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UNITED STATES
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,j NUCLEAR REGULATORY COMMISSION W ASHINGTON. D.
C.
20555 MAR 0 31975 DOCKET No.:
50-471 APPLICANT:
Boston Edison Company (BECo)
FACILITY:
Pilgrim Unit 2
SUMMARY
OF MEETING HELD ON JANUARY 30, 1975 TO DISCUSS _ ACCIDENT DOSES-TO CONTROL ROOM PERSONNEL AND O_FFSITE DOSES DUE TO LEAKAGE OF POST-LOCA RECIRCULATION SUMP WATER FROM COMPONENTS OUTSIDE OF CONTAINMENT A meeting was held on January 30, 1975 in Bethesda, Maryland with representatives of BECo and Bechtel. The meeting was a follow-up to a previous meeting held on December 10, 1974.
BECo discussed the staff's assumptions used in calculating the loss-of-coolant accident (LOCA) doses to control room personnel and several proposed alternative assumptions.
In addition, BECo proposed modifications to the control room ventilation system design to further reduce the doses.
With regard to offsite doses due to leakage of recirculation sump water from components outside of containment, BECo discussed their proposed leakoff collection system including the pros and cons of such a system as compared to a ventilation-filtration system serving the enclosure complex.
As a result of the meeting, the staff will recalculate post-LOCA doses to control room personnel based on the new meteorology data (see Sumraary of December 10, 1974 meeting) and the modified system design.
In addition, BECo will provide further information on the leakoff collection system design for staff review.
An attendance list is enclosed as Enclosure 1.
Discussion Doses to' Control Room Personnel The staff's original evaluation of control room doses is enclosed as, entitled, " Pilgrim Unit No. 2 Control Room Habitability Analysis, December 1974." This analysis was given to BECo at our previous meeting on December 10, 1974.
BECo objected to our assumption of an occupancy factor of 1.0 for an individual for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the accident (see page 2 of ).
They indicated that operating procedures would require
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4 gg" 0 o 1913 crew changes on eight-hour shifts and that a more appropriate assumption would be an occupancy factor of 1.0 for the first 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> which would allow four hours for contingencies. We indicated that our assumption was a conservative one and a standard one for our calculation of control room doses and we did not intend to alter the assumption.
i BECo inquired as to the acceptability of using the assumption of time dependent build-up of activity in-the control room since-it will take some time to accomplish a complete' change of the air in the control room. BECo stated that their calculations showed that this change in assumptions could result in a significant reduction in the 0-8 hour calculated whole body dose to control room personnel. We indicated that time dependent build-up of the activity in the control room was an acceptable approach.
1 With regard to unfiltered inleakage when the ventilation system was in the pressurization mode, we indicated that when we rerun our calculations, we will assume 5 cfm unfiltered inleakage based on the information to date regarding the inlet door design. We indicated
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that any further reduction in the unfiltered inleakage assumption j
would have to be justified by further design information on the double door inlet design.
i BECo indicated that they intended to modify the system design to i
provide for recirculation of a portion of the air, i.e., a mode in 3
which 750 cfm would be taken in through the once-through filtered outside air intake and 1250 cfm would be recirculated through the recirculation filters. This modification will further reduce the i
calculated doses to control room personnel, i
We indicated that when we received the new information on the system design and using the updated meteorology data, we would recalculate i
our doses to control room personnel and determine their acceptability.
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Post-LOCA Offsite Doses Due to Leakage of Recirculation Sump Water from Components in the Enclosure Complex As a follow-up to our previous meeting on December 10, 1974, BECo provided further details about their proposed leakoff collection system for l
enclosure complex post-LOCA recirculation pumps and valves. Our position expressed at the earlier meeting was that the enclosure complex must be served by a filter system designed to engineered safety feature i
criteria.
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. BECo discussed the advantages of the system, which included quick identification of the source of leakage so that action could be taken to isolate the leaking components. A filtration system would offer no means of identifying the source of leakage. We indicated, however, that with the filtration system, the offsite doses could be reduced to an acceptable level regardless of the source.
We indicated that the leakoff collection system design was new to us as a means for reducing accident doses, and we would have to give it further review prior to making a decision regarding its acceptability, BECo indicated that they would provide us with further informatien regarding the leakoff collection system design and the associated dose model. The information provided following the meeting and prior to formally amending the PSAR is provided as Enclosure 3.
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a M. B. A cock, Project Manager Light Water Reactor Projects Branch 1-1 Division of Reactor Licensing j
Enclosures:
1.
Attendance List 2.
Pilgrim Unit 2 Control Room Habitability Analysis, December 1974 3.
Description of Enclosure Complex Leakoff Collection System and Dose Model 1
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ENCLOSURE 1 ATTENDANCE LIST JANUARY 30, 1975 MEETING BECo i
W. W. Larson Bechtel S. Grabowski R. Tosetti NRC M.
B. Aycock K. Murphy L. Soffer t
t MAR 0 31975
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f DISTRIBUTION:
Docket File R. Tedesco NRC PDR V. Stello Incal PDR R. Maccary NRR Reading (M. Groff)
H. Denton R. DeYoung V. Moore V. Benaroya J. Collins D. Skovholt J. Kastner iD. Muller G. Lainas R. Denise D. Ross K. Goll'r e
G. Lear T. Ippolito J. Knight W. Butler S. Pawlicki J. Stolz L. Shao R. Clark B. Grimes T. Speis W. Gammill D. Vassallo R. Ballard K. Kniel P. Fine O. Parr T. Novak A. Schwencer D. Ziemnn M. Spangler P. Collins EP Project Manager - R.
Froelich A
R. Purple rney, ELD
.E (3)
G. Knighton J. Lee G. Dicker ACRS (16)
B. J. Youngblood W. H. Regan, Jr.
Project Manager - G. L. Chipman R. Vollmer LWR 1-1 File R. Baer W. Houston S. Varga R. Fluegge L.
Barit R. Klecker R. Heineman J. Nehemias Bill Hewitt I
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