ML20147F111

Forwards Addl Info Re Control Room Habitability Sys,Per NRC 871215 Request

ML20147F111
Person / Time
Site:	Rancho Seco
Issue date:	01/13/1988
From:	Firlit J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Miraglia F Office of Nuclear Reactor Regulation
Shared Package
ML20147F117	List: ML20147F111 ML20147H877 ML20147H926
References
AGM-NPP-88-006, AGM-NPP-88-6, NUDOCS 8801210279
Download: ML20147F111 (21)

Text

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$SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 62o1 S Street. P.o. Box 15830, S xremento CA 95852 1830,(916) 452 3211 AN ELECTRIC SYSTEM SERVING THE HEARf OF CAllFORNIA 3AN131988 AGM/NPP 88-006 U. S. Nuclear Regulatory Commission Attn: Frank J. Miraglia, Jr.

Associate Director for Projects P.11111ps Building 7920 Norfolk avenue Bethesda, MD 20014 Docket No. 50-312 Rancho Seco Nuclear Generating Station License No. DPR-54 CONTR08 ROOM HABITABILITY REQUEST FOR ADDITIONAL INFORMATION

Dear Mr. Miraglia:

On December 15, 1987, the NRC staff requested additional information regarding the contral room habitability systems. Attached are the District's responses to the staff's questions.

Please contact me if you Nye any questions. Members of your staff with questions requiring addf;ional infomation or clarification ma contact John Atwell at (239) 333-2935, extension 4917.

Sincerely, be Joseph. F. firl*.t '

A*!istant General Manager, Jar Porf;r Production

-technent

., s . 5- NRC Bethesda

a. 1 & : , NRC, Rancho Seco

• .in, NRC, Walnut Creek i 8801210279 880113 N Ob PDn ADOCK 0500 g2 q)O i P l;l RANCHO SECO NUCLEAR GENERATING STATION D 1444o Twin Cities Road Herald CA 95638 9799;(209) 333 2935 b

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-AGM/NPP 88-006 F.J. Miraglia JAN131988 bc:

w/o atch w/atch X General Manager HS 41

.lL.l; l 7_

3 Chief Executive Officer, Nuclear MS 209 X Executive Assistant MS 204 AGM, Nuclear Tech. & Adm. Services MS 206 X X AGH, Nuclear Power Production MS 254' X X Director,~ Nuclear Quality MS 271 Director, Nuclear Tech. Services MS 206A Director, Nuclear Ops. & Maint. MS 257 X Director, Plant Support MS 258 Director, Sys. Rev. & Test Prgm. MS 259 Modifications Manager MS 201 X _)L Manager, Nuclear Training MS 296 L JL ,__

Manager, Nuclear Licensing MS 286 X X Manager, Nuclear Engineer'.ng MS 208-6 Manager, Cost Control Services MS 270 X Public Information MS 299 Manager, Maintenane.e MS 254 Plant Support Eng. Manager MS 208-6 X _X. Manager, Operations MS 255 Manager, Env. Protection MS 292A Manager, Rad. Protection MS 244 Manager, duclear Chemistry MS 244 X X H& nager, Plant Performance M3 258 Risk Manager (D. hears) MS 40 MSRC Secretary (J. Palmer) MS 274 Surveillance Coordinator MS 278 X X IIRG HS 298 l_ X NAC (6) MS 204 T. Baxter F. Burke (B&W)

LER Files MS 298 X X Licensing Files MS 286 X X PRC Package MS 286 X l_ RIC Files MS 224 Special Report Files MS 286 Tech. Spec./PA Files  ;.S 298

__ NOV/N00 Files MS 286 Licensing Verification MS 286

_1_ X Elizabeth Gebut  !!S 286 X X Jerry Delezenski MS 298 X X Bob Little (Bethesda) MS

• 1 copy w/atch & 1 w/o atch

NRC QUESTIONS AND ANSHERS Question 1.a: Provide assurance that test data presented to the review team represents data recorded during the operation of distinct, continuous test cycles for the HVAC system modes of operation, or provide justification that data obtained in interrupted runs are acceptable.

Response 1.a: The testing performed between April 29 and 30, 1987 was performed continuously from 17:30pm to 04:30 am. Adjustments to all outlets were made in the toxic gas mode. Once these adjustments had been performed, each train was operated in the radiation mode and the outside air volume dampers were adjusted to achieve positive pressure within the CR/15C envelope.

Question 1.b: Provide the data sheets associated with measurements (traverses on the A & B unit supply and return) referred to in the remarks section of the procedure dated April 29, 1987.

