ML20004F004
| ML20004F004 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 06/12/1981 |
| From: | Crane P PACIFIC GAS & ELECTRIC CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0612, RTR-NUREG-612 NUDOCS 8106160370 | |
| Download: ML20004F004 (4) | |
Text
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FACIFIC GAS AND ELECTR,IC C O M PANY 77 BE ALE STREET,31ST FLOO R, S AN FR ANCISCO, C ALIFORNI A 94106 P. O. BOX 7442 26W3 TELECOPIER (415) 543 7813 T E LE PH O N E (415) 781 4 211 y
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Mr. Darrell G. Eisenhut, Director NI ls iO Divisicn of Beactor Licensiry y
Office of Nuclec Beactor Regulaticn U. S. Nuclear Regulatory Camtission g\\
i Washington, D. C. 20555 3
Be: Docket No. 50-133 g1 N 151984 k g
License No. DPR-7
Dear Mr. Eisenhut:
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In your letter of Decmber 22, 1980, you reques_
we review our ocntrols for the handling of heavy loads to determine the extent to which the gtiidalines of NUREG-0612 are presently satisfied at our famlity. In addition, you requested that we identify the changes and Imaifications that would be required in order to ful.Ly satit.2y these guidelines. The gnidalines of NUREG-0612 have been reviewed as they apply to the current shutdown status of Humboldt Bay Power Plant, Unit No. 3.
NUREG-0612 states that the objectives of the gtiidalines can be met if the
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consequences of a failure can be shown to be acceptable (Section 5.1, i
Criteria I-IV). An evaluation of the criteria dicmiscad in the NUREG is l
as follows:
5.1 Criteria I "Pelease of radinactive material that may result frcm damage to spent fuel based cn en1mila-tion involving accidental dropping of a postulated heavy load prednewi doses that are well within 10 CFR Part 100 Ilmits of 300 rem thyroid, 25 rem whole body (analyses should show that doses are equal to or less than 1/4 of Part 100 limitsi."
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r Mr. Darrell G. Eisenhut June 12, 1981 Respcnse
'Ihe generic evaluation in Secticn 2.1 of NUREG-0612 states that for a BWR that had been subcritical for 4
120 days when the load drop occurred, 1.6x10 assen-blies would be required to be da=w;ad to reach 1/4 of the Part 100 limits. Humboldt Bay Unit No. 3 has been gh +Aew since July 1976. Since the reactor t
core ocntains cnly 184 fuel assenblies and there are only 250 fuel assenblies in the spent fuel pool, it is not ocnceivable that a load drop could result in a radiological release approaching 1/4 of the Part 100 limits.
5.1 Criteria II " Damage to fuel and fuel storage racks hacad en calcula& ions involving accidantal dropping of a postulated heavy load does not result in a configuration of the fuel such that Keff is larger than 0.95."
W ae Secticn 2.26 of NUREG-0612 states that there waars to be no potential for criticality due to a heavy load drop in a BWR core, if it is postulated that the drop of a heavy load will not drive the control rods out of the core.
Addar*= A to the Final Hazards Stanary Report states that an analysis of the acci-l dental dropping of the fuel transfer cask into the reactor vessel was ' performed and the energy would be at:-- i+1 by the bending, abaaring and ccnpressing of reactor vessel in*amala. 'Ihe ccntrol rod drive index tube would remain in the extended position.
With regard to the fuel assenblies in the spent fuel pool, Section 2.2.6 of NUREG-0612 states that the I
potential for criticality would cnly be a problsn if l
the fuel racks contained non-spent fuel. 'Ihe spent fuel pool at 2*1dt Bay contains culy totally spent fuel.
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Althcxgh a calculaticn of the Keff resulting frcm a postulated load drop was not pa*"- i, based up:n the generic analysis of Secticn 2.2 of NUREG-0612, there is no potential for criticality as a result of a load drop.
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Mr. Darrell G. Eisenhut June 12, 1981 5.1 Criteria III "D ange to the reactor vessel or the spent fuel pool based cm calmlations of dmage following wi%tal dropping of a postulated heavy load is limited so as not to result in water leak-age that could uncover the fuel."
Bes;mse Due to the length of the current shutdown, the decay heat of fuel in the reactor is not sufficient to cause fuel dmage even if all water were lost out of the reactor vessel. '1his is an extranely unlikely event and sources of makeup water to the reactor vessel are still available. The loss of water level in the reactor as a result of the drop of a heavy load is not a concern at this time.
Ioss of water frm the fuel si. vie =;is pool as the result of dropping the fuel transfer cask or spent fuel ah4 ping cask, was analyzed and the results I
teru M in our letter of June 14, 1974 fr m Mr. J. D.
Worthington to Mr. Dcmald J. Skovholt. 'Ihe wvlifica-ticms and g +an al controls da*Ma in that letter i
have been atmpleted.
5.1 Criteria IV "n=== to equignent in redundant or dual safe shutdown paths, Maad cm calmlaticns assming the accidantal dropping of a postulated heavy load, will be limited so as not to result in loss of required safe shutdown functicos."
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l H mboldt Bay Unit No. 3 is presently shutdown and the decay heat is negligible. Dmage to the equignent necessary for a reactor shutdown and for decay heat removal is not a concern due to the current static plant conditions.
In addition to meeting the intent of the gnidalines of NUREG-0612 plant pro-mhwes and maintenance practices are provided to minimize the potential for and consequences of a load drop. '1hese procedures include the following:
A progra for periodic maintenance, inspecticn, a.
testing and certification of cranes;
Mr. Darrell G. Eisenhut June 12, 1981 b.
Operating and maintenance prorwhires which desig-nate safe load paths and prean*ients to be observed for lifting the largest and heaviest lewl= routinely moved in the refueling biilding; c.
Prrrwh1res and clecklists for the inspection of lifting equignent each shift prior to use.
Additicmal plant pro dures will be developed to designate safe load paths for movement of lewla not covered by a specific gocedare and to require an approved procedure for the movenent of heavy loads over irradiated fuel.
Pro dures will also require that cnly galifiad crane operators will be permitted to operate cranes in the refueling biilding.
In sumary, with the %Licn of the additicmal gucedures described above, there are no changes or modificaticms necessary to meet the guide-lines of NUREG-0612 for the present shutdown ccmdition of thxnboldt Bay Power Plant Unit No. 3.
As you are aware, PGandE has sought to withdraw its moticn to restart thxnboMt. 'Ihis segment is currently pending before the Atcznic Safety and Lie *naing Board (ASIB). In that moticn, we advised the ASLB that due to the uncertainty of NBC backfit policy, the Ccmpany was at this time unable to make an informed de+aminaticn on the future status of thanboldt. If, upcn resoluticn of that uncertainty' the decisic;n is, made to resune operation of the Unit, extensive modification which may affect this review may be required. At that time, additional reviews will"be ccoducted and a report including the informaticm identified in Section 2.1 through 2.3 of Enclosure 3 to your nae - har 22, 1980 letter will be subnitted for your review.
Very truly yours, c-r
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