§ Mr. Ashdownasked the Secretary of State for Energy whether the Nuclear Installations Inspectorate had sight of all relevant reports and accompanying correspondence from Mr. Peter Phelan before signing off the long-term safety reviews for Chapelcross and Calder Hall power stations; and if he will make a statement.
§ Mr. Goodlad[pursuant to his reply, 4 March 1986, c. 85–86]: I am advised by the Nuclear Installations Inspectorate that the responsibility for making a safety case in respect of any matter concerned with a licensed nuclear installation rests with the licensee. Any report which contains the licensee's safety case must contain adequate technical and scientific justification of his arguments, and all references must be identified and made available to the NII. Where a licensee uses consultants to assist him in carrying out an appropriate analysis, he is required to make available only those documents or correspondence necessary to support his safety case. The NII would not expect to receive any copy of correspondence between a licensee and an individual member of the consultant's staff unless it formed a necessary part of a reference. The assessment submitted by BNFL to the NII contained no reference or correspondence which can be identified as arising from Mr. Peter Phelan.
§ Mr. Ashdownasked the Secretary of State for Energy what steps the Nuclear Installations Inspectorate has taken to satisfy itself of the capacity of Chapelcross and Calder Hall nuclear power stations to withstand seismological shocks; and if he will make a statement.
§ Mr. Goodlad[pursuant to his reply, 4 March 1986, c. 85–86]: I am advised by the Nuclear Installations Inspectorate that it asked BNFL to submit assessments of the effect of seismic events on the nuclear power stations at Calder Hall and Chapelcross as part of BNFL's 124W comprehensive long term safety reviews. Because of the special expertise required to analyse seismic events and their potential effects on reactor structures, BNFL employed consultants to assist them in this task. Similarly, the NII has employed its own independent consultants in order to satisfy itself about the adequacy of BNFL's assessments.
§ Mr. Ashdownasked the Secretary of State for Energy (1) if he will specify the magnitude of seismic events expected to occur at least once in a nominal 40-year operating life at Chapelcross or Calder Hall:
(2) if he will specify the most severe seismic event expected to occur at Chapelcross or Calder Hall in a nominal 40-year operating life.
§ Mr. Goodlad[pursuant to his reply, 4 March 1986, c. 85–86]: I am advised by the Nuclear Installations Inspectorate that seismic events are qualified in terms of their severity and their frequency of occurrence. Earthquakes which would be sufficiently severe to damage Calder Hall or Chapelcross are extremely rare. The probability of an earthquake reduces very rapidly as its magnitude increases. It is estimated that the peak free field horizontal acceleration which would occur in a normal 40-year life for these stations is about 0.035g.
§ Mr. Ashdownasked the Secretary of State for Energy if he will specify the maximum mangnitude of seismic events which, in the light of recent research studies, could be expected to permit the nuclear reactors at Chapelcross and Calder Hall to survive, be safely shut down and subsequently be maintained in safe condition.
§ Mr. Goodlad[pursuant to his reply, 4 March 1986, c. 85–86] I am advised by the Nuclear Installations Inspectorate that the seismic structural assessments carried out by BNFL for the Calder Hall and Chapelcross reactor demonstrate that the reactor could be safely shut down and maintained in a safe condition following an earthquake with a peak free field horizontal acceleration of 0.11g although some damage to non-essential service buildings could occur.