ML17264A284
| ML17264A284 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 12/04/1995 |
| From: | Mecredy R ROCHESTER GAS & ELECTRIC CORP. |
| To: | Andrea Johnson NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9512120224 | |
| Download: ML17264A284 (6) | |
Text
PR.IC)AIWY (ACCELERATED RIDS PROCI'.SSIXG)
REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9512120224 DOC.DATE: 95/12/04 NOTARIZED: NO DOCKET FACIL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G
05000244 AUTH.NAME AUTHOR AFFILIATION MECREDY,R.C.
Rochester Gas
& Electric Corp.
RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
JOHNSON,A.R.
Project Directorate I-1 (PDl-1)
(Post 941001)
SUBJECT:
Special rept:on 951027,staff discovered that portion of overall basis for approval of exemption was not being met due to removal of shield wall.Inserted kaowool within 6 inch gap now being used as temporary seal.
DISTRIBUTION CODE:
IE22D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.
NOTES:License Exp date in accordance with 10CFR2,2.109(9/19/72).
05000244 RECIPIENT ID CODE/NAME PD1-1 PD INTERNAL E
FILE CEN EELB NRR/DRCH/HHFB NRR/DRCH/HOLB NRR/DRPM/PECB NRR/DSSA/SRXB RGN1 FILE 01 EXTERNAL: L ST LOBBY WARD NOAC MURPHY,G.A NRC PDR COPIES LTTR ENCL 1
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RECIPIENT ID CODE/NAME JOHNSON,A AEOD/SPD/RRAB NRR/DE/ECGB NRR/DE/EMEB NRR/DRCH/HICB NRR/DRCH/HQMB NRR/DSSA/SPLB RES/DSIR/EIB LITCO BRYCE,J H
NOAC POORE,W.
NUDOCS FULL TXT COPIES LTTR ENCL 1
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YOTE TO ALL"RlDS" RECIPIENTS:
PLE:XSE HELP l:S TO REDUCE 4VKSTE! CONTACTTIIE DOCUXIE4TCONTROL DESK, ROONI Pl-37 IEXT. 504-20S3 I'I'0 ELIXIINATE YOUR X'AhfE F ROTI DISTRIBUTIONLIS'I'S I:OR DOCUMI:.X'I'SYOU DO/,"I'l I:.I)!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 25 ENCL 25
ROCHESTER GAS ANDFIECTRIC CORPORATlOh/
~ 89 EAST AVENUE, ROCHESTER, hl. V, 1J6d9 OGOI AREA CODE 7/4 Sd6 2r00 ROBERT C. MECREDY" V:ce Pres.cens r 'vcr ear 0 perctions December 4,
1995 U.S. Nuclear Regulatory Commission Document Control Desk Attn:
Allen R. Johnson Project Directorate I-1 Washington, D.C.
20555
Subject:
Thirty (30)
Day Special Report Inoperable Fire Barrier Penetration Seal in the Auxiliary Building R.E.
Ginna Nuclear Power Plant Docket No. 50-244 Reference (a):
NRC Safety Evaluation Report dated March 21,
- 1985, Exemption from Section III.G of 10CFR50 Appendix R
Dear Mr. Johnson:
In accordance with the Ginna Station Updated Final Safety Analysis Report (UFSAR), Table 9.5-2, Item 6, this thirty day special report on an inoperable fire barrier penetration seal is being submitted.
Between September 25 and October 12, 1995 work activities were performed to disassemble and remove an 8 foot high block wall that extended circumferentially around a portion of the refueling water storage tank (RWST) on the operating level (floor elevation 271' 0>>) of the auxiliary building.
The wall was originally installed as a radiological shield barrier, a feature no longer necessary for that area.
The wall disassembly was being conducted to facilitate installation of supports for the RWST in conjunction with seismic upgrade (SQUG) efforts.
The floor between the operating level of the auxiliary building (ABO) and the level below, the auxiliary building mezzanine (ABM), constitutes a fire barrier necessary for compliance with 10CFR50 Appendix R, Section ZII.G.2.
There is a 6>> gap around the RWST at the floor elevation of ABO.
The existence of this gap received NRC approval (documented in the SER, reference (a), Section 2.0.) under an exemption to Appendix R,Section III.G.2, to the extent that a continuous fire rated barrier exist between redundant trains of safe shutdown equipment.
Among several other plant attributes that formed the basis for approval of that exemption was the "chimney>> effect, created by the block wall, that would cause a tendency for products of combustion to be channelled upward and away from safeguards bus 14 and other safety-related motor control centers in fire zone ABO, should a postulated unmitigated fire occur in the fire zones below at elevations 253'-
0>>
(ABM) or 235'-8>>
(ABB).
On October 27,
- 1995, members of RG&E's staff discovered that a
portion of the overall basis for approval of this exemption was not being
- met, due to the removal of the shield wall.
As a
PDR ADOCK 05000244 9512120224 951204 8
conservative
- measure, an hourly fire watch was immediately posted as required by the UFSAR Table 9.5-2, Item 6, as if the entire fire barrier representing the floor separating the auxiliary building mezzanine level (fire zone ABM) and the operating level (fire zone ABO) was inoperable.
Efforts to xestore the fire barrier penetration'eal to operable status commenced by planning the installation of a temporary fire penetration seal around the RWST within the 6" gap area.
Restoration of the penetration seal to fully operable status within the 7 days allowed in the UFSAR was not possible, therefore, this 30 day report is being submitted.
