View source for HBL-86-026, Forwards Comments on Des for Decommissioning of Humboldt Bay Power Plant,Unit 3.Fission Chamber Strings Cut Up to Separate Chambers & Minimize Stored Waste Vol

{{Adams
| number = ML20203L274
| issue date = 08/14/1986
| title = Forwards Comments on Des for Decommissioning of Humboldt Bay Power Plant,Unit 3.Fission Chamber Strings Cut Up to Separate Chambers & Minimize Stored Waste Vol
| author name = Shiffer J
| author affiliation = PACIFIC GAS &amp; ELECTRIC CO.
| addressee name = Philips J, Phillips J
| addressee affiliation = NRC OFFICE OF ADMINISTRATION (ADM)
| docket = 05000133
| license number = 
| contact person = 
| case reference number = FRN-51FR15853
| document report number = 86-9, HBL-86-026, HBL-86-26, NUDOCS 8608250459
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE, UTILITY TO NRC
| page count = 3
}}

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PGandE Letter No.: HBL-86-026 Mr. John D. Philips, Chief Rules and Procedures Branch Division of Rules and Records Office of Administration, MNBB U. S. Nuclear Regulatory Commission Hashington, D.C. 20555 Re: Docket No. 50-133, OL-DPR-7 Humboldt Bay Power Plant, Unit 3 Comments on Draft Environmental Statement for Decommissioning

==Dear Mr. Philips:==

PGandE has reviewed the Draft Environmental Statement (DES) for Decommissioning of Humboldt Bay Power Plant, Unit No. 3. The Enclosure to this letter contains our comments on the DES.
Kindly acknowledge receipt of this material on the enclosed copy of this letter and return it in the enclosed addressed envelope.
Sincerely, M,
J.    . Shiffer Enclosure cc:     P. B. Erickson (2)
J. B. Martin Humboldt Distribution Service List (Decommissioning) 0996S/0047K/GHH/1739                                                                                            58^
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PGandE Letter No.:  HBL-86-026 ENCLOSURE
: 1. Page 1-2, Section 1.2 - In the last sentence of the first paragraph, the "18 in-core fission chambers" should be "54 in-core fission chambers."
The fission chambers were initially contained in 18 fission chamber strings containing 3 chambers each. The strings have since been cut up to separate the chambers and minimize stored waste volume.     

==Reference:==

Environmental Report, page 4-51.
: 2. Page 2-1, Section 2.1 - third paragraph - Same comment as above (item 1).
: 3. Page 2-5, Section 2.2 - This section states that when approval of SAFSTOR is obtained, the licensee will complete modification of the plant security system. In LAR 86-01 (HBL-86-16), dated May 14, 1986, a proposed security plan was submitted based on the Possession-Only License amendment approved in July 1985. Following NRC approval of this LAR, the modification to the security system will be completed. Approval of SAFSTOR will not be required to complete these modifications.
: 4. Page 3-6, Section 3.2.2 - fourth paragraph - This paragraph, both in the first sentence and the last sentence, can be read to imply that waste analysis and solidification will be completed by the same contractor.
This is not presently how this is done, and it is not likely to be the way it will be done in the future. These two sentences should be replaced with the following:
                      "A sample will then be taken by the plant staff and sent to an off-site contractor for analysis. Upon receipt of sample analysis results, a 1
contractor will solidify the waste using portable equipment."
: 5. Page 3-9, Section 3.2.3 - In the second paragraph, it is stated that Boral neutron absorbing blankets surround each assembly to ensure subtriticality. One fuel assembly will not be surrounded by the Boral material. This fuel assembly was damaged in 1975 (PGandE letter to Region V dated June 11, 1975) and is stored in a stainless steel box constructed for this purpose. The box is stored in the spent fuel storage racks.
: 6. Page 3-10, Section 3.2.3.4, Item (1) - Same comment as above (item 5).
: 7. Page 3-11, Section 3.2.3.4 - PGandE believes the following discussion will better reflect the conservatism of the criticality analysis:
These calculations make the assumption that since the Boral plates were designed as an integral part of the fuel assemblies, any distortions of the racks would still leave each fuel assembly surrounded by Boral plates. While this assumption cannot be proved to be valid under all array-altering physical mechanisms, the following statements show the calculations are conservative:                     .
0996S/0047K                                - _ _ _ .      _                                 -      - _ _

The licensee assumed the presence of fresh fuel at the highest enrichment with no credit for the presence of gadolinium, a burnable poison. This is conservative as even a small amount of burnup will reduce reactivity, and none of the fuel in the pool is fresh.
* No credit was taken for neutron absorption in the materials 'f the fuel storage racks, the fuel channel, or the aluminum outside of the B4 C containing core of the Boral.
The 2-D neutron transport calculation assumed an infinite array of infinitely tall fuel assemblies, thus no credit was taken for radial or axial leakage.
Optimal moderation was imposed by varying the gap between assemblies, the inner dimension of the poison can, and the fuel rod pitch within the poison can. This is considered to be a very conservative assumption, since it is extremely unlikely that a distortion of the fuel racks would lead to optimal moderation.
Since no radial or axial leakage was assumed and optimal moderation was imposed, it is very unlikely that any credible rearrangement of the stored spent fuel by crushing under seismic or other loads would increase reactivity enough to make the system critical. Even if a local pile of fuel pellets from the assemblies were formed, it would very likely be undermoderated and, therefore, subtritical.
Based on the above, there is a negligibly small likelihood that there is any credible means of achieving criticality in the stored spent fuel array.            PGandE believes that the DES should be revised accordingly to reflect these considerations.
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