ML20149G759

Forwards Request for Addl Info Re Util 880113 Response to NRC Re Control Room Habitability Sys

ML20149G759
Person / Time
Site:	Rancho Seco
Issue date:	02/08/1988
From:	Kalman G Office of Nuclear Reactor Regulation
To:	Andognini G SACRAMENTO MUNICIPAL UTILITY DISTRICT
References
TAC-61413, NUDOCS 8802180394
Download: ML20149G759 (4)

Text

February 8, 1988 Docket No.: 50-312 Mr. G. Carl Andognini Chief Executive Officer, Nuclear Rancho Seco Nuclear Gnerationg Station 14440 Twin Cities Road Herald, California 95638-9799

SUBJECT:

CONTROL ROOM HABITABILITY - REQUEST FOR ADDITIONA'L INFORMATION (TACN0.61413)

On December 15, 1987 the NRC staff requested additional information regarding the Rancho Seco control room habitability systems. Your responded by letter dated January 13, 1988.

The staff has reviewed you response and finds that the enclosed additional information (RAI No. 2) is needed to complete the review. All information requested pertains to your response to information previously requested in the December 15, 1987 staff letter.

You are requested to respond to the attached request for additional information expeditiously to enable the staff to complete its review without impacting the projected restart schedule.

Sincerely, original signed by George Kalman, Project Manager Project Directorate V Division of Reactor Projects - III, IV, V and Special Projects

Enclosure:

Request for Additional Information cc: See next Page.

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m 0FFICIAL RECORD COPY

Mr. G. Carl Andognini Rancho Seco Nuclear Generating Chief Executive Officer, Nuclear Station Sacrarnento Municipal Utility District CC:

Mr. David S. Kaplan, Secretary Mr. John Bartus and General Ccunsel Ms. JoAnne Scott Sacramento Municipal Utility Federal Energy Regulatory Comission District 825 North Capitol Street, N. E.

6201 S Street Washington, D.C. 20426 P. O. Box 15830 Sacramento, California 95C13 Thomas A. Baxter, Esq.

Shaw, Pittman, Potts & Trowbridge 2300 N Street, N.W.

Washington, D.C. 20037 Mr. Jchn V. Vinguist Acting Fanager, Nuclear Licensing Sacramento Municipal Utility District Rancho Seco Nuclear Generating Station 14440 Twin Cities Road Herald, California 95C38-9799 Mr. Rcbert R. Borsum Babcock & Wilcox Nuclear Power Generation Division 1700 Rockville Pike - Suite 525 Rockville, Maryland 20852 Resident Inspector / Rancho Seco e/sU.S.N.R.C.

14440 Twin Cities Road Herald, California 95638 Regional Administrator, Region V U.S. Nuclear Regulatory Connission 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Mr. Jack McGurk, Acting Chief Radiological Health Branch State Departroent of Health Services 714 P Street Office Building !8 Sacramento, California 95814 Sacramento County Board of Supervisors 827 7th Street, Room 424 Sacramento, California 95814 Ms. Helen Hubbard P. O. Box G3 Sunol, California 94586 i , ~. _ _

l RANCHO SECO RESTART l CONTROL ROOM HABITABILITY SYSTEMS REQUEST FOR ADDITIONAL INFORMATION NO. 2 PLANT SYSTEMS BRANCH

1. Rancho Seco's procedure for air balance of ventilation systents, i M-lli, "HVAC Maintenance Procedure for Air Balance of Ventilation Systems," is relied on for providing assurance that unfiltered air inleakage in within the bounds of the assumptions used in the dose calculations and toxic gas analyses, and the system otherwise functions as designed. In the initial request for additional information (RAI),

eleven specific items were requested regarding M-111 and the results obtained. Based on our review of the licensee's response to the initial RAI and our understanding that the licensee is performing a new air balance for the control room HVAC system in accordance with M-111, provide all final data sheets, results, evaluations, and conclusions based on the new air balance regarding the adequacy of the air flow rates assumed in i the dose calculations and toxic gas analyses and concerning the system functions. Items 1(a), 1(1) and the concern noted in Item 1(k) of the initial RAI remain applicable.

