ML20214P560

Forwards 861027-31 Site Visit Summary Rept Re Generic Issue 83 on Control Room Habitability

ML20214P560
Person / Time
Site:	Fort Calhoun
Issue date:	12/15/1986
From:	Driscoll J ARGONNE NATIONAL LABORATORY
To:	Hayes J Office of Nuclear Reactor Regulation
Shared Package
ML20214P511	List: ML20214P507 ML20214P560
References
CON-FIN-A-2328, REF-GTECI-083, REF-GTECI-NI, TASK-083, TASK-83, TASK-OR NUDOCS 8706030435
Download: ML20214P560 (14)

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- ENCLOSURE US Dgwen d Ew ARCONNE NATIONAL LABORATORY Tcicpbc 208/526 7657 ARCONNE-WEST PO Box 2528 Idaho Falls. idaho 834 03-2528 December 15, 1986 U.S. Nuclear Regulatory Comission Nuclear Reactor Regulatory DSI/RP I4 ail Stop 416 Washington, DC 20555 Attention: J. Hayes

Subject:

Generic Studies Related to Generic Issue 83 on Control Room Habitability Fin A-2328 Gentlemen:

Enclosed is the Plant Visit Sumary Report for the visit to the fort Calhoun Nuclear Station on October 27-31, 1986. If you have any questiens concerning this report, contact me at (FTS 583-7657).

Very truly yours, V

John W. Driscoll Argonne Project Manager JWD:jt cc: D. W. Cissel, EBR-II R. Dalton. DOE-CH M. J. Lineberry, SSP 0 R. N. Smith, EBR-II pg 6988s BE 88 es p PDR Tk UMestrvdasxo

- Fort Calhoun Nuclear Station Page 1 PLANT VISIT SUM M RY REPORT

1. Plant: Fort Calhoun Nuclear Station

2. Utility: Omaha Public Power District

3. Location: Blair, Nebraska

4. NRC Region: IV

5. Visit Date: October 27-31, 1986

6. Participants from Argonne National Laboratory: J. W. Driscoll R. A. Evans

7. Scope The plant visit was made to gather information on control room habitability - Generic Issue 83. As a part of the review, the '

Plant Technical Specifications were reviewed and compared to the safety analysis (including 111.D.3.4. submittal and the NRC staff safety evaluation) and plant procedures to detemine what opera-tional practices are being employed. System airflow measurements were made to detemine the unfiltered air inleakage into the con-l trol room envelope and system performance.

8. System Description

The Fort Calhoun Station is a single-unit station. The control room can be accessed through two security doors which open into a common corridor. A third door also opens into the corridor from the computer room, but is used as an emergency exit only. The corridor opens to the turbine building and to an elevator shaft which connects to the turbine building. There is also an observa-l tion room in the north east corner of the control room which has a window with a pass through opening for passing paper work from the i

e - , - , - - , , , , - - - - - - - - - , ,--,---. - - , - , , - - - -, nn-,-

, , Fcrt Calhoun Nuclear Station Page 2 control rcos to the observation room. The observation room con-nects to the turbine building. I The control room envelope consists of the control room, computer room, toilet, Shift Supervisor's of fice, observation room, and control room corridor. The HVAC equipment for the control room envelope is located in the turbine building.

The HVAC system includes redundant air handling units (AHU) equipped with component cooling water coils for cooling. Electri-cal heating coils are located incide of each AHU. The AHU's have an outside air makeup supply to ;,; ovide the necessary fresh air makeup. The AHU circulates and conditions air to the control room during all modes of system operation. The recircui tion flow from the control room to the AHUS can be exhausted to the outside or returned.

The pressurization / cleanup filter train consists of a single filter unit with a HEPA filter and charcoal adsorber. There is one fan associated with the filter train. The filter train has an outside ,

air intake and discharges to the suction of the AHUs. There is no provision for recirculation flow through the emergency filter train.