The temporary seal consists of ceramic fiber (kaowool) insulation materials with a density of 8 lbs/cu. ft. installed in a friction fit configuration to a
minimum depth of 12 inches.
The installation of the material within this gap is judged to be an acceptable temporary seal and an. acceptable configuration which would limit the passage of the products of combustion from a
postulated fire in the levels below.
This conclusion is based upon a detailed analysis performed in accordance with the guidance of Generic Letter 86-10 and documented in Design Analysis DA-ME-95-154 dated 11/1/95.
It was concluded that this temporary seal configuration provides an increased resistance to potential fire propagation from fire zone ABM as compaWed to the previous configuration with a 6 inch gap and the shield wall in place.
Prior to completion of the temporary seal configuration, the hourly fire watch remained in effect.
Additional administrative controls were also put in place, involving the prohibition of transient combustibles in the area of the RWST and all safety-related equipment adjacent to the RWST.
The posting of an hourly fire watch was consistent with the requirements of the UFSAR, since fire detection system components on one side of the barrier were in service.
These consisted of the detection components that are part of suppression system S03; detection system Z03 near the penetration area cable trays on the 253'-0" elevation; detection system ZO4 on the 271'-0" elevation; and detection system ZO2 in the basement level west end of the 235'-8" elevation.
The temporary seal configuration was completed and the penetration seal declared operable on November 28, 1995.
The hourly fire watch was removed.-
The degraded condition that existed between September 25,
- 1995, when disassembly of the wall commenced, and October 27,
- 1995, when the condition was discovered and the fire watch posted, is not judged to have had a significant impact on plant safety.
The principal fire barrier was not seriously degraded and all other significant factors forming the basis for the approved exemption remained in effect, which would have acceptably minimized the impact of a potential fire in the 253'-0" elevation from affecting components on the 271'-0" elevation.
These factors include:
1)
The width of the gap around the RWST is small, only 6 inches, and the floor barrier is constructed of poured concrete of nominal 18 inches depth so that the amount of heat/flame which would flow through the gap would have been limited.
2)
The average combustible loading in fire zone ABM (253'-0") is low, only 23,000 BTU/sq.ft. or a fire severity of 18 minutes.
3)
The average combustible loading in fire zone ABB (235'-8") is low, only 6245 BTU/sq.ft. or a fire severity of 5 minutes.
5)
The open floor to ceiling height of 50 feet would still have allowed the products of combustion to rise up through the gap and dissipate in the large ceiling area of the auxiliary building operating level.
All cable trays forming the concentrated combustible loading of approximately 100,000 BTU/sq.ft. in the vicinity of the cable tunnel entrance of fire zone ABM are protected by automatic pre-action sprinklers in the trays and smoke detection.
6)
The 235'-8" elevation concentrated combustible loading in the area of the safety injection pump cable trays are protected by a pre-action sprinkler system and smoke detection.
7)
The detection and suppression systems alarm both audibly and visually in the control room.
8)
The minimum separation between the RWST gap and safeguards bus 14 is 6.5 feet and increases to 20 feet due to the curvature of the RWST.
9)
All other floor barrier penetrations at the 271'-0" elevation are sealed to provide a level of fire protection commensurate with the hazards.
10)
Control room auxiliary'perator rounds through the auxiliary building occur every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
Plant security staff tours for each major area outside containment, such as the auxiliary building, occur every hour, although by design do not occur in the same order or frequency.
- Thus, the area received routine visual surveillance.
12)
During the disassembly period between September 25 and October 12, personnel performing the work were in the immediate area of concern, thereby providing the equivalent of a fire watch.
Based upon the above factors, our GL 86-10 evaluation concluded that the lack of the 8 foot high shield wall around the RWST at the auxiliary building operating level during the time interval prior to posting of the fire watch did not result in a fire penetration seal degraded to an extent that would invalidate the basis for the previously approved exemption.
The most probable cause which created the condition in which this one portion of the Appendix R exemption was not being met was a
mis-classification of the safety class for the 8 foot high block
wall.
While it was known that the wall was originally installed as a radiological shield wall, and that the 6 inch gap around.the RWST was the subject of an Appendix R exemption, the credit taken for the chimney effect of the wall was not generally known.
The safety classification for the wall incorrectly contained no association with Appendix R.
Disassembly of the wall was preliminary work as part of an overall plant structural modification to the RWST.
The modification design includes covering the 6
inch gap with 3/4-inch steel plate
- sections, welded together and pinned to the floor, together with the attachment of stiffeners to the RWST for structural support as part of the SQUG program.
Since the modification would remove the original need for the Appendix R exemption, it was believed that the Appendix R issues were being adequately addressed.
Because the insertion of kaowool within the 6 inch gap is now being utilized as a temporary seal (to restore the fire penetration seal to operable status and allow removal of the fire watch), that seal will remain in place as a permanent portion of the gap closure in conjunction with the 3/4-inch thick steel plate.
This combined seal will provide a far superior fire seal than either the 8 foot high shield wall or the temporary seal previously described.
The gap closure will also eliminate the need to track the 6 inch gap configuration as an Appendix R exemption.
The new seal around the RWST will be made part of the fire barrier penetration seal program and as such be surveilled every 18 months to ensure that. the seal is appropriately maintained and controlled.
Very truly yours, GAH4409 Robert C. Mecredy xc:
Mr. Allen R. Johnson (Mail Stop 14B2)
Project Directorate I-1 Washington, D.C.
20555 U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Ginna Senior Resident Inspector