ML20199K517

Forwards Response to 860428 Request for Info Re Automatic Isolation of Containment Purge & Vent Valves on High Containment Radiation Signal.Procedures for Venting Containment Have Separate Sections for Drywell & Torus

ML20199K517
Person / Time
Site:	Hatch
Issue date:	06/26/1986
From:	Gucwa L GEORGIA POWER CO.
To:	Muller D Office of Nuclear Reactor Regulation
References
2785N, SL-883, TAC-56049, TAC-59542, NUDOCS 8607090181
Download: ML20199K517 (10)

Text

Georgia ibwer Company 333 Piedmont Avenue

. Atlanta, Georgia 30308 k sphone 404 526 6526 Mailing Address:

Fbst Office Box 4545 Atlanta, Georgta 30302 Georgia Power L T. Gucwa #4 *U Nt'\"UC F "

Manager Nuclear Safety and Licensing i

SL-883  !

l 2785N June 26, 1986 Director of Nuclear Reactor Regulation Attention: Mr. D. Muller, Project Director BWR Project Directorate No. 2 Division of Boiling Water Reactor Licensing U. S. Nuclear Regulatory Commission Washington, D. C. 20555 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57, NPF-5 EDWIN I. HATCH NUCLEAR PLANT UNITS 1, 2 ISOLATION OF CONTAINMENT PURGE AND VENT VALVES Gentlemen:

By letter dated April 28, 1986, Georgia Power Company (GPC) was requested to provide information related to the automatic isolation of containment purge and vent valves on a high containment radiation signal.

The requested information is provided in the enclosure.

If you have questions in this regard, please contact this office at any time.

Sincerely, L. T. Gucwa JH/mb Enclosure xc: Georgia Power Company U. S. Nuclear Regulatory Commission Mr. J. P. O'Reilly Dr. J. N. Grace, Regional Administrator Mr. J. T. Beckham, Jr. Senior Resident Inspector Mr. H. C. Nix, Jr.

300 gef 368!BUeje[

ENCLOSURE GeorgiaPower d PLANT E. I. HATCH UNITS 1 AND 2 CONTAINMENT PURGE AND VENT VALVE ISOLATION I. INTRODUCTION The automatic isolation of containment purge and vent valves on a high containment radiation signal was implemented in Hatch Units 1 and 2 to satisfy the requirements of NUREG-0737, Item II.E.4.2(7). A description of the modifications was provided, prior to their installation, in an April 10, 1984, submittal . Changes to the Hatch Unit 1 Technical Specifications were requested in submittals dated August 20, 1985, and January 7,1986 Unit 2 Technical Specification changes were requested in a September 5,1985, submittal.

II. ADDITIONAL INFORMATION A.1 Staff Request "For all primary containment vent and purge lines, please provide the following information:

a) inside diameter of the line; b) expected flow rates (maximum and design) when open to the environment, c) frequency and duration of the line being open to the environment, and d) length of seismic Category I piping, including the isolation c.lves, outside the primary containment (if diameter changes, please provide the lengths of each section)."

A.2 Response Tables 1 and 2 (pages 2 and 3, respectively) provide the requested data. We note that containment purge and vent lines are not opened directly to the environment. Purge supply lines open to secondary containment; nitrogen supply lines open to the nitrogen supply system; and vent lines open to the standby gas treatment system (SGTS).

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GeorgiaPower d ENCLOSURE (Continued)

PLANT E. I. HATCH UNITS 1 AND 2 CONTAINMENT PURGE AND VENT VALVE ISOLATION TABLE 1 HATCH 1 CONTAINMENT PURGE AND VENT LINES Length of Inside Flow

• Usage Frequency Seismic Cat. I Line Diameter (in. ) (sf 3/ min) and Duration Pipe (ft)

Drywell purge 17.250 3000 Shutdown /as req'd 30 supply Drywell N2 6.065 3000 Startup/4 hours 71 supply Drywell N2 0.957 100 As req'd 59**

normal makeup Drywel1 N2 1.939 100 As req'd 12**

emergency makeup (2 lines)

Drywell main 17.250 3000/5200 max Shutdown and 154***

exhaust startup/as req'd Drywell exhaust 1.930 100 As req'd 46 normal bypass Drywell exhaust 1.939/2.067 100 As req'd 61 /4 emergency bypass (2 lines)

Torus purge 17.250/19.250 3000 Shutdown /as req'd 20/34 supply Torus N2 supply 6.065 3000 Startup/4 hours 7

, Torus N2 0.957 100 As req'd 32**

normal makeup Torus N2 1.939 100 As req'd 26**

emergency makeup (2 Lines)

Torus main 17.250 3000/5200 max Shutdown and 163***

exhaust startup/as req'd Torus exhaust 1.939 100 As req'd 22 normal bypass Torus exhaust 1.939/2.067 100 As req'd 44/4 emergency bypass (2 lines)

• Design flow is specified unless otherwise indicated.

