ML20028A375
| ML20028A375 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 11/01/1982 |
| From: | Dircks W NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Ahearne J NRC COMMISSION (OCM) |
| Shared Package | |
| ML20027A873 | List: |
| References | |
| REF-GTECI-A-47, REF-GTECI-SY, TASK-1.D.1, TASK-A-47, TASK-OR, TASK-TM NUDOCS 8211190330 | |
| Download: ML20028A375 (5) | |
Text
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..y NOV 011962 Decket No. 50-313 MEMORANDuft FOR: Connissioner Ahearne FROM:
Willian J. Dircks Executive Director for Operations
SUBJECT:
AE00 REPORT ON ARKANSAS UNIT 1 OVERFILL EVENT j
Your nenorandun of October 13, 1982, requested NRR's connents on two concerns identified in the AE00 Report on Arkansas Unit 1 Overfill Event and ar, assessment of the implications of the operator actions during an overcooling event on Pressurized Thernal Shock (PTS) to the reactor pressure vessel.
NRR reviewed both the draft AE00 report and the final version. Copies of previous NRR connents are enclosed and address the specific findings and recalmendations of the report.
In general, NRR agrees that steam generator overfill is an inportant concern which needs to be resolved and has on-going programs ad-dressing all of the inportant aspects of the problen. The USI A-47 (Safety Iaplication of Control Systens) is directly addressing the need for :utomatic action or adequate operator action times for protection against steam generator overfill. He agree that for sone overfill events, operator action is required in about two minutes to preclude water carryover into the main stean lines.
Automatic action should be considered unless it is concluded that the safety risks resulting from failure of the autonatic controls exceed the safety risks resulting fron the overfill event. Related activities are under way in the Control Roon Design Review (TMI Action Plan Iten I.D.1).
In addition, NRR consideration of the Pressurized Thernal Shock (PTS) concern is addressing control system nalfunction (particularly excessive feadwater flow) as a potential cause of PTS.
NRR has considered both th9 probability and consequences of stean generator overfill events in deternining that continued plant operation is justified while the above mentioned programs are being pursued.
For example, the probability of a control systen failure resulting in excessive feedwater flow (similar to the Rancho Seco " light bulb event") was specifically addressed in the ftRR study justifying continued operation in light of the PTS Concern.
The resolution of USI A-47 will establish the requirenents and review criteria for steaa generator overfill protection. At that time all operating PRR's will be reviewed against those criteria.
In the mean tine, several B&W plant licensee's have voluntarily committed to or are considering feedwater systs, nodifications which may resolve the OTSG overfill concerns.
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i The enclosed Table 1 provides a status of B&W OTSG Overfill Protection. As indicated in this status, actions by licensees are underway which nay resolve or nitigate the overfill concern even before the implementation of requirements stenning fron US'I A-47 These voluntary changes are being reviewed to assure that safety related functions such as auxiliary feedwater initiation are not adversely affected; however, their effectiveness in preventing stean generator overfill is not being evaluated since the requirenents and criteria in this area have not been formulated.
(Signed) Jack W. Roe William J. Dircks i
Executive Director for Operations
Enclosure:
As Stated cc:
l SECY Chairnan Palladino Connissioner Gilinsky Connissioner Asselstine Connissioner Roberts OPE OGC DISTRIBUTION
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. The enclosed Table I provides a status of B?A OTSG Overf111 Protection. As indicated in this status, actions by licensees are underway which may resolve or mitigate the overfill concern even before the implementation of requirenents sterming from USI A-47.
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we s-y J illiam J. Dircks Y Executive Director for Operations
Enclosure:
As Stated cc:
SECY Chairnan Palladino Comissioner Gilinsky Connissioner Asselstine Comissioner Roberts OPE OGC DISTRIBUTION iDocket. File w/inc;"y Cunningham NRC PDR LUnderwood L PDR PPAS ED0 Rdg SHanauer ORB #4 Rdg RMattson WDircks Riot 1ner HDenton HThompson ECase PCheck DEisenhut BSnyder OELD OCA-3 AE0D MBridgers Program Support, NRR MGarver JStolz MStine w/inc. & ticket RJacobs w/inc. & ticket RIngram Gray File, Rm 416 Green ticket file w/inc. & ticket, Rm. 416 IE
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(pm. t.au W1111ao J. Dircks Executive Director for Operations
Enclosure:
As Stated cc:
SECY PE GE DISTRIBUTION eDocket.f11e w/incP Cunningham NRC PDR LUnderwood L PDR PPAS ED0 Rdg SHanauer ORB #4 Rdg RMattson kDircks RVo11mer HDenton HThompson ECase PCheck DEisenhut BSnyder OELD OCA-3 AE0D M ridgers Program Support, NRR MGarver JStolz MStine w/inc. & ticket RJacobs w/inc. & ticket RIngram Gray File, Rm. 416 Green ticket file w/inc & ticket, Rm. 416 IE SECY
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TABLE 1 STATUS OF BW OTSG OVERFILL PROTECTION Plant
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ANo.1 The licensee has proposed main feedwater isolation on high level plus a safety grade emergemcy feedwater level control system Crystal River 3 The licensee has proposed. main feedwater. isolation on high level plus a safety grade emergeracy feedwater level control system Rancho Seco The licensee has proposed main feedwater isolation on '
high level plus a safety grade emergemcy'feedwater 1evel control system Midland The licensee has proposed main feedwater isolation on high level plus a safety grade emergemey feedwater level control system THI-1 The license 6 has comited, at the restart hearings, to provide oversfill protection Da vis-Bes se The licensee has informally indicated -that a system.
like the AND-1 overfill protection. syr-tem is being considered 0:enee 1/2/3 These units have control grade high'le vel protection for tripping the main feedwater pumps '.(no overfill protection is included for the emerger.::y feedwater system)
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