ML20205P750
| ML20205P750 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 05/06/1985 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8605210559 | |
| Download: ML20205P750 (3) | |
Text
e TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 37401 SN 157B Lookout Place S
,1h85
,e'0...'l, ;May BLRD-50-438/83-53 BLRD-50-439/83-46 U.S. Nuclear Regulatory Commission Region II Attn:
Dr. J. Nelson Grace, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
Dear Dr. Grace:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - SIZE OF LINES OF FLOW RESTRICTORS IS ABOVE THAT WHICH ENSURES A CONTROLLABLE COOLDOWN PER FSAR -
BLRD-50-438/83-53, BLRD-50-439/83 FINAL REPORT The subject deficiency was initially reported to NRC-OIE Inspector Linda Watson on October 6,1983 in accordance with 10 CFR 50.55(e) as NCR BLN NEB 8311. Enclosed is our final report.
If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY e
R. L. Crldley, Di tor Nuclear Safety and Licensing Enclosure Mr. James Taylor, Director (Enclosure) cc:
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Records Center (Enclosure)
Institute of Nuclear Power Operations 1100 circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 8605210559 850506 PDR ADOCK 05000438 S
PDR An Equal Opportunity Employer l
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A ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 SIZE OF LINES OF FLOW RESTRICTORS IS ABOVE THAT WHICH ENSURES A CONTROLLABLE COOLDOWN PER FSAR BLRD-50-438/83-53 AND BLRD-50-439/83-46 10 CFR 50.55(e)
NCR BLN NEB 8311 FINAL REPORT Description of Deficiency TVA design criteria N4-50-D754 RO, " Classification of Piping, Pumps, Valves, and Vessels," specifies a 3/4-inch inside diameter (Section 3.7, page 8) for sensing, sampling, and radiation monitoring lines. This is based on the mnormal makeup capacity of the makeup and purification system and is intended
- to meet 10 CFR 50, Appendix A, General Design criterion 33.
It is also the basis for the use of flow restrictors that permit the classification change from ASME,Section III Class 1, to ASME,Section III, Class 2--per 10 CFR 50.55a(d), footnote 2.
This also agrees with Babcock and Wilcox (B&W) letter D-2424 dated March 10, 1977, where B&W stated that a break larger than 3/4 inches must be considered as a loss-of-coolant-sized break. FSAR Section 9.3.6.1 (page 9.3-41), 9.3.6.3 (1} (page 9.3-58), and 9.3.6.3 (2g] (page 4,3-60) specify on opening equivalent to a 3/4-inch schedule 160 pipe (0.614-inch inside diameter) as the limiting break size for which a controllable cooldown can be ensured. The discrepancy is that the break size stated in the FSAR does not agree with the break size specified by the design criteria and the design drawings.
The 3BWO422-NK series drawings for the reactor coolant drain and vent system have a number of flow restrictors larger than 0.614-inch inside diameter; and drawings 3BWO422-NK-05 R9 (Section B-B, detail A) and 3BWO422-NK-09 R8 (Section A-A) show 3/4-inch inside diameter flow restrictors--all of which are in agreement with the design criteria.
Drawings 3BWO422-NK-07 R8 (Section E7-E7) and 3BWO422-NK-08 R10 (Section F-F) show 1-inch by 3/4-inch schedule 80 reducers (0.742-inch inside diameter) welded at the small diameter.
The reducers are ASME,Section III, class 2.
The upstream reducer should be ASME,Section III, Class 1--per design criteria drawing 3BWO622-NK-01 R8.
The flow restrictor ASME classification specified by the design drawing does not agree with that specified by the design criteria diagram. The deficiency in the ASME classification difference between reducers can be attributed to an error in the detailed piping design whereby the wrong mark numbers were assigned to the reducers.
This deficiency represents an isolated case where a 3/4-inch break (.75") and a 3/4-schedule 160 pipe break (.612" I.D.) were used interchangeably in correspondence between TVA and B&W.
This resulted in some flow restrictors being oversized in the NK system.
TVA has determined that the cited deficiency was unique to Bellefonte, and no other TVA plants are similarly affected.
> Safety Implications The reactor coolant system (RCS) inventory makeup capacity of the makeup and purification (NU/PU) system is based on a limiting break size of 0.614 inches. A circular break opening (or its equivalent) that exceeds this specification could result in a loss of RCS inventory greater than the makeup capacity of the NU/PU system. As noted in the description of deficiency, this could adversely affect the ability to control reactor cooldown and thus the safety of operations of the plant.
Corrective Action TVA design criteria N4-50-D754 has been revised to specify the correct leak size.
Four reducers were incorrectly specified on design drawing.
The TVA drawings were revised to correctly specify a 3/4-schedule 160 pipe size reducer for three of the four reducers.
On the fourth, the TVA drawings were revised to delete the reducer and reference a B&W field change package (FCP) that contains the correctly sized reducer. The FCP (#267) has been received and reviewed by TVA.
Formal acceptance of the FCP was given by TVA letter K-9399.
TVA's Division of Nuclear Construction is presently implementing FCP 267.
Corrective actions will be complete on each unit no later than six months before fuel load of the unit in question.
Since the deficiency was a unique problem, no actions to prevent recurrence are required.
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