Response 1.b: All readings / data taken dur..ig the April 29/30 runs were of a preliminary nature. This being the case, not all the data sheets were retained. The specific data sheets requested,

everal of which are available in the pu kage provided, have no bearing on the final acceptance of the system. Final data for the measurements requested are provided in the package given to the staff (sheets marked final data and dated 6/3/87).

Question 1.c: Provide the data sheet associated with the measurement (traverse on the A train outside air intake) referred to in the remarks section of the procedure dated April 29, 1987.

.9esponse 1.c: All readings / data taken during the April 29/30 runs were of a preliminary nature. This being the case, not all the data sheets were retained. The specific data sheets requested, several of which are available in the package provided, have no bearing on the final acceptance of the system. Final data for the measurements requested are provided in the package given to the staff (sheets marked final data and dated 6/3/87).

Question 1.d: Provide justification for the validity of the readings recorded on the data sheet associated with the TSC return air data dated April 30, 1987.

Response 1.d: Preliminary duct flow measurement; were taken and considered representative of what would be 4.he final confiqqrction.

Actual return grill data was not taken due to tae hole in the 1SC ceiling. As stated previously, i;nal data (6/3/87) was used for acceptance of the system.

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Question 1.e: Provide data sheets associated with traverse readings taken on the control room supply and return to the filtration unit as referred to in remarks dated May 7 1987, as well as data sheets for the several other measurements recorded in the remarks dated May 7, 1987.

Response 1.e: Re catc taken on May 7, 1987, and referred to in the question >

were trial runs and were not retained. Final data was used for acceptance of the system.

Question 1.f: Provide flow measurement data sheet' for outside air makeup to both of the HVAC trains for data taken on June 3, 1987.

Response 1.f: The final acceptance testing for the radiation mode was done on September 21, 1987. The data obtained on June 3, 198' was for toxic gas mode only.

Question 1.g: Provide the correct date associated with a flow measurement data sheet for the B train control roer. return.

Response 1.g: The correct date for the data sheet in question was June 3, 1987 as evidenced by the log.

Question 1.h: Provide additional inft.,rmation to support the statement made in item 2.1.E of the most recent III.D.3.4 submittal dated July 22, 1987, that the system has been tested to verify that the control room TSC can be pressurized to at least 1/8 inch water gauge relative to all sarrounding spaces.

Response 1.h: Surveillance Procedures (SPs) 618A & B dated 10/28/87 and 10/29/87, respectively, provide the results of the pressure test. The results indicate that 1 1/8 inch water gauge relative to all surrounding spaces was attained.

Quest %n 1.1: Procedure M-111 did not include any flow measurements in the ducts of the normal HVAC system or for any of the idle bran:hes of the HVAC system. Provide justification es to why H-111 is sti'1 adequate since it doesn't mae these eam remcnts.

Response 1.i: Procedure M-ll) is intended to verify the flow distritation within the CR/TSC envelope and will provide assurance that adequate cooling will riccur. Pressi'rization of the CR/TSC is verified via SPs 618A & B. The attached figure provides the s

i location of the traverse point. throughout the system where flow measurements are taken. ,

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Question 1.j: Air balance data for the air hanaling units taken cn April 23, 1987 and September 30, 1987 indicate that the air inlet and the air outlet flows are exactly the same for both air handling units. Provide additional information to support these data measurements.

Response 1.j: A review of the data sheets in q'uestion indicate that two columns of numbers were provided. The "Design" values for both trains are identical; however, the actual measured values vary slightly, as would be expected.

Question 1.k: Provide assurance that inleakage flow through the isolation

' damper in the normal supply duct from AH-H-2 during operation in emergency modes is adequately addressed by the assumptions of the dose calculation and toxic gas calculations and is not relied on for assuring adequate pressurization of the control room enV? lope.

Response 1.k: The June 3, 1987 test data in question was obtained from travarse measurements in supply and exhaust ducts for the TSC when the Essential HVAC was operating in a recirculation (toxic gas) mode. Inleakage is not a concern for the radiological mode as the pressure in the TSC supply duct downstream of the bubble tight isolation dampers HV-54717 and HV-54718 is greater than the upstream supply duct from air handling unit AH-H-2.

To verify the June 3rd results, traverses of the TSC supply and reti,rn ducts were conducted on December 26, 1987, with the Essential HVAC operating in the toxic gas mode, and at locations which would provide the least amount of turbulence and a better flow representation. From the measurements, return / supply duct flow differences were calculated. For Train A and B return air flow was greater than the supply air (150 SCFM and 232 SCFM, respectively). The District considers these return / supply air flow differences to be within the error band for the method of measurement and not due to inleakage through the isolation dampers in the AH-H-2 supply duct. In addition, a powder "puff" test was conducted across the bubble tight isolation dampers HV-54717 and HV-54718 with no evidences of leakage.

