ML17324B226

Trip Rept of 860915-19 Site Visit Re Generic Issue 83 Concerning Control Room Habitability

ML17324B226
Person / Time
Site:	Cook
Issue date:	11/24/1986
From:	Driscoll J ARGONNE NATIONAL LABORATORY - ARGONNE WEST
To:	Hayes J Office of Nuclear Reactor Regulation
Shared Package
ML17324B225	List: ML17324B224 ML17324B226
References
CON-FIN-A-2328, REF-GTECI-083, REF-GTECI-NI, TASK-083, TASK-3.D.3.4, TASK-83, TASK-OR, TASK-TM NUDOCS 8702060376
Download: ML17324B226 (16)

Text

ARGONNE NATIONALLABORATORY ARCONNE WEST PO. Box 2528, Idaho Falls, Idaho 8Ã0$-2>28 TElEpho~E 208/526-7657 November 24, 1986 U.S. Nuclear Regulatory Commission Nuclear Reactor Regulatory DSI/RP Hail 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 D. C. Cook Nuclear Station on September 15-19, 1986.

If you have any questions concerning this report, contact me at (FTS 583-7657).

Very truly yours, John W. Driscoll Argonne Pro5ect Hanager JWD:0t cc:

D.

W. Cissel, EBR-. II R. Dalton, DOE-CH M. J. Lineberry, SSPO R. N. Smith, EBR-II 87OaOSoivi 8702OZ PDR ADOCK 05000315 P

PDR

tD. C. Cook Nuclear Station,.

Page 1

PLANT VISIT SUHHARY REPORT 1.

Plant:

D. C. Cook Nuclear Station 2.

Utility:

Indiana

& Hichigan Electric Co.

3.

Location:

8ridgman, Hichigan 4.

NRC Region:

III 5.

Visit Date:

.September 15-19, 1986 6.

Participants from Argonne National Laboratory:

H. D. Garnes J.

M. 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 III.D.3.4. submittal and the NRC staff safety evaluation) and plant procedures to determine what opera-tional practices are being employed.

System airflow measurements were made to determine the-unfiltered air inleakage into the con-

'rol room envelope and system performance.

8.

S stem Descri tion The D. C. Cook Station is a two-unit station with a separate control room for each unit.

The control rooms are accessed through common security doors but are divided into separate independent ventilation zones.

The ventilation zones are identical for. the two units except that Unit 1 supplies ventilation for the kitchen area and Unit 2 supplies ventilation for the toilet.

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Cook Nuclear Station

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The control room envelope consists of the control room, computer

room, and HVAC equ1pment room.

Unit 1's envelope also 1ncludes the kitchen and Unit 2's envelope 1ncludes the toilet.

The HVAC system for each un1t includes redundant a1r handl1ng un1ts (AHU) equipped with chilled water coils for air conditioning.

Electrical heating coils are located downstream of each AHU.'The AHU's have an outs1de a1r makeup supply to provide the necessary fresh air makeup.

The AHU circulates and conditions air to the control room during all modes of system operation and is completely 1solated from the pressurization/cleanup filter tra1n.

The pressurizat1on/cleanup filter train cons1sts of a single filter un1t with a prefilter, HEPA filter, and charcoal adsorber.

There

.are two fans associated with the filter train.

The filter train has an outside air intake which is mechan1cally stopped at a

predetermined sett1ng in the closed pos1tion to allow 1100 cfm makeup for Un1t 1 and 800 cfm in Unit 2.

9.

~F3ndkn s

9.2 Procedures 9.1.1 Procedures 2-0HP-4030.STP.025S, "South Control Room Pressur1zer/Cleanup F1lter System Operability Test" and 2-0HP.4030.STP.025N, "North Control Room Pressurizer/Cleanup Filter System Operability Test" should have the title changed and any, references to the fan changed from north and south to east and west or the fan numbers ACRF-1 and ACRF-2 should be used as labeled on P&IO OP-2-15149.

9.1.2 In the procedures in item 8.2.1 (above) and the applicable procedures for.Unit 1, it would seem to be a good eng1neer1ng pract1ce to record filter train different1al pressures when the filter train 1s tested.

