ML20137B972

Forwards Summary of Chlorine Transport Analysis Demonstrating That Control Room Operators Have at Least 2 Minutes to Respond to Chlorine Leak Alarm,Per NUREG-0737, Item III.D.3.4

ML20137B972
Person / Time
Site:	Oyster Creek
Issue date:	08/16/1985
From:	Wilson R GENERAL PUBLIC UTILITIES CORP.
To:	Zwolinski J Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-3.D.3.4, TASK-TM RFW-0589, RFW-589, NUDOCS 8508220183
Download: ML20137B972 (7)

Text

/

o GPU Nuclear NQQIgf 100 Interpace Parkway Parsippany, New Jersey 07054 201 263-6500 TELEX 136-482 Writer's Direct Dial Number:

August 16, 1985 RFW-0589 Mr. John A. Zwolinski, Chief Operating Reactors Branch No. 5 U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Oyster Creek Nuclear Generating Station Docket No. 50-219 Control Room Habitability (NUREG-0737, Item III.D.3.4)

Results of Chlorine Transport Analysis By letter dated June 4, 1985, GPU Nuclear Corporation committed to submit to the NRC staff a chlorine transport analysis which demonstrates that the control room operators have at least 2 minutes to respond to a chlorine leak alarm.

Enclosed is a summary that provides the general methodology, assumptions, data, and results from the calculations performed by Stone & Webster Engineering Corporation (SWEC) to determine the time available to the control room operators following an on-site chlorine release. This enclosure fulfills the requirements contained in Item 7 of Attachment I for the interim system upgrades for control room habitability at the Oyster Creek Nuclear Generating Station as stated in our June 4, 1985 submittal.

The chlorine transport analysis demonstrates that the control room operators will have at least 2 minutes to respond to a chlorine leak alarm. This is based on a 450 CFM infiltration rate. We are currently determining the most limiting permissible infiltration rate which would apply to both the chlorine release scenario and the radiological release scenario. GPU Nuclear Corporation will submit the limiting system flow characteristics in proposed Technical Specifications at a later date in accordance with the commitment contained in our June 4, 1985 letter.

Administratively, procedures will be developed to instruct the control room operators to shift the control room HVAC system into the isolation mode whenever work is performed on the chlorine system that would lead to a significant chlorine release.

8508220183 850816 PDR ADOCK 05000219 8gd F PDR

'I / N i

GPU Nuclear is a part of the General Public Utilities System i

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

~

Mr. John A. Zwolinski, Chief

~

August 16, 1985 Page Two If you have any questions regarding this information, please contact M. W. Laggart, Manager, BWR Licensing at (201) 299-2341.

ry t uly yours, W . \% -

R. F. Wi son Director Technical Functions cc: Dr. Thomas E. Murley, Administrator Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of' Prussia, PA 19406 Mr. Jack N. Donohew, Jr.-

U.S. Nuclear Regulatory Comission 7920 Norfolk Avenue, Phillips Bldg.

Bethesda, MD 20014 Mail Stop.No. 314 NRC Resident Inspector Oyster Creek Nuclear Generating Station Forked River, NJ 08731

[^

i l

l

(

1 l

ENCLOSURE

SUMMARY

OF OYSTER CREEK CONTROL ROOM HABITABILITY ANALYSIS AS A RESULT OF AN ON-SITE CHLORINE ACCIDENT General Methodology Stone & Webster Engineering Corporation's (SWEC's) computer program VAPOR was used to determine chlorine time-history concentrations at both the outside (i.e., fresh air intake) and inside control room locations for postulated handling and distribution line break accident releases. The VAPOR program is based upon the methodology described in NUREG-0570 and the assumptions presented in Nuclear Regulatory Commission (NRC) Regulatory Guide 1.78.

NUREG-0570 presents a calculational method, which has been accepted by the NRC, for the assessment of toxic vapor concentrations that may result from an accidental release. Furthermore, NUREG-0570 describes how to use the assumptions presented in Regulatory Guide 1.78. In addition to Regulatory Guide 1.78 and NUREG-0570, Regulatory Guide 1.95 describes specific design features and procedures that are acceptable to the NRC to reduce the hazards to control room personnel if an accidental chlorine release were to occur.

However, Regulatory Guide 1.95 does not present a calculational method or assu'mptions to assess the effects of an accidental chlorine release upon the control room.

SHEC computer program EN-199 VAPOR, which was used in the chlorine transport analysis, calculates chlorine time-history concentrations at both the outside and inside control room locations.

In the calculations of gaseous concentration in air, the following two processes are considered:

1. Transfer of mass to the atmosphere

2. Dispersion of mass in the atmosphere The amount and rate of mass transfer.to the atmosphere are dependent upon the characteristics of the stored chemical. A fractional amount of low boiling point liquids (e.g., chlorine) and compressed gases will flash off into a

" puff", with the remaining amount evaporating into a continuous plume. This condition is considered in the tSlorine transport analysis for Oyster Creek.

In performing the chlorine transport analysis, the following two accidents were evaluated which were considered to be applicable to Oyster Creek:

1. The distribution line break chlorine accident is considered to be a complete break of a 3/8-in. pipe which transfers chlorine from the 1-ton storage tank to the main header pipe. The pipe break is assumed to occur at a location closest to the storage tank which results in a constant chlorine discharge rate from the tank.

2200f I s

2. The handling accident or worst case condition assumes that a complete rupture of the 1-ton storage occurs, releasing the entire chlorine inventory.

The VAPOR program was run using a wide range of meteorological conditions (i.e., atmospheric stability and wind speed) to determine whether the toxic limit for chlorine of 0.045 g/m' (15 ppm) is exceeded inside the control room for either the chlorine handling accident or the line break accident scenarios.

