ML20234B030
| ML20234B030 | |
| Person / Time | |
|---|---|
| Site: | Shoreham File:Long Island Lighting Company icon.png |
| Issue date: | 09/15/1987 |
| From: | Boger B Office of Nuclear Reactor Regulation |
| To: | Thadani A Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8709180239 | |
| Download: ML20234B030 (3) | |
Text
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September 15, 1987 cv-ww e
MEMORANDUM T0: - Ashok C. Thadani, Assistant Director Assistant Director for Systems
'FROM:
Bruce A. Boger, Assistant Director for Region I Reactors Division of Reactor Projects I/II
SUBJECT:
SAFETY REVIEW 0F THE PROPOSED SUPPLEMENTAL CONTAINMENT SYSTEM
.(SCS) FOR SHOREHAM i
L
-As you are aware, the Long Island Lighting Company (LILCo) is preparing to proceed with contractual commitments for the design'and construction of the SCS for Shoreham.- In a meeting which you attended on July 21, 1987, the staff raised a number of safety concerns about the SCS (see Enclosure 1, Meeting Summary). LILCo has reviewed the meeting transcript and wishes to resolve the staff's concerns and obtain the staff's guidance on design and procedural requirements before proceeding)further on the SCS project.28, 1987 (Enclo By letter dated August staff's questions. LILCo will supplement this letter in October, 1987 to complete its ' retponses.
l
.We request DEST to perform a safety review and prepare an SER on the SCS for Shoreham. The purpose of the review is to assure that the SCS does not degrade overall safety at the Shoreham Station.
If the staff's safety concerns can be resolved through this review process, LILCo can perform a 50.59 review based on the staff's SER and document the design features of the SCS in its periodic update of the Shoreham FSAR. On the other hand, if the review' indicates that licensing actions in the form of new License Conditions or changes to the Technical Specifications would be required, LILCo would like to be informed of those requirements.
Finally, the review should also reflect the staff's guidance (which LILCo has. requested) on the various design bases for the SCS.
Ronnie Lo will be coordinating your review activities in this area with those of other groups within NRR and Region I.
la/
Bruce A. Boger, Assistant Director l
for Region I Reactors Division of Reactor Projects I/II
Enclosures:
As stated DISTRIBUTION:
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VEMORANDUM T0: Ashok C. Thadani, Assistant Director Assistant Director for Systems Fh0M:
Bruce A. Boger, Assistant Director for Region I Reactors Division of Reactor Projects I/II
SUBJECT:
SAFETY REVIEW 0F THE PROPOSED SUPPLEM TAL CONTAINMENT SYSTEM (SCS) FOR SHOREHAM N
As you are aware,Nthe Long Island Lighting Co any (LILCo) is preparing to proceed with contractual commitments for the design and construction of the SCS for Shoreham.
In'Nt meeting which you tended on July 21, 1987, the staff raised a number o hpafety concerns bout the SCS (see Enclosure 1, Meeting Summary).
LILCo ti reviewed e meeting transcript and wishes to resolve the staff's concerns nd obt n the staff's guidance on design and procedural requirements before ro eding further on the SCS project. By l
letter dated August 28,1987(En osure 2), LILCo has responded to some of the staff's questions.
LILCo will upp ment this letter in October, 1987 to complete its responses.
i We request DEST to perfor a safety revie nd prepare an SER on the SCS for
)
Shoreham.
The purpose the review is to a ure that the SCS does not l
degrade overall safety at the Shoreham Station.
If the staff's safety concerns can be res Tved through this review proc s, LILCo can perform a 50.59 review base n the staff's SER and document he design features of the
.,l SCS in its peri c update of the Shoreham FSAR.
On e other hand, if the I
review indica s that licensing actions in the form of n License Conditions i
or changes t the Technical Specifications would be requir
, LILCo would like to be info ed of those requirements.
Finally, the review s uld also reflect the staff s guidance (which LILCo has requested) on the variou design bases for thVSCS.