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Cook Nuclear Station

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9.1.3 Procedure 1-OHP 4021-028-015, "Operation of the Control Room Pressurizer/Cleanup Filter System,"

references procedures 1-0HP.4030-STP-024N and

.024S.

The referenced procedures should be 024E and 024M.

9.1.4 Procedures

• • 12THP 4030 STP-229 should have a step that requires adequate levels of lighting when making the visual inspection.

9.1.5 Procedure ~l THP 6040 PER.094, "Control Room Venti-lation Balancing," should have an acceptance criteria for the quanity of outside air makeup.

9.2 2~f2 9.2.1 Carbon Oioxide Fire Extim uishin S stem for

~29 The fire extinguishing system for the computer rooms are equipped with a C02 fire extinguishing system

~ which is manually actuated.

On actuation of the C02 system, the computer room ventilation supply is isolated.

However, the computer room comunicates with the HVAC equipment room via grated louvers.

There is a fire damper between the louvers but isolation requires heat to melt a fuseable link which allows the fire damper to close.

the fire damper appears to be the louvered or venetian blind type that have demonstrated a propensity of "hanging up" on an edge when they are released after the fusible link melts.

Thus, in the event of actuation of the computer room C02 system, C02 will probably be circulated throughout the control room envelope due to the failure of the fire damper to isolate the computer room.

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Cook Nuclear Station,.

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Page 4

Toxic Gas The Cook Station is staffed by six people per unit.

There are two emergency breathing units in the control room with 10 additional units immedi-ately outside the control room for a total of 12 units readily available.

Reg.

Guide 1.95 requires that there be one extra emergency air breathing unit for every three units required.

Reg.

Guide 1.95 also requires the emergency air breathing units be donned and in use within two minutes of receiving a

chlorine alarm. It is doubtful that operators could don the air breathing units in two minutes if the units are outside the control room.

Therefore a

total of 16 units should be available to the control room ~

Charcoal Adsorber Efficienc The FSAR Section 9.10.2 indicates that charcoal adsorbers have a removal efficiency of 99.9X of entrained methyl iodide or iodine vapor and Table 14.3.5-9 indicates a removal efficiency of 95K for the same charcoal adsorber.

If a charcoal efficiency of 95Ã is to be used in the calculations for control room operator exposure for a DBA, the charcoa'l must be tested for an efficiency of 99.3X.

Using a test criteria of 90K as required by Technical Specification would require a value of 30K be used for the dose calculation.

The dose calculations following a DBA should be reevaluated based on allowable charcoal efficiencies based on actual test specifications. If 1100 cfm filtered air makeup and 10 cfm unfiltered inleakage is assumed, the thyroid dose is 17 Rem per Figure 3, Technical Specification page B3/4 7-Sc of the

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Cook Nuclear Station Page 5

July 10, 1986 Submittal.

Using this as a basis and assuming 905 instead of 95K for charcoal efficiency, the GDC-19 thyroid dose would be exceeded.

9.2.4 Sin le Failure Criterion The outside air intakes for the air handling units should have two isolation valves in series to meet the single failure criteria.

Reg.

Guide 1.95 requires that the C12 detectors cause an automatic isolation of the control room within 10 seconds of sensing chlorine in the duct and that the Cl2 be sensed by two physically separated channels for each fresh air inlet.

Cook has only one channel on the normal outside air inlet in each unit and the C12 detectors actuates alarms with isolation by manual operation.

9.3 Technical S ecifications

~

The following comnents are based on the July 10, 1986 Technical Specif ication Submittal:

9.3.1 In Technical Specification 4.7.5.1.e.3, the HVAC Mechanical Equipment Room is part of the control room envelope, it should be maintained at 1/8-inch W.G.

hP to surrounding areas.

9.3.2 In Technical Specifications 4.7.5.1.c.3, 4.7.5.1.d.l and 4.7.5.1.d.2, laboratory test for charcoal does not have the correct acceptance criteria. If 95K efficiency is assumed for the safety analysis, the laboratory test should demonstrate an efficiency of

>99.3X (<0.7X penetration).

