AECM-81-498, Final Deficiency Rept Re Low Flow Heating,Ventilation & Air Conditioning Conditions,Initially Reported 810925.Caused by Undersized Air Handling Equipment.Guidelines Developed for Ductwork & Piping Sys Flow Design by 811218

Final Deficiency Rept Re Low Flow Heating,Ventilation & Air Conditioning Conditions,Initially Reported 810925.Caused by Undersized Air Handling Equipment.Guidelines Developed for Ductwork & Piping Sys Flow Design by 811218

ML20069B465
Person / Time
Site:	Grand Gulf
Issue date:	12/15/1981
From:	Mcgaughy J MISSISSIPPI POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
10CFR-050.55E, 10CFR-50.55E, AECM-81-498, NUDOCS 8112240226
Download: ML20069B465 (4)

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jj mlSSISSIPPI POWER & LIGHT COlyJPAN_Y_

Helping Build Mississippi l f ,R i.j ' A I' P. O. B O X 16 4 0, J A C K S O N M i S S t S S i P P I 3'9~2 0 5 Emihhibhiled J AVES P. McGAUGHY, JR.

AS$iSTMT veCE NCOT December 15, 1981 hbf fh /k h . 6 Office of Inspection & Enforcement '

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U. S. Nuclear Regulatory Commission ,

Region II /' ,, ..

101 Marietta Street, N.W. j .

ND p' Suite 3100  ! L'; L 'o g r-Atlanta, Georgia 30303 b^i

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Attention: Mr. J. P. O'Reilly, Regional Administrator

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SUBJECT:

Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416/417 File 0260/15525/15526 PRD-81/38, Final Report, Low Flow HVAC Conditions AECM-81/498

Reference:

AECM-81/417, 10/22/81 On September 25, 1981, Mississippi Power & Light Company notified Mr. P.

A. Taylor, of your of fice, of a Potentially Reportable Deficiency (PRD) at the Grand Gulf Nuclear Station (GGNS) construction site. The deficiency concerns low flow HVAC conditions.

We have determined that had this deficiency remained uncorrected it would ha re adversely af fected the safety of operations of the nuclear power plant and is reportable under the provisions of 10CFR50.55(e). The affected systems have not been of fered for acceptance to MP&L so the deficiency is not reportable under 10CFR21.

All details are given in our attached Final Report.

Yours truly, J. P. McGaughy, Jr.

KDS:dr ATTACHMENT cc: See page 2 8112240226 811215 O rcs,,'d M, PDR ADOCK 05000416 S PDR -

A Member Middle South Utilities System s

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4D Mr. J. P. O'Reilly AECM-81/498 NRC Page 2 cc: Mr. N. L. Stampley Mr. R. B. McGehee Mr. T. B. Conner Mr. Richard C. DeYoung, Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. G. B. Taylor South Miss. Electric Power Association P. O. Box 1589 Hattiesburg, MS 39401

Attechment to AECM-81/498 Pags 1 of.2 FINAL REPORT FOR PRD-81/38

1. Description of the Deficiency During HVAC flow balancing, a nuaber of systems exhibited flow rates 20 to 40% below the designed flow rates. The deficiency was originally identified in the Emergency Switchgea and Battery Room Ventilation System (Z77).

Another deficiency of the same magnitude was identified in the Control Room HVAC System (Z51). In our previous report it had been reported that the deficiency also af fected the Radwaste Building HVAC (V41),' Turbine Building HVAC (U41), Fuel Handling Area HVAC (*i42), and Drywell Cooling (M51). These systems, however, are not safety-related and the deficiency would not af fect the safe operation of the nuclear power plant.

Also, at the time of our previous report it was thought that the deficiency might possibly affect the Standby Gas Treatment System (T48). 'This system, however, has now been tested and has been shown to be not af fected by the deficiency.

The deficiency affects only Unit I and does not apply to the NSSS vendor.

II. Analysis of Safety-Implications Our Architect / Engineer has determined that if the low flow condition had remained uncorrected, it could have prevented the equipment in the Emergency Switchgear and Battery Room and the Control Room f rom performing its intended safety function. Therefore, this deficiency is reportable under the provisions of 10CFR50.55(e) The affected systems have not been offered for acceptance to MP&L so this condition is not reportable under the provisions of 10CFR21.

III. Corrective A:tions Taken The low HVAC flow rates were primarily caused by undersized air handling equipment. Several factors contributed to this equipment being undersized.

Because of the extremely long lead times on qualified HVAC equipment, the supply and exhaust fans were sized approximately one and a half years before the duct design was issued for construction. Therefore, a static pressure requirement for the fans was based cn preliminary designs and estimated on normal duct system requirements. Since the two systems affected were design 94 with complete redundancy, including the ductwork, large quantities of ductwork were installed whi:h resulted in ardous ductwork runs that caused pressure drops in excess of those anticipated. The design was inadequately monitored and co-ordinated. Therefore, the specified fans were not capable of producing the static pressure actually required to maintain the design air finw.

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Attrchment to AECM-81/498 Page 2 of 2 A comparison between calculated system parameters and actual system parameters also indicates that extremely high air velocities existing through the supply air handling unit heating coils further degrade fan performance.

However, installed conditions preclude determining the actual contribution of the high velocities to the overall lack of satisfactory fan performance.

The deficiency affects only the Emergency Switchgear and Battery Room Ventilation System (Z77) and the Control Room HVAC. System -(Z51).

In the Control Room HVAC System (Z51) the 40HP fan motors are to be replaced with 50HP fan motors and a set of intermediate speed sheaves will be added.

The new motors are scoeduled for delivery by December 15, 1981.

In the Emergency Switchgear and Battery Room Ventilation System (Z77) an additional supply fan and exhaust fan have been installed in each division.

The system will now utilize two (2) full capacity fans run at half load in parallel to achieve acceptable design objectives.

Documentation has been revised to reflect the changes in each system.

To preclude recurrence, our Architect / Engineer's HVAC Design Personnel will be notified of any changes to the HVAC ductwork that are necessary during the installation. This will enable the Design Personnel to evaluate any ductwork changes in accordance with the original HVAC design criteria. Also, a review is being performed to establish criteria to be incorporated into a discipline guideline to be used specifically for ductwork and . piping systems flow

. design. These guidelines shall include requirements to ensure that design evaluation is properly interfaced and monitored, and configuration changes of ductwork and piping be reviewed / evaluated periodically to identify and correct significant changes that may af fect acceptance of the final (as built) design. These guidelines shall be issued by December 18, 1981, as a supplement to the existing discipline work assignments and standards of pe rfo rmance.

All corrective action will be completed by December 24, 1981.