Ro n to will be coordinating your review activities in this area w those o other groups within NRR and Region I.
N.
Bruce A. Boger, Assistant Director for Region I Reactors Division of Reactor Projects I/II
Enclosures:
As stated DISTRIBUTION:
Docket File RLo/GRivenbark NRC PDR/LPDR OGC - Bethesda PDI-2 Reading EJordan SVarga/BBoger JPartlow W8utler ACRS (10)
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Septeober 15, 1987 a
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MEMORANDUM TO:.Ashok C. Thadani, Assistant Director Assistant Dircctor for Systems FROM:
Bruce A.,Boger; Assistant Director i
for Region 1 Reactors i'
Division of Reactor Projects I/II
SUBJECT:
SAFETY REVIEW 0F THE PROPOSED SUPPLEMENTAL CONTAINMENT SYSTEM (SCS) FOR SHOREHAM j
5 i
~
As you are aware, the Long' Island Lighting Company (LILCo) is preparing to proceed with contractual commitments for the design and construction of the SCS for Shoreham.
In'a meetirg which you attended on July 21, 1987, the staff raised a number of safety concerns about the SCS (see Enclosure 1, j
Meeting Summary).
LILCo has reviewed the meeting transcript and wishes to resolve the staff's concerns and obtain the staff's guidance on design and procedural requirements before proceeding)further on the SCS project.28, 1987 (Enclosuj By
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letter dated August staff's questions.
LILCo will supplement this letter in October,1987 to i
complete its responses.
I We request DEST tol perform a safety review and prepare an SER on the SCS for Shoreham. The purpose of the review is to assure that the SCS does not degrade overall safety at the Shoreham Station.
The SER will identify the conditions under which the staff finds =the SCS acceptable.
Finally, the review should i
also reflect the staff's guidance (which LILCo has requested) on the various l
design bases for the SCS. :The conclusions of the review will form the bases for LILCo's decisions with respect to the SCS.
Ronnie Lo will be coordinating your review activities in this area with those of other groups within NRR and Region I.
Bruce A. Boge, Assistant Director for Region I Reactors Division of Reactor Projects I/II
Enclosures:
3 As' stated 1
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July 28, 1987 s
...s Docket No.-
50-322 I
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LICENSEE: Long Island Lighting Company FACILITY: Shoreham huclear Station, Unit - 1 1
d
SUBJECT:
SUMMADY OF MEETING WITH LILCO ON JULY 21, 1987 REGARDING THE DES:GN l
OF A SUPPLEMENTAL CONTAINMENT SYSTEM (SCS)
At the request of Long Island Lighting Company.(LILCo), a meeting between thi.
I NRC staff and the management of LILCo was held in Bethesda, MD, on Jdy 21, l,
c 1987.
The purpose of the meeting was for the staff to receive a briefing from 1
LILCo on its plan to design and construct a Supplemental Containment Syster' (SCS) for the Shoreham Nuclear Stetion. The discussions in the meeting were transcribed and e copy of the transcript is provided as Enclosure 1.
The principal speake-s included LILCo's Vice President, Mr. John Leonard and Dr. Thonas Murley who led the' staff in discussing the safety aspects of the SCS. The meeting was also attended by Mr. Gregory Minor, representing Suffolk Courty, N.Y., which is a party intervening in the licensing proceedings of the Shoreher plant. A list of attendees, along with the viewgraphs used in LILCo's presentatier are included in Enclosure 1.
The following summary notes!the saliert peints of the discussior. The associated pages of the transcript I
are shown in parentheses.
The primarv pu*oose of the SCS is to provide a mechanism to relieve the pressure in tha wetwell Pirspace for a class of low probability /high consequence severe accidents which could challenge the structural integrity o' the containment (9). The Shoreham containment design pressure is 48 psig and the ultimate structural pressure is approximately 130 psig (10). The pressure setpoint o' the rupture disc in the vent path leading to the Filtra Building of the SCS wil1 be set at 60 psig. This setpoint is chosen to ensure the integrity of the drywell floor seal (12). The Filtra Building will be similar to the j
Swedish installatier at the Barseback plant.