Based on these results, the District considers the unfiltered air inleakage rates to be within what is allowed by the

. criteria in ANSI N509-1980 and what has been assumed in the radiological dose and toxic gas calculations for Rancho Seco (See Response 7).

Question 2: Provide additional information which assures that the carbon trays have been properly reinstalled (thereby limiting bypass flow) without performance of this type of test, or modify the test procedure or otherwise provide assurance that the adsorber section will be leak tested.

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Response 2: The STPs referenced b the question (1063A & B) were perTormed on July 31, 1987. Subsequent to these tests, SPs 618A & B were performed. Thn performance of these tests provides assurance that the carbon trays were properly reinstalled, as evidenced by successful completion of the SPs. Technical Specification 4.10.1.B requires that this testing be performed

. . . after each partial or complete replacement of the HEPA.

. . or charcoal adsorber bank. . ."

Question 3.a: Verify that the detectors are capable of detecting a chlorine concentration of 5 ppm per Po:ition C.4.d(1) of Regulatory Guide 1.95.

Response 3.a: The chlorine detectors are tested (I.044) and are scheduled by Preventive Maintenance (PM) Task Number 06641 on a two week interval. This task checks the probe sensitivity for chlorine concentration by using an a;;proximataly 10 ppm standard ,

calibration gas (certifk content). This gas is used to calibrate instrument in in accordance with the vendor -

acceptance criterie ror probe sensitivity (Anacon Technical Manual).

Question 3.b: Freque1cy of the x bation.

Response 3.b: Calibration of the chlorine analyzer is performed using procedurc I.045 on a six month interval (PM Task Numbers 07439

& 07440). This procedure checks the alarm setpoint of 1 ppm.

Question 3.c: Verify that routine operational checks are conducted at one l

week intervals per Position c.4.d(6) and R.G. 1.95 or justification for any deviation.

Response 3.c: Proposed Amendment No. 164. Revision 0, Supplement 2 (dated 11/25/87) updates Technical Specification Table 4.1-1 to include a weekly check of the chlorine detectors. (Currently under staff review.)

Question 3.d: It is not evident that either procedure I.044 or I.045 verifles that this response time is being met for the detectors.

Provide justification for this apparent deviation.

Response 3.d: The CR/TSC response time will be checked every refueling interval using SPs 485A & B. This procedure will he revised and rerun prior to criticality to provide assurance that the CR/TSC (Trains A & B) HVAC alli isolate in sufficient time to meet the habitability requirements.

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Question 4: Provide additional information 16 synport the apparcnt l deviation from R.G. 1,95 Position 4.b.(3) that a control room exit leading directly tc the outside of the building should have two interucking iow-leakage acMs in series.

5 Response 4: Regulatory Guide 1.95 indicates that steps sbcald be uken te ensure that the isolated exchange rate is n5t inadvertently increased oy design or operating error.

Doeratina Error To assure that the leak tightness configuration of the Control Room is not jeopardized by inadvertent oper.ing of the door in the shift supervisor's office, the door is classified as A controlled door leading to a vita 1 area. As such, it is equipped with an immediate alarm that alerts Security whin the door is openeo Administrative controls require that approval be obtained from Security prior to opening the door. In addition, the door is clearly marked indicating security must be contacted prior to opening the door.

Desian -

The condition of the airtight seals on all eav61 ope doors are inspected as part of existing Maintenance Procedures and  :

repaired as necessary. In addition, the leak tightness of  :

this dcor will be tested during the performance of the periodic pressure test of the CR/TSC envelope.  ;

The District considers that adequate steps have been taken in the design and operational considerations to assure integrity of the CR/TSC envelope.

Question 5: Describe the measured parameters and how they provide assurances that the sealant is performing the function to adequately limit air inleakage. Otherwise, provide means for verifying over the life of the plant the inleakage rates assumed to the dose calculations, e.g., periodic testing of the function of the sealant.

Response 5: The silicone sealant will be examined for degradation on a refpeling interval, e.g., visual indication of separation from the surface of the metal and leaks (dirt streaking or accumulation). Any degraded silicone observed during inspection will be removed and replaced. This provides assurance that laboratory testing is not solely relied upon to show the adequacy of the sealant. In addition, the periodic testing of the system will also provide indication of the leak tightnest of the sealant.  :

Question 6: Provide a description (including results) of evaluations, analyses, measurements, changes, craining, revisi6ns, verifications, corrections, tests performed or planneo (provide ,

schedule) to resolve each of the related licensee-identified problems and concerns. Justify these cases where you do not plan resolution prior to restart.