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- The inaakes for the control room HVAC system are at the same eleva-tion as the diesel exhausts and on the day of the visit, wind was j blowing across the diesel exhaust towards the HVAC intakes.

9. Findings 9.1 Procedure 9.1.1 Several procedures need to be clarified so that there is no doubt as to how systems are operated, i.e., it is not clear in procedures 01-VA-3 that fan VA-49 is automatically isolated during a radiological challenge. Step IV.A.3 indicates

v -

, Fort Calhoun Nuclear Station Page 3 that the fan is shutdown and isolated but step IV.A.4 indicates that the f an is independently operated. The discussion with plant personnel indicated that the steps are not related and that revision to procedure '01-VA-3 is being made to clarify VA-49 operation.

9.1.2 EP-31, " Loss of Control Room Air Conditioning,"

does not adequately address actions to be taken on high temperature in control room. The proce-dures outlines steps to be taken at 120*F. The 120*F is not a realis  : temperature for actions to begin. A new proci are AOP 13 has replaced EP-31. There was some uncertainty as to whether

. A0P-13 covers high temperature conditior.s during recirculation mode of operation.

9.1.3 Procedure ST-CRV-1, " Control Room Ventilation "

does not include provisions to monitor control room dP to all adjacent areas. The sensing .

i lines to perform these measurements should be installed.

i l

9.1.4 The control room positive pressure test is only l

performed after new HEPA filters and charcoal adsorbers have been installed (Step F-3.a.1).

By testing in this mode only. OPPD would never be aware that the control room positive pres-sure could not be maintained.

9.1.5 Rm-065 was installed to monitor iodine intake into the control room. 01-VA-03 says: the unit is only operated in the event of a DBA.

The reason given for not continuously operating l

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_ _ _ , . . - , . . , _ , - . . . . , _ _ , _ _ _ _ , _ . , _ . , , _ , , . _ ___m._.v m,,_.-,,,_y,,,,_ . _ , _ .__,_r _y, ..m.--,_- , , - - , ~

fort Calhoun Nuclear Station Page 4 Rm-065 was high noise level of Rm-065 is irri-tating to control room operation. OPPD should evaluate the need for this unit to be operated continuously. There is no way of knowing if the unit will function when it is only used during a DBA.

i 9.1.6 Procedure CP-6286A-M and CP-62868-M deal with calibrating hydrogen chloride monitors Cali-bration cards are used in these procedures.

The procedures call for dif 6.ent desired reading. In fact, the rrosings are different because different calibration cards are used.

OPPD personnel indicated that the cards could be interchanged and used on different detec-tors. The procedures should be revised to indicate desired reading based on which cali-bration card is used. 'The calibration proce-dures could be condensed to one p ocedure for both units. .

9.1.7 Procedures need to be updated in a timely manner. The calibration procedures for toxic gas monitors calls for installation of jumpers where override switches are now installed. The procedures should be replaced as modifications are installed not at some later date.

9.2 Safety Analysis 9.2.1 The control room HVAC equiprent is exposed to main steam and feedwater lines. Failure of these lines could cause steam intrusion into the control room through HVAC equipment (AHU housing and ductwork) failure.

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fcrt Calhoun Nuclear Station

. Page 5 9.2.2 OPPD used zero (0) infiltration in the calcula-tions for radiation exposure to control room operations following a design base accident.

SRP 6.4 recommends a value of 10 cfm infiltra-tion be used for ingress-egress. Leakage through dampers, ductwork, and fan housings and leakage past door seals should also be incorporated into the safety analysis.

9.2.3 The safety analysis assumed the control room envelope would be pressurized to 1/8-in. W.G.

in the pressurization mode of operation. In our observation the control room was only slightly positive 0.02 in. H O2 and was negative at some points that were monitored. See Table 1.

9.2.4 OPPD has used 100,000 3ft as the volume of the control room envelope. This includes the stair hall which we were told was not part of the envelope. The volume of air was not reduced for equipment. A more conservative volume should be used for dose calculations since' free volume it less than 100,000 ft 3. Due to the smaller veoame, the envelope will reach an equilibrium concentration at a faster rate.