It consists of a steel-lined concrete structure with a volume of 10,000 cubic meters containing about 14,000 kg of quart 71te-type gravel material as the filter medium (22). The design basis for the SCS is OA Category I to the Containment Pressure Boundary (CpB) j and QA Category 11 beyond the CPB. The mechanical design basis is ASME !!1, Class 2 up to the CPR and ASME 111, Class 3 beyond the CPB (31,88).
The main concerns raised by the staff during the meeting were related to assurance that no potentially unsafe conditions will be introduced by the SCS. The following is a highlight of some of the staff's concerns and questions:
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l How will the activatior cf filtered venting be considered in conjunction with the unfiltered venting procedure in the EOD (18).
Analyses to cuertify the reduction of public risk (24).
' " yi Analyses on the releases frorr the SCS in new accident sequences where the containment is recoverable (25, 26, 41-43, 50).
Response nf tre SCS to a short duration pressure pulse in the containment (38).
t Analyses *cf acccident sequences which could lead to pump cavitation and co-e dz.r.ege. beceuse: nf the pressure relief, although the containment integrity is mairtainad (44, 52-54).
Ctecerns about the potential of the containtnent approaching a negative
.r,ressure,in the ever.t that the containment spray is activated (81-83).
I U LCo irtends to review the trarscript and respond to the steff's concerns which.
are not limitec tc those highlighted above. LILCo would wish to obtain the resolution of' tN safety concerns and staff guidance or design requirements id; prior to comMtting major design and construction contracts. (104). The schedule for project completion is 36 months following the award of the design Contract.
. Ic Y c Ronnie Lo, Project Manager Project Directorate PDI-2 Division of Reactor Projects 1/11 Enclosura:
As stated cc w/o enclosure:
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[gg LONG ISL.AND LIGHTING CO,MPANY SHOREHAM NUCLEAM POWE8t STATION m,.m P.O. BOX 915. NORTH CQuNTRY Mc AD 6 WACING RtVsR, N.Y.11782 JOHN D. LEONARD, JM.
viet pat 10LNr.stuct.tu ott A Atrons AUG 28 587 suRC-1367 U. S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, DC 20555 Supplemental Contaitiment System,the Proposed Request for Concurrence with (SCS) Plan and Response to 8taff Concerns Sboreham Nuclear Power Station Docket No. 5C 322 Gentlemen l._
LILCO has reviewed the' transcript of the July 21. 1987 meeting
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With the Staff concerning the proposed Supplemental Containment System (SCS) for Shoreham.
The purpose of our review was to
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identify an4 respond to those concerns raised by the Staff during the presentation, that were over and above those specifically highlighted in the Staff's letter to LILCO dated July 26, 1987.
In accordance with the results of the review, attached are formalized LILCO responses to the Staff's questions.
The pages of transcript associated with each Staff question are shown in Currently, it is our intent to respond to those parentheses.
additional questions highlighted in the July 28 letter in October.
The October submittal date is governed b the scheduled completion date of the currently on-going PRA anal sisi the results of which will be used to respond to the hi blighted questions.
In order for LILCO to proceed in a deliberate manner with the design and construction of the Supplemental Containment System, it is necessary to determine the appropriate criteria to which it should be built.
We have determined that that portion from the primary containment to the two containment isolation valves, rupture disk, and assooisted controls, should be treated as safety related and built in accordance with Shoreham's Category I otandards.
We have also determined that the part of the
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Alf, 31 87 11 : 30 P,3 SNRC-1367 Page 2 Supplemental Containment System which is downstream of the isolation valves and rupture disk should be built to standards appropriate with a Category II designation.
This has a significant impact on the cost of this system.
l For LILCO to proceed on a deliberate basis with the engineering l
of the. Supplemental Containment System, we request your concurrence in these two broad, general categories, with the understanding that the Staff reserves the right to review and comment.upon the detailed design submittal which will be forwarded to you as the design is finalized.