• • Up to containment isolation valves, also Seismic Cat. I to N2 tank in yard.

• • • Up to SGTS, also Seismic Category I to main stack.

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Georgia Power [ ENCLOSURE (Continued)

PLANT E. I. HATCH UNITS 1 AND 2 CONTAINMENT PURGE AND VENT VALVE ISOLATION TABLE 2 HATCH 2 CONTAINMENT PURGE AND VENT LINES Length of Inside Flow

• Usage Frequency Seismic Cat. I Line Diameter (in.) (sf 3/ min) and Duration Pipe (ft)

Drywell purge 17.250 3000 Shutdown /as req'd 28 supply Drywell N2 6.065 3000 Startup/4 hours 47 supply Drywell N2 0.957 100 As req'd 10**

normal makeup Drywell N2 1.939 100 As req'd 33**

emergency makeup (2 Lines)

Drywell main 17.250 4000/6600 max Shutdown and 140***

exhaust startup/as req'd Drywell exhaust 1.939 100 As req' d 22 normal bypass Drywell exhaust 1.939 100 As req'd 118 emergency bypass (2 lines)

Torus purge 17.250/19.250 3000 Shutdown /as reg'd 28/12 supply Torus N2 supply 6.065 3000 Startup/4 hours 12 Torus N2 0.957 100 at req'd 55**

normal makeup Torus N2 1.939 100 as req'd 16**

emergency makeup ,

(2 lines) l Torus main 17.250 4000/6600 max Shutdown and 167***

exhaust startup/as req'd Torus exhaust 1.939 100 as req'd 20 normal bypass Torus exhaust 1.939 100 As req'd 58 emergency bypass (2 lines)

• Design flow is specified unless otherwise indicated.

• • Up to containment isolation valves, also Seismic Cat. I to N2 tank in yard o**Up to SGTS, also Seismic Category I to main stack.

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GeorgiaPower d ENCLOSURE (Continued)

PLANT E. I. HATCH UNITS 1 AND 2 CONTAINMENT PURGE AND VENT VALVE ISOLATION B.1 Staff Request "What are the restrictions, if any, on the number of lines being simultaneously open to the environment? Of these lines, identify those which would provide a leakage pathway from the containment to the environment. (Include inlet as well as exhaust lines and use the assumption that the drywell is at 2 psig.)"

B.2 Response The following plant procedures control which lines can be opened:

S0-T48-002-lN Containment atmosphere dilution system S0-T48-002-2 Containment atmosphere dilution system S0-T48-004-15 Primary containment atmospheric control system S0-T48-004-2 Primary containment atmospheric control system Procedures for venting containment have separate sections for the drywell and torus. They pennit two 2-in. vent paths to be opened concurrently from either the drywell or the torus. The de-inerting path opens concurrently all four 18-in. lines (inlet and outlet) to primary containment. The inerting path supplies N2 to the. torus via the 6-in. to the 18-in. line into the torus and exhaust from the drywell via the 18-in. line.

Electrical interlocks are provided that prevent opening of the outboard normal H2 supply and makeup valves (F103 and F104) if the outboard purge supply valves (F308 and F324) are open. No other electrical interlocks are provided between the lines.

The following lines could provide a leakage path:

in drywell exhaust emergency bypass (2 lines / unit) in torus exhaust emergency bypass (2 lines / unit) in drywell N2 emergency makeup (2 lines / unit) in torus N2 emergency makeup (2 lines / unit)

All other lines would remain isolated due to high drywell pressure.