9.2.5 Containment charcoal filters art assumed to remove 90% of the radiocode, while Technical Specifications only requires the filters to be tested to 85%.

9.2.6 OPPD has a standing order to review chemicals for onsite toxic gas hazards on a periodic basis. OPPD should establish a procedure for

Fcrt Calhoun Nuclear Station Page 6 periodic review of toxic chemicals offsite within a five mile radius.

9.2.7 The charcoal adsorber f an (FAN VA-63) and isolation dampers, PVC'-860A, PCV-860C, PCV-846, and VA-84 are subject to single f ailure. In the event of a single failure in any of the above active equipment, the control room opera-tors would not be adequately protected from radiation exposure during a design base acci-dent.

9.2.8 It appears that safety analysis assumes 95%

efficiency for rethyl iodine in the control room HVAC system adsorber. The Technical Specifications require the adsorbers to be tested at 90% efficiency. The charcoal t adsorber should be tested at 98.6% ef ficiency.

t 9.3 Technical Specifications .

9.3.1 Technical Specifications should be written so as not to be redundant, i.e., Technical Spect-fication for laboratory testing of charcoal for initial batch tests and refueling tests should contain the same requirements. These two specifications could be written as one specifi-cation (see Table 3-5, items 10a.2.a and 10a.2.b).

i 9.3.2 Technical Specification Table 3-5, item 10a.3.c should include the fan flow rate.

9.3.3 Technical Specification Table 3-5, item 10a.4

~

should include the signals that initiate auto-matic initiation of the control room emergency W

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r- ,m. , -,. n,-e.-,., - - .a ,-, ,-,,.. r - ,-

- FSrt Calhoun Nuclear Station Page 7 filter train. Surveillance tests should be performed to verify actuation.

9.3.4 Technical Specification Table 3-5, item 10a-3a should be revised to operate for one hour each month to prove operability. The equipment to be operated should be spelled out.

9.3.5 Technical Specification Table 3-3, item 29 should include toxic gas monitor se,t points.

9.3.6 Technical Specification 2.12 should be revised to reflect actual control room temperatures that would prevent instrument qualification temperatures from being exceeded.

9.3.7 Technical Specification 2.12 should be revised to allow plant operation for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following loss of the CR emergency filter fan.

9.3.8 Technical Specification Table 3.3, item 10 should be revised to include a pressurization limit. Based upon the III.D.3.4 evaluation the limit should be 1/8 in. W.G.

9.3.9 Technical Specification Table 3.5, item 10a should be revised to test charcoal in accor-dance with ASTM D 3803 test method at a flow velocity within i 4% of the control room venti-lation system. Test conditions should be 30*C with a relative humidity of 95%. Acceptance criteria should be 1.4% penetrations (98.6%

ef ficiency).

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Fcrt Calhoun Nuclear Station Page 8 9.3.10 The test requirements for charcoal adsorbers should be in agreement with the safety analysis.

9.4 HVAC Flow and Temperature Data 9.4.1 Temperature Data Air temperature was measured in the control room with the plant operating near full power. Temperature dc.3 was taken with the control room HVAC system operating in the normal, filtered air makeup, And internal recirculation modes of operation. Data was taken over a two (2) day period with similar outside temperatures and humidity conditions during the period.

Temperature Data (Average Temperatures)

Filtered Normal Makeup Recirculation VA-46A VA-468 VA-46A VA-468 VA-46A VA-468 Occupied Area No Data 74.1*F 75.5*F 74.3*F 76.5'F 73.8'F of Control Room Back of Main No Data 73.5'F 74.3*F 73.4*F 75.1*F 74.6*F Control Panels Back of Panels No Data -0.6*F -1.2*F -0.9'F -1.4*F +0.8'F i to Front of Panel Differential High to Low No Data 1.8'F 4.3*F 2.6*F 6.1*F 3.0*F Point Differentici 1

- , , - - - - - - - .---.--,_.. ,,,- ----,-.----n .-, , - ~ - - - - - - - - - - .

