ML20095C596
| ML20095C596 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry, Salem, 05000000 |
| Issue date: | 07/27/1984 |
| From: | Domenici P SENATE |
| To: | Kammerer C NRC |
| Shared Package | |
| ML20095C594 | List: |
| References | |
| NUDOCS 8408230063 | |
| Download: ML20095C596 (8) | |
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30nifeb.Sfafes Sennfe WASHINGTON, D.C.
20510 July 27, 1984 Mr. Carlton C. Kammerer Nuclear Regulatory Commission Matomic Building 1717 H Street, NW Suite 1159 Washington, D.C.
20555
Dear Mr. Kammerer:
Because of my desire to be responsive to all inqui-ries and communications directed to this office, and knowing that your objectives are similar in this regard, the attached communication is referred to you for consid-eration.
I would very much appreciate your evaluating the information presented and taking whatever action is re-quired to resolve the situation.
At your earliest conve-nience, I would be grateful for your findings and views, in duplicate form.
Please send your response to the atten-
~ ion of Marco A. Caceres.
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My warmest personal regards.
Inc rel
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Pete V. Domenici United States Senator PVD/mc Enclosure 840823 2
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J 2265 Avalon Las Cruces, NM 88005 27 June 1984 Pete Domenici U.S. Senator-
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Santa Fe-3004 New Postal Bldg.
Santa Fe, NM 87501 9
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Dear Mr. Domenici:
Ever since the first Boildng Water Reactor (BWR) went on line it A
seems that a lot of reactors have been having trouble with their scram (Safety Control Rod Automatic Mechanism) system. "This kind of failure, the nuclear industry has long believed, has a negligible chance of occurring, 3
on the orier of once in a million reactor operating years. Yet it has f
happened several times already."1 The two most mentioned caises have been Browns Ferry Unit 3 and Salem NJ reactors 1 ard 2. If we interd to keep uring nuclear reactors as a source of energy we must do something about
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the scram system.
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On June 28, 1980, at the Browns Ferry Unit 3 BWR, 76 of 185 control l>
rods failed to insert fully into the core when a scram was called for by f
the reactor operator. ' Fortunately, this occurred during a rout.ine shut-down from power, rather than during the kini of reactor transient in which complete ani rapid scram of all the rods might have been very important,."2 Shortly after the Browns Ferry Unit 3 event, the Nuclear Regulatory
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Commission's (FRC's) Office of Analysis ani Evaluation of Operational Data (AECD) initiated an intendent stuly of the design and operation of the ~
Browns Ferry Unit 3 scram systen and the special scram systems tests ani inspection which was performed at the plant site during the daysimmediately s
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following the event. "The purpose of the study was to provide an irxlepen--
dent assessment of the cause of the event to determine the lessons learned, and to recomment corrective actions."3 The apperent cause of this event was found to be water accumulation in the scram discharge volume (SDV) prior to the attempted scram.
After the operator aw the water accumulation it took 4 tries to get the control rods to drop manually. The elapsed time from the first scram through the forth was-14 minutes. "Nor:nally all the rods insert within 3 seconds."4 "The following is the principal findings of the AEOD study of the Browns Ferry Unit 3."5
- The Browns Ferry 3 SIV high-level-scram function did not ani cannot provide protection against the unietected accumulation of water in the east SDV header with attendant loss of the east bank scram capability even during unobstucted venting and draining con 11tions.
- A single blockage in the venting system or drain line of the west header SDV can result in an undetected accumulation of water in both the east and west headers, whici) could disable the scram capability of all control rods.
-With the current SDV-SIV design a blockage in the SDV drain or vent path can cause a partial loss of scram capability and disable the protection system that was installed to ensure detection ani corrective action.
- There are numerous actual ani potential mechanisms for introducir4 ani retaining water in the SDV with no accumulation in the SIV.
The current SDV-SIV design permits the automatic high-level-scram safety function to be adversely influenced by the clean radioactive-waste drain system for the reactor buildir4. This system is not safety related.
- The Browns Ferry 3 partial scram failure, together with recent events at other BWR's shows that float-type inst ruments for monitoring 2
water levels have a significant degree of unreliability.
--If a scram condition exists which cannot be by passed in SHUTDOWN or REFUEL mode and if the SDV vent or the SIV drain valve fails to close, an inisolatable blowndown of reactor coolant outside the primary containment can occur.
- lhe Browns Ferry 3 emergency operating instructions did not incluie a procedure or guidance for the operator to follow in the event of a partial or complete scram failure.
"The AECD also found out if a postulated that attendant to a reactor scram a break may occur in the SDV system piping downstream of the scram outlet valves and upstream of the SDV system vent or drain valves."6 The partial scram failure that occured at Browns Ferry 3 demonstrated that SUR scram systems as presently designed are susceptible to loss of scram capability while operating at full power. " Futhermore, the event showed that the loss of scram capability can occur in a way which goes undetected by the operator ani unprotected by the reactor protection system."7 The second most talked about failure of scram devices happened twice in three days. Tre dates were February 22, 1983 and again on Febr e / 25, 1983. The place was Salen, NJ.
