ML20213D454
| ML20213D454 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Sequoyah |
| Issue date: | 10/31/1986 |
| From: | Mccomb S, Murphy M, Russell J TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML082401853 | List: |
| References | |
| 301.05-SQN, 301.05-SQN-R01, 301.05-SQN-R1, NUDOCS 8611120108 | |
| Download: ML20213D454 (7) | |
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TVA EMPI4YEE CONCERNS REPORT NUMBER: 301.05-SQN SPECIAL PROGRAM REPORT TYPE: Sequoyah Nuclear Plant-Element REVISION NUMBER: 1 TITLE: Questionable Design and Construction Practices REASON FOR REVISION:
Revised to incorporate SRP and TAS comments Revision 1 PREPARATION
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PREPARED BY:
Scott McComb 10-24-86 SIGNATURE DATE REVIEWS PEER:
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TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT EMPLOYEE CONCERNS TASK GROUP UPERATIONS CEG Subcategory: Mechanical Equipment Reliability / Design Element: Questionable Design and Construction Practices Report Number:
301.05-SQN Revision 1 MAS-86-002 RCM-85-001 I-86-233-SQN Evaluator:
Scott McComb 10-24-86 Scott Mc mb Date Reviewed by:
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I.
Questionable Design and Construction Practices at Sequoyah Nuclear Plant This report specifically addresses three employee concerns about the design and construction practices at Sequoyah Nuclear Plant (SQN). All three of the concerns are specific to SQN. Two of these concerns were determined to be nuclear safety related by the NSRS.
II.
Specific Evaluation Methodology Three specific concerns are evaluated in this report.
(El MAS-86-002:
" Improper mounting of limit switches on 2-FCV-30-15."
RCM-85-001:
" Failed check valve on B-CST allowed water on top of lR1 bladder. Bladder could get into ERCW suction."
I-86-233-SQN:
"An anonymous individual mailed in a potential safety hazard associated with the condensate demineralizer waste evaporator (CDWE) on elevation 706 of the Auxiliary Building at Sequoyah Nuclear Plant (SQN). The original stainless steel piping for pumping " Bottoms" from the CDWE was removed and replaced by a temporary rubber hose. Extensive modifications are being performed over the rubber hose. Welding hot chips have been observed falling on the rubber hose. Damage to or rupture in the hose would result in possible personnel exposure of a high amount."
Concerns NAS-86-002 and RCM-85-001 were expressed through the concerned individuals' supervisor. Concern I-86-233-SQN was mailed in by an anonymous individual.
The three concerns are specific in nature and will be addressed separately.
A review of previous evaluations was performed.
Items reviewed are listed in the Reference Section of this report.
Interviews with cognizant DNE and SQN maintenance personnel were performed, when needed, lR1 to address these concerns.
Due to the specific nature of these concerns, no review of regulatory req'uirements or plant procedures was performed.
III. Findings MAS-86-002:
1 1.
A memorandum from B. M. Patterson to R. W. Olson dated March 7, 1986, "Sequoyah Nuclear Plant - Zone Switch Mountings,"
states that "During field verification and after cycling of zone switches following maintenance, a mounting problem of zone switches on butterfly valves with circular movement of the actuator was identified." The memorandum identifies the following zone switches:
Page 1 of 4
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III. Findings (continued) 1-ZS-30-7 1-A 1-ZS-30-14 1-A 1-ZS-30-16 1-B 2-ZS-30-14 1-A i
2-ZS-30-15 1-B 2-ZS-30-16 1-B The memorandum suggests straightening the zone switch on existing mounting so that the actuation level arm lever is tangent to the strike plate's circular plate (Reference 1).
2.
A memorandum from R. W. Olson to B. N. Patterson on April 11, 1986, "Sequoyah Nuclear Plant - Zone Switch Mountings," states that, "The f
zone switches referenced in the March 7, 1986 memorandum (S53 860124 910) were investigated, and it was found that a mounting problem existed on 2-ZS-30-15 only. It also states that the problem with j
2-ZS-30-15 was corrected by work request B-110369 (Reference 2).
3.
A memorandum from M. A. Skarzinski to F. C. Nashburn dated April 28, 1986, " MAS-86-002," states that, "2-ZS-30-15 has been repaired, and concern NAS-86-002 is closed." The memorandum also states, "We will continue to evaluate these conditions as they are identified and will push Modifications for a resolution of the previously identified ZSs they claim require no fine tuning" (Reference 3).
RCM-85-001: Informal telephone interview with a modification engineer at SQN revealed:
i 1.
The CST check valve problem was the result of five styrofoam float valves at the top of the bladder decaying. These five styrofoam l
discs were supposed to seal off five holes in the top of the bladder when the water reaches the top of the bladder. These styrofoam discs shrank in size until they passed through the holes they were to seal against.
2.
The check valve problem was fixed by replacing the styrofoam discs with nonshrinkable plastic discs, under WP 11844 initiated by ECN lR1 L6515 and Category D, FCR 3317. No further problems with the check valves have been reported since this modification.
l 3.
There was a concern with the liner being drawn into the auxiliary feedwater vacuum dragline. The cage around the suction inlet was 4
enlarged to prevent this potential occurrence. This work was also initiated by ECN-L 6515.
I-86-233-SQN: Informal interview with a site services engineer revealed the following:
j 1.
