ML20215H958
| ML20215H958 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 03/17/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20215G262 | List: |
| References | |
| NUDOCS 8705070164 | |
| Download: ML20215H958 (4) | |
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UNITED STATES l
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NUCLEAR REGULATORY COMMISSION
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-a g*....j SAFETY EVALUATION TECHNICAL SPECIFICATION CHANGE REQUEST PILGRIM NUCLEAR POWER STATION, UNIT NO. 1 i
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j DOCKET N0. 50-293 l
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1.0 INTRODUCTION
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'By letters dated January 19, and 27, 1987, Boston Edison Company transmitted, under exigent circumstances, a proposal to change Pilgrim Technical i
i Specifications. The requested change is to be implemented in the fom of an
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f amendment to Appendix A of Operating License No. DPR-35. The licensee has proposed (1) to increase the pressure drop across the filter unit in the Control Room High Efficiency Air Filtration (CRNEAF) system to 6 inches of i
water (currently the Technical Specification specifies less than 3 inches of 5
water), and (2) to add a 10 percent tolerance (t 10%) to the air flow rate to i
be used with the filter unit during filter surveillance testing.
i 2.0 EVALUATION j
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The CRHEAF system provides outside makeup air for pressurizing the control room following a design basis accident. The CRNEAF system is an engineered j
safety feature system. The system consists of two redundant filtration
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units.
Each unit contains a heating coil, a preffiter, an upstream HEPA l
filter, a charcoal adsorber, and a final HEPA filter. Each unit is designed j
for an air flow intake capacity of 1,000 cfm.
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The current Pilgrim Technical Specification Section 4.7.8.2.a specifies that:
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j "At least once every 18 months the pressure drops across each combined l
filter train shall be demonstrated to be less than 3 inches of water at 1,000 cfm."
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The licensee has proposed to increase the acceptable pressure drop to 6 inches of water across the filter unit when the air flow rate is 1,000 cfh
- 10%.
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The staff estimates that the pressure drop across a HEPA filter should be less than 1 inch of water when the filter is new and operated at rated design air flow capacity. The pressure drop will increase as particulates and dust are collected in the filter. The licensee stated in the referenced letters that the HEPA filter vendor recommends limiting the maximum allowable pressure drop to 8 inches of water across each HEPA filter and to 3 inches of water for the filter replacement. Therefore, the proposed pressure drop of less than 6 inches water across the entire filter unit (one prefilter, two HEPA filters, and one charcoal adsorber) is reasonable and acceptable. This change is also consistent with the value specified in GE/8WR Standard Technical Specifications (NUREG-0123, Revisions 3and4),aswellasintechnical specifications recently issued for other BWRs.
The staff also finds that the addition of a 10 percent tolerance to the air flow rate (i.e.,1,000 cfm t 10%) is acceptable, since it is consistent with GE/BWR Standard Technical Specifications.
It should be noted, however, that the CRHEAF system at Pilgrim Station is not provided with an air flow irdicator and/or a recorder.
Instead, the licensee has been utilizing Pitot tube air velocity measurements to estimate the air flow rate. The licensee has proposed that the air flow rate surveillance requirement of 1,000 cfm i 10% will be met by the use of Pitot tube air velocity measurements in accordance with the plant established calculational procedure.
The staff believes that within this flow range (i.e.,1,000 cfm i 10%), the design objectives of the CRHEAF system still can be met (e.g., slight positive pressurization of the control room, air residence time in the charcoal adsorber). Therefore, the staff finds that the licensee's method for determining the air flow rate is acceptable. The revised Section 4.7.2.a of the pilgrim Technical Specifications will state, in part:
... less than 6 inches of water at 1,000 cfm 10% or the calculated equivalent."
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3.0 CONCLUSION
On the basis of the above evaluation, we conclude that the ifcensee's proposed Pilgrim Technical Specification changes are acceptable. The bases for acceptance are:
(1)proposedTechnicalSpecificationsareconsistentwith recently Ifcensed BWR technical specifications as well as BWR Standard Technical Specifications, and (2) proposed Technical Specifications conform with acceptable design and operating practices for engineered safety feature ventilation systems.
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SALP INPUT FROM THE PLANT SYSTEMS 8 RANCH FOR PILGRIM NUCLEAR POWER STATION, TS CHANGE RE CONTROL ROOM HIGH EFFICIENCY AIR FILTER SYSTEM l
Functional Areas I
1.
Management involvement in assuring qualfty.
Management involvement was prompt and adequate throughout.
Rating: Category 1 2.
Approach to Resolution of Technteal Issues from a safety Standpoint.
Plant technical personnel clearly understood the issues, and were technically sound and thorough in their approaches.
Rating: Category 1 3.
Responsiveness to NRC Initiatives N/A 4.
Enforcement History N/A 5.
Operational and Construction Events N/A 6.
Staff thg (including Management)
N/A 7.
Training and Qualification Effectiveness N/A
Reference:
NRC Manual Appendix 0516 - Systematic Assessment of Licensee Performance l
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