ML19331D997

Provides Addl Response to IE Bulletin 80-17.Results of Analysis of ATWS W/O Recirculation Pump Trip Encl.Analyses Required No Deratings to Remain Below Svc Level C Limit

ML19331D997
Person / Time
Site:	Dresden, Quad Cities
Issue date:	07/14/1980
From:	Janecek R COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-80-17, NUDOCS 8009040632
Download: ML19331D997 (6)

Text

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[' N Commonwealth Edison it one First National Pirza. Chiergo, Illinois (TT7 y Address Reply to: Post Office Box 767 Chicago, Illinois 60690 4

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July 14, 1980  ?

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i Mr. James G. Keppler, Director Directorate of Inspection and Enforcement - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137

Subject:

Dresden Station Units 2 and 3 Quad Cities Station Units 1 and 2 Additional Response to IE Bulletin 80-17 NRC Docket Nos. 50-237/249 and 50-254/265 Reference (a): J. G. Keppler letter to C. Reed dated July 3, 1980

Dear Mr. Keppler:

This letter is to provide an additional response for Dresden 2/3 and Quad Cities 1/2 to the subject bulletin which was transmitted by Reference (a).

Item 7 of the bulletin requested that analyses be performed on plants without a ATWS related RPT to determine any derating necessary to ensure service Level C limits are not exceeded. The I attachment to this letter contains the results of these analyses for Dresden Units 2/3 and Quad Cities Units 1/2. As indicated, the analyses performed were for a MSIV closure with 1/2 of the control i

I rods failing to scram and a turbine trip with bypass event with all l control rods falling to scram. These analyses required no deratings l to remain below the service Level C limit.

The analyses were performed by the NSSS vendor for these units, the General Electric Co. General Electric has indicated that, through their discussion and understanding with the NRC, submittal of these test results will satisfy the requirements of the i

h AU6 6 1880 8009040 N Q _ _ - --

Commonwealth Edison Mr. James G. Keppler, Director July 14, 1980 Page 2 *

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gulletin. If any additional information is required, please contact this office.

Very truly yours,

.86M ~2 Robert F. Janecek Nuclear Licensing Administrator Boiling Water Reactors cc: Directur, Division of Reactor Operations Inspection i

i SUBSCRIBED and SWORN to before me Ahisy /e/-r// , day of Relv , 1980 Notary Public i 5203A l

. 1 RESPONSE TO IE BULLETIN. 60-17 ATWS WITHOUT RPT FOR DRESUEN UNITS 2 AND 3 .

Intro' duction QUAD CITIES UNITS 1 AND 2 -

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i This document provides th I i

required by Item 7 of IE Bulletin 80 17 tra NRC, an assessment ATWS) of a

- without full recirculation ATWS i pumon of antici is required as part of an anal

.> "removal Service Level C" ysis limitnofplantsof the 150such net not safety having ofthat RPT imp calculated derating systems. plants by the General This evaluation Electric ressures 0 Company psig considering was do not provided exceed allt availabl e the assu

. e heat Discussion o Commonwealth Edison General Electric believes onBrowns a complete failure to scram doe that b

~ at Ferry Unit 3. asing decisions relative to plant s f s not1% properly reflect the a ety occurr imately 36% to less It should than be scram noted at that Browns al partialence initi the Ferry U Ferry 3 occurrence hasAbeen .

pe f conservative evaluation x- of thed in recirculation pump trip rincorporat ormed by50% GE for plants which d e Browns indicate that the mitigate the consequences of antici scram ed inof their design. o not have '

of thepatedcontrol transients.rods will effectivelThese y

an ATWS transients are presentedIn light of the abo and in response to B bounding of the core and case for MSIV closure.

2 These transients are: ulletin 80-17 two

1) a generic with no scra,ma as plant specific by case IE Bullfor ti turbine t iwith s re) quired e sector MSIV Closure n 80-17. r p with bypass A generic bounding case was an l of the core are inserted a during sccore ram. only control rods in a 180' c ycle conditions half of the General core were Electric believes assumed this to sector remain in the full power pThe control case bounds any possible nonositicn.

able with the current n c arge. volume guration. instrumentdettetable which are not detect co fiw non-functional 180For rods we this evaluation the control 70 seconds. reactor sectorspower of thewas core.re conservatively separated into calfunctional ~and Under these conditions the' A bounding analysis of the peak culated . to fall to 40%-in the first following characteristics: scram condition '

e half was perfor closure in a plant with the

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Initial Power Level 100% l Scram Worth -3$ i Void Coefficient -11 C/%

Safety Valve Setpoint/ Capacity 1255 psia /16% NBR '

Relief Valve Setpoint/ Capacity 1110 psia /40% NBR

The results of this analysis show that the peak vessel pressure (without j RPT) is less than 1460 psig at 47 seconds.

i Based on the above it is concluded that for a conservatively defined partial scram condition in plants without RPT and with combined safety and relief valve capacity of 56% NER, the peak pressure is maintained well below 1500 psig. The safety and relief valve capacity and reactor vessel size used in this assessment is small compared to operating BWR's which do not incorporate RPT, thereby maximizing the peak vessel pressure.

In addition, a conservative void coefficient was used. Previous sensitivity studies have shown that this combination of parameters is a limiting case for operating BWR's without RPT and hence it can be concluded that this generic analysis indeed bounds the results which would be obtained for individual plants.

Turbine Trip With Bvpass A plant specific analysis of the turbine trip with bypass transient for which no scram occurs has been performed for Dresden Units 2 and 3. The input parameters for this analysis are given in Table 1. No credit is taken for heat removal systems other than the safety and relief valves, and/or the turbine. bypass to the main condensor.

The results of this analysis show that the peak vessel pressure reaches 1322 psig in 8.3 seconds for full power operation. The transient response of the system is shown in Figure 1.

Conclusion ,

Based on the above evaluation no plant derates are necessary to meet the 1500 psig limit. The conservative bounding MSIV half scram evaluation shows that the 1500 psig limit is not exceeded. The plant specific analysis of turbine trip with bypass shows that the 1500 psig limit is not exceeded for the very conservative case of no scram. Therefore, it can be concluded that continued operation without ATW5 RPT is not an unreviewed safety question and does not produce a safety hazard to the

, general public. ~

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TABLE 1 Transient Input Parameters

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Y Power Level (mwt) 2527

{ 6 Rated Core Flow (10 lb/hr) 98.0 6 9.77 Rated Steam Flow (10 lb/hr)

Steam Dome Pressure (psig) 1005 Turbine Bypass capacity (% rated steam flow) 40 Number of Relief Valves 5 Setpoints (psig) 1125 27.8 Capacity (% rated steam flow at setpoint)

Number of Safety Valves - 8 .

Setpoint (psig) 1253 Capacity (% rated steam flow at setpoint) 50 Number of Safety / Relief Valves .

N/A Setpoint (psig)

Capacity (% rated steam flow at setpoint)

Void Fraction (%) 34.5 Void Coefficient (-C/% Rg)' 7.4 -

Doppler Coefficient (-C/*F) 0.31

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Figure 1 Time Response of Turbine Trip With Bypass, No Scram, 100%/100%.

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