ML20209F841
| ML20209F841 | |
| Person / Time | |
|---|---|
| Issue date: | 09/09/1986 |
| From: | Russell W Office of Nuclear Reactor Regulation |
| To: | Bernero R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20209C630 | List: |
| References | |
| FOIA-87-10 NUDOCS 8609120278 | |
| Download: ML20209F841 (3) | |
Text
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NUCLEAR REGULATORY COMMISSION WASmNGTON. D. C. 20555
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'....." September 9, 1986.
MEMORAt:0UM FOR: Robert M. Bernero, Director
!- Division of BWR Licensing, NRR FROM: William T. Russell, Director i
Division of Human Factors Technology, NRP.
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SUBJECT:
GENERIC REOUIREMENTS FOR BWR CONTAINMENT RESPONSE TO SEVERE ACCIDENTS The Division of Human Factors Technology concurs with the technical content of your generic letter to BWR Licensees and Applicants on " Proposed BWR Severe Accident Containment Requirements (Generic Letter 86- )." We suggest, however, for the sake of clarity, that the editorial consnents on the enclosed marked-up copy be implemented.
1 bf William . Russell, Director Division of Human Factors Technology, NRR
Enclosure:
As stated cc w/ enclosures:
H. R. Denton R. H. Vollmer R. W. Houston
. G. C. Lainas H. L. Thompson '
i G. Holahan J. L. Funches M. Srinivasan J. A. Zwolinski
- 0. R. Muller E. G. Adensam W. R. Butler l B. D. Liaw f M. W. Hodges L. Hulman ~ / g, D. B. Vassallo f01N
CONTACT: Millard L. Wohl, NRR 0 (49-29853)
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ENCLOS &E UNITED STATES
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4s, ,i NUCLEAR REGULATORY COMMISSION wassiNcros.o. c. 20sss g
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- ,, . . . . . /TO ALL BOILING WATER REAtTOR (BWR) LICE B0ILING WATER REACTOR LICENSES Gentlemen:
SUBJECT:
PROPOSED BWR SEVERE ACCIDENT CONTAINMENT (GENERICLETTER86-
) ,
l er Severe accidents doreinate the risk to theence public of assoc plant accidents.
4 Policy is,to take all reasonable stepsofto reduce such an accident >the chances should R of o a severe accident and to mitigate the consequencesThe the Reactor cne occur.
'the I.robabilities of accidents resulting inSubsequent d core melt tended towere low, but containment perfomance following a severe accident actions was poor an
, offset the benefits of low BWR core melt probabilitfes. difications and i resulting from the TMI Action Plan have led totheseveral likelihoodplant mo - -
required improvements in plant procedures to'further red of severe accidents.
accidents resulted in the fonnation of the Industry Degradedamaging a valuations
.(IDCOR) group to address the concerns related to core 20COR effort has led to industry methodo7ogy forhas The staff Indivess concluded, system reliab (IPEs) to search for the risk outMers and p has been containment performance on a plant sprJff . basis. t inment however, that for SWR containments,'a ld be possible via set of g perfomance Severe andaccident will leadanalyses to speedier haveimplemeMation indicated several than follows: areas wou for the IPEs.
improvement in BWR containments which should be prompt f urge l
- 1. Provisions should'be made for symptomatic that the lead to and vent pa*is at set pressure conditions as a dmeans ath tofor assure s
cor.tainment pressure from beyond-design-b l as a releases which will maximize the use of the suppression poo
- condensing and filtering medium. t ll _
2.
Provisions should be made for reliable operation of drywell o -
containment sprays for a broad spectrumBackup of acrident water sequ blackout sequences. ld be sources.
enhanced by providing independent water and power l sources and pumps, hose connection ld be explicitly and use of
' considered. WR Owners Group exposures' that could result from Such provisions manual d assure action development of the Emergency Procedures Guidelines.
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' should minimize the risk of implosion,and ii hydrogen combus thattheequipmentwouldbe/preservedinunfloodedcondton.
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Combustible s control provisions should provide bstantial assurance
- 3. ent failure due to hydrogen combusti n is not likely in the that contai The more likel severe accident sequences, including # blackout sequences.
periods of cperations while Mark I and II containments are deinerted while at power, particularly during potential preshutdown conditions, should be minimized by reducing the present Technical Specifications permitted value of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
- 4. Paths for core debris travel should be the Where evaluated expectedforpath conditions of debrisrepresenta-travel tive of a large scale core melt.
indicates a substantial likelihood of loss of the suppression pool as a release filtering or debris quenching medium in Mark I containments, the torus room under the suppression pool should contain a 3 foot high barrier to trap water and core debris.
- 5. Emergency procedures and training should be reviewe conditions and use plant equipment to best advantage under s conditions.
be implemented promptly following the staff's review and approval.
In addition, improved automatic depressurization system operation for station blackout response (battery backs), and drywell debris barriers in front of suppression pool vents for Mark I containments are highly desirable. The st believes that such barriers are justified if the cost does not greatly exceed about one million dollars. -
This proposed generic le'tter We has identified areas for im welcome coments on the which can be implemented at a reasonable cost. The goal is to proposed actions and other suggestions on the subject ma Sincerely, Robert M. Bernero Director Division of BWR Licensing Office of Nuclear Reactor Regulation
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