2. R.G. 1.52. Position 5.d provides that leak testing of the carbon adsorber section should be conducted if the integrity of the adsorber is affected.

Rancho Seco Technical Specification 4.10.1.B requires that leak testing be performed "...after each partial or complete replacement of the...

charcoal adsorber bank." Provide a comitment to conduct this leak testing after reinsta11ation of the carbon filter trays which are removed in accordance with the procedures (STP 1063A) for conducting air / aerosol mixing uniformity tests.

3. Clarify how procedure I.044, which "checks the probe sensitivity for chlorine concentration by using an approximately 10 ppm standard calibration gas," is used to verify that the detection are capable of detection a chlorine concentration of 5 ppm are per R.G. 1.95 and how this relates to the use of I.045 to "check the alarm setpoint of 1 ppm."

4. Clarify how plant security's procedures for approving opening of the l control room exit leading directly to the outside of the building i provides assurance that control room habitability is maintained during i emergencies, or provide additional rationale to justify reliance on means -

other than administrative controls acting in conjunction with security to l provide this assurance.

5. Provide a comitmer.t to perform periodic testing which will be relied on for indication of the leak tightness of the silicone sealant employed to limit air inleakage to the control room. Provide a detailed i description of the tests. This description may be provided subsequently with a scheduled comitment to do so at this time.

6. Provide the resolution, including schedules, and supporting rationale for the following licensee identified issues:

i m-- _ _ .__ _

(1) Automatic initiation of CR/TSC Essential Air Syster operation increases control room operator work load during certain critical plant operating phases; and (2) CR/TSC Essential HVAC controls and operating status indication in the Control Room are not adequate.

In addition, with reference to the above, provide rationale supporting the capability of the design to provide automatic initiation if needed, following manual shutdown of one or both trains of the Essential HVAC >

System.

7. The staff is unable to conclude, based on information received to date, that reasonable assurance has been provided that the control room operators would be adequately protected against a chlorine gas release from the chlorine storage building area. Such a release could reach the centrol room air intakes but by-pass the "semi-remote" current location if the chlorine detectors considering the intake air flow rates (normal and radiation protection modes) and assured maximum inleakage rates.

Provide additional assurance to support the existing chlorine detector location, or commit to a proposed schedule for evaluating alternative designs and implementing an appropriate design modification to provide further chlorine gas protection, diring which time clearly adequate protection is provided including, if appropriate, the absence of such pctential chlorine release sources from the site.

8(a).R.G. 1.52 provides that a 95% removal efficiency (5% penetration) for organic iodide can be assigned for a 2-inch charcoal adsorber bed if the laboratory tests show a penetration of 1% or less. This corresponds to a "safety factor" of 5 or greater. The Rancho Seco Technical Specifications provide for an assigned 90% removal efficiency (10%

penetration) for each of the 2-inch beds if the laboratory tests show penetrations of 5% or less. This corresponds to a "safety factor" of 2 or greater. Justify this apparent discrepancy.

(b). Clarify the applicability of the discussion in your January 13, 1988 submittal regarding statistical analyses of laboratory testing criteria.

9. Provide a dose evaluation for all potential release points other than '

those identified in your response (e.g., ground level auxiliary building exhaust), or provide rationale for concluding that calculated doses for the identified potential release points exceed the doses that would be calculated for the other release points.

10. With regard to safety-related instrumentation display and readout, justify where applicable, not meeting minimum engineered safety feature instrument provisions of SRP 6.5.1, Table 6.5.1-1, which refers to ANSI H509 and R.G. 1.52

11. Justify reliance on the non-safety related IDADS computer system for HVAC equipment status monitoring during emergencies considering the nature of its power supplies.

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