R:sponse 6: The c"tstanding issues on the CR/TSC HVAC have been incorprated into and are being tracked by the Restart Scope List /Long Range Scopa List (RSL/LRSL) process. Currently there are 66 items in RSL/LRSL pertaining to the CR/TSC system. These include the System Status Report problems, Expanded Augmented Systems Review and Test Nogram issues and other issues bown to exist, Of the 66 items on CR/TSC, 52 have been closed, seven are long range (post restart), and seven are being worked prior to restart. The items to be completed prior to restart are:

• Effects on carbon filter of the diesel exhaust.

• Effects on the CR/TSC habitability from the diesel exhaust.

• Procedure for calibratior af the CPJTSC essential filtration unit. Flow transmission will be instituted.

e Insolate - Hot Gas bypass, suction return, condenser &

compressor lines and oil separator vessel.

• Tert CR/TSC essential dead bus transfers and correct any flaws.

• Hrtte maintenance procedures for several non-routine refrigeration system maintenance tasks.

• Perform a study to determine the need for starting both essential trains upon safety features inittation.

This listing has been provided to the NRC along with the

, justification process for long range items. Monthly status

! reports are provided to the NRC (Region V).

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. Question 7: Provide assurance that there will be no unfiltered inleakage,

! while operating in any emergency mode, through the return ducts around the essential filtration units. Describe the safety l significance of establishing steady flow through the essential I filtration unit prior to opening the outside air intake dampers after receipt of a radiological emergency signal. Provide assurance tnat this sequence will occur in radiolojical omergencies.

Response 7: The amount of unfiltered inleakage has been calculated for each train under both the toxic and radiation modes of operation. The results are as follows:

l 1. Infiltration duiing radiological mode l Train A 90.7 cfm l Train B 85.6 cfm and

2. Infiltration during toxic mode Train A 100 cfm Train B 101 cfm Infiltration values of 100 cfm during radiological mode and 110 cfm during toxic mode have been used in the habitability calculations. These values are higher th?n the calculated inleakage values and provide assurance of the control room habitability.

In the case of failure of the booster fan or if the fan takes slightly longer to pick up speed with respect to the main air handling unit fan, there is a possibility of admitting unfiltered high radiation air through the return duct around the filtration unit if the outside air intake damper was to open imediat91y. This logic will prevent the bypassing of unfiltered air until enough negative pressure has been developed by the booster fan to induce return air. This sequence is assured by periodic calibration of the associated instrumentation (IO38L).

Question 8: Provide assurance that filter by-pass and other potential air flow through drains will not adversely affect operation of the control room habitability system.

Respor.3e 8: Surveillance Procedures 618A & B and 84A & B provide assurance, via periodic testing, that bypass flow (e.g.,

filters and drains) will not adversely impact CR/TSC habitability.

Question 9: Provide assurance that the reliance on the installed "semi-remote" chlorine detectors and the absence of ammonia detectors is in compliance with SRP 6.4 and meets the intent of RGs 1.78 and 1.95, considering:

(a) shipments of chlorine and ammonia to the site, (b) meteorological conditions, including uullding Ake effects, th:t would transport released chlorine or ammonia to the control room but not be detected in time to adequately protect the control room operators, (c) potential improvements to safety afforded by reliance on chlorine detectors and annonia detectors located at the points of potential release and administrative controls during deliveries of these materials to the site, (d) exhausts from operation of the emergency diesels.

Response 9.a: Regulatory Guide 1.78 requires that shiprents of toxic chenicals stored or frequently transported near nuclear power plants be considered in the control room habitability evaluation if the quantities exceed those given in Table C-2 of Regulatory Guide 1.78. Shipments are considered "frequent" for truck traffic if the number of shipments is greater than or equal to 10 per year (Regulatory Position C.2 of Regulatory Guide 1.78).

In addition, NUREG/CR-2650 evaluated the appropriateness of the 10 per year frequency criterion specified in Regulatory Guide 1.78 and concluded that this annual frequency was overly conservative and that an even larger number of shipments poses a neg'igible risk.

Shipment of 1-ton C12 cylinders to Rancho Seco could occur as many as six times per year, typically involving the delipery of only a single 1-ton cylinder per shipment. Review of the ammonia shipments made to the site revealed that only one 4,000 gallon shipment is made per year.

For the above reasons, it is the District's position that a chlorine or amrrania release from a truck bringing these cylinders to the site poses a negligible risk and does nct require consideration as a design basis event.

Response 9.b: Calculations brie shown that the current semi-remote placement of the chlorine detectors would afford the control room operators with sufficient time to don self-contained breathing apparatus prior to the control room chlorine concentration reaching the toxicity limit for this postulated event.

Placement of the detectors at their present location provides the control room operators with additional time between detection and the arrival of the toxic cloud at the control room outside air intake, to take protective action.

