 14, 1983, July 13,1984, September 14, 1984, and July 9,1985. Responses to 9 of the 11 questions were included in the District's October 31, 1985 submittal . Two questions were deferred pending the B&W Owner's Group R.G.1.97 Task Force's generic position. This submittal responds to the remaining two questions.

To facilitate the review of the information in Attachment I, the District has included in Attachment II, revisions to it's September 14, 1984 Reg. Guide 1.97 report. Attachment II consists of replacement pages with revision change bars (REV. 3) in the margin. All scheduler revisions will follow the District's Living Schedule procedures.

If you have any questions, please contact Jerry Delezenski at Rancho Seco.

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/M R. J. RODRIG EZ ASSISTANT GEtERAL MANAGER .

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PDR ADOCK 05000312 F PDR Attachment (2)

1. Pressurizer Level Request:

" Pressurizer Level -- the license should supply additional analyses to support the deviation from the recommended range."

Response

The range of indicated liquid level in the pressurizer is limited by the location of the upper and lower pressure taps to 320" (or 72% of the straight side height). For anticipated transients such as decreasing feedwater temperature, excessive main feedwater flow, loss of main decreasing steam flow, small steam leaks, loss of external feedwater load, loss flow,ff-site of o power, loss of condenser vacuum and small steam generator tube leaks, the existing ranges for the pressurizer level are sufficient such that indicated level should remain on-scale.

For severe transients (accidents) such as steam line break, steam generator tube rupture and many small break LOCAs, the pressurizer voids.

Following SFAS actuation of the HPI system, actions can be taken as necessary to stabilize the plant. Those actions are based on subcooling margin and RCS pressure, not pressurizer level. For the case of a total loss of feedwater, the pressurizer will go solid unless either main or auxiliary feedwater is restored to the steam generators within about 15 minutes. Actions taken are dependent on when feedwater is restored, subcooling margin and RCS pressure, not pressurizer level.

In general, for severe transients or accidents the pressurizer will either void or go solid. A voided pressurizer will cause indicated level to go off-scale low followed by a rapid decrease in RCS pressure to saturation.

A solid pressurizer will cause indicated level to go off-scale high accompanied by high RCS pressure, possible large and rapid changes in RCS pressure, PORV and pressurizer safety valve actuation. All of these indications are available in the control room.

Based on this information the existing ranges of pressurizer level indication are sufficient for anticipated transients. For severe transients or accidents, indicated pressurizer level will go off-scale high or low due to the pressurizer going solid or voiding and, as a result, top to bottom instruments would provide no significant additional information. In these cases, subcooling margin, RCS pressure, PORV status and pressurizer safety valve status are monitored to determine actions to be taken. (This is consistent with the 08WOG Reg. Guide 1.97 task force's generic position.)

2. Pressurizer Heater Status Request:

" Pressurizer heater status -- the licensee should provide the instrumentation recommended by Regulatory Guide 1.97."

Response

The District will provide current indication for pressurizer er*gency heaters for Cycle 9 startup. The District's living Schedule will reflect this addition.

4 Var. Variable Per Sr.:JD S4UD Conputer IRC SMUD .

tb. R.G. 1.97 Rev. 3 Tag Ibs. Cat. Display Range Range Contrents

'I'(PR D VA11TAREPS Cont'd.

45 Pressurizer 14CC S2A2 2 IDADS Electric Comply Living Schedule b 11 eater Status MCC S2B2 Current (Category 2) 46 Quench Tank I!P-21905 3 Ubp to 0-10 f t. ,

Invel Bottom Upper ib1f (Category 3) (0-23'5") See Ibte 46 47 Quench Tank TE-21801 3 500 to 7500P 500F to 6000P See Living Schedule b ibnrerature (Category 3) tbte 47 48 Quench Tank PP-21920 3 0 to 0-200 psig Pressure design See (Category 3) pressure !bte 48 (235 psig) 49 Steam Generator LT-20507 A,B 1 SPDS Prom tube 6-619" Living Schedule Invel LT-20508 A,B IDADS Sheet to See Same as Variable 4 (Category 1) Separators tbte 49 50 Steam Generator PP-20544 A,B 1 SPDS Prom ATf4 0-1200 Living Schedule Pressure PP-20545 A,B IDADS pressure to psig Sane as Variable 5 (Category 2) 20% above See lowest Inte 50 safety valve setting 51 Safety Relief XE-20533 N/A IDADS Closed / Open/Not Valve Ibsition XE-20534 See Not Closed Open See (Category 2) XF-20544 lbte !bte 51 to 20559 51 XI;-20571 A,B,C XE-20562 A,B,C 23 nov. 3-

Variable Explanation 43 Each valve is monitored by two acoustic steam flow detectors.

Indication in the control room is labeled Valve Open/Not Open.

The acoustic detection system does not monitor valve position directly. However, it is reliabic and has been accepted for this use at Rancho Seco by the NRC for NUREG 0737 (accepted by the NRC in the letter dated 5/1/80, Reid to Mattimoe).

44 The range of indicated liquid level in the pressurizer is limited by the location of the upper and lower pressure taps to 320" (or 72% of the straight side height). For anticipated transients such as decreasing feedwater temperature, excessive main feedwater flow, loss of main feedwater flow, decreasing steam flow, small steam leaks, loss of external load, loss of off-site power, loss of condenser vacuum and small steam generator tube leaks, the existing ranges for the pressurizer level are sufficient such that indicated level should remain on-scale.

For severe transients (accidents) such as steam line break, steam generator tube rupture and many small break LOCAs, the pressurizer voids. Following SFAS actuation of the FPI system, actions can be A taken as necessary to stabilize the plant. Those actions are LL based on subcooling margin and RCS pressure, not pressurizer level . For the case of a total loss of feedwater, the pressurizer will go solid unless either main or auxiliary feedwater is restored to the steam generators within about 15 minutes. Actions taken are dependent on when feedwater is restored, subcooling margin and RCS pressure, not pressurizer level.

In general, for severe transiants or accidents the pressurizer will either void or go solid. A voided pressurizer will cause indicated level to go off-scale low followed by a rapid decrease in RCS pressure to saturation. A solid pressurizer will cause indicated level to go off-scale high accompanied by high RCS pressure, possible large and rapid changes in RCS pressure, PORY and pressurizer safety valve actuation. All of these indications are available in the control room.

Based on this information the existing ranges of pressurizer level indication are sufficient for anticipated transients. For severe transients or accidents, indicated pressurizer level will go off-scale high or low due to the pressurizer going solid or voiding and, as a result, top to bottom instruments would provide no significant additional information. In these cases, subcooling margin, RCS pressure, PORY status and pressurizer safety valve status are monitored to determine actions to be taken. (This is consistent with the B&WOG Reg. Guide 1.97 task force's generic position.)

36 Rev. 3

Variable Explanation b-46 The Pressurizer Relief Tank (Quench Tank) at Rancho Seco is a vertical, cyclindrical tank with a straight shell height of 17'-7". The 10' range of level indication covers fully the upper 62% of shell height. Normal water level is greater than 50% on the indicated range. Quench Tank level is useful as a backup indication of RCS inventory discharge through the Pressurizer Relief valves. Since the effect on liquid level due to discharge to the Quench Tank is to increase the level, the indicated range covers fully the range which could be of use to the operator in post accident scenarios.

36A Rev. 3

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