Assumptions and Input Data

1. Natural phenomena criteria do not initiate a chlorine release.

2. The control room HVAC is adjusted to the isolation mode during chlorine system maintenance, tank delivery, and handling. Ventilation infiltration to the control room HVAC system during the isolation _ mode is assumed to be 450 cu. ft./ min. for this analysis.

3. The following accident scenarios were considered:

a. Handling Accident: The entire 1-ton (2000 lb) inventory of one storage tank is assumed to be released instantaneously to the atmosphere as a result of an on-site chlorine tank handling accident.

Twenty-five percent of the total 1-ton chlorine storage amount is initially flashed off into a puff to the atmosphere.

b. Distribution Line Break Accident: The entire 1-ton (2000 lb) inventory of the storage tank is assumed to be released to the atmosphere under a constant discharge rate through the 3/8-in. pipe connected to the tank. The rate of liquid chlorine discharged from the 1-ton storage tank has been calculated to be 6.82 lb per sec (3093 grams per sec). The rate of discharge will be constant until the entire chlorine inventory in the tank has been exhausted. It will take 5 min to discharge all the chlorine in the tank.

4. Liquid chlorine discharged from the tank will vaporize instantaneously as it is released to the atmosphere.

5. The release of chlorine gas is detected immediately upon its release at the chlorination facility with an alarm sounding inside the control room.

6. No mixing of the chlorine. plume due to building wake ~ effects is considered.

7. The actual fresh air intake height (i.e., 41 ft) above ground lavel is used in determining chlorine concentrations inside the control room for both accident scenarios.

8. The wind direction is such that the centerline of the chlorine plume at ground level blows directly towards the control room fresh air intake.

9. The following are the meteorological conditions examined for both accident scenarios:

2200f 2

1 Wind Speed Atmospheric Stability (mph) Temperature (*F)

A (Extremely Unstable) 1.1, 2.2, 5.6, 11.2 86 B (Moderately Unstable) 1.1, 2.2, 5.6, 11.2 86 C (Slightly Unstable) 1.1, 2.2, 5.6, 11.2 86 0 (Neutral) 1.1, 2.2, 5.6, 11.2, 16.8 86 E (Slightly Stable) 1.1, 2.2, 5.6, 11.2, 16.8 86 F (Moderately Stable) 1.1, 2.2, 5.6, 11.2 86 G (Extremely Stable) 1.1, 2.2, 5.6, 11.2 86

10. A chlorine toxicity limit of 0.045 g/m' (15 ppm) from NRC Regulatory Guide 1.78 is used in determining operator response time.

Summary of Results The results of the analysis of each accident are summarized in the attached tables. For both cases analyzed, the control room personnel would have 2 min to don protective equipment upon receiving a chlorine alarm in the control room.

A minimum of 152 see would be available after a tank handling accident, and a minimum of 194 sec would be available after a distribution line break accident.

3

TABLE 1 CHLORINE CONCENTRATIONS INSIDE THE OYSTER CREEK CONTROL ROOM AND SUBSEQUENT RESPONSE TIME AFTER RELEASE OCCURS FOR VARIOUS METEOROLOGICAL CONDITIONS 450 cfm Chlorine Handling Accident Time After Release When Control Room Stability Hind Control Room Concentration Class Speed (mph) Concentration (g/m') Exceeds Toxic Limit A 1.1 0.045 152 see A 2.2 0.045 344 sec A 5.6 * -

A 11.2 -

B 1.1 0.045 161 sec B 2.2 0.045 686 sec B 5.6 -

B 11.2 -

C 1.1 0.045 922 sec C 2.2 * -

C 5.6 * -

C 11.2 -

D 1.1 -

D 2.2 * -

D 5.6 -

0 11.2 -

0 16.8 -

E 1.1 -

E 2.2 * -

E 5.6 * -

E 11.2 * -

F 1.1 -

F 2.2 * -

F 5.6 -

F 11.2 -

G 1.~ 1 -

l G 2.2 * -

l G 5.6 * -

) G 11.2 -

I

• NOTE: Chlorine concentration inside the control room does not exceed the 0.045 g/m' toxic limit for this meteorological condition.

2200f 4 l

r w TABLE 2 CHLORINE CONCENTRATIONS INSIDE THE OYSTER CREEK CONTROL ROOM AND SUBSEQUENT RESPONSE TIME AFTER RELEASE OCCURS FOR VARIOUS METEOROLOGICAL CONDITIONS 450 cfm 3/8 In. Distribution Line Break l

Time After Release

. When Control Room Stability Hind Control Room Concentration Class Speed (mph) Concentration (q/m') Exceeds Toxic Limit A 1.1 0.045 194 see A 2.2 .0.045 210 sec A 5.6 0.045 413 sec A 11.2 0.045 796 sec B 1.1 0.045 218 see B 2.2 0.045 257 sec B 5.6 0.045 518 sec l B 11.2 0.045 1,023 sec l

l C 1.1 0.045 371 sec C 2.2 0.045 573 sec l C 5.6 0.045 1,354 sec l C 11.2 0.045 2,930.sec

! D 1.1 -

D 2.2 -

D 5.6 -

0 11.2 -

D 16.8 -

l E 1.1 -

l E 2.2 * -

! E 5.6 -

E 11.2 -

F 1.1 -

F 2.2 * -

F 5.6 -

F 11.2 -

G 1.1 -

G 2.2 * -

G 5.6 -

G 11.2 -

• NOTE: Control room concentration does not exceed the 0.045 g/:n' toxic limit.

2200f 5

_ , _ _ . _ . . _ . . , _