A long term chronic release of chlorine from a postulated broken valve on a 1-ton chlorine cylinder at the chlorine storage building has also been analyzed. This conservative evaluation ojo not take credit for the existing semi-remote detectors nor for isolation of the control room by either automatic or manual mons. The analysis showed that for this long term chronic release scenario, the operators would have sufficient time between odor detection and incapacitation t0 don self-contained breathing apparatus. (By the criteria of Regulatory Position C.7 of Regulatory Guide 1.78, odor detec-tion qualifies as an acceptable form of local detection.)

Additionally, the calcblation determined chlorine concentra-tions whi d would be seen at the semi-remote detectors due to either a catastrophic release or a long term chronic release, assuming unobstructed flow between the release point and chlorine detectors. It was determined that even if the toxic cloud concentrations were diluted by a factor of 300 for the chronic release, or by a factor of 390,000 for a catastrophic release, the detectors would still be able to detect the presence of chlorine and thus provide warning to the control

- room operators of the approach of a chlorine cloud as well as initiate automatic control room isolation.

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District-evaluations show that the current placement of seQi-remote chlorine detectors provides adequate time for the control room operators to take protective action and hence is in compliance with the intent of Regulatory Guides 1.78 and 1.95 as well as the objectives of Standard Review Plan Sectior 6.4 as described above.

The effect of a postulated catastrophic rupture of a 12,000-gallon cylinder of 28't, ammonia located at the chemical storage area has been evaluated. This conservative evaluation did not take credit for the isolation of the control room by manual means. The analysis showed that for this scenario, including wake effects, the operators would have more than two minutes between odor detection and the time at which the toxicity limit is exceeded to don self-contained breathing apparatuses.

In conclusion, the evaluation indicates that odor detection should provide sufficient time to take protective action, hence ammonia detectors either in the outside air intakes or remotely placed at the ammoni& storaga area are not required.

Response 9.c: Since a chic,rine-contaminated cloud would have an additional increment of distance to travel between remote detectors located at the chlorine storage building and the control room outside air intake, the potential improvemt .t to safety afforded by reliance on remote detectors ,culd be the additional increment of time between detection and arrival of the cloud. As discussed in the Response to 9.b, the present ,

semi-remote locations of the chlorine detectors will provide adequate time for the control room operators to take protective dCtion and therefore afford a level of protection in compliance with Regulatory Guides 1.78 and 1.95, as well as SRP Section 6.4.

t Concerning administotive controls which might be invoked during deliveries of 1-ton chlorine cylinders to the site, no ,

such controls are considered to be necessary or to have the potential to significantly reduce the risk of incapacitating the control room operators on the basis of the extremely low likelihood that a spill would occur anywhere othar than the chlorine storage area (Refer to the Response to Question 9.a).

Response 9.d: The District has performed a preliminary evaluation of the diesel exhaust impact on the CR/TSC Essential HVAC charcoal and CR/TSC habitability. This study included a test of the atmospheric dispersion from the diesel exhaust to various areas around the plant site. From this test, X/0 values were developed for the intake, both normal and essential, to the CR/TSC HVAC systems.

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The prelicinary results indicate that during the period of diesel operation with proper wind conditions (i.e., impact on the HVAC intakes) N detrimental impact was found. Degradation of the charcoal will occur over an extended period of time (i.e., greater than 7 days); however, for the period that the diesels would be expected to operate, no detrimental impact is expected to occur. With respect to the CR/TSC habitability the primary constituents of the diesel exhaust (i.e., S0 and N0x) were evaluated. In the S0x case the TLV level of 2 ppm would not be reached at either the normal or essential HVAC intake. The NOx TLV concentration (3 ppm) will not be exceeded at the normal CR/TSC intake. For the essential intake the N0x concentration may exceed the TLV value at the intake but would not be expected to exceed 10 ppm. Reviews of available information indicates that N0x concentrations less than 10 ppm will have no deleterious effects on the control room operators.

Based on finalization of these evaluations the District considers the impact on the CR/TSC envelope from the diesel exhaust to be acceptable.

Question 10: Provide justification for the deviation from the RG 1.78 regarding provision of readout of the toxic gas monitors in the control room.

Response 10: When the chlorine concentrations at the detectors exceed the detector setpoint of 1 ppm by volume, an audible alarm sounds in the control room and a computer screen indicates high chlorine as the cause of the alarm. Additionally, a light in the control room will turn red indicating high chlorine at the detectors. This is comparable to what is currently provided for control rooms at other nuclear plants.

Chlorine detection at Rancho Seco is either by the semi-remote chlorine detectors or local (in the control room) odor detection. Control room personnel are trained to immediately begin donning breathing apparatus and to complete this action within two minutes upon odor detection of chlorine within the control room or toxic gas auto isolation of the CR/TSC HVAC.