Should you desire to discuss our request further, or require any additional information, please do not hesitate to contact my office.
'7 vary truly yours, 3
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J D.
on r, Jr.
Vi e President - N'c1 ar Operations hc L/ lac
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Enclosures cc W. Russell - Region I Administrator R. Le C. Warren
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403 31 '87 11:3G p,4 Attachment
.NRC Staff Concerns 1.
Why does Shoreham need a vent (FILTRA) that will not accomplish the same purpose as venting? (10)
The purpose of the Supplemental Containment Systam Response: (SCS) le to improve upon the venting capability already installed at Shoreham.
The SCB provides an engineered passive primary containment wetwell airspace vent with the ability to control releases for post accident management.
Existing venting capabilities, including those currently available through the implementation of the EPG Revision 4 guidelines, have limitations in their ability to What mitigate certain types of severe accidents, the SCS does is to increase the venting capability to cope with those accidents currently within the exieting venting abilities plus additional severe accident scenarios, The SCS has the added benefit of also being able to filter the releases, signifi-cantly reducing the extent of radioactive particu-late that could be r'eleased to the atmosphere during a severe accident, 3
fk 2.
Has LILCO looked at the possibility of the drywell head remaining intact at 130 psig, the ultimate capacity? (10)
In support of the 1983 Shoreham Probabilistic Risk
Response
Assessment (PRA), the drywell head was analyzed to determine its ultimate structural capacity along with other structural elements of the primary The results of this analysis showed containment, that the drywell head reaches a general yield state At this pressure, at approximately 130 psig.
relaxation of the 0-ring seal between the drywell head flanges was found to be negligible..Contain-ment structural integrity is being considered in the current PRA efforts, the results of which will l
be provided in the October submittal.
Has the omegs seal (connecting the drywell floor with the 3.
containannt wall) been analyzed for failure at high temperature? (12) has been Responses The omega seal (drywell floor seal) analyzed to ensure its ability to function,during The the DBA-LOCA conditions of 48 psig and 340 F.
functional and environmental material testing programs for the drywell floor seal are detailed in subsection 3.9.1.7.2 of the USAR.
The drywell 4 'f floor seal has not been specifically analyzed at the higher temperatures associatsd with those
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AUG 31 '87 11:36 P.5 l
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l Attachment
$NRC-1367 Page 2 l
accidents outside of the design basis of the plant.
Bowever, the design basis for the SCS has been established assuming that drywell to wetwell bypass exists.
Is LILCO planning to contract with a Swedish company for the 4.
SCS project or simply planning to buy the rights to the design, including the calculations? (22,23)
LILCO is presently engaged in contract negotiations I
Response: with SwedPower, who Vlli provide us with the technology, design documents, research data and licensing support for the FILTRA structure and the auxiliary building.
The balance of plant (B0p)
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i engineering, which represents the scope of work l
from the primary containment penetration out to the auxiliary building, will be competitively bid to an j
I architect-engineer.
Do the dissimilarities of Barseback and Shoreham make a big 5.
difference in terms of copying the desigo? (32) s Through design discussions with SwedPower, LILCO has evaluated the ability to utilise the Barseback Responset We have "7
design to meet Shoreham's design criteria.
concluded it is feasible to adapt the Barseback FILTRA design to Shoreham.
6.
What is the pressure at the vent top? (35)
[
Pressure relief capabilities locktad at the top of
Response
the Shoreham vent structure are comprised of two The high capacity (large discharge lines.
diameter) discharge line is equipped with relief valves set at approximately 45 psig, and a rupture disc to maintain the nitrogen atmowphere and pro-tect the relief valves from the outside environ-It should be noted that the incorporation of ment.
the relief valves is still under consideration.
is The low capacity discharge line (rms11 diameter) equipped with a remote manusi valve and ruptureThis disc which actuates at approximately 4 psig.
low capacity line is normally valved off (locked) and is only used in long term recovery to depressurize the FILTRA.
