ML20207E291

Forwards Request for Addl Info Re Response to Generic Ltr 86-05, Implementation of TMI Action Item II.K.3.5. Use of Multiple Subcooling Margin Setpoints Needs Discussion

ML20207E291
Person / Time
Site:	Rancho Seco
Issue date:	08/11/1988
From:	Kalman G Office of Nuclear Reactor Regulation
To:	Firlit J SACRAMENTO MUNICIPAL UTILITY DISTRICT
References
TASK-2.K.3.05, TASK-TM GL-86-05, GL-86-5, TAC-49680, NUDOCS 8808170300
Download: ML20207E291 (7)

Text

_. .

August 110 1988 C Oocket No.: 50-312 Mr. Joe Firlit Chief Executive Office, Nucleat Sacramento Municipal Utility District 14440 Twin Cities Road Herald, California 95638-9799

SUBJECT:

THI ACTION ITEM II.K.3.5, TAC 49680 Please respond to the enclosed request for additional information. The requested information is required to complete our review of ye"r responses to TMI Action Item II.K.3.5.

Sincerely, original signed by George Knighton for George Kalman Project Manager Project Directorate Y Division of Reactor Projects - !!!,

IV, Y and Special Projects Office of Nuclear Reactor Regulation

Enclosure:

As stated cc: Shih-Liang Wu DISTRIBUTION:

g~r Diktet nle '

MRC~& Local PDR's GKalman ACRS(10)

OGC BGrimes EJordan DRSP)$ PM D PDV GKa % W 'cw

. Glut .

cn 8/// /sa 08/p /88 esos1jo g ge gon ,,

PNU q.

DFo.

- '\ w

August 11, 1988

.. Docket No.: 50-312 Mr. Joe Firlit Chief Executive Office, Nuclear Soc)amento Municipal Utility District 14440 Twin Cities Road Herald, California 95638-9799

SUBJECT:

TMI ACTION ITEM t!.K.3.5, TAC 49680 Please respond to the enclosed request for additional information. The requested information is required to complete our review of your responses to THI Action Item II.K.3.5.

Sincerely, original signed by George Knighton for George Kalman, Project Manager Project Directorate V Division of Reactor Projects - III, IV, Y and Special Projects Office of Nuclear Reactor Regulation

Enclosure:

As stated cc: Shih-Liang Wu DISTRIBUTION:

Docket File NRC & Local PDR's GKalman ACRS(10)

OGC BGrimes EJordan DRSP PM PDV GKa hY.cw G %n 8////88 08/) /88 l

1. 'o,, UNITED STATES

[' p, , NUCLEAR REGULATORY COMMIS3 TON

,G  :

l WASHING TON, D. C. 20655

% ,,,,, August 11, 1988 Docket No.: 50-312 Mr. Joe Firlit Chief Executive Office, Nuclear Sacramento Municipal Utility District 14440 Twin Cities Road Herald, California 95638-9799

SUBJECT:

TMI ACTION ITEM II.K.3.5, TAC 49680 Please respond to the enclosed request for additional information. The requested information is required to complete our review of your responses to TMI Action Item II.K.3.5.

Sincerely, 8 f George alman, Pro ct Manager Project Directorate V Division of Reactor Projects - III, ,

IV, Y and Special Projects Office of Nuclear Reactor Reg'.iiation

Enclosure:

As stated cc

Shih-Liang Wu i

l l

I

A

. Mr. Joe Firlit Rancho Seco Nuclear Generating Chief Executive Officer, Nuclear Station Sacram nto Municipal Utility District ,

14440 Twin Cities Road Herald, California 95rA8-9799 cc:

Mr. David S. Kaplan, Secretary Mr. John Bartu: -

and General Counsel Ms. JoAnne Scott Sacramento Municipal Utility Federal Energy Regulatory Comission District 825 North Capitoi Street, N. E.

6201 S Street Washington, D.C. 20426 P. O. Box 15830 Sacramentu, California 95813 Mr. Barclay S. Lew Pacific Gas and Electric Company Thomas A. Baxter, Esq. 77 Beale Street (333/A613)

Shaw, Pittman, Potts & Trowbridge San Francisco, CA 94106 2300 N Street, N.W.