The semi-remote detectors have a detection range of 1 to 10 ppm; hence a detailed readout in the control room would also be limited to this range and concentrations exceeding 10 or a would simply cause the display to go c'f-scale. Due to ' e existing procedures as well as the chlorine detector range limitations, it is felt that chlorine detector readout in the control room would r:3 improve the ability of control room operators to take protective action given a chlorine release.

Current safeguards in the control room are in compliance with the intent of Regulatory Guide 1.78.

It should be noted that Casualty Procedure 46C (Chlorine Release) requires the control room to contact Chemistry for sampling of the CR/TSC environment prior to declaring the envelope habitable. Thus, sampling of the air in the CR/TSC envelope will be taken prior to removal of breathing apparatus.

Question 11: Regarding RG 1.52, provide justification for the discrepancy between the charcoal efficiency used in the dose calctlations, and the laboratory testing acceptance criteria used.

Response 11: The CR/TSC essential filtration units remove particulate, organic, and elemental iodine species. The iodine removal efficiencies of these filtration units are addressed below.

Particulate Iodine Removal Efficiency Per Technical Specification 4.10.1, the HEPA filter is to be tested to ensure a removal efficiency of greater than or equal to 99.9 percent. The basis for this Technical Specification is so that a Decontamination Factor (DF) of 100 may be used in the CR/TSC radiation dose analyses. This DF corresponds to a HEPA filter efficiency of 99 percent.

Testing has assured compliance with the Technical Specification requirement. Standard ORNL-NSIC-65 Certificates of Compliance verify that the HEPA filter efficiency requirement of greater than 99.9 percent is achieved. This validates the use of a particulate iodine removal efficiency of 99 percent in the dose calculation.

Oraanic Iodine Removal Efficiency Per Technical Specification 4.10.1, the charcoal filter absorbers are to be tested to ensure that one absorber will have a removal efficiency of greater than or equal to 95 percent of radioactive methyl iodide, and that two absorbers in series will remove at least 99.5 percent. The basis for this Technical Specification is so that a Decontamination Factor (DF) of 10 for one charcoal filter absorber may be used in the CR/TSC radiation dose analyses. Two absorbers in series will therefore have an overall DF of 100. This DF corresponds to an overall organic iodine charcoal filter removal efficiency of 99 percent.

Independent Laboratory testing at charcoal bed temperatures ranging from 77,0'F to 260.0*F and at a relative humidity of 95.0 percent has assured compliance with the Technical Specification requirement. A statistical analysis of the Independent Laboratory testina 'ts indicates with 95 percent confidence that 99.9 ps ,at of all filter testing of a 2-inch absorber bed will verify an organic iodine removal efficiency of at least 97.7 percent. Two absorber beds in series should remove at least 99.95 percent cf the organic iodine passed through them. This validates the use of an organic iodine removal efficiency of 99 percent in the dose calculation.

Elemental Iodine Removal Efficiency Technical Specification 4.10.1 does not require that the charcoal filter absorbers be tested for elemental iodine removal efficiency. Nevertheless, Independent Laboratory testing has been conducted at a charcoal bed temperature of 86.0*F and at a relative humidity of 95.0 percent. A statistical analysis of the Independent Laboratory testing results indicates with 55 percent confidence that 99.9 percent of all filter testing on a 2-inch absorber bed will verify an elemental iodine removal efficiency of at least 99.9 percent.

Two absorber beds in series should remove at least 99.99 percent of the elemental iodine passed through them. This validates the use of an elemental iodine rennval efficiency of 99 percent in the dose calculation.

Question 12: Provide an evaluation of all potential release points that have not been previously analyzed in conjunction with the operator dose calculations (e.g., radiation waste exhaust vent on the auxiliary building level).

Response 12: The CR/TSC dose calculation has specifically considered the following radiation sources:

• Containn ant leakage e Recirculation loop ESF leakage

• LOCA coincident with containment minipurge (including an RCS Iodine spike)

• Outside cloud direct shine e Reactor Building direct shine e Contaminated essential HVAC charc?al direct shine

• Hechanical containment penetrations direct shine

• Electrical containment penetrations direct shine

• Auxiliary Building contaminated piping and components direct shine Question 13: Provide an evaluation of accident doses to the operators involving all potential pathways other than from the outside through the auxiliary building louvered door.

Response 13: The results of this analysis show that the thirty day post-Accident control roon,and TSC dose meet the 30 Rei thyrold, 30 Rem Beta-skin, cnd 5 Rem whole body dose requirements of General Desig. Criterion 19. The 30 day doses are summarized in fable 1.