- - ,- - - . e , - - -

fort Calhoun Nuclear Station Page 9 The temperature distribution in the fort Calhoun control room is very good ar4 is the first plant observed where the temperature in the vicinity of back panels has been lower than the occupied area of the control room.

9.4.2 Flow Measurement flow measurements were taken with the control room HVAC system operating in three mods of operation and six configurations due to redun-dant air handling units. Differential pressure date was also taken across four (4) control room boundaries. Table I conttins the differ-ential pressure data, Table !! contains the average flow at each data point, and Table !!!

is a summary of the flow data.

It is concluded from the flow data that due to significant backflow through idle air handling units, and due to excessive leakage from the -

air handling units to the auxiliary building in the vicinity of the AHUs. The control room cannot be pressurized to 1/8 in. W.G. as assumed in the !!!.0.3.4 submittal. During all modes of operation there was never a positive pressure indicated on the installed manometer in the fort Calhoun control room. This con-stitutes a violation of Technical Specification Table 3.3 item 10.

9.5 Outside Air Infi) ion In the control room operator exposure calculation OPPD assumed that the unfiltered inleakage term is zero (0).

Standard review plan 6.4 suggests that 10 cfm be used in

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TABLE I FORT CALHOUN NUCLEAR STATION O!FFERENTIAL PRESSURE DATA l OATA SET; CONTROL ROOM l CONTROL ROOM l OBSERVATION l CONTROL ROOM l l UNIT & l CORR 100R TO l CORRIDOR TO l ROOM TO l'TO OUTSIDE  !

l TURBINE BLOG. l ELEVATOR 000R l TURBINE BLOG. l ATMOSPHERE l l MODE

!  !  !  ! l l

l l l l l l

l l l l1 l l l VA-46A l -0.04  ; 0.00 l NO DATA l -0.06 l l l l l l NORMAL l '

l  !  !

l l l l l l l l l l l l l l2 l l

-0.07 l VA-46B l -0.04 l 0.00 l -0.03 l l l l l l l NORMAL l l- l l l l l

!  !  ! l l

l l l3 l l l

-0.01 +0.015 l +0.015 l 0.00 l l VA-46B l l l l l l FILTERE0l l l l l l l MAKEUP l l l  ! l l l

!  !  !  ! l l

l l l l

, l l '

l l l4 l l l

-0.01 l VA-46A l -0.005 l +0.01 l +0.02 l l l l l l FILTERE0l l l l l l l MAKEUP l l l  !  !

l l

!  !  !  ! l l 1 l l l l l5 l l

-0.035 l VA-46A l -0.055 l +0.005 l +0.015 l l l l l l RECIRC. l l l l  !  !

l l

!  !  !  ! l l l l l l l l l l l6 l l

-0.02 l VA-468 l -0.05 l 0.00 l -0.015 l l l  ! l l RECIRC. l l .

l l l  !

l l

"~ - - =- - -.__.,-y -

TABLE !!

FORT CALHOUN NUCLEAR STATION CONTROL ROOM HVAC SYSTEM FLOW DATA l Pol %T: LOCATION  : DATA : DATA : DATA l OATA : DATA : DATA :

l e l l SET l SET l SET l SET l SET l SET l l  !  ! 1  ! 2  ! 3  ! 4  ! 5  ! 6 l l l l i  :. l l l1A l'FRESHAIRINLETTOVA-46A l 794 l 671 l 34J l 1128 l 1122 l 44 l l  !  ! ~!  !  !  !  ! l l 18 l'FRESHAIRINLETTOVA-463 l 1040 l 809 l 1832 l 1084 l 365 l 1480 l l  !  !  !  !  !  !  ! l l l l l l l l  :  :

