ML20077F936
| ML20077F936 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 07/29/1983 |
| From: | Harrington W BOSTON EDISON CO. |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20077F939 | List: |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3.28, TASK-TM 83-202, NUDOCS 8308030216 | |
| Download: ML20077F936 (6) | |
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50sTON EDIDON COMPANY B00 BOvLaTON STREET 90sTON. MASSACHUSETTS 02199 WILLIAM D. HARRINGTON stween viss pareensar mom.
July 29, 1983 BECo Letter No.83-202 Mr. Domenic B. Vassallo, Chief Operating Reactors Branch #2 Division of Licensing Office of 'luclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 License No. DPR-35 Docket No. 50-293
Subject:
Response to Request for Additional Information - NUREG-0737, Item II.K.3.28, Qualification of ADS Accumulators.
Reference:
(A) NRC Letter (D.B. Vassallo) to Boston Edison Company ( A.V. Morisi),
dated May 11, 1983.
Dear Sir:
In Reference (A) eleven questions were submitted to Boston Edison Company in which additional information was requested regarding our position on NUREG-0737 Item II.K.3.28.
The Attachment to this letter provides responses to all of the submitted questions.
This information should be adequate for you to complete your review of this Item.
l Should you have any additional questions regarding this subject, please de not hesitate to contact us.
I Very,truly you l
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Response to Request, for A[iditional Inforniation NOREG-0737, Item II.K.3.28, Qualification of ADS Accif6iolators g t
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Ouestion No. 1
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e When taking into account leakage, seismic events pad harsh enyigprenent, what'is the length of time the accumulators are available to perform their function, both at normal containment pressure and at a speciff e'd percent (i.e.,' 70%) of drywell pressure, following an accident? Does this meet the requirements :5pecifieddn the plant's FSAR?
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Response
s The ADS accumulator system does meet the requirements of the Pilgrim Station s
FSAR in this area.
Our calculations show that at 41.7 psia drywell pressure, the accumulators, main-tain capacity to allow for twenty actuations of each valve within a time perjod i
of eight hours following a loss of instrument air supply. 41.7 psia corresponds to approximately 50% design drywell pressure and is consistent with the highest pressure specified in FSAR Section 5.2.
Analyses of accidents which lead to higher drywell pressures do not consider actuation of ADS.
FSAR Section 7.4 specifies that each accumulator snall have the capacity for twenty actuations of the corresponding safety relief valve. The eight hour time period is consistent with the analysis of the integrated operation of core standby cooling systems given in FSAR Sectior 6.5 and the Pilgrim Station operating procedures.
Question No. 2 Describe the ADS accumulator system design and operation (e.g., trains, air supply, capacity, alarms, instrumentation, and their location, etc.).
Response
The function of the ADS accumulator system is to provide a reserve of compressed air or nitrogen for operation of the ADS relief valves in the case of a failure of the drywell instrument air supply.
The ADS accumulator system consists of the following components:
o accumulators T221 A-D o accumulator pressure relief valves RV9084 A-D o accumulator drain line isolation valves o solenoid valves SV203-3 A-D o check valves between accumulators and air supply 1
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and the following piping:
o 1" instrument air lines bounded by check valves, accumulators and ADS relief valves o 3/4" lines from accumulators to the respective drain line isolation valves and accumulator pressure relief valves The ADS control circuitry is not included in the ADS accumulator system.
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All of this equipment is located in the drywell.
Except for pressure gauges that are temporarily installed for leak rate testing, there are no alarms or instrumentation associated with the system.
See the enclosed sketch (Enclosure No.1) for a diagram of the system.
Question No. 3 Define the basis for the allowable leakage criteria for the ADS accumulator system (e.g., boundary conditions, environmental, and seismic parameters, operator interface, margin, etc.).
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Response
Allowable leakage is that which maintains the capability of the ADS accumulator system to function as described in the response to Question 1.
Testing of the accumulators is carried out by a pressure decay measurement test over a four hour period.
Question No. 4 What margin is in the allowable leakage criteria to account for possible increase in leakage resulting from the effects of a harsh environment and/or a seismic event.
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Response
There is no margin in the allowable leakage criteria to account for possible l
increase in leakage resulting from the effects of a harsh environment or seismic event. The ADS accumulator components are seismically qualified. Harsh environ-ments in the drywell do not adversely affect the mechanical components of the ADS accumulator system. Non-metallic portior,s of the mechanical components (i.e.
the soft seating materials in the check valves) are able to withstand the dry-well harsh environment.
Steps are being taken to ensure that the soft seating material in the check valve will be replaced as required by environmental condi-tions. Environmental qualification of electrical components of the ADS accumula-tor system is addressed in the response to Question 5 and are environmentally qualified with the exceptions stated therein. Hence, the harsh environment and/
or seismic event should not lead to an increase in leakage.
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Ouestion No. 5 A statement that test and/or analysis performed verified that a harsh environment and/or seismic event would not increase the leakage rate.
Response
Only electric equipment requires qualification to the drywell harsh environment.
The only pertinent electric equipment are the solenoid valves (see response to Question 2). These are qualified with the exception of qualified life analysis and integration into the plant maintenance program. The exceptions will be addressed in the IEB 79-01B long term program. The qualification of the solenoid valve is documented in Wyle Laboratories Report No. 17446-13.
(see also BEco Letter 83-129).
The method of seismically designing each of the items listed in the response to Question 2 was investigated. The investigation indicated that all pertinent equipment was designed for Seismic Class I.
A number of documents which support this conclusion are available for review.
Question No. 6 A statement that verifies that no credit was taken for non-safety related equip-ment and instrumentation when establishing the allowable leakage criteria.
Response
The equipment listed in the response to Question 2 is that credited for action in the analyses of the leak rate performance of the ADS accumulators.
All of this equipment is listed in the Boston Edison Company 0-List, and is therefore safety-related.
Question No. 7 Define the periodic leak testing of the ADS accumulator system (i.e. the time interval between these leak tests, along with a concise description of the test procedure employed).
Response
Leak testing of the ADS accumulator system is performed once per operating cycle, but not to exceed two years. The test procedure is succinctly outlined in the enclosed Pilgrim Nuclear Power Station Procedure 8.7.1.10, Revision 3, Pressure Test ADS Accumulator System Integrity (Enclosure No. 2).
Ourstion No. 8 A concise description of the surveillance performed, and how frequent, on alarms and instrumentation associated with the ADS accumulator system.
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Response
The question is not applicable to the ADS accumulator system because there are no associated alarms or instrumentation. See response to Question No. 2.
Question No. 9 V
A statement that confirms that the ADS accumulator system, associated equipment and control circuitry, are seismically qualified.
Response
See response to Question No. 5.
The ADS accumulator system and associated equip-ment are classified as Seismic Class I.
Question No. 10 A statement that confirms that tne ADS accumulator system and associated equip-ment and control circuitry are environmentally qualified for conditions associated with nonnal operation, maintenance, testing, and postulated accidents.
Response
See response to Question No. 5.
The conditions listed in Question No. 10 are addressed in the qualification to the drywell harsh environment.
Question No. 11 A statement verifying that the ADS valves, accumulators, associated equipment and i
instrumentation are capable of performing their function during and following an j
accident situation while taking no credit for non-safety related equipment and instrumentation.
Response
The equipment listed under Question 2 is the only equipment required for the function of the ADS accumulator system as specified in the FSA<.
As discussed in our response to Question No. 6, all of this equipment is safety-related. No non-safety-related equipment is required.
In particular, the drywell instrument air supply, which is not safety-related, is not required.
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Enclosure No.1
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