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TABLE 1 30-DAY CONTROL ROOM DOSES (REM) 30-0AY TSC DOSES (REH)

HHOLE HHOLE RADIATION SOURCE THYROID BETA SKIN BODY THYROID BETA SKIN BODY Containment leakage 1.76E+01 1.77E+01 7.40E-01 1.37E+01 1.69E+01 6.90E-01 Recirculation oop 2.23E+00 0.00 0.00 2.23E+01 0.00 0.00 ESF leakage LOCA coincident with 4.67E+00 2.00E-02 0.00 1.54E-00 1.00E-02 0.00 containment minipurge (including an RCS Iodine spike)

Outside cloud direct 0.00 0.00 2.25E+00 0.00 0.00 1.90E+00 shine Reactor building 0.00 0.00 4.50E-03 0.00 0.00 2.60E-03 shine Contaminated 0.00 0.00 1.95E-02 0.00 0.00 3.33E-01 essential HVAC charcoal direct shine Mechanical contain- 0.00 0.00 3.48E-03 0.00 0.00 2.03E+00 ment penetrations direct shine Electrical contain- 0.00 0.00 4.79E-04 0.00 0.00 7.60E-04 ment penetrations direct shine Auxiliary Building 0.00 0.00 0.00 0.00 0.00 0.00 contaminated piping and components direct shine TOTAL 30 DAY DOSE 24.48 17.69 3.01 17.42 16.95 4.95 L.

Question 14: Provide dose calculations to include the time during which both trains of the emergency filtration system would be running and the time required for flow stabilization after system initiation. Provide assurance that the system will be operated within the bounds of the dose calculations (i.e.,

limit times for both trains running and for flow stabilization).

Response 14: The CR/TSC HVAC model used in the dose calculation addresses the following HVAC flow conditions:

1. Normal HVAC flow conditions from the start of the accident, continuing until normal isolation occurs. Isolation occurs following the detection of high radiation at the outside air intake duct to the normal HVAC units.

2. Maximum air flow through both essential HVAC filtration units, continuing until flow stabilization has been -

achieved.

3. Stabilized air flow through both essential HVAC filtration units, continuing until control room operators isolate one of the two units.

4. Stabilize air flow through one essential HVAC filtration unit, continuing until the end of the 30 day post-Accident period.

The results to this evaluation and pathways considered have been provided in the Responses 12 and 13.

NOTE: The calculation assumes flow stabilization within 8 minutes (test results indicate 3-5 minutes) and isolation of one train of HVAC (OP C.51 requires the operators to isolate one train) within 15 minutes of receiving the radiation signal.

No specific time period is provided in the casualty procedure; however, 15 minutes is considered to be reasonable for an action which can be taken within the control room.

l Question 15: Provide additional information which confirms that control room operators are adequately trained regarding HVAC equipment potential failures (single failures, etc.) to be able to promptly identify failures and take the necessary corrective actions.

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Response 15: Reactor Operator Systens Training for the HVAC consists of tho 00 21I 6000 lesson plan entitled, "Plant Heating, Ventilation, and Air Conditioning System." This lesson is designed to provide a licensed operator candidate with a basic understand-ing of the system with specific emphasis on its function and purpose within the plant. The draft of the new vperating procedure is used for this training.

In addition, operator systems training has an on-shift study task on the CR HVAC system which covers the following:

• The purpose of the CR/TSC Essential HVAC system and exnlanation of how this purpose is accomplished.

• System arrangement and possible flow paths.

• Purpose and operation of controls and interlocks associated with the system.

• The associated Technical Specifications.

• The function of instrumentation both local and remote.

• The purpose of and operator action following system alarms.

• The purpose and operation of controls and interlocks.

• The major steps of the operating procedures with respect to normal operation, infrequent operation and casualty operations.

The Reactor Operator Requalification Program consists of the two complimentary lessons. 00 24C 0108 and OD 240 3300. These lessons are designated, "Essential HVAC System." The 00 240 3300 is a newly developed restart operator requalification lesson plan and compliments the 00 24C 0108 lesson which was for the original Cycle 7 Restart. These lesson plans include operation of the HVAC essential system

during a loss of off-site power with and without SFAS initiation of the HVAC essential system. The requalification l

i training program includes:

• Actuation Signals  :

• Hodes of Operation

• Essential System Stops and Isolation

• Operation Hith Loss of Offsite Power

• Test Switches l

• Control Switches i

0 The District has a training prograo that addresses HVAC essential system operation with the presence of a single failure. <

Question 16: Provide additional information to demonstrate adequate detailed operator training in use of the self-contained breathing apparatus in the control room.

Response 16: General Employee Training series, ST OlC 0300, "Resoiratory Protection," covers using self-contained breathing apparatus to reduce exposure to airborne radioactivity. The priinary objectives of the training series are:

• To know the limitation concerning the wearing of the SCBA units.

• To know the locations for both SCBA units and air compressors.

