ML19308C262
| ML19308C262 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 01/16/1980 |
| From: | Wilson R METROPOLITAN EDISON CO. |
| To: | |
| References | |
| TLL-010, TLL-10, NUDOCS 8001220466 | |
| Download: ML19308C262 (4) | |
Text
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Metropolitan Edison Company Post CMfice Box 480 e
Middletown, Pennsylvania 17057 717 9444041 s
Wnter's Direct Dial Number January 16 1980 TLL 010 TMI-II Support Attn:
R. H. Vollmer, Director U. S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Sir:
Three Mile Island Nuclear Station, Unit II (TMI-2)
License No. DPR-73 Docket No. 50-320 TMI-II Ventilation Air Flow Ouantities Auxiliary and Fue.' Handling Buildings The rehabilitation effort associated with the TMI-II ventilation system in the Fuel Handling Building and Auxil.'.ary Building has established benchmark air flowrates of 65,000 cfm i 10% for the Auxiliary Building and 46,000 cfm i 10% for the Fuel Handliig Building. The Auxiliary Building flowrate value is near the desi gn value for the system, the Fuel Handling Building flowrate value is appraximately 28% greater than the system design value. System testing has shown these values for system flowrates to be reasonable and appropriate.
Furthermore, the suggested Technical Specification building negative pressure is stipulated to be greater than or equal to 1/8 inch Water Gauge relative to the outside atmosphere during system operation. It is requested that the specified building negative pressure in the Technical Specifications be changed to " great _r than or equal to 0.025 inches Water Gauge relative to the outside atmosphere." Justification for this request follows:
The negative pressure produced inside the buildings by the ventilation systems induces a flow of air through any opening connected to an area of higher pressure including the outside. This should preclude contamination of the environment by radioactive particulate or gaseous products that may be present within the buildings.
Mr. Orlan Yarbro of Oak Ridge National Laboratories has advised us that the accepted industry guideline used for limiting the spread of such radioactivity has been a velocity of 100 feet per minute (fpm) through openings. The Air Conference Government Industrial Hygienists " Industrial Ventilation" manual of recommended practice, 15th edition, provides a Table 7-1, " Negative Pressures and Corresponding Velocities Through Crack Openings." The table is generally used in developing considerations for fuel conservation, draft elimination, non uniform space temperatures, and cross contamination aspects of ventilation design. Crack openings are 00I
/s infiltration paths.
di Metrecchtan Ecison Ccmpany s a Memter of me General Pucoc Ltitres System 8001320 yg
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R. H. Vollmer January 19 1980 TLL 010 I
The design of the ventilation systems for the Auxiliary and Fuel Handling Buildings of TMI-II is such that a contro' point of 0.125" Water Gauge was established. This negative pressure curresponds to a crack velocity of 845 fpm, as indicated in Table 7-1.
This control point is maintained by automatic operation of the exhaust fans vortex dampers.
As increased infiltration paths occur, the vortex dmapers open to allow for increased exhaust air flow to maintain negative pressure and crack velocities. When the infiltration paths grow to a point where crack design is exceeded, the negative pressure decays. The decay point for alarm during unit operation is.06" WG; Table 7-1 indicates a crack velocity of 590 fpm for this pressure.
Such an alarm would be an infrequent occurrence occasioned by a large infiltration path from the outside in conjunction with some interior building interconnecting doors being opened. This pressure decay could also be occasioned by a ventilative system malfunction.
We recognize the infiltration paths during recovery will be somewhat greater than expected during unit operation. This will result from the more frequent ingress and egress of personnel and materials through portals.
We therefore do not expect to be able to maintain the same degree of negative pressure associated with unit operation, i.e.
.125" (1/8) WG.
We do expect to maintain infiltration velocities greater than normal industry guidelines of 100 fpm during recovery operations. Our system operation design control point will remain.125" (1/8) WG and we will achieve this value when conditions permit.
1 We suggest, however, in consideration of the foregoing that the Recovery Technical Specifications for the Fuel Handling and Auxiliary buildings ventilation systems specify a minimum negative pressure relative to the outside atmosphere of.025" WG; Table 7-1, indicates this equates to a crack velocity of 380 fpm, which is certainly in excess of the 100 fpm industry guidelines.
We conclude that the operation of the ventilation system as described should provide infiltration velocities in excess of the 100 fpm accepted industry guidelines and provide assurance of meeting the established site boundry radiation dose rate.
As a result of the efforts expended to date, it is requested that Technical Specification 4.9 read as follows:
"4.9 LIQUID RADI0 ACTIVE WASTE STORAGE FUEL HANDLING BUILDING / AUXILIARY BUILDING AIR CLEANUP SYSTEMS i
4.9.12 The fuel handling building / auxiliary building air cleanup systems shall be demonstrated operable:
a.
At least once per 31 days by initiating, from the control room, flow through the HEPA filters and charcoal absorbers and verifying that the system operates for at least 15 minutes.
l b.
Initially, and at least once per 18 months or (1) af ter any.
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R. H. Vollmer Jcnuary 16, 1980 TLL 010 structural maintenance on the HEPA filter or charcoal absorber housings, or (2) following painting, fire or chemical release in any ventilation zone communicating with the system by:
1.
Verifying a fuel handling building system flowrate of 46,000 cfm i 10% during system operation when tested l
in accordance with ANSI N510-1975.
2.
Verifying an auxiliary building system flowrate of 65,000 cfm i 10% during system operation when tested in accordance with ANSI N510-1975.
c.
At least once per 18 months by:
1.
Verifying that the pressure drop across the combined HEPA filters and charcoal absorber banks of the fuel handling building system is less than 6 inches Water Gauge while g
operating the system at 46,000 cfm i 10%.
I 2.
Verifying that the pressure drop across the combined HEPA filters and charcoal absorber banks of the auxiliary building system is less than 6 inches Water Gauge while operating the system at a flowrate of 65,000 cfm i 10%.
3.
Verifying that the fuel handling building system maintains the fuel handling building at a negative pressure of greater than or equal to 0.025 inch Water Gauge relative to the l
outside atmosphere during system operation.
4.
Verifying that the auxiliary building system maintains the auxiliary building at a negative pressure of greater than or equal to 0.025 inch Water Gauge relative to the outside l
atmosphere during system operation, d.
After each complete or partial replacement of a HEPA filter bank in the fuel handling building system by verifying that the HEPA filter banks in this system remove greater than or equal to 99% of the DOP when they are tested in-place in accordance with ANSI N510-1975 while operating the system at a floarate of 46,000 cfm i 10%.
e.
After each complete or partial replacement of a HEPA filter bank in the auxiliary building system by verifying that the HEPA filter banks in this system remove greater than or equal to 99% of the DOP when they are tested in-place in accordance with ANSI N510-1975 while operating the system at a flowrate of 65,000 cfm i 10%."
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R. H. Vollmer January 16 1980 TLL 010 It is further requested that these words be factored into the Three Mile Island Nuclear Station, Unit II proposed Technical Specifications - Appendix "A" to License No. DPR prior to issuance. Should you have any questions or comments regarding the above request, please contact either myself or Mr. L. W. Harding at (717) 948-8551.
- incerply,
- .Mw
. F. W lson Director-TMI-II RFW:LWH: hah cc:
J. T. Collins I
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