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Cook Nuclear Station

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Page 6

9.3.3 In Technical Specification 4.7.5.1.c.3, the labora-tory test conditions for charcoal should be speci-fied at 30'C, 95K R.H.

Test method ASTM D 3803 should be specified.

9.3.4 Specification 4.7.5.1.a.

requires once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> the control room temperature be verified

<120'F.

A more realistic temperature should be selected based on equipment qualification tempera-tures and a temperature survey to determine where the hottest areas of the control room are and what effect those hot spots have on instrumentation.

9.3.5 The inplace test for HEPA filter and/or charcoal adsorbers in Specification 4.7.5.1.c.1, 4.7.5.1.c.2, 4.7.5.1.c.3, 4.7.5.1.d.2, 4.7.5.1.f, and 4.7.5.l.g should specify <0.05K penetration per ANSI N509-1980.

9.3.6 In Specification 4.7.5.1.c.2, an additional step should be added to verify isolation on a high radia-tion signal from the control room area monitor.

9.4 HVAC Flow and CRE Te erature Measurements 9.4.1 ~tt 4 Air temperature was measured in the control rooms with both plants operating near full power..

Data was taken with the HVAC system in normal, toxic gas and pressurization/cleanup modes of operation.

Data sets were taken on different days.

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D. C.

Cook Nuclear Station Page 7

Tem erature Data Unft 1 S stem Confi uration and AHU In Service Location Normal Mode ACRA-2 Average Tempera-

• 85.1'F ture in Occupied Area of Control Room Toxic Pressurization/,

1 Md

~dt Md ACRA-2 ACRA-2 68.6'F No data Average Tempera-

• 88.6'F ture in Back of Main Control Panels 72.6 F

75.1'F aT Between

+3.5'F

+4.0'F Back of Panels

'o Front of Panels Tem erature Data Un1t 2 S stem Confi uration and AHU In Service Location Normal Mode ACRA-2 Toxic Pressurization/

d tdd

~dt 11 d ACRA-2 ACRA-2 Average Tempera-67.2 F

ture Occupied Area of Control Room No data No data Average Tempera-72.9'F ture in Back of Main Control Panels 72.5'F 75.2'F dT Between Back

+5.7'F of Panels to Front of Panel

• Temperature was not this high - translation in data error.

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Cook Nuclear Station..

Page 8

9.4.2 Flow Measurements Flow measurements were taken in each unit with the HVAC system operating in three modes of operation and eight different configurations due to redundant equipment.

Tables 1 through 4 list and summarize the flow data.

.Table 5 shows the differential pressure from the control rooms to the turbine building, control room to control room, mechanical equipment room to turbine building and mechanical equipment room to mechanical equipment room.

The following conclusions are made based on the data:

(1)

There is significant amounts of inleakage from the outside air intakes through the charcoal adsorbers and into the control room envelope during the toxic gas mode of operation.

(2)

There is a significant inleakage into the Unit 2 emergency filter train when the system is operating in the emergency mode of opera-tion.

The outlet flow was as much as 3000 cfm greater than the inlet.

This would suggest that.the.installed flow measuring device, can

• only reflect flow in the filter trains supply duct and may not be showing all the flow in the

.filter housing which exists due to filter housing leaks.

It would seem appropriate to install a flow-measuring device in the outlet ductwork.

(3)

The Unit 2 AHU supplies more air to the control room than the Unit 1 AHU's.

The differential pressure data also verifies that Unit 2 control room is at a slightly positive pressure to the

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Cook Nuclear Station

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age 9

Unit 1 control room.

The mechanical equipment room hP also leads to the same conclusion.

(4)

There is a significant outleakage (1050-4050 cfm from the Unit 1 AHU's (see Table 3).

(5)

Unit 1 east emergency filter fan shows a con-siderable amount of inleakage and the west fan shows a considerable amount of outleakage.

(6)

Bubble tight dampers leakage is approximately 50 cfm for Unit 1 and 40 cfm for Unit 2.