The bottoms piping is stainless steel and has not been replaced by l
a temporary rubber hose. The piping for offgrade distillate from lR1 the CDWE system was replaced with a temporary rubber hose. Note l
that this medium, although higher in conductivity than the normal l
distillates, is nonradioactive. The old piping routed the offgrade l
Page 2 of 4
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,' III. Findings (continued) distillate to the floor drains. This resulted in the floor drain getting clogged because of boric acid percipitates. To ensure that this did not happen again, a temporary hose for offgrade distillate was run directly to the floor drain collector tank. This 2-inch hose is about 400 feet long and drops about 80 feet from the CDWE to i
the floor drain collector tant.
2.
The pressure in the hose is very low. In fact, the 80-foot drop between the CDWE system and the floor drain collector tank (FDCT) results in a vacuum on the line.
3.
An informal interview with a design engineer in Knoxville revealed that ECN-6326 was written to install permanent piping from the CDWE system to the FDCT. This ECN was the result of DCR 2152. This ECN has not yet been worked.
Conclusions 1.
Concern MAS-86-002 on zone switch 2-ZS-30-15 was valid; the problem was corrected by work performed under work request B-110369. The zone switch was straightened on its existing mounting so that the actuation lever arm travel is tangent to the strike plate's circular path.
2.
There was a problem with the check valves on the CST bladder. These valves have been replaced, and a larger inlet grate has been installed over the auxiliary feedwater vacuum dragline inlet in the CST. Concern RCM-85-001 was valid, but all repairs at SQN have been made.
3.
There is a temporary rubber hose installed between the CDWE system and the FDCT. This bose carries offgrade distillate from CDWE to FDCT. This hose is not under high pressure and does not carry CDWE
" Bottoms." A rupture of this hose would not expose personnel to a high amount of radiation. Further, an ECN has been issued to replace lR1 the rubber hose with permanent piping.
Concern I-86-233-SQN is not l
valid.
4.
Based on the findings presented above no outstanding nuclear lR1 I
safety-related issues were found.
l IV.
Root Causes The results of this evaluation have determined these concerns to be specific and isolated problems. The original design may be a potential root cause for all three concerns.
Page 3 of 4
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V.
Generic Applicability Since WBN and SQN's are similiar plants, these three concerns need to be evaluated at WBN. Also, the zone switch problem and CST bladder problem need to be evaluated for applicability to Browns Ferry and Bellefonte i
i Nuclear Plants.
VI.
References 1.
Memorandum from B. M. Patterson to R. W. Olson dated March 1986, "Sequoyah Nuclear Plant - Zone Switch Mountings" 2.
Memorandum from R. W. Olson to B. M. Patterson dated April 11, 1986, "Sequoyah Nuclear Plant - Zone Switch Mountings.
3.
Memorandum from M. A. Skarzinski to F. C. Mashburn dated April 28, 1986, " MAS-86-002" VII.
Immediate or Long-term Corrective Action The zone (limit) switch mounting problem was an isolated case. The CST lR1 bladder check valve discs were replaced with an upgraded material so as I
to prevent recurrence of the of the problem. Therefore, no corrective I
action is required.
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.EFERENCE
- ECPS120J-ECPS121C TENNESSEE VALLEY AUTHORITY PAGE 143
'REQUENCY
- REQUEST OFFICE OF NUCLEAR POWER RUN TIME - 12:19:18-NP - 1555 - RHM EMPLOYEE CONCERN PROGRAM SYSTEM (ECPS)
RUN DATE - 10/05/86 4
LIST OF EMPLOYEE CONCERN INFORMATION i
TEGORY: OP PLANT OPER. SUPPORT SUBCATEGORY: 30105 QUESTIONABLE DESION/ CONSTRUCTION PRACTICE GENERIC KEYNORD A i
H APPL QTC/NSR$
P KEYWORD B CONCERN SUB R PLT BBSN INVESTIGATION S
CONCERN KEYWORD C i
NUMBER CAT CAT D LOC FLQB REPORT R
DESCRIPTION KEYNORD D i 235-SQN OP 3010$ $ SQN NNNN NS AN ANONYMOUS INDIVIDUAL MAILED IN A OP 30804 K-FORM PDTENTIAL SAFETY HAZARD ASSOCIATED W 1
ITH THE CONDENSATE DEMINERALIZER NAS j
TE EVAPORATOR (CDHE) ON EL 706 0F TH E AUXILLARY BUILDING AT SQN.
THE OR 10!NAL STAINLESS STEEL PIPING FOR PU MPINO " BOTTOMS" FROM THE CDHE HAS RE MOVED AND REPLACED BY'A TEMPORARY RU BBER HOSE.
EXTENSIVE MODIFICATIONS f
ARE BEING PERFORMED OVER THE RUBBER I
HOSE. HELDING HOT CHIPS HAVE BEEN O BSERVED FALLING ON THE RUBBER HOSE.
DAMAGE TO OR RUPTURE IN THE HOSE NO J
ULD RESULT IN POSSIBLE PERSONNEL i
j t$-86-002 OP 30105 N SQN NNNN NS IMPROPER MOUNTING OF LIMIT SWITCHES K-FORM ON 2-FCV-30-15 4
i l
l lM-85-001 OP 30105 N SQN NNNN SS FAILED CHECK VALVE ON BCST ALLOWED H GE IN 0 ERCH EN.
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3 CONCERNS FOR CATEGORY OP SUBCATEGORY 30105
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