ML17194A348
| ML17194A348 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/15/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Delgeorge L COMMONWEALTH EDISON CO. |
| References | |
| TASK-15-14, TASK-RR LSO5-86-62-046, LSO5-86-62-46, NUDOCS 8112210418 | |
| Download: ML17194A348 (4) | |
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December 15, 1981 Docket No. 50-237 LSOS12-046 Mr. L. Del George Director of Nuclear Lfcensfng Commonwealth Edison Company Post Office Box 767 Chicago. Illinois 60690
Dear Mr. Del *George:
SUBJECT:
By letter dated October 15, 1981, you submittted a safety assessment report for the above topic. The staff has reviewed thf s assessment and our con-clusions are* presented in the enclosed safety evaluation report, which com-
. pletes the systems review of thfs topfc for Dresden 2.
Thfs evaluation will be a basic input to the integrated assessment for your facilfty.
The evaluatfon may be revfsed in the future ff your facility design is changed or ff NRC crfteria relating to this topfc are modified before the integrated assessment f s completed.
Enclosur~:
As stated cc w/enclosure:
See next page L
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Sincerely, Dennf s M. Crutchfield, Chf ef Operating Reactors Branch No. 5 Division of Licensing
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NRC FORM 318 (10-80) NRCM 0240 -
OFFICIAL RECORD COPY USGPO: 1981""7335-960
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- .DRESDEN 2.
SEP TOPIC XV-14 Inadvertent *operation of Emergency Core Cooli.ng Systems (ECCSl'That:!nb~~ase Reactor Coolant Inventory I. Introduction The only ECC system capable of delivering flow to the vessel at normal operating pressure is the High Pressure Coolant Injection (HPCI} system.
The p~imary water source for this system is the condensate storage tank and the suppression pool serves as a backup source. The HPCI has one turbine driven pump which injects water in the feedwater line. The rated capacity of the system is about 29% of the feedwater_ system capacity.
An inadvertent operation of HPCI will reduce feedwater temperature.
If the reactor*
level control system fails to run back the feedwater system the total volume flow to the vessel may also.increase.
Increase in ne~tron flux results from the cooler core inlet temperature and the reduction in voids.
The licensee has riot presented an analysis of the inadvertent operation of the HPCI but has stated that it is bounded by the analysis for loss of feedwater heating.
This transient is considered under SEP Topic XV-1.
II.
Review Criteria Section 50.34 of 10 CFR Part 50 requires that each fPPlicant for a clnstruction permit or operating license provide an* analysis and evaluation of the design and performance of structures,- systems, and components of the facility with the objective of assessing the-risk.to public_ health and safety resulting from operation of the* facility, including determination of the margins of safety during normal operations and transient conditions anticipated during the life of the facility.
Section 50.36 of 10 CFR Part 50 requires the Technical Specifications to include safety _limits which protect the integrity of the physical barriers which guard against
- the uncontrolled release of radiOactivity.
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-.~. The-General Design Criteria (Appendix A to 10 CFR P~rt 50) establish-~i~imum
- requirements for the principal design criteria for -~ater-cooled reactors.
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GDC 10 "Reactor Design" requires that the core and_ a_ssociated coolant, control and protection systems b~de~igned with appropriate:margin to *assure that specified acceptable fuel_ design limits ar~ not exceeded during normal operation, including the effects of anticipated operational occurrence.
GDC 15 "Reactor Coolant System Design" requires that the reactor coolant and associated protection systems be designed with sufficient margin to assure that the design conditions of the reactor coolant pressure boundary are not exceeded during normal operation, including the effects of anticipated operational occurrences.
GDC 26 "Reactivity Control System Redundance and Capability"- requires.tha:t the reactivity control systems be capable of reliably controlling reactivity changes to assure that under conditions of normal operation, including anticipated operational occurrences, and with appropriate margin for malfunctions stich as stuck rods, specified acceptable fuel design limits are not exceeded.
III. Related Safety Topics
~rious other SEP topics evaluate such items. as the reactor protection system.
The effects of single failures on safe shutdown capability are considered under Topic VI I-3.
IV.
Review Guidelines
. The review is conducted in accordance with SRP 15.5.1, 15.5.2. The evaluation includes
.review of the analysis for the event and identificati.on of the features in the plant that mitigate the consequences of the event as weil as the ability of these systems to function as required.
The extent to which operator action is_ required is also evaluated.
Deviations from the criteria specified in the Standard Review Plan are identified.
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The licensee has performed analyses. for each reload. on.loss of 145°F feedwater
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heating. These analyses bound the inadvertent operation of HPCI which can decrease the feedwater temperature at rno~t by.87°F; assuming 40.. ~,f minimum temperature for the HPCI water.
If the reactor level control system is assumed to f9il.and the HPCI flow is added to the full feedwater fl ow the core inlet subcool ing is still somewh?t-less than during loss of feedwater heati_ng transient. Thus. inadvertent operation of ECCS transient is bound~d by the loss of feedwater heating transient. The continuous mismatch in the reactor coolant inventory would cause the vessel level to increase until the HPCI pump turbine is tripped by redundant h_igh level signals.
VI Cone l us i ans As part of the SEP revie~ of Dresden 2, the inadvertent ope~ation of ECCS was evaluated and we have concluded that this transient is bounded by the loss of feedwater heating transient which is evaluated under SEP Topic XV-1.
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