ML20202E436
| ML20202E436 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/27/1999 |
| From: | Stephen Dembek NRC (Affiliation Not Assigned) |
| To: | NRC (Affiliation Not Assigned) |
| References | |
| TAC-MA4361, NUDOCS 9902030021 | |
| Download: ML20202E436 (4) | |
Text
1 January 27,1999
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MEMORANDUM TO: Docket File FROM:
Stephen Dembek, Project Manager d
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Project Directorate 1-2 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation i
SUBJECT:
MILLSTONE NUCLEAR POWER STATION, UNIT 2, DRAFT REQUEST FOR ADDITIONAL INFORMATION, POST-LOSS-OF-COOLANT ACCIDENT LONG TERM COOLING (TAC NO. MA4361) i The attached request for additional information (RAI) was transmitted by facsimile on January 27,1999, to Ravi Joshi of licensee's staff. Review of the RAI would allow the licensee to determine and agree upon a schedule to respond to the RAI and/or clarify issues that may not need a formal response from the licensee. This memorandum and the attachment do not i
convey a formal request for information or represent an NRC staff position.
l Docket No 50-336 Attachmerit: As stated l
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January 27,1999 MEMORANDUM TO: Docket File Stephen Dembek, Project Manager j # /A FROM:
Project Directorate 1-2 Division of Reactor Projects - 1/II Office of Nuclear Reactor Regulation
SUBJECT:
MILLSTONE NUCLEAR POWER STATION, UNIT 2, DRAFT REQUEST FOR ADDITIONAL INFORMATION, POST-LOSS-OF-COOLANT ACCIDENT LONG TERM COOLING (TAC NO. MA4361)
The attached request for additional information (RAl) was transmitted by facsimile on January 26,1999, to Ravi Joshi of licensee's staff. Review of the RAI would allow the licensee to determine and agree upon a schedule to respond to the RAI and/or clarify issues that may not need a formal response from the licensee. This memorandum and the attachment do not convey a formal request for information or represent an NRC staff position.
l Docket No. 50-336
Attachment:
As stated i
I I
I i
January 27,1999 Millstone Post-LOCA Long Term Cooling, TAC MA4361 Items that SRXB would like to discuss to develop issue perspective - this is not a formal request for information at this time 1.
Numerous references are to use of LPI pumps. Have you established that all LOCAs can be depressurized to conditions where LPI pumps are effective for hot leg injection?
(See, for example, INSERT K, and the comment about atmospheric steam dump valves being limiting.)
2.
A potential problem with single failure associated with SITS was recently discovered. Are you addressing this and, if so, what have you found? (Note we do not plan to tie the issues together for review purpose, but they are closely related, and we probably will recognize the recent discovery in commenting about INSERT M, Figure 14.6.5.3-1, and the ability to isolate the SITS.)
3.
What is the power supply for 2-SI-656 (Fig 2)?
4.
With respect to 2-SI-651, we need a better understanding of the potential for a LOCA outside containment. The following (and considerations we may have overlooked) will I
help us achieve this understanding:
a.
Do we correctly understand that an inadvertent transfer of 2-SI-651 power is only indicated in the control room by an annunciator? That the transfer could be accomplished from outside the control room (Attachment 1 Page 12)? That it results in no control room indication? In no control capability from the control room?
b.
What is the source of power for the annunciator?
c.
On page 11 of Attachment 1, you indicate that the annunciator may be disabled.
What are the conditions when that is the case?
d.
If 2-SI-651 and -652 were to be open with pressure above 280 psia, at what pressure can they no longer be closed?
e.
Is LOCA outside containment via 2-SI-651 and -652 considered as an accident previously evaluated or as a new or different kind of accident from any eccident previously evaluated? Have any probabilistic analyses been performed that include operator error in assessing potentialimpact of the proposed modification?
4.
Please discuss reference to the charging system in INSERT G.
5.
In addition to the above reference to INSERT M and the SITS, we need to better understand the following aspects of INSERT M:
a.
"At 8 to 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> post-LOCA the operator will determine if the RCS is filled by checking pressurizer level." How is this sufficient with respect to subcooling
f margin and potentially a significant gas discharge into the RCS? See also the end of Section 14.6.5.3.4 and others, such as Section 14.6.5.3.6.
b.
- lf SDC cannot be established... due to.. SDC pressure / temperature limits unsatisfied..." How are boron control requirements met if SDC limits are not met? At what RCS pressure is sufficient flow rate achieved via hot leg injection?
(Note also the break size discussion at the end of Section 14.6.5.3.6.
c.
Item 9 references the precipitation limit in saturated water at 14.7 psia. Does this limit include the 4 weight percent margin that is typically used for licensing purposes with respect to control of boron precipitation? If not, please justify.
Have you addressed the effect of impurities in the water in determining boron precipitation concentrations?
d.
Please confirm that the NRC has accepted each of the codes identified in Section 14.6.5.3.4.
e.
Section 14.6.5.3.6 states "For a cold leg break, the core flushing flow is the difference between the hot side injection flow rate and the core boiloff flow rate."
Have you considered bypass flow between the upper vassel and the downcomer by such means as nozzle gaps or other leakage pains?
f.
If the RCS inventory has been depleted so that natural circulation has been lost, and it is then replenished via steam generator cooling, does this result in generation of boron depleted water in parts of the RCS? If so, have you addressed potential recriticality due to such actions as restart of reactor coolant pumps? Restart of natural circulation?
6.
With respect to Table 14.6.5.3-1, was the boric acid storage tank inventory was considered in calculation of time to reaching the boron precipitation limit in the core?
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