ML20198Q818
| ML20198Q818 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/16/1986 |
| From: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| REF-PT21-86, REF-PT21-86-195-000 ANPP-36616-EEVB, DER-86-18, DER-86-186-EEVB, PT21-86-195, PT21-86-195-000, NUDOCS 8606090385 | |
| Download: ML20198Q818 (5) | |
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Arizona Nuclear Power Project P.O BOX 52034
- PHOENIX, ARIZol. A 85072-2034
] 03 May 16, 1986
?;.3,3 ANPP-36616-EEVB/LAS/DRIN, 92.11 U. S. Nuclear Regulatory Commission Region V 1450 Maria Lane - Suite 210 Walnut Creek, California 94596-5368 Attention: Mr. D. F. Kirsch, Acting Director Division of Reactor Safety and Projects Palo Verde Nuclear Generating Station (PVNGS)
Units 1, 2, 3 Docket Nos. 50/528, 529, 530
Subject:
Final Report - DER 86-18 A 50.55(e) and 10CFR21 Reportable Condition Relating to Unsealed Penetrations in the AFW Pump Rooms File: 86-006-216; 86-056-026; D.4.33.2
Reference:
(A) Telephone Conversation between A. Toth and D. R. Larkin on April 18, 1986.
(Initial Reportability - DER 86-18)
Dear Sir:
Attached, is our final written report of the Reportable Deficiency under 10CFR50.55(e) referenced above. The 10CFR21 evaluation is also included.
Very truly yours, GAL dLL E. E. Van Brunt, Jr.
Executive Vice President Project Director EEVBJr/DRL/1df Idf/001/FR8618 Attachments cc: See Page 2 8606090305 060bi6 PDR ADOCK 00000320 PDR l
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DER 86 Final Report Mr. D. F. Kirsch Acting Director ANPP-36616-EEVB/LAS/DRL-92.11 May 16, 1986 Page 2 cc:
J. M. Taylor, Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 A. C. Gehr (4141)
R. P. Zimmerman (6295)
Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway - Suite 1500 Atlanta, Georgia 30339 l
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Idf/009/ FORM-7
FINAL REPORT - DER 86-18 DEFICIENCY EVALUATION 50.55(e) i ARIZONA NUCLEAR POWER PROJECT (ANPP)
I.
Description of Deficiency I
The Main Steam Support Structure (MSSS) (System ZM) Detailed Design l
Criteria, paragraph 1.5.2, states: "The portion of the structure below l
elevation 100 foot - 0 inches shall be designed to be watertight both l
from external sources of water and internal sources above elevation 100 l
foot - 0 inches".
To implement this criteria, all penetrations through slabs and walls are required to be sealed. Contrary to this, in Units 1, 2 and 3, six penetrations for piping in the MSSS west wall to the Containment seismic gap were not sealed.
In each of the two AFW pump rooms, there were two unused penetrations plus one for the 6 inch AFW discharge pipe. The 6 inch wide seismic gap between the MSSS and the containment allows flow between the two pump rooms and the spaces above elevation 100 foot, via the unsealed penetrations. The MSSS is the only plant structure abutting the Containment that has a second wall, parallel to the Containment and separated by a seismic gap. All other buildings.
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adjacent to the Containment, share the Containment wall as a single dividing structure.
Evaluation All project walkdowns and reviews are based on architectural drawings.
The penetrations in questions were not transfered from civil to architectural drawings, as is customary, due to an oversight.
Since the architectural drawings did not reflect the penetrations, the design seal schedule did not include a requirement to seal them. Also, the ANPP system acceptance checklist. (73AC-0ZZO4, Appendix L Page 10) referred the walkdown engineer to the architectural design documents as stated above.
Verification of previous DER's, primarily DER 84-31, utilized documen-tation from reviews and walkdowns based upon architectural design documents.
Root Cause The root cause was determined to be a failure to transfer the west wall penetrations, located in the Main Steam Support Structure (MSSS), from Civil to Architectural drawings.
Transportability Engineering has reviewed the Civil and Architectural drawings for penetrations located in the Unit 2 auxiliary building and MSSS. Transfer of information from Civil to Architectural drawings is made only where penetrations are involved.
