ML17326A595
| ML17326A595 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 02/29/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17326A594 | List: |
| References | |
| NUDOCS 8003310224 | |
| Download: ML17326A595 (7) | |
Text
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+O Wp*~4 UNITEDSTATES NUCLEAR REGULATORYCOMMlSSION WASHINGTON, O. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.36 TO FACILITY OPERATING LICENSE NO.
DPR-58 AND AMENDMENT NO. 18TO FACILITY OPERATING LICENSE NO.
DPR-74 INDIANA AND MICHIGAN ELECTRIC COMPANY DONALD C.
COOK NUCLEAR PLANT UNIT NOS.
1 AND 2 DOCKET NOS. 50-315 AND 50-316 Introduction In r esponse to NRC staff letter dated August 1, 1979, the Indiana and Michigan Electric Company, the licensee submitted, by letter dated October 25, 1979, a
proposed license condition requiring implementation of a secondary side water chemistry monitoring and control program, and requested the present Technical Specification on secondary side chemistry, and the related surveillance require= ---
ments associated with those Technical Specifications, be deleted.
By letter dated November 30, 1979, the licensee submitted the control logic for an alarm designed to alert the reactor operator to possible loss of flow in the residual heat removal system.
This submittal was to satisfy a license condition on the D.C.
Cook Unit No. 2, Facility Operating License.
Discussion and Evaluation Secondar Water Chemsstr
- Addition of a Licensin Condition in Place of Ex>stin Technical S ecifscatsons The NRC staff recognizes that different utilities use different secondary water treatment methods to limit steam generator tube corrosion.
- Moreover, we recognize that a licensee's choich of a particular water treatment
- method, including specific values of operating limits for chemistry parameters, is governed by plant and site characteristics that are unique to each facility.
In addition, we do not believe at this time that sufficient service experience exists to conclude that any particular method is superior to another for controlling impurities that may be introduced into the secondary coolant.
Such experience would be necessary before prescriptive Technical Specifica-tions on secondary water chemistry could, with assurance, minimize tube degradation.
Restricting the amount of chemical additions to control the water chemistry parameters would not ensure the desired steam generator operating conditions.
Realizing that meeting the secondary coolant water quality criteria would not SIIossr s~yq.
e
-2" be possible during all periods of operation, it is necessary that the most effective procedure for reestablishing out-of-specification chemistry parameters be available without unduly restricting plant operations.
This can be accomplished most rapidly by continuing to operate the unit so that chemical additives to the secondary water can be made 'to achieve a balanced chemistry.
In particular, we have concluded that the Technical Specification on secondary water chemistry does not provide adequate flexibilityto allow desired water conditions to be achieved gradually or ensure long-term tube integrity.
In addition, these specifications may not limit specific types of severe tube degradation, particularly "denting."
Furthermore, the possible adverse effects of any secondary water parameter limits on the steam purity that could lead to potential failure of rotating turbine components must also be considered before specific limits are required.
,We believe that other methods for reducing the impurity concentration in the steam generator such as periodic chemical cleaning for long-term solution, fluxing or free surface boiling for an intermediate term solution, or the use of chelating agents for the control of secondary water purity are more practical'hese methods are likely to be more effective in limiting corro" sion than specific Technical Specifications that may lack the flexibility needed for proper control of secondary water chemistry.
The NSSS vendors are now considering these alternate methods in lieu of -restrictive secondary water chemistry limits for assuring steam generator tube integrity.
We proposed that the licensee implement a secondary water chemistry monitoring program to-inhibit steam generator tube degradation.
By letter dated October 25, 1979, the licensee agreed to the program and applied for a license amendment to so condition the license.
In addition, other existing Technical Specification limiting conditions for operation and surveillance requirements for secondary water monitoring require-ments provide assurance that steam generator tube integrity will not be reduced below an acceptable level for adequate margins of safety.
These specifications are:
1.
Technical Specification 3.7. 1.4 - Secondary Water Activity Monitoring Requirements.
2.
Technical Specification 3.4.6.2 - Primary to Secondary Leakage Rates.
3.
Technical Specification 3.4.5 - Steam Generator Tube Surveillance and Plugging Criterion Based on the above, we conclude that a license condition requiring a
secondary water chemistry monitorinq program is an acceptable replacement for Spe=ifications 3.7.1.6 and 4.7.1.6 and Tables 3.7-3 and 4.7-3 of the existing Technical Specifications.
Residual Heat Removal S stem Low Flow Alarm - Removal of License Condition The D.C.
Cook Unit No.
2 residual heat removal (RHR) system includes a single suction line with isolation valves in series.
During the original review of
w 3 the Unit 2 Facility Operating License application, it was determined that inadvertent closure of one of these valves during RHR operation would result in loss of RHR flow and possible failure of the RHR pump.
Since the RHR system provides normal core cooling during shutdown and long-term cooling following an accident, the integrity of the RHR system is important.'o protect against the possible loss of the RHR pump, the applicant proposed an alarm to alert the operator to loss of RHR flow.
A license condition was added to the Facility Operating License No.
OPR74 reflecting the licensee's proposed actions and commitments.
The license condition is as follows:
2.C(3)(l) "Residual Heat Removal S stem Low Flow Alarm Indiana and Michigan Power Company shall prior to startup, following the first regularly scheduled refueling outage, develop and submit for Commission review and approval the control logic for an alarm designed to alert the reactor operator to possible loss of flow in the residual heat removal system.
Following initial startup and prior to installation of the alarm, Indiana and Michigan Power Company shall station an operator at a local panel to monitor cool-down flow when the residual heat removal system is in operation and the vessel head is in place."
On November 30, 1979, the licensee submitted the control logic for the alarm as required by the license condition.
The alarm was installed and tested-prior to October 4, 1979.
The alarm will be actuated if either or both RHR pump(s) is (are) operating and if the RHR flowrate should drop below 2000 gallons per minute.
The alarm which has been described is acceptable to satisfy the commitment in the license condition, and with this commitment satisfied, the D.C.
Cook Unit 2 plant may be released from the requirement to provide a dedicated operator to monitor cooldown flow when the RHR system is in operation and the vessel head is in place.
Accordingly, the license condi-tions have been met and the license condition 2.C(3)(l) on Residual Heat Removal System Low Flow Alarm may be removed from the Unit 2, Facility Operating License.
Environmental Consideration Me have determined that the amendments do not authorize a change in effluent types or total amounts nor an increase in power level and will not result in significant environmental impact.
Having made this determination, we have further concluded that the amendments involve an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR f51.5(d)(4),
that an environmental impact statement or negative declaration and environ".
mental impact appraisal need not be prepared in connection with the issuance of these amendments.
Conclusion Me have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the
probability or consequences of accidents previously considered and do not inVolve a significant decrease in a safety margin, the amendments do not involve a significant'azards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, and (3) such activities will be conducted in com-pliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Date:
February 29, 1980