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90G31['8714:42 P.2 a
Attachment SNRC-1367 Page 3 C.
7.
What'is the seismic design category of the SCs? (45)
Response
The SCS is an added safety measure which is neither required nor relied upon to'most the plant design basis.
Accordingly, LILCO has classified the SCB as QA Category I up to the containment interface (i.e.r the two safety-related isolation valves and rupture disk) and QA category II for the balance of the system.
However, in view of the significance of the ses in mitigating severe accidents beyond the design basis of the plant, the main process system of the sc8 (i.e., passive filtering and venting) will be designed to the seismic loading criteria established for the licensing basis of the Shoreham plant.
Thus, those structures, systems, and components whose failure may affect the critical functions of
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the BCS will, in general, be designed to seismic j
Category I leads and criteria as specified in the Shoreham USAR and other applicable documents. Using this definition, Seismic Category I requirements will be followed as a guide for the design of the
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FILTRA structure, auxiliary building, and all
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structures and components directly associated with the primary vent path.
In addition, the main process system and, in particular, the FILTRA and auxiliary building shall be designed for the 9
effects of tornado leading.
80 Discuss inspection and testing requirements for the SC8 (46, 94)
Responses An appropriate prnoperationni test program will be developed for the BCs.
Testing will include routine equipment checkout and various power and logic circuit checks, special tests beyohd these requirements will be formulated at a later date.
9a Discuss the isolation valves with respect to operator actions. (48)
Response: The design philosophy of the SCS is that the acti-vation is a passive function requiring no operator action.
Accordingly, the normal position Of the i
containment isolation valves in the main process piping is the open position, system logic is such that if flow is detected in the discharge line with l.
pressure less than the containment design pressure, the containment isolation valves will close.
In I
the other case where the containment pressure rises to a point beyond a 55 psig permissive and flow 1
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AUG 31 f87 11:43 P7 Attachment
'SNRC-1367
,Page 4 Y '
is detected, system logic will cause the containment isolation valves to remain open.
The logic will be sealed in auch a way that the~ valves l
Will not close should the pressure subsequently fell below the 55 psig permissive.
The isolation 4
valves upstroon of the rupture disc can be operated.
Pro-by remote manual control in the control room.
cedures will be developed to instruct the operator when to open or close the valves.
The containment isolation valves in the smaller drywell vent line leading to the FILTRA structure i
are normally closed and can be manually activated from the control room operator for long term venting.
Procedures will also be developed to instruct the operator in the use of these valves,
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- 10. Could the step to lower the water level in ATWB procedures be eliminated? (56)
The SCS will allow dreater flexibility for the
Response
operator to cope with higher power levels in an ATWS situation.
With this additional benefit, there is no need to eliminate the step'in the ATWS
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. procedures that directs the operator to lower water level.
At this time, LILCO anticipates that the basic philosophy in dealing with an ATWS will remain the same,
- 11. Has LTLCO looked at the radial displacement of the l
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containment at 60 psig? (58)
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Radial displacement considerations have currently
Response
not been evaluated since only a conceptual piping layout has been developed.
However, as part of the detailed piping design, stress analyses will be performed to evaluate the effects of radial displacement of the containment.
This process will ensure that the 808 piping system will accommodate l-any displacement and prevent excess stress on both the pipe and containment.
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- 12. Provida a clarification of the valves in the FILTRA building, including controls on the valves. (62) (87)
The FILTRA is designed to accommodate flow through Response: a high capacity discharge line (30 inch diameter),
but is also equipped with a low capacity discharge l
line (12 inch diameter).
The normal flow path is b#
through the high capacity line with its corres,
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Al)G 31 '87 11:46 P,8 Attachment SNRC-1367 Paga 5 J
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ponding main isolation A0V maintained in the open, position.
The low capacity discharge line is primarily used for the depressurisation of the FILTRA during post accident recove n activities.
Hence, the main isolation A0V in this line is normally closed.