The Salen Unit i reactor centrol rads failed to insert upon receipt of an automatic trip signal from the reactor protection system. However, the rods did insert and shutdown tne plant upon receipt of a manual initial trip signal. Cn February 25, 1983, approximately two hours after the Salem Unit 1 event, the cause of the failure to trip was determined by licensee instrumentation technicians to be failure of the UV t. rip device in both FT3s to function as designed. The same problem had cccured 3
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on February 22, 1983, but it was not recognized by the licensee. As previously discussed, the plant on both occasions was shut down by manual operator
-action. Fossible contributors to the failure of the UV trip devices are
- 1) dust ard dirt; 2) lack of lubrication; 3) wear; 4) more frequent operation thannintended by design; and 5) nicking of latch surfaces caused from repeated operation of the breakers. Base on an indeperdent evalution of the failed UV trip devices identified by the licensee, the NRC staff concluded that, while the Salem Unit 1 breaker failures occurred as a re-sult of several contributors, the predominant cause use excessive wear accelerated by lack of lubrication and improper maintenance.
It appears that no preventive maintenance was conducted on the Salem 1
Unit 1 DB-50 circuit breakers until January 1983. Additionally, the lub-rication reconmendations of the Westin6 house 1974 Technical Bulletin and Data Letter were not implemented during the January 1983 maintenance, since personnel performing the maintenance (including a Westinghouse ser-vice representative) were not aware of this information. "The January main-tenacne was preformed because of a breaker problem which occurred at Salem Unit 2 on January 6, 1983. In this event, a reactor trip occurred due to a low-low water level cordition in one steam generator ard only one RTS operated. The second RT3 finally opened 25 minutes later, although the reactor had already tripped from opening of the other RT3. The failure of this R*3 use concluded by the licensee to be due to dirt and corrosion interfering with proper operation of the UV trip devices. As a result of this event, maintenance was conducted on all Unit 1 RT3s, at least one of which involved supervision of the RT3 vender, Westinghouse. The licensee also reported that all reactor trip breakers were tested after maintenance per plant procedures."O 4
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My opinion on the scram is, do not let the NRC give out anymcre
!1icenses to private corporations until the manufacture (Westin6 house) upgrades the efficiency of the scram system to where the plant operator
~is-not worrying about the control rods not closing completely as required.
When the NRC makes the privste corporations and the manufacture of the scram systems work together, then and only then will the production of nuclear energy be safe.
Sincerely, AbA [ hil,,s,,-yJl V
Steve L. 3enavidez 5
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A ENDN0'IES i
1Eliot Marshall, " The Salem Case: A failure.of Nuclear Logic,"
S cience, 15 April 1983, p. 280 2 David Ckrent, " Anticipated Transients Without Scram," Nuclear Reactor Safety, 2 May 1983, p. 260
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3Villiam R. Casto, " Partial Failure to Srcam at Browns Ferry 3,"
. Nuclear Safety, March-April 1981, p. 226 4Jilliam R. Casto, " Fartial Failure to Scram at Browns Ferry 3,"
Nuclear Safety, Earch-April 1981, p. 227 i
SUilliam R. Casto, " Neutronics Analysis of Browns Ferry 3 Fartial Control Rod Insertion," Nuclear Safety, September-Cetober 1982, p. 573 6
.W. Ha6en, " Cperation ard Safety Concerns of the BUR Scrams E
System," Nuclear Safety, Earch-April 1982, p.160 7William R. Casto, " Operating Experiences," Nuclear Safety, March-April 1981. p. 227 O.S. Nuclear Regulatory Ccamission, Reuort M Congress on Abnornal U
Cccurrences (Washington, D.C.: U.S..Goverment Erinting Cffice January-harch 1983), p.p. 10-11 6
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. re,.:,
BIBLICCRAFhT Report U.S.1;uclear Regulatory Commission, Retort M Congress on Abnormal Cccurrences (Washin6 ton,D.C.: U.S. Goverment Printing Cffice January-Earch 1983),
p. p. 10-11 '
r Articles Casto, William R. " Fartial Failure to Scram at Browns Ferry." Nuclear Safety, March-April 1981, p. 226 l
Casto, William R. " Ueutronices Analysis of Browns Ferry 3 Fartial Control Rod Insertion," Nuclear Safety, September-Cctober 1982., p. 573 Casto, William R. " Cperating Experiences," Huclear Safety, March-April 1981, p. 227 l
Hagen, E.U. " Operation and Safety Concern of the BWR Scram Systems,"
Nuclear Safety, March-April 1982, p.160 Marshall, Eliot " The Salem Case: A Failure of liuclear Logic," Science, 15 April 1983, p. 280 Ckrent, David " Anticipated Transients Uithout Scram," Euclear Reactor l_
Safety, 2 May 1983, p. 260 l
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