l 2A l SHIFT SUPERVISORS OFFICE SUPPLY l 670 l 716 l 760 l 790 l 690 l 749 l

!  !  !  !  !  !  !  ! l l l l l l l  : l l 28 l ZONE 2 TOTAL SUPPLY l 7782 l 8022 l 8009 l 8091 l 8374 l 7634 l l  !  !  !  !  !  !  ! l l l l  :  :  ; l l l

l 2C l ZONE 3 TOTAL SUPPLY (COMP.) l 2469 l 2737 l 2662 l 2513 l 2644 l 2789 l l  !  !  !  !  !  !  ! l l l l l l l l l l l3 l CONTROL ROOM EXHAUST / RETURN AIR DUCT l11497 l11208 l11707 l11418 l11556 l12484 l l  !  !  !  !  !  !  ! l l l  : l  ;  ; l-l l l4 l OAI DOWNSTREAM OF PCV-860C l 688 l 1423 l 1106 l 743 l 619 l 1425 l l  !  !  !  !  !  !  ! l l l l l l l l  : l l 5A l RECIRC AIR INLET TO VA-46A l13074 l-1326 l -962 l14667 l14170 l-1126 l l

;  ;

:  : l l 58 l RECIRC AIR INLET TO VA-468 l -387 l12792 l12240 l-1755 l-1039 l10693 l l  !  !  !  !  !  !  !' l l l l l l 1 l l l6 l TOILET EXHAUST l 153 l 129 l 1l 1l 9l 1l l  !  !  !  !  !  !  ! l l l l l l l l l l l7 l EXHAUST AIR UPSTREAM OF PCV-846 l 2304 l 2574 l 2465 l 2307 l 2335 l 2352 l l  !

;  ;  ;  ;  ; l l8 l FILTERED AIR SUPPLY 00WNSTREAM OF VA 63 l 30 l 46 l 1416 l 1334 l 27 l 91 l l  !  !  !  !  !  !  ! l l

: i  :  :  : ,

l 9A l VA-45A SUPPLY TO ZONE 1 l 1453 l -137 ! -116 l 1436 l 1345 l -104 l

!  !  !  !  !  !  ! l l

l t i  : l l l I l l 98 l VA-46A SUPPLY T0 ZONE 2 l 7689 l -636 l-1174 l12526 l 7543 l-1169 l l  !

i  : i i l l 9C l VA-468 SUPPLY TO ZONE 3 l 3174 l -166 l-1248 l 3201 l 3097 l -260 ;

!  !  !  !  !  !  ! l l

l l l l 1 i l l l l 10A : VA-468 SUPPLY TO ZONE 1 , l -187 l 996 ! 1407 l -168 l -193 l 1268 l

!  !  !  !  !  !  ! l l

i  : i i l l l

! i l -903 l 8110 !!4104 l-2067 l-2109 l13099 l j 108 l VA-468 $UPPLY TO ZONE 2 l l l l l l -!

l l l  ; l l l 1 l l l l

l 10c l VA-468 $UPPLY TO ZONE 3 l -414 l 3047 ! 1344 l -337 l -111 l 2974 l

!  !  !  !  !  !  ! l

TABLE !!!

FORT CALHOUN NUCLEAR STATION HVAC FLOW COMPARISONS l l4+8+5A+58 = 9A+98+9C; 4+8 = 1A + 18  ; 3 = 7 + SA +58 l 2A+28+2C = 9A+98+9C+

l l +10A+108+10C l l l 10A+108+10C = 3+6 l l OUTSIDE MAKEUP PLUSl FRESH AIR TO AHU'S l CONTROL ROOM RETURN' ZONE SUPPLIES =AHU E l l RECIRCULATION = l= OUTSIDE AIR SUPPLY l = EXHAUST + RETURN l = RETURN + TOILET EXH.

l~ AHU O!SCHARGE  : DIRECT & VIA FILTER l 70 AHU's  !

i' ; 688 1,453  ; 688 794 l 11,497 2,304 ; 670 1.453 11,497 l l 30 7,689 l 30 1,040 l 13.074 l 7,782 7,689 153 l l 13.074 3,174 l l -387 l 2.469 3,174 l l -387 -187 l l l -187 l -903  ! l l -903