However, since these valves are remotely operable, the operator does have the i
capability of manipulating these valves to alter the flow path through the low flow capacity line should conditions necessitate such action.
Procedures will be developed to instruct the operator in the use of these valves.
- 13. Will the SCS have a flow element on the system for normal type operation? (64) 7 l
Response
Flow measuring devices will be incorporated in the design of the SCS.
The current design configur-ation incorporates flow measuring devices in the l
I vicinity of the containment isolation valves that interplay with the talve logic as previously divoussed in question 9.
Additional flow measuring devices will be included in both the high and low capacity discharge lines to monitor any releases to the environment.
- 14. Are there provisions for makeup water to the suppression pool in ATWS sequences?
(67; Responser The volume of water in the suppres.sion pool, reactor, and condensate storage tank are significantly larger than the FILTRA itself can condense.
In any accident, many hours of steam production would have to occur before experiencing any significant depletion of water inventory.
There is no new system needed to make up inventory as a result of the 80S installation.
- 15. Has any evaluation been done on the possibility of a water and steam mixture going through the vent as a result of the containment sprays? (70)
Response
Two phase flow in the vent line due to containment spray operation is not considered to be significant.
The containment sprays are located in the drywell, which is sealed off from the wetwell airspace, where the vent opening is located.
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Therefore, contribution from these sprays is not of significance.
ALG 31 "'87 11: 50 P.9
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Attachment SNRC-1367
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Page 6 The watwell airspace sprays operate at a low flow (about 500 gpm).
This will create some rate suspended liquid in the wetwell airspace, but notThe of the proportions as from the dryws11 sprays.
possibility of a steam / water mixture flowing through the vent line consistent with the above design conditions will be evaluated in the design of the BOP system.
- 16. Eas LILCO evaluated ATWS sequences above 8 percent, especially 20 percent power level? (70)
The PRA currently being performed by LILCO will Responset evaluate the full spectrwm of ATWs power levels and
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Realistically, the ultimate their consequences.
steam flow capacity of the FILTRA is significantly above 84
- 17. Does the amount of steam condbnsed determine when the vent relief valves would lift? (76)
As previously discussed, the FILTRA is maintained
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Response
in a nitrogen inerted environment.
As a result,
,, j the initial relief valve lift will depend upon the volume available to accomodate non-condensables The amount (primarily nitrogen) within the system.
of steam alone cannot be used to make the determination when or if they will lift.
The PRA will develop a timeframe for t.;is phenomena in more detail and will be provided in the October submittal.
- 18. What are the chances of activating the systam and not activating the vents? (78) y It is anticipated that there are some severe occident scenarios in which the event is terminated
Response
quickly, resulting in negligible releases from the FILTRA vent.
For these scenarios, initial pressurization and release from the FILTRA is due As a to the nitrogen atmosphere within the FILTRA.
result, it is anticipated that the nitrogen and only a small fraction of noncondensibles would be Subsequent repressQri-re19rsed to the atmosphere.
astten cf 'sne FILTRA structure would be long term and probably not sufficient to reactivate the These events are discharge line relief valves.
ourrently being assessed in the PRA, the results of which will be discussed in the October submittal.
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R>G 31 87 11:53 P.10 Attachment SNRC-1367
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Page,7 l
- 19. Discuss the testability and surveillance of the FILTRA system. (89)
The specifics of these programs have not yet been Responset ' developed, however, appropriate equipment preventative maintenance will be performed as a minimum.
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- 20. How will the relief valve logic handle a steam spike where the pressure drops off rapidly 7 (87)
There is no logic currently anticipated to control.
Responset the activation of the relief valves within the SCS.
Operation of these valves is due entirely to the I
pressurization rate of the FILTRA structure.
Operation of the containment isolation valves is controlled by the system logic previously discussed in question number 9.
During the development of the safety related logic, consideration of potential steam spikes will be evaluated against the accuracy and response times of the logic 5f' instrumentation.
The inclusion of time delays in
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the logie will be considered.
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