(7)

There is more air returning from the control room and computer room than is being supplied in almost all modes of operation (see Tables 3

and 4).

(8)

Smoke tests showed that,air flowed into or out of the condensate drain lines for the air handling units.

This condition existed in both Unit 1 and Unit 2 and the direction of flow varied depending upon which pieces of equipment were running.

If a proper loop seal existed on the drain lines, there would be no air flow.

Station personnel explained that drain piping from both equipment rooms are joined together and then go to a co@non loop seal.

The conden-sate drain lines connect the two control rooms together.

Therefore, if the integrity of one control room envelope is broken the other control room envelope is also broken.

(9)

The discharge of the air handling units in the Unit 2 control room HVAC system has a

consistently lower flow than the inlet to the

tD. C.

Cook Nuclear Station Page 10 AHU's.

The combination of branches (control room and computer room supplies) downstream of the AHU's discharge is always higher.

The utility should investigate this condition and determine why the flow at points 5 and 6 are lower than the downstream combinat1on of points 7 and 8 (see Table 2 and Table 4).

9.5 Outside Air Inf1 1trat1on The approach used by D. C. Cook to use a matrix for control room operator exposure allows for variable amounts of filtered and unfiltered inleakage.

This method does not tie the utility to a single set of parameters.

This is a good concept and should be considered for use by other utilities.

With the mechanical equipment room at a very low positive pressure

-0.02 in. H20, there is a high probability that the control room envelope will always see a sign1ficant amount of unfiltered inleakage.

There 1s also as much as 39 cfm 1nleak-age through the normal outs1de air intake during the pressurization/cleanup mode.

Although the control room is being pressurized to greater than 0.125 1n.

H20, credit is only taken for 0.0625 in. H20.

With th1s assumption, a value higher than 10 cfm should be used for unfiltered air inleakage due to ingress-egress.

Assum1ng 20 cfm unfiltered 1nleakage due to ingress-egress and -40 cfm inleakage across isolation

dampers, the chart used for thyroid dose is at the upper 11m1t of 60 cfm unfiltered 1nleakage.

With 60 cfm unfiltered in-leakage and 1100 cfm f1ltered outside air makeup, there is not much margin before the GDC-19 11m1t of 30 rem thyroid is reached.

9.6 LER Evaluation There were no LER's associated with the loss of cooling to the control room envelope.

The AHU capacity for both units seem to be more than adequate.

However, the Techn1cal Specifica-t1on Limit of 120 F needs further evaluation (see Item 8.4.4).

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C.

COOK NUCLEAR BTATIQl'.

C.

COOK NUCLEAR STATION UNIT 1

CONTROL ROOM HVAC SYSTEM MEASUREMENNTS MODE OF OPERATION NORM" NORM.

TOXIC TOXIC EMERB EMERG EMERB EMERB OPERATINB AHU SOUTH NORTH NORTH SOUTH SOUTH SOUTH NORTH NORTH

'OPERATINB FILTER FAN NONE NONE NONE NONE WEST EAST EAST WEST NORMAL INTAKE (OUTSIDE)

NORTH AHU DISCHARGE SOUTH AHU DISCHARGE 233 634 13337 13559 475 420 396 12094 13052 13955 348 341 12838 1309'2 12569 309 301 7

COMPUTER ROOM SUPPLY 1481 1772 1850 1770 1912 2315 1630 1875 CONTROL ROOM NORMAL SUPPLY HVAC ROOM RETURN NORMAL RETURN FROM CONTROL ROOM 11275 10025 9687 11896 11160 10239 12004 10930 1321 1544 1278 1444 1442 1411 1506 1450 6528 7400 6608 6664 7064 7240 5992 6656 12 14 EMERG. FILTER OAI EMERB. FILTER SUPPLY TO C.

R, (GRILL) liA NORMAL RETURN FROM CONTROL ROOM 7528 7064 7336 81 12 8136 7056 8728 8160 72 196 172 256 884 820 940 1072 29 47 52 29 9068 7420 4435 7455 14A EMERG. FILTER RETURN 2404 FROM C R.