All other architectural drawings are developed from scratch and undergo ANS1 N45.2.11 design review. Verification of the Unit 2 auxiliary building and MSSS, represents approximately a 70%
sampic of areas requiring penetrations.
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Final Report - DER 86-18 Page Two Fire-related rooms which makes up the largest portion of the remaining areas, have not been re-verified since, each one has already received a thorough walkdown to ensure that all proper features, which includes penetration seals, have been installed.
Based on a review of information compiled from the approximate 70%
sample, Engineering has concluded that no other walls were omitted from the Architectural drawings and that this was an isolated occurrence.
II.
Analysis of Safety Implications Safety-related Train A and B Auxiliary Feedwater (AFW) pumps are located in the MSSS below elevation 100 foot. One of these pumps is required to be functional under all postulated accident conditions, including fire and high energy line breaks. The unsealed penetrations above and below elevation 100 foot could simultaneously expose both AFW pumps to fire, flood, or environmental conditions for which they have not been qualified. Thus, the operability of the AFW pumps might not be assured.
The resulting loss of auxiliary feed capability could adversely affect the safe shutdown of the reactor.
A review of the potential hazards has resulted in the following conclusions:
1.
Fire A fire hazard does not exist.
Appendix F, 10CFR50 requires a horizontal separation between safe shutdown components of at least 20 feet without intervening combustibles. This requirement is met.
2.
Flood Flooding of one AFW pump room from a full area break in the other AFW pump discharge line is highly unlikely.
Flooding of the other pump room would be prevented by one of three mechanisms:
a.
Leakage through the seismic gap flashing. The AEW pump output at runout is 1560 gpm. The floor drains would drain 200 gpm.
The pump room would fill to the 89' 1/2" level (the lowest open penetration) in about 20 minutes. The 18ga. galvanized steel flashing in the 6" gap at the juncture of the Containment, MSSS and Auxiliary Buildings (See Drawing 13-A-ZYD-016, Detail 3) is not watertight. Leakage through this flashing into the Auxiliary Building will be caused by the head of water in the gap. This water would have to reach a depth of 11 feet before it could enter the other pump room.
b.
Operator action to stop the flow. ANS1 N18.2 defines an AFW pipe break as a Condition III category for design.
ANSI /ANS58.8-1984 indicates that for such a failure, corrective operator action (stopping the submerged pump) can be assumed to start within 20 minutes.
i Final Report - DER 86-18 Page Three c.
Pump failure. As the water level in the AFW pump rooms rises, the pumps will become submerged and cease to function.
3.
Steam i
The main steam and feedwater pipes in the MSSS, above elevation 100 foot, are in a no-break zone and their failure is not considered credible.
Potential flooding effects, from a postulated 1 square foot area break or other small pipe failures, will be mitigated by t
drainage past the seismic gap flashing.
Exposure of equipment, in both AFW pump rooms, to elevated temperature and pressure conditions resulting from postulated pipe breaks in the NSSS, above elevation 100 foot, is possible. Assuming the NRC specified one square foot i
area break (BTP ASB 3-1) in a steam line, the maximum pressure in the pump rooms is calcula~.ed (Reference 1) to be 1.3 psig and the maximum tersperature is 240*F.
These conditions exceed the present environmental qualification requirements for equipment in the pump rooms. Even though these elevated environmental conditions would likely exist for only a short time, AFW system operation may be affected.
Thus, the unsealed penetrations represent a defect in design and, if left uncorrected, could preclude the safe shutdown of the reactor.
l Based on the above, this condition is evaluated as reportable under 10CFR 50.55(e) and 10CFR Part 21 since, if left uncorrected it would constitute a significant safety condition.
III. Corrective Action EER 86-ZH-001 has been issued for Units 1 and 2.
All effected Unit 1 and Unit 2 penetrations have been sealed.
Field Change Requests #99116-C and 99106-C were issued to seal the four unused penetrations and to install sealing boots on the AFW pipes.
This work is scheduled to be completed prior to Unit 3 fuel load.
References 1.
Calculation 13-NC-MS-003, Rev. 4 m
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