ML20054K507
| ML20054K507 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 06/25/1982 |
| From: | Caruso R Office of Nuclear Reactor Regulation |
| To: | Kay J YANKEE ATOMIC ELECTRIC CO. |
| References | |
| TASK-15-09, TASK-15-9, TASK-RR LSO5-82-06-108, LSO5-82-6-108, NUDOCS 8207020265 | |
| Download: ML20054K507 (6) | |
Text
June 25,1982 Docket flo.50-029 LS05-82 108 Mr. James A. Kay Senior Engineer - Licensing Yankee Atomic Electric Company 1671 Worcester Road Framingham, Massachusetts 01701
Dear !!r. Kay:
SUBJECT:
SEP TOPIC XV-9 STARTUP OF AN INACTIVE LOOP YANKEE By letter dated June 30, 1981, you submitted a safety assessment on this topic. The staff has reviewed your assessment and our conclusions are presented in the enclosed final topic evaluation. With respect to this topic, the Yankee Nuclear Power Station meets current licensing criteria.
This evaluation will be a basic input to the integrated safety assessment for your facility unless you identify changes needed to reflect the as-built conditions at your facility. This assessment may be revised in the future if your facility design is changed or if NRC criteria relating to this subject are modified before the integrated assessment is cocpleted.
Sincerely, Ralph Caruso, Project Manager Operating Reactors Branch No. 5 Division of Licensing
Enclosure:
As stated
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. Mr. James A. Kay Cc Mr. James E. Tribble, President Yankee Atomic Electric Company 25 Research Drive Westborough, Massachusetts 01581 Chairman Board of Selectmen Town of Rowe Rowe, Massachusetts 01367 Energy Facilities Siting Council 14th Floor One A.chburton Place Bc: ton, Massachusetts 02108 i
U. S. Environmental Protection Agency I
Region I Office ATTN:
Regional Radiation Representative JFK Federal Building Boston, Massachusetts 02293 Resident Inspector Yankee Rowe Nuclear Power Station c/o U.S. NRC Post Office Box 28 Monroe Bridge,* Massachusetts 01350 Ronald C. Haynes, Regional Administrator Nuclear Regulatory Commission, Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 l
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t 9
SYSTEMATIC EVALUATION PROGRAM TOPIC XV-9~
STARTUP 0F AN INACTIVE LOOP YANKEE I.
INTRODUCTION The startup of an inactive coolant loop at an incorrect temperature is examined to assure that the consequences are acceptable.
The guidance for review of this topic is provided by SRP Sections 15.4.4 and 15.4.5.
The concern is that the influx of cooler water will cause an increase in core power (due to a negative moderator reactivity coeffi-cient) which will reduce thermal margins.
The calculated minimum departure from nucleate boiling ratio (DNBR) is compared to the acceptable minimum DNBR limit to demonstrate that fuel failures will not occur.
II.
REVIEW CRITERIA Section 50.34 of 10 CFR Part 50 requires that each applicant for a construction permit or operating license provide an analysis and evalua-tion of the design and performance of structures, systems and components of the facility with the objective of assessing the risk to public health ano 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.
The General Design Criteria (Appendix A to 10 CFR Part 50) set forth the criteria for the design of water-cooled reactors.
GDC 10, " Reactor Design" requires that the core and associated cooling, control, and protection systems be designed with appropriate margin to assure that specified acceptable fuel design limits are not exceeded during normal operation. including the effects of anticipated operational occurrences.
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 20, " Protection System Functions" requires that the protection system be designed to initiate automatically the operation of reactivity control systems to assure that specified acceptable fuel design limits are not exceeded as a result of anticipated operational occurrences.
. GDC 26, " Reactivity Control System Redundancy and Capability" requires that the reactivity control system 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 such as stuck rods, specified acceptable fuel design limits are not exceeded.
GDC 28, " Reactivity Limits" requires that the reactivity control systems be designed with appropriate limits on the potential amount and rate of reactivity increase to ensure that the effects of postulated reactivity accidents can neither (1) result in damage to the reactor coolant pressure boundary greater than limited local yielding, nor (2) sufficiently disturb the core, its support structures, or other reactor pressure vessel internals to impair significantly the capability to cool the core.
These postulated reactivity accidents shall include consideration of cold water addition.
III.
RELATED SAFETY TOPICS Various other SEP topics evaluate such items as the reactor protection system.
The effects of single failures on safe shutdown capability are considered under Topic VII-3.
Topic IV-1.A addresses operation with less than all loops in service.
IV.
REVIEW GUIDELINES The review is conducted in accordance with SRP 15.4.4 and 15.4.5.
The evaluation includes review of the analysis for the event and identi-fication of the features in the plant that mitigate the consequences of the event as well as the ability of these systems to function as required.
l The extent to which operator action is required is also evaluated.
Devia-tions from the criteria specified in the Standard Review Plan are identified.
V.
EVALUATION The startup of an isolated loop was evaluated for the Yankee Nuclear Power Station in Reference 1.
Currently three (out of four) loop operation is not permitted; however, the licensee anticipates three loop operation at up to 75% power following approval of their 3 loop LOCA analysis.
Existing Technical Specifications require that the plant be at least 1%A4> subcritical before an isolated loop is placed into service.
Inter-locks prevent opening of isolated loop stop valves when the temperature of the isolated loop is 30 F (or more) lower than other cold leg temperatures.
Additionally, administrative procedures require that the boron concentration in the isolated loop be greater than the boron concentration in the rest of the primary system.
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. The analyses of the startup of an inactive loop at Yankee utilized the following assumptions:
1.
Isolated Loop Temperature is at 68 F 2.
Power is 78%, (3% calorimetric error) 3.
The most negative moderator temperature coefficient (-4.57 x 10-4 op/ F), and the least negative doppler coefficient are used.
4.
Initial flow is the 3 loop value of 78%, and the flow increase is proportional to the cross sectional flow area of the motor operated gate valve.
The transient analysis was performed with the FLASH-4 code and hot channel analysis performed with the COBRA-3C code.
Results show a power increase to 116% which causes a high flux trip at 9 seconds.
Perfect mixing of isolated loop water with higher temperature water was assumed, which gives similar results to the imperfect mixing cases as shown by comparisons of perfect and imperfect mixing on other PWRs.
The minimum DNBR is 2.97.
The system pressure did not increase above the initial value.
VI.
CONCLUSION r
The staff has reviewed the Yankee submittal on SEP Topic XV-9, Startup of an Inactive Loop.
Results of the licensee's analyses indicate that the Yankee plant is in conformance with SRP Sections 15.4.4 and 15.4.5 requirements and is acceptable.
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4 e REFERENCE Electric Company to Directorate of Licensing, f
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