(GRILL)

FILTER TRAIN COMBINED INLET (DIRECT READING) 914 1455 2607 4813 4912 4359 4417 0

250 250 6200 6300 6000 6350 EMERG FILTER TRAIN SUPPLY TO CONTROL ROOM 36 48 48 6188 5796 6120 5188 17 NORTH COMPUTER ROOM 1018 EXHAUST (GRILL) 1130 1149 1096 1176 iiii 1210 1147 18 SOUTH COMPUTER ROOM EXHAUST (GRILL)

EXHAUST ABOVE MICROWAVE OVEN 1071 1065 932 972 1063 1214 1 1 13 668 228 239'68 246 245 247 261 247 20 OUTSIDE AIR SUPPLY 0

TO AHU'S 9 VFX-309 NOTE! ALL READINGS ARE IN CUBIC 221 48 37 35 46 38 29 FEET PER MINUTE (CFM)

TABLE 1

D Ce COOK NUCLEAR STATIOl D.

C.

COOK NUCLEAR STATION UNIT 2 CONTROL ROOM HVAC SYSTEM MEASUREMENTS MODE OF OPERATION OPERATING AHU OPERATING FILTER FAN NORM'ORTH NONE NORM TOXIC TOXIC EMERG EMERG EMERG EMERG SOUTH NORTH SOUTH SOUTH SOUTH NORTH NORTH NONE NONE NONE WEST EAST EAST WEST NORMAL INTAKE (OUTSIDE) 461 530 27 39 19 '4 17 21 5

NORTH AHU DISCHARGE 15840 752 16743 451 269 309 14280 15008 6

SOUTH AHU DISCHARGE 958 15602 1212 1750 15579 16347 1014 1560 7

COMPUTER ROOM SUPPLY 1551 1929 1495 1762 2081 1919 1922 2124 CONTROL ROOM NORMAL SUPPLY 16552 16675 17066 18492 15892 17495 16061 16076 HUAC EQUIPMENT ROOM RETURN NORMAL RETURN FROM CONTROL ROOM 11A NORMAL RETURN FROM CONTROL ROOM 12 OUTSIDE AIR SUPPLY TO EMERG FILTER TRAIN ~

15 COMBINED INLET TO EMERG.

FILTER TRAIN (DIRECT READING) ib EMERG.

FILTER TRAIN SUPPLY TO CONTROL ROOM 17 NORTH COMPUTER ROOM EXHAUST (GRILL) 18 SOUTH COMPUTER ROOM EXHAUST (GRILL) 19 TOILET EXHAUST 776 812 721 721 759 1098 675 728 9192 8536 9824 9968 10864 8456 9552 9440 244 208 360 496 744 784 '24 856 0

250 6350 6400 6250 6200 40 40 7488 9560 9820 9844 821 1010 934 962 1151 1111 1119 1144 859 962 953 1002 1130 1166 1113 1046 283 262 1

10 8232 10056 9168 8272 7896 9728 8736 8440 NOTE! ALL MEABUREMENTB ARE IN CUBIC FEET PER MINUTE (CFM)

TABLE 2

D.

C.

COOK NUCLEAR STATION D.

C.

COOK UNI 1

FLOW EASUREMENTS tDATAI

!SET INo.

I AHU INLET VS AHU OUTLET VS SUPPLY TO C.R.

h COMP FILTER INLET! COMP.

RM. IN!

VS I

'VS

!FILTER OUTLETICOMP.

RM.

OUTa I

t CR SUPPLY VS CR EXHAUST I OAI TO FILTER VS IC.R.

RETURN!

! VIA FILTER tSUP.

etc RET.I I

-I t

I 1+9+1 1+1 1A+19!

= 5+6 ~ 7+8 t

15649 ~

14589 3*

12756 16480 ~

13685 =

11797 15494 =

13900 12756 15 = ib 0 ~ 28 0 ~ 36 250 ~ 48 7 ~ 17+18 1481

~ 2089 1772 ~ 2195 1850 ~ 2081 8 ~

ii+iiA+19+14+14A 11275 ~ 16717 10025 ~ 15664 9687 ~ 15719 l12 ~ 14+14AI 72 ~ 2433 I

196 ~ 961 I

l t

172 = 1507!