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Georgia Power [ ENCLOSURE (Continued)

PLANT E. I. HATCH UNITS 1 AND 2 CONTAINMENT PURGE AND VENT VALVE ISOLATION C.1 Staff Request "In an April 10, 1984 letter from L. T. Gucwa of Georgia Power Company to J. F. Stolz of the NRC, it was stated that the high radiation isolation signal will originate from the high-range containment radiation monitors which were installed in response to NUREG-0737 Item I I .F .1( 3) . Pl ease provide the following information:

a) Where are the two detectors specifically located in the drywell?

b) Do these monitors meet the requirements of Table II.F.1-3 in NUREG-0737? If not, please describe the differences, c) What activity levels (in curies per cubic feet) in the effluent leaking out the open vent and purge lines correspond to the isolation signal setpoint of 138 roentgens per hour after taking into account instrument accuracy, calibration errors, and drift of the setpoint that could occur during the interval between calibrations? Please provide the assumptions used in the exposure dose rate calculations.

d) What are the normal radiation levels in the drywell? And what is the highest level dxpected in normal operation?

e) What is the maximum time for closure of the vent and purge isolation valves on a high containment radiation signal?

Include the time to reach the isolation signal setpoint, instrument delay times, and time for the valve to be in the fully closed position after actuator power has reached the operator assembly."

C.2 Response a) The detectors are located as follows:

Unit 1 Dll-RE-N003A elevation 156 ft Azimuth 270 degrees Dll-RE-N003B elevation 156 ft Azimuth 90 degrees Unit 2 2Dll-RE-N003A elevation 156 ft Azimuth 210 degrees 2Dll-RE-N003B elevation 156 ft Azimuth 80 degrees 2785N 700775

GeorgiaPower d ENCLOSURE (Continued)

PLANT E. I. HATCH UNITS 1 AND 2 CONTAINMENT PURGE AND VENT VALVE ISOLATION b) The monitors meet the requirements of NUREG-0737, Item II.F.1, Attachment 3 and Regulatory Guide 1.97, Revision 2 c) It should be noted that the setpoint is 100 rem / hour and that the 138 rem / hour stated includes an allowance for dri f t, '

l equipment accuracy, and calibration errors as required by j Regulatory Guide 1.105 The release that corresponds to 138 rem /h,iur in the drywell is 0.1 ci/ft3 in the effluent.

d) Normal drywell radiation levels are 8 rem / hour based on operating data. Calculated peak drywell radiation levels per Unit 2 Final Safety Analysis Report (FSAR), Table 3.11-4 are:

Inside the vessel shield: 6.5 X 104 rads / hour gamma 6.3 X 10 neutrons /cm neutron Outside the vessel shield: 50 rads /gourgamma 1.4 X 10 neutrons /cm neutron e) Maximum closure times are as follows:

Unit 1 Unit 2 (seconds) (seconds)

Detector response 1 1 Electronics response 1 1 Valve stroke time 5 5 Totals: 7 7 D.1 Staff Request

"Please provide an analysis of the radiological consequences of a small line failure (e.g., instrument lines and sample lines) inside containment assuming direct flow of flashed coolant to the environment through an open vent or purge line with appropriate credit taken for mixing and dilution. The procedures and assumptions outlined in Standard Review Plan Section 15.6.2 (Radiological Consequences of the Failure of Small Lines Carrying Primary Coolant Outside Containment) should be used in the analysis. Al ternatively, please provide an analysis which demonstrates based on geometric configuration, expected flow rates, or other considerations that the small line failure case is bounded by the accident scenario outlined in the June 14, 1982 letter from T. J. Dente of the BWR Owner's Group to D. G. Eisenhut of the NRC (copy attached) which assumed the drywell to be at 2 psig."

2785N

.I l

Georgia Power A ENCLOSURE (Continued) l PLANT E. I. HATCH UNITS 1 AND 2 CONTAINMENT PURGE AND VENT VALVE ISOLATION D.2 Response

, The drywell isolation setpoints for Unit 1 and Unit 2 have a maximum trip value of 138 rem / hour, including instrument uncertainties. This will ensure that only a small fraction of the EPA's Protective Action Guide (PAG) recommended levels for initiation of protective action, i.e.,1 rem whole body or 5 rem to

~

the thyroid, are ever reached.

The upper limit for the setpoint was determined by assuming accumulation of the PAG doses in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> at the site boundary and then calculating the corresponding dose rates in the drywell. The i isolation setpoint was established at less than 0.01 times the drywell dose rates.

