ML20064M730

Notifies of Delay in Implementation of Mods for High Radiation Signal for Isolation Scheme.Also Forwards Synopsis of NUREG-0737,Item II.E.4.2, High Radiation Signal to Containment Vent & Purge Valves

ML20064M730
Person / Time
Site:	Shoreham File:Long Island Lighting Company icon.png
Issue date:	08/31/1982
From:	James Smith LONG ISLAND LIGHTING CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML20064M732	List: ML20064M730 ML20064M757
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.E.4.2, TASK-TM SNRC-762, NUDOCS 8209080090
Download: ML20064M730 (4)

Text

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P.O. BOX 618, NORTH COUNTRY ROAD e WADING RIVER, N.Y.11792 August 31, 1982 SNRC-762 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 High Radiation Signal to Purge Valves SER Issue II.E.4.2 Shoreham Nuclear Power Station - Unit 1 Docket No. 50-322

Reference:

1) Letter BWROG-8222, BWR Owners' Group (T. J.

Dente) to NRC (D. G. Eisenhut) dated 6/14/82 (Attachment 3)

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Dear Mr. Denton:

In Supplement No. 1 to the Shoreham Safety Evaluation Report (SER), Item II.E.4.2, the staff has re-stated the requirement, as expressed in NUREG 0737, that the purge line used during normal operation have a high radiation signal to effect isolation. The staff also noted that LILCO had committed to follow the resolution of this issue between the BWR Owners' Group (BWROG) and the NRC, and found this commitment satisfactory. In SNRC-657 dated 1/11/82, LILCO committed to provide.this isolation signal.

This isolation scheme cannot be installed prior to fuel load.

LILCO believes that this status is acceptable because the reliability of the existing isolation signals is extremely high and the probability that automatic isolation on high radiation >

would be required is extremely low as it would require a specific break size coincident with purge valve operation. The BWROG has j conducted an evaluation (refer to Reference 1) for a typical l plant of the radiological consequences of the limiting reactor coolant system break which would not result in automatic containment isolation. Utilizing various key input assumptions l

and analytical procedures from this evaluation, a specific

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analysis has been done for Shoreham which determined that the l offsite thyroid dose for this extremely remote event was l approximately .003 Rem. This is well below the EPA's Protective Action Guide value of 5 Rem. A synopsis of this specific calculation including certain key input assumptions and plant specific data is included as Attachment 1.

8209080090 820831 I PDR ADOCK 05000322 1 A PDR

August'31,-1982 SNRC-762 Page 2.

At Shoreham, the purge valves are 6" and 4" globe type valves, which isolate on the same signals that initiate the Reactor Building Standby Ventilation System, i.e., RPV low water level, high'drywell pressure, refueling platform level high radiation and reactor building high. differential' pressure. A conceptual design has been developed as-shown on the sketch included as Attachment 2. Basically, Dll-PNL-19 (non-safety grade) would be modified to produce a single output signal. This single output signal will activate a suitable isolation device. (electrical isolation) which would-serve'to " split" the signal into two trains. These two signals will then activate closure of the

-eight purge valves utilized during power operation.

Based on the high reliability of the existing isolation signals, the low probability that automatic isolation on high radiation signal will be required, and the negligible radiological consequences for-such an event, it is felt that a delay in implementation of this modification is warranted until the first refueling outage to permit procurement of materials and system installation and testing.

-Should you have any questions, please contact this office.

Very truly yours, Y-J. L. Smith Manager, Special Projects

'Shoreham Nuclear Power Station-RWG:mp Attachment cc: J. Higgins All parties

Attachment 1 NUREG-0737, Item II.E.4.2(7)

High Radiation Signal to Containment Vent and Purge Valves The assumptions and procedures provided by the BWR Owners' Group were used for evaluation of the ten minute release due to a delay in closure of the containment vent and purge isolation valves.

The offsite thyroid dose was found to be 2.7 mrem which is significantly smaller than the EPA's Protective Action Guide of 5 Rem. The corresponding offsite volumetric leakage and the break flow rates were 4,000 cfm and 70 gpm, respectively.

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The assumptions or plant specific data which were used in addition to those given in the procedure are listed below:

1. Flow out the vent line only,

2. Diameter of vent line = (*) 6 in.,

3. Four butterfly valves,

4. Seven 90' elbows

5. Ventpipe length (to stack inlet) = 120 ft.,

6. No elevation change (Z -Z = 0),

2 1

7. Primary coolant iodine Tech. Spec. limit = 0.2 uCi jg

8. Mass of primary coolant = 476,720. lbm,

9. No. of fuel bundles = 560,

10. Spiking activity per bundle = 3.27 Ci of Iodine, 6

L 11. I-131 dose conversion factor = 1.49 x 10 Rem /Ci,

12. Breathing rate = 3.47 x 10 ~4m3 /sec.,

13. Site boundary 457m ESE, annual average atmosphere X

sec/m 3, factor /O = 8.44 x 10 In addition, no credit was taken for iodine plateout, mixing in

, the drywell, or purge filters.

i This assumption was made based on the fact that the first 50 ft, of the purge line from the primary containment exit is 6 in ID.

COA /CEPTUAL. PUME

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"HI-RAD INTERLOCK" VEH T l

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/SOLATOP DIV 2 (REM =- =

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FLT- S u y (CHARCO/L) TO h' VALVES TO '8' VALVES

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\ $UPPRESSION s IT46% A0Y-0798' CHAM 8ER '--lT24 + ADV-OO48 IT46%ADV-079A NOTE :

SKETCH HAS 8EEN PRAWN TO FUNCT/CNALLY $HOW THE PURPOSE FOR WHICH THE VALVES WERE INSTALLEO. THE SWETCH DOES A/07' 6HOW OTHER VALVES AMD LIAJES BECAUSE THEY ARE NOT REQUIREO TO /SOLATE FOR THE PURalNG AT POV/ER OPERATIOA).

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