-414

'T}ul$ 13,405 l = 10,812 l l

718 = 1.834 l

l 11,497 = 14,991 l -414 l 10,921 = 10,812 = 11,650 l% R  :  :

l2; 1,423 -137  ; 1,423 671 l 11,208 2,574 l 716 -137 11,208 l

46 -636 l 46 809 l -1,326 l 8,022 -636 129 l l -1,326 -166 l l 12,797 l 2,737 -166 -

l l 12,792 996 l l l 996 lg;; 8,110 l l 8,110

'e 3 3,047 l l 3,047 l

12,935 = 11,214 1,469 = 1,480 11,208 = 14,045 l 11.475 = 11,214 = 11,337 l4g l

l l

l39 1,106 -116 l 1,106 340 l 11,707 2,465 l 760 -116 11,707 l 3 1,416 -1,174 l 1,416 1,832 l -962 l 8,009 -1,174 1 l 2 -962 -1,248 l l 12.240 l 2,662 -1,248 l g 12,240 1,407 l l 1,407 l

lm 14,104 l l l 14,104 l* 5 1,344 l l l 1.344 l4 3; 13,800 = 14,317 l 2,522 = 2,172  ! 11,707 = 13,743 ! 11,431 = 14.317 = 11,708 l>v  !  !  !

!43 743 1,4 3 f, l 743 1,128 l 11,418 2,307 l 790 1,436 11.418

! 3 1,334 12.526 l 1,334 1,084 l 14,667 l 8,091 12,526 1 l g 14,667 3,201 l l -1,755 l 2,513 3.201 l g -1,755 -168 l l l -168 l, S -2,067 l l l -2,067

'e v -337 * '

-337 l

!l>W h 14,909 = 14,591 ,!

2,077 = 2,212 l 11.418 = 15.219 l 11,394 = 14,591 = 11.419 l5' 619 1,345 l 619 1,122 l 11,556 2,335 l 690 1,345 11,565 ,

l d 27 7,543 l 27 365 l 14,170 l 8,374 7,543 9 14,170 3,097 l  ! -1,039 l 2,644 3,097  ;

! ] -1,039 -193 -193 ld l

l*.h;

-2,109

-111 l

l l

l l

l -2,109 l

l l l -111 l l4 8 13,777 = 9,572 l 646 = 1,487 l 11,556 = 15,466 l 11,708 = 9,572 = 11,565 l

!>9  !  !  ! l l6; 1,425 -104 l 1,425 44 l 12,484 2,352 l 749 -104 12,484 l l 8 91 -1,169 l 91 1,480 l -1,126 l 7,634 -1,169 1l l 0 -1,126 -260 l l 10,693 l 2,789 -260 l l ,5 10,693 1,268 l l l 1,268 l i 3 13,099 l l l 13,099 l j e*, 3 2,974 l _

! l 2,974 l l4 11,083 = 15,808 l 1,516 = 1,524 12,484 = 11,919 l 11,172 = 15,808 = 12,485

l. .

- - - - . _ _ . _ , - _ _ _ , . . _ . _ - , . - - - _ .,m.-

k\

i fort Calhoun Nuclear Station Page 10 the unfiltered inleakage term to compensate for ingress-egress to the control room during the course of the accident. The 10 cfm is based on the contro'1 room being pressurized to 1/8 in. W.G. to the adjacent boundaries.

OPPD should also take into consideration leakage across isolated dampers and duct and f an housing inleakage. The duct work outside of the control room is a lock-seas type duct and will allow leakage into the duct in the areas where the duct is negative with respect to the surround-ing area. Seals should be installed on doors which penetrate the control room envelope boundary.

9.6 LER Evaluation There are no LERs. at Fort Calhoun, associated with the loss of cooling to the control room envelope. The AHU capacity seems to be more than adequate. However, the Technical Specification limit of 120*F for control room temperature needs further evaluation.

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