ML19331D997
| 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 Address Reply to: Post Office Box 767 y
Chicago, Illinois 60690 4
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July 14, 1980
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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 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 rods failing to scram and a turbine trip with bypass event with all control rods falling to scram.
These analyses required no deratings 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 Relv 1980 of 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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This document provides th
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Ei required by Item 7 of IE Bulletin 80 17 tra i
ATWS) without recirculation pumon of antici NRC, an assessment of a full ATWS i is required as part of an anal n plants not having RPT imp
" Service Level C" limit of 150such that calculated ysis of the net safety of derating removal systems.
ressures do not exceed the assu plants 0 psig considering all availabl This evaluation was provided t by the General Electric Company e
e heat o Commonwealth Edison Discussion General Electric believes that b on a complete failure to scram doe asing decisions relative to plant s f at Browns Ferry Unit 3.
s not properly reflect the occurr imately 36% to less than 1% scram at Browns Ferry U It should be noted that the initi
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a ety Ferry 3 occurrence has been pe f ence A conservative evaluation of thed i al partial recirculation pump trip incorporat r ormed by GE for plants which d indicate that the scram of 50%
x-e Browns mitigate the consequences of antici ed in their design.
o not have of the control rods will effectivelThese a ATWS transients are presentedIn light of the abo pated transients.
y bounding case for MSIV closure.
and in response to B These transients are: ulletin 80-17 two of the core a plant specific case for turbine t iwith s and 2 with no scra,m as re) quired by IE Bull ti 1) a generic sector MSIV Closure e
n 80-17.
r p with bypass A generic bounding case was an l of the core are inserted during sccore conditions half of the core were assumed to a
only control rods in a 180' ycle c
General Electric believes this ram.
remain in the full power pThe control sector able with the current instrument co fiw case bounds any possible nonositicn.
c arge. volume which are not detect dettetable non-functional 180For this evaluation the control n
guration.
rods we 70 seconds. reactor power was conservatively cal sectors of the core.re separated into functional ~and Under these conditions the' culated to fall to 40%-in the first A bounding analysis of the peak following characteristics: scram condition was perfor closure in a plant with the e half
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Initial Power Level 100%
Scram Worth
-3$
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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Power Level (mwt) 2527 6
Rated Core Flow (10 lb/hr) 98.0 6
Rated Steam Flow (10 lb/hr) 9.77 Steam Dome Pressure (psig) 1005 Turbine Bypass capacity (% rated steam flow) 40 Number of Relief Valves 5
Setpoints (psig) 1125 Capacity (% rated steam flow at setpoint) 27.8 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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