I 4

I 16471

~

13313 ~

13666 250 ~ 48 1770 ~ 2068 11896

~ 17658 256 = 2853t I

t I

I I

I OAI TO FIL I+ C R.

RET. I t~ FILTER IN!

I8+ih=ii+iiA+14A+i9li2+14A=

15I'6896

~

13512 ~

13072 15961 12965 ~

12554 16493

~

12403 ~

13634 8

I 16522

~

13353 ~

12805 6200

~ 6188 6300 ~ 5796 6000

~ 6120 6350 5188 1912 = 2239 2315 = 2325 1630

~ 2323 1875 ~ 1815 17348

~ 20258 16035 ~ 19455 18124 ~ 19340 16118 ~ 19480

!5697 = 6200t I

I l

I

!5732 = 6300l l5299 ~ 6000!

I I

t5489 = 6350t I

I NOTE<

ALL MEASUREMENTS ARE IN CUBIC FEET PER MINUTE (CFM)

TABLE 3

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C.

COOK NUCLEAR STATIOt UMMARY MEASUREMENTS DATA COOK UNIT 2 FLOW C.

FILTER INLET VS FILTER OUTLET CR SUPPLY VS CR EXHAUST COMP.

RM. IN VS COMP.

RM OUT AHU INLET VS AHU OUTLET DATA SET No.

VS SUPPLY TO C.R.

h COMP 1+9+ii+11A

= 5+6 ~ 7+8 8 = 11+11A+19+12 7 ~ 17+18 1551

= 1680 l

18661

~

16798 ~

18103 16552 ~ 17951 0 ~ 244 16675 ~ 19062 1929 ~ 1972 0 ~ 40 19934 ~

16354 ~

18604 17066 ~ 19360 19740 =

17955 ~

18561 1495 ~ 1887 t

0 ~ 40 18492 ~ 18739 19000 ~

17962 ~

20254 1762 ~ 1964 250 ~ 40 t

e8+ib=ii+iiA+14A+19a 23380 ~ 25113 19538 ~

15848 ~

17973 2081

~ 2281 6350 ~ 7488 27055 ~ 24585 19316 =

16656 ~

19414 1919 ~ 2277 6400 ~ 9560 7

25881

~ 24539 18980 =

15294 ~

17983 1922 ~ 2232 6250 ~ 9820 25920

~ 24090 18629 16568 =

18200 2124 ~ 2190 6200 ~ 9844 NOTE: ALL MEASUREMENTS TABLE 4 ARE IN CUBIC FEET PER MINUTE (CFM)

D. C.

COOK NUCLEAR STATION D.

C.

COOK DIFF RENTIAL PRESSURE EASURE ENTS DAT DATA SET Nu.

UNIT 1 CONTROL ROOM TO TURBINE BUILDING NO DATA UNIT 2

! UNIT 1 CONTROL CONTROL ROOM TO ROOM TO

! TURBINE l UNIT 2

! -BUILDING l CONTROL l

ROOM l

NO DATA NO DATA UNIT 1 MECH EQUIP ROOM TO TURNINE BUILDING NO DATA UNIT 2 MECH EQUIP ROOM TO TURBINE BUILDING NO DATA

! UNIT 1

! EQUIP.

ROOM TO UNIT 2 EQUIP>

ROOM NO DATA

-0.01 M~02 NO DATA NO DATA l

-0 Oi 0 00

+0, 02

+0. 02 NO DATA NO DATA NO DATA M.03 NO DATA Os00

+0 02

-0.02'. 00

+0. 18

+0 19

! ~.0i5

+0. 02

+0. 02

+0. 01

+0. 185

+Os 165

-0.01

+0 025

+0 025 0 00 NO DATA NO DATA NO DATA

+0, 01

+0 02

-0 015

+0. 155

+0. 15 NO DATA

+Os 02

+0 02

-0.005 NOTEs ALL MEASUREMENTS ARE IN INCHES OF HmO TABLE