Washington, D.C. 20037 Ms. Helen Hubbard P. O. Box 63 Mr. Steven Crunk Sunol, California 94586 Manager, Nuclear Licensing Sacramento Municipal Utility District Rancho Seco Nuclear Generating Station 14440 Twin Cities Road Herald, California 95638-9799 Mr. R]bert B. Borsum, Licensing Representative Babcock & Wilcox Nucivar Power Division 1700 Rockville Pike - Suite 525 Rockville, Maryland 20852 Resident Inspector / Rancho Seco

/o V. S. N. R. C.

14440 Twin Cities Road Herald, California 95638 Regional Administrator, Region V U.S. Nuclear Regulatory Comission 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Mr. Jack McGurk, Acting Chief Radiological Health Branch State Department of Health Services "

714 P Street, Office Building #8 Sacramento, California 95814 Sacramento County Board of Supervisors 700 H Street, Suite 2450 Sacramento, California 95614

REQUE3T FOR ADDITIONAL INFORMATION RANCHO SECC DOCKET NO. 50-312 RESPONSE TO GENERIC LETTER 86-05 f "lMPLEMENTATION OF TMI ACTION ITEM !!.K.3.5"

REFERENCES:

1. Lotter from J. E. Ward (SMUD) to F. J. Miraglia (NRC), SMUD Letter JEW 87-491, April 28,1987.

2. Babcock and Wilcox Report 77-1149091-00, May 16,1986.

3. NRC Geaeric Letter 86-05, May 29,1986.

QUESTIONS:

1. The generic BWOG analysis (Ref. 2) supports the use of "loss of subcooling margin" as the appropriate RCP trip criterion. The analysis ,

indicated that each licensee needed to account for ir.strumentation uncertainties when determining the critical SCM setpoint value used to trip the pumps. The use of multiple subcooling margin (SCM) setpoints, which varied according to the reacter coolant pressure, was .

not discussed.

l a. Explain how two SCM setpoints (20F and 50F) are used to assess the need for RCP trip, i.e. describe the procedures which enable f

! the operator to properly diagnose the event and/or symptoms.

Identify too reactor coolant pressure / temperature switch-point l

(Ref. 1),, where the SCM setpoint changes from 20F to 50F.

l b. The licensee indicated that subcooling margin can be determined using the safety parameter display r,ystem (SPDS) or the subcooling margin monitors (SP94). Identify the preferred

( '

method. Ensure that the operator is adequately trained to recognize a bad reading and to use the alternate method.

r

.4.

l- .

e c. The 50F subcooling margin limit was stated to be applicable for the Sub ooling margin Monitor, but the 20F limit was ro'. mentioned.

Cla:ify the SCM limits (covering the upper and lower ranges of the saturation curve, if applicable) that are used for the Siti.  ;

d. The Licensee indicated [ref.1] that the calculation of instrumentation uncertainties is consistent with the manufacturer's specifications. The instrumentation uncertainties were identified as (301 psig,12F) and (270 psig, 6F) for the SPDS and Sffi, respectively. Briefly explain how the pressure and temperature uncertainties were combined to determine the subcooling margin setpoints which cover the upper and lower ranges of the saturation curve. The Licensee can provide information copies of the uncertainty calculations and manufacturer data to resolve this question, if it is appropriate.

2. The licensee's response to Question A.3 did not provide enough information to determine how the generic assumptions used in tt.e BWOG analyses affect the results as they apply to Rancho Seco. Therefore, identify tha plant specific features that are not representative of the reference plant used in BWOG 77-1149091 (ref.2). At a minimum SMUD should discuss core power, decay heat HP1 capacity, makeup flows, setpoints for steam generator safety valves, reactor trip, safety injection, and accumulat'6r injection. Show that the values used in the generic analyses are either representative of those for Rancho Seco, or are conservative. If a reference plant parameter is not conservative for f Rancho Seco, discuss how this was considered in determining the plant specific setpoints.

3. The generic report (ref.2) warns licensees about the adverse affects of isolating the seal bleedoff line. Isolation of this line could affect tne pr.:ssure staging across the seals and cause heat to build up.

Describe the procedures in place that prevent this problem from occurring at Rancho Seco,

i.

r

4. The response to question C did not identify the Emcgency Operating Procedures used to address voids, e.g. natural circulation, restore ,

primary to secondary heat transfer, monitor vessel inventory, "feed and bleed" procedures, and (if applicable) monitoring pump motor curr2nt as an indication of primary system void fraction. The Licensee is requested ,

to provide, at a minimum, the number and title of the E0Ps.

t l

[

}

f t

r 9

, - , -