• To be able to demonstrate the proper steps for inspecting, donning and removal of the SCBA units.

The training includes practical exercises of inspection, donning and removal of SCBA units which are repeated in a drill type manner until the trainee feels confident to be able to don I and use the equipment.

The use of SCBA equipment is also covered in the Fire Protection /First Aid Training Series, FP 01A 0100 and FP 01Z 0000. Both classroom and practical sessions are used with the Reactor Operator Requalification Program.

This training is considered adequate to assure the operators will be able to raspond quickly to the need for donning of breathing apparatus, i Question 17: Provide justification for the significant reliance on the non-safety related IDADS computer system for HVAC equipment status information.

Response 17: The District response to this concern is in two parts:

1) The appropriateness of operator training for use of 10 ADS.

2) A software improvement to the IDADS parameter display.

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Reactor Operator Syste;s Training for the IDADS is covered by the classroom lesson plan, 00 21I 6700. In addition, the licensed operator candidate has on-shift training consisting of the following:

• How the parameter values are obtained by IDADS.

• Describe the major components of the computer system.

• Describe the functions provided to the control room by the IDADS.

• Know the alarm group indications, the point alarm indications, and the quality status indications.

The Reactor Operator Requalification Program incorporates a lesson plan, 00 24C 0106 which covers the operation and use of the IDADS. The HVAC system is included in the plant systems covered.

This training is complimented by class instruction on the loss of IDADS. This is intended to familiarize the operators with the purpose, basis, and sequencing of steps in the associated operating procedure (OP.C.39). The emphasis of this trsining is to explain how the system could be recovered or other parameters that should be monitored until IDADS is recovered.

The failure modes of the system will be discussed.

In addition, the requalification lectures for the HVAC essential system also includes the use of IDADS.

A software change has been implemented that will result in a much quicker parameter display time.

The District's extensive operator training and the software change that will he implemented prior to startup are considered adequate to addre,s this concern. (Note: Indication available on the status of the CR/TSC Essential HVAC can be found in Figure 9.7-2, Sheet 3 of the Rancho Seco USAR.)

Question 18: Provide additional information which justifies that the IDADS computer's flow response time in displaying changing HVAC system flow rates will not impact the ability to operate the system properly.

Response 18: The observed delay of approximately 16 minutes resulted from IDADS reading the flow data point as invalid (i.e., bad). The IDADS system requires 16 scans at 1 minute intervals before data is considered valid.

Software changes are now in place so the data will not be judged bad (by IDADS) until a -160 CFM limit is reached. The system, after this software change, only requires one scan of good data to display valid flow display. The new display will allow a very low flow value at all times rather than the old method of displaying a bad data flag of red question mark;

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Question 19: Provide additional information to explain the staff's observation of flow measurement readout in the IDADS output when the particular train of the system was considered shutdown and inoperable.

Response 19: IDADS may show very low flow when the unit is shutdown. The digital nature of signal processing in IDADS is the reason for such a display. The 0-5" range transmitter has a .257. full scale ability. This translates to 0.0125" H2O or approximately i 100 to i 150 CFM of flow. The display can therefore show up to 1 150 CFM on the digital display anytime the unit is off. Thus, any value about 0 CFM shows the unit to be shutdown. (Note: The Technical Specification operational limit is 3200 CFM 300 CFM.)

Question 20: Provide additional information that justifies that the control room boundary doors will be properly maintained closed in order to ensure control room integrity durinc emergencies.

Specifically consider maintenance of seals and provisions of administrative controls to ensure closure.

Response 20: The control room access doors and the TSC personnel doors have self-closing devices to shut the doors automatically and the doors are equipped with separate card readers. Also training is provided to individuals with access to card controlled areas to verify proper closure of doors upon entry / exit.

The access doors to the corridor between the control room and the 1SC are equipped with self-closing devices. The doors are instrumented for fire protection security alert and administrative controls over the doors are in effect.

Condition of the airtight seals on the access doors are inspected as part of existing Maintenance Procedures and repaired as necessary.

It is our position that the isolation doors are adequately equipped and maintained to sufficiently address the NRC concern.

Question 21: Provide additional information that confirms that current surveillance procedures adequately provide for the surveillance of hardcast tape installations or provide specific identification of hardcast tape installation locations along with the procedure.

Response 21: Routine test RT-HVS-011 has been revised to specifically indicate the hardcast tape locations and their surveillance.

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Question 22: In addition, the staff will request that the syste: be operated and maintenance / surveillance testing be conducted in accordance with approved station procedures and observed by the staff.

Response 22: It is our intention to run SPs 84 and 485 (Train A attached) during the site visit. Review of chese procedures indicate they will fulfill the staff's request for observation of system operation.

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