ML20150F195
| ML20150F195 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/02/1988 |
| From: | Epstein E THREE MILE ISLAND ALERT |
| To: | NRC OFFICE OF THE SECRETARY (SECY) |
| References | |
| FRN-53FR11311, RULE-PR-50 53FR11311-00011, 53FR11311-11, NUDOCS 8807180175 | |
| Download: ML20150F195 (2) | |
Text
.
o THREE MILE $3 LAND ALERT, MC.
TMIE 34 Peffer St Manisberg. Penna.17102 (7171133 7897 t
mn G KET l E.'LER gn FQPOSED.'dE sji 60 July 2T8192 -5 P2:37 53FK//3)J)
Secretary of the Commission
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QQ.. iwcl Washington, D.C.
20555 Attention: Docketing and Servicing Branch ERMk"
Dear Secretary,
T1.ree Mile Island Alert (TMIA) is a non-profit citizens group formed in 1977 after the construction of Three Mile Island (TMI) Unit 1 and Unit 2, and the licensing of Unit 1. In the last nine years we have been an active interrenor in hearings before the Nuclear Regulatory Commission (NRC) on safety, managerial and technical issues. Our organization is concerned with a proposal currently under consideration by the NRC.
The NRC is soliciting comments on leak-before-break technology for emergency core cooling systems (ECCS) and environmental qualification (EQ) of safety related electrical and mechanical equipment. Aoparently the Commission feels that there are several benefit, associated with this technology such as dose reductions, improved inspections and an improved performance during earthquakes.
The technology for detecting and sizing cracks, Ultra-Sonic Testing (UT), is imperfect and questionable at best. And in fact the Advisory Committee on Reactor Safeguards (ACRS) indicated that dependence on Ultra-Senic Testing is a "delusion...we can find no consistent experimental evidence or body of expert opinion indicating that measured crack depths bear any direct relationship to the actual crack depths." For this reason alone, "defense-in-depth" should not be discarded for an experimental and unproven technology such as Ultra-Sonic Testing.
Our own experience with experimental tube technologies at Three Mile Island accentuates our anxiety. In 1981, the steam generators at TMI-1 were severely damaged by the inadvertent introduction of a sulf ur compound into the reactor 's primary system, which corroded the inside of all 31,000 of the plant 's steam generator tubes.
No steam generator in the country has suffered the amount of damage as has TMI-l's steam generators. GPU chose to repair the steam generators with a highly experimental process by which most of the cracks were scaled by exploding each of the 31,000 tubes against the surrounding two foot long tubesheet. In addition, those tubes most cariously cracked - those with cracks greater than 40 % through the wall of the tubes - were plugg nd removed from service, as required by TMI-l's license.
8807180175 080'02 (DFbNgb PDR PR 50 53FR113f1 FDR
In 1984, GPU discovered that a number of tubes were showing new cracks, many of which were greater than 40 % throughwall.
Under standard NRC license requirements, these tubes were required to be plugged. But NRC requirements also prohibit a plant from operating at full capacity with more than a certain number of plugged tubes, TMI-1 is now approaching the plugging limit.
Recognizing that tube degradation was likely to get worse, in November, 1985, the company submitted an unprecedented request to the NRC to amend its license to change the plugging criteria, so that tubes with up to 70 % throughwall cracks could remain in service.
There were a number of safety questions which concerned the NRC Staff: a lack of definitive information concerning the cause and form of the new degradation; inaccuracies in the testing process; and the failure of the new criteria to comply with the NRC requirements. The NRC's greatest concern was the failure of the company to verifv its technical analysis, by removing an actual steam generater tube from the reactor and conduc*-ing a metallurgical examination. The Staff told the company t.at such destructive testing would be required before its approving this unprecedented request.
Despite much internal disagreement, the Staff decided to reverse its position. It advised GPU thac if it submitted a modified, less extensive, "temporary" request to change the plugging criteria, the Staff would approve such a request without requiring any destructive testing and without resolution of the many concerns about the condition of TMI l 's steam generators.
The staff advised the company how to formulate the request in order to keep it outside the scope of the hearing process l
which was already underway, and to permit the Commission to l
approve the amendment immediately, without a prior hearing.
l The fia.ico at TMI 1 points to the danger of utilizing an I
experimental technology on steam generator tubes. If the NRC were to condone the use of leak-before-break technology, it would i
surely repeat some the mistakes made at TMI 1. Ultimately, l
utilities would be enccuraged to relax their standards in order l
to accommodate unforeseen :omplications, thereby decreasing the l
margin of safety. TMIA believes that the NRC should thoroughly l
re-evaluate lea'<-before-break technology before considering the safety benefits incurred when employing its use.
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Eric Epstein, Spokesperson, TMI-Alart l
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