The method used to determine the drywell dose rates corresponding to site boundary PAG 1evels was to: (1) calculate the offsite dose r

esulting from a release of 100 percent of the noble gas activity 1

' in the core and (2) determine the ratio of that offsite dose to i

the desired limit of 1-rem whole-body. This ratio, or release fraction, was then divided so that the release fraction applying to the radio-f odines was 25 percent of that for the noble gases, to conform to PAG guidelines (Section 5.1.1). It was confirmed that the resultant offsite thyroid doses were also within the PA guidelines. The whole-body dose rate in the drywell (5.7 x 10g

-rem / hour) corresponding to these offsite doses was used as a basis l for the setpoint.

l The following assumptions were used in this analysis:

o neous with a subsequent The release release to thetoatmosphere the drywellofwas 3000 instantg/

ft min, the flow rate of j the purge fan.

o The drywell purge exhausts through the SGTS filters which have an efficiency of 95 percent.

o The release to the atmosphere was over a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> time period.

o The accident X/Q for an elevated release, 1. 7x10-6 sec/m3 ,

was used.

o The 0- to 2-hour accident breathing rate of 3.47x10-4 m3 /sec was assumed.

o The TID 14844 spectrum was used as the source, with a power level of 2550 Wt-2785N 4

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Georgia Power [ ENCLOSURE (Continued)

PLANT E. I. HATCH UNITS 1 AND 2 CONTAINMENT PURGE AND VENT VALVE ISOLATION This analysis did not evaluate any specific accident but did evaluate a release that would result in site boundary doses reachin A setpoint was established far below this level. g PAG guidelines.

Subsection 15.1.32 of the Hatch Unit 2 FSAR examines the effects of a small line break. A sample line break in the secondary containment is bounding for a similar break in the drywell and is used for a worsg-case The resultant site boundary doses are 6.94 x 10- rem analysis.

to whole body and 1.87 x 10-1 rem to the thyroid (Table 15.1-12 of the FSAR). These doses are well within PAG guidelines.

E.1 Staff Request "In the request to change the Technical Specifications for Hatch Unit 1 (transmitted in September 5, 1984, August 20, 1985 and January 7,1986 letters from J. T. Beckham, Jr., of the Georgia Power Company to J. F. Stolz of the NRC), proposed revisions to Unit 1 Tables 3.2-1 and 4.2-1 and Unit 2 Tables 3.3.2-1 and 3.3.2-2 are presented. Unit 1 Table 3.7-1 and Unit 2 Table 3.6.3-1,

" Primary Containment Isolation Valves," also need to be revised.

Please submit revised Tables which specifically show which isolation valves will close on a high containment radiation signal."

E.2 Response The request to change the Unit 1 Technical Specifications (letters dated August 20, 1985 and January 7,1986) included a revision of Table 3.7-1. The request to change the Unit 2 Technical Specifications (letter dated September 5,1984) did not include a revision to Table 3.6.3-1. A revision to the table will be submitted for approval prior to startup following the scheduled Fall 1986 Unit 2 refueling outage.

F.1 Staff Request "Specifically, will the isolation valves (T48-F103) and 2748-F103

[ sic] on the drywell and suppression chamber nitrogen supply lines for Unit 1 and Unit 2 respectively automatically close on a high containment radiation signal? If not, please provide the justification for not isolating this valve on high containment radiation. "

2785N

GeorgiaPower d ENCLOSURE (Continued)

PLANT E. I. HATCH UNITS 1 AND 2 CONTAINMENT PURGE AND VENT VALVE ISOLATION F.2 Response N

2 supply valves T48-F103 and 2T48-F103 do not close on a high drywell radiation signal; these valves are normally closed, fail closed valves which are installed on the N2 supply line from the steam vaporize r. The N2 supply line is only used for approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> during startup to inert the containment when high volumes of N2 are required. The line is not used for N2 makeup during normal operation or emergency conditions. The supply line is designed for 150 psig. N2 supply pressure will exceed drywell pressure unless there is a major high-energy line break (HELB) in the containment. In such case, the N2 supply valves would isolate at 2 psig due to high dryde, pressure. A HELB is not considered credible during the brief period of time that the supply valves would be open.

G.1 Staff Request "Your August 20, 1985 submittal indicates that there will be two operable v trip systems with one operable channel per trip system for ent and purge line isolation on high containment radiation (see note b on Table 3.2-1) whenever primary containment integrity is required. Your April 10, 1984 submittal states that the Technical Specification will be revised to require that one radiation monitor which initiates high radiation isolation be operable at all times except cold shutdwns and refueling outages. Please resolve this apparent discrepancy."

G.2 Response GPC will